58 results on '"Kwon NJ"'
Search Results
2. Longitudinal Comparative Analysis of Circulating Tumor DNA and Matched Tumor Tissue DNA in Patients with Metastatic Colorectal Cancer Receiving Palliative First-Line Systemic Anti-Cancer Therapy.
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Lee SB, Kim JW, Kim HG, Hwang SH, Kim KJ, Lee JH, Seo J, Kang M, Jung EH, Suh KJ, Kim SH, Kim JW, Kim YJ, Kim JH, Kwon NJ, and Lee KW
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- Humans, Male, Female, Middle Aged, Aged, Adult, Aged, 80 and over, Biomarkers, Tumor genetics, Longitudinal Studies, DNA, Neoplasm genetics, DNA, Neoplasm blood, Neoplasm Metastasis, Prognosis, Circulating Tumor DNA genetics, Circulating Tumor DNA blood, Colorectal Neoplasms genetics, Colorectal Neoplasms drug therapy, Colorectal Neoplasms pathology, Colorectal Neoplasms blood, Colorectal Neoplasms mortality, Palliative Care methods, Mutation
- Abstract
Purpose: This study aimed to compare tumor tissue DNA (ttDNA) and circulating tumor DNA (ctDNA) to explore the clinical applicability of ctDNA and to better understand clonal evolution in patients with metastatic colorectal cancer undergoing palliative first-line systemic therapy., Materials and Methods: We performed targeted sequencing analysis of 88 cancer-associated genes using germline DNA, ctDNA at baseline (baseline-ctDNA), and ctDNA at progressive disease (PD-ctDNA). The results were compared with ttDNA data., Results: Among 208 consecutively enrolled patients, we selected 84 (41 males; median age, 59 years; range, 35 to 90 years) with all four sample types available. A total of 202 driver mutations were found in 34 genes. ttDNA exhibited the highest mutation frequency (n=232), followed by baseline-ctDNA (n=155) and PD-ctDNA (n=117). Sequencing ctDNA alongside ttDNA revealed additional mutations in 40 patients (47.6%). PD-ctDNA detected 13 novel mutations in 10 patients (11.9%) compared to ttDNA and baseline-ctDNA. Notably, seven mutations in five patients (6.0%) were missense or nonsense mutations in APC, TP53, SMAD4, and CDH1 genes. In baseline-ctDNA, higher maximal variant allele frequency (VAF) values (p=0.010) and higher VAF values of APC (p=0.012), TP53 (p=0.012), and KRAS (p=0.005) mutations were significantly associated with worse overall survival., Conclusion: While ttDNA remains more sensitive than ctDNA, our ctDNA platform demonstrated validity and potential value when ttDNA was unavailable. Post-treatment analysis of PD-ctDNA unveiled new pathogenic mutations, signifying cancer's clonal evolution. Additionally, baseline-ctDNA's VAF values were prognostic after treatment.
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- 2024
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3. Effector Function Characteristics of Exhausted CD8+ T-Cell in Microsatellite Stable and Unstable Gastric Cancer.
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Han DS, Kwak Y, Lee S, Nam SK, Kong SH, Park DJ, Lee HJ, Kwon NJ, Lee HS, and Yang HK
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- Humans, Tumor Microenvironment immunology, Male, Gene Expression Profiling, Female, Middle Aged, Single-Cell Analysis, Stomach Neoplasms genetics, Stomach Neoplasms immunology, CD8-Positive T-Lymphocytes immunology, CD8-Positive T-Lymphocytes metabolism, Microsatellite Instability
- Abstract
Purpose: Gastric cancer exhibits molecular heterogeneity, with the microsatellite instability-high (MSI-H) subtype drawing attention for its distinct features. Despite a higher survival rate, MSI-H gastric cancer lack significant benefits from conventional chemotherapy. The immune checkpoint inhibitors, presents a potential avenue, but a deeper understanding of the tumor immune microenvironment of MSI-H gastric cancer is essential., Materials and Methods: We explored the molecular characteristics of CD8+ T-cell subtypes in three MSI-H and three microsatellite stable (MSS) gastric cancer samples using single-cell RNA sequencing and spatial transcriptome analysis., Results: In MSI-H gastric cancer, significantly higher proportions of effector memory T cell (Tem), exhausted T cell (Tex), proliferative exhausted T cell (pTex), and proliferative T cell were observed, while MSS gastric cancer exhibited significantly higher proportions of mucosal-associated invariant T cell and natural killer T cell. In MSI-H gastric cancer, Tex and pTex exhibited a significant upregulation of the exhaustion marker LAG3, as well as elevated expression of effector function markers such as IFNG, GZMB, GZMH, and GZMK, compared to those in MSS gastric cancer. The interferon γ (IFN-γ) signaling pathway of Tex and pTex was retained compared to those of MSS gastric cancer. The spatial transcriptome analysis demonstrates the IFN-γ signaling pathway between neighboring Tex and malignant cell, showcasing a significantly elevated interaction in MSI-H gastric cancer., Conclusion: Our study reveals novel finding indicating that IFN-γ signaling pathway is retained in Tex and pTex of MSI-H gastric cancer, offering a comprehensive perspective for future investigations into immunotherapy for gastric cancer.
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- 2024
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4. T cell receptor clonotype in tumor microenvironment contributes to intratumoral signaling network in patients with colorectal cancer.
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Song IH, Lee SB, Jeong BK, Park J, Kim H, Lee G, Cha SM, Lee H, Gong G, Kwon NJ, and Lee HJ
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Single-cell RNA sequencing (scRNA-seq) has contributed to understanding cellular heterogeneity and immune profiling in cancer. The aim of the study was to investigate gene expression and immune profiling in colorectal cancer (CRC) using scRNA-seq. We analyzed single-cell gene expression and T cell receptor (TCR) sequences in 30 pairs of CRC and matched normal tissue. Intratumoral lymphocytes were measured with digital image analysis. CRC had more T cells, epithelial cells, and myeloid cells than normal colorectal tissue. CRCs with microsatellite instability had more abundant T cells than those without microsatellite instability. Immune cell compositions of CRC and normal colorectal tissue were inversely correlated. CD4 + or CD8 + proliferating T cells, CD4 + effector memory T cells, CD8 + naïve T cells, and regulatory T cells of CRC showed higher TCR clonal expansion. Tumor epithelial cells interacted with immune cells more strongly than normal. T cells, myeloid cells, and fibroblasts from CRCs of expanded T cell clonotypes showed increased expression of genes related to TNF and NFKB signaling and T cell activation. CRCs of expanded T cell clonotypes also showed stronger cellular interactions among immune cells, fibroblasts, and endothelial cells. Pro-inflammatory CXCL and TNF signaling were activated in CRCs of expanded T cell clonotype. In conclusion, scRNA-seq analysis revealed different immune cell compositions, differential gene expression, and diverse TCR clonotype dynamics in CRC. TCR clonality expansion is associated with immune activation through T cell signaling and chemokine signaling. Patients with CRCs of expanded clonotype can be promising candidates for immunotherapy., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)
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- 2024
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5. MUC16 as a serum-based prognostic indicator of prometastatic gastric cancer.
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Lee J, Lee SW, Kang SH, Seol D, Yoo M, Hwang D, Lee E, Park YS, Ahn SH, Suh YS, Park KU, Kwon NJ, and Kim HH
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- Humans, Male, Female, Middle Aged, Prognosis, Aged, Membrane Proteins blood, Membrane Proteins genetics, Membrane Proteins metabolism, Neoplasm Metastasis, Retrospective Studies, Adult, Stomach Neoplasms pathology, Stomach Neoplasms blood, Biomarkers, Tumor blood, CA-125 Antigen blood
- Abstract
Metastatic gastric cancer (GC) presents significant clinical challenges due to its poor prognosis and limited treatment options. To address this, we conducted a targeted protein biomarker discovery study to identify markers predictive of metastasis in advanced GC (AGC). Serum samples from 176 AGC patients (T stage 3 or higher) were analyzed using the Olink Proteomics Target panels. Patients were retrospectively categorized into nonmetastatic, metastatic, and recurrence groups, and differential protein expression was assessed. Machine learning and gene set enrichment analysis (GSEA) methods were applied to discover biomarkers and predict prognosis. Four proteins (MUC16, CAIX, 5'-NT, and CD8A) were significantly elevated in metastatic GC patients compared to the control group. Additionally, GSEA indicated that the response to interleukin-4 and hypoxia-related pathways were enriched in metastatic patients. Random forest classification and decision-tree modeling showed that MUC16 could be a predictive marker for metastasis in GC patients. Additionally, ELISA validation confirmed elevated MUC16 levels in metastatic patients. Notably, high MUC16 levels were independently associated with metastatic progression in T3 or higher GC. These findings suggest the potential of MUC16 as a clinically relevant biomarker for identifying GC patients at high risk of metastasis., (© 2024. The Author(s).)
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- 2024
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6. Single-Cell and Spatial Transcriptome Analysis of Dermal Fibroblast Development in Perinatal Mouse Skin: Dynamic Lineage Differentiation and Key Driver Genes.
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Lee H, Kim SY, Kwon NJ, Jo SJ, Kwon O, and Kim JI
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- Animals, Mice, Gene Expression Profiling, Gene Expression Regulation, Developmental, Transcriptome, Skin cytology, Skin metabolism, Animals, Newborn, Dermis cytology, Female, Fibroblasts metabolism, Fibroblasts cytology, Single-Cell Analysis, Cell Differentiation genetics, Cell Lineage genetics
- Abstract
Several single-cell RNA studies of developing mouse skin have elucidated the molecular and cellular processes involved in skin development. However, they have primarily focused on either the fetal or early postnatal period, leaving a gap in our understanding of skin development. In this study, we conducted a comprehensive time-series analysis by combining single-cell RNA-sequencing datasets collected at different stages of development (embryonic days 13.5, 14.5, and 16.5 and postnatal days 0, 2, and 4) and validated our findings through multipanel in situ spatial transcriptomics. Our analysis indicated that embryonic fibroblasts exhibit heterogeneity from a very early stage and that the rapid determination of each lineage occurs within days after birth. The expression of putative key driver genes, including Hey1, Ebf1, Runx3, and Sox11 for the dermal papilla trajectory; Lrrc15 for the dermal sheath trajectory; Zfp536 and Nrn1 for the papillary fibroblast trajectory; and Lrrn4cl and Mfap5 for the fascia fibroblast trajectory, was detected in the corresponding, spatially identified cell types. Finally, cell-to-cell interaction analysis indicated that the dermal papilla lineage is the primary source of the noncanonical Wnt pathway during skin development. Together, our study provides a transcriptomic reference for future research in the field of skin development and regeneration., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)
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- 2024
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7. Multiplex analysis for the identification of plasma protein biomarkers for predicting lung cancer immunotherapy response.
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Hong M, Lee SW, Cho BC, Hong MH, Lim SM, and Kwon NJ
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Background: Programmed death-ligand (PD-L1) expression serves as a predictive biomarker for immune checkpoint inhibitor (ICI) sensitivity in non-small cell lung cancer (NSCLC). Nevertheless, the development of biomarkers that reliably predict ICI response remains an ongoing endeavor due to imperfections in existing methodologies., Objectives: ICIs have led to a new paradigm in the treatment of NSCLC. The current companion PD-L1 diagnostics are insufficient in predicting ICI response. Therefore, we sought whether the Olink platform could be applied to predict response to ICIs in NSCLC., Design: We collected blood samples from patients with NSCLC before ICI treatment and retrospectively analyzed proteomes based on their response to ICI., Methods: Overall, 76 NSCLC patients' samples were analyzed. Proteomic plasma analysis was performed using the Olink platform. Intraplate reproducibility, validation, and statistical analyses using elastic net regression and generalized linear models with clinical parameters were evaluated., Results: Intraplate coefficient of variation (CV) assays ranged from 3% to 6%, and the interplate CV was 14%. In addition, the Pearson correlation coefficient of the Olink Normalized Protein eXpression data was validated. No statistical differences were observed in the analyses of progressive disease and response to ICIs. Furthermore, no single proteome showed prognostic value in terms of progression-free survival., Conclusion: In this study, the proximity extension assay-based approach of the Olink panel could not predict the patient's response to ICIs. Our proteomic analysis failed to achieve predictive value in both response or progression to ICIs and progression-free survival (PFS)., Competing Interests: The authors declare that there is no conflict of interest., (© The Author(s), 2024.)
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- 2024
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8. IDH -wildtype secondary glioblastoma arising in IDH -mutant diffuse astrocytoma: a case report.
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Yoon BH, Park JS, Kang S, Kwon NJ, Lee KS, Kim CY, and Choe G
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- Female, Humans, Adult, Isocitrate Dehydrogenase genetics, Mutation, Glioblastoma diagnostic imaging, Glioblastoma genetics, Glioblastoma surgery, Brain Neoplasms diagnostic imaging, Brain Neoplasms genetics, Brain Neoplasms surgery, Astrocytoma diagnostic imaging, Astrocytoma genetics, Astrocytoma surgery, Glioma pathology
- Abstract
Primary glioblastoma develops de novo without clinical or histological evidence of a low-grade precursor lesion, whereas secondary glioblastoma develops from a low-grade glioma. The present report describes an extraordinary case of IDH -wildtype secondary glioblastoma arising in IDH -mutant diffuse astrocytoma. A 31-year-old female had a surgical history of IDH -mutant diffuse astrocytoma on the left frontal lobe six years before. Magnetic resonance imaging revealed new infiltrative lesions in the left frontal lobe adjacent to the previous lesion. The patient underwent tumourectomy, and the new infiltrative lesion was diagnosed as glioblastoma. Interestingly, the IDH -1 (p.Arg132His) mutation was found in diffuse astrocytoma but not in glioblastoma based on next generation sequencing. ATRX (p.Gln1670Ter) and TP53 (p.His193Arg) mutations were found in both lesions. Additionally, the PTEN (p.His296Pro) mutation was identified only in glioblastoma. A well-accepted hypothesis is that the IDH mutation initiates in glial progenitor cells and causes secondary glioblastoma harboring the IDH mutation to develop from low grade glioma with IDH mutation. However, this case showed that the other genetic mutations can be initiated before the IDH mutation in glioma oncogenesis. Contrary to the previous hypothesis, this is the first case of IDH -wildtype secondary glioblastoma arising in IDH -mutant diffuse astrocytoma.
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- 2023
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9. A whole-genome reference panel of 14,393 individuals for East Asian populations accelerates discovery of rare functional variants.
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Choi J, Kim S, Kim J, Son HY, Yoo SK, Kim CU, Park YJ, Moon S, Cha B, Jeon MC, Park K, Yun JM, Cho B, Kim N, Kim C, Kwon NJ, Park YJ, Matsuda F, Momozawa Y, Kubo M, Kim HJ, Park JH, Seo JS, Kim JI, and Im SW
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- Humans, Genome, Human, Polymorphism, Single Nucleotide, Genotype, Receptors, G-Protein-Coupled genetics, Genome-Wide Association Study, East Asian People
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Underrepresentation of non-European (EUR) populations hinders growth of global precision medicine. Resources such as imputation reference panels that match the study population are necessary to find low-frequency variants with substantial effects. We created a reference panel consisting of 14,393 whole-genome sequences including more than 11,000 Asian individuals. Genome-wide association studies were conducted using the reference panel and a population-specific genotype array of 72,298 subjects for eight phenotypes. This panel yields improved imputation accuracy of rare and low-frequency variants within East Asian populations compared with the largest reference panel. Thirty-nine previously unidentified associations were found, and more than half of the variants were East Asian specific. We discovered genes with rare protein-altering variants, including LTBP1 for height and GPR75 for body mass index, as well as putative regulatory mechanisms for rare noncoding variants with cell type-specific effects. We suggest that this dataset will add to the potential value of Asian precision medicine.
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- 2023
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10. Clinical validity of oncogenic driver genes detected from circulating tumor DNA in the blood of lung cancer patients.
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Kim S, Kim S, Kim SH, Jung EH, Suh KJ, Kim YJ, Kwon NJ, Kim H, Chung JH, and Lee JS
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Background: This study aimed to evaluate the concordance of oncogenic driver mutations between tumor tissues and circulating tumor DNA (ctDNA) in patients with lung cancer. In addition, this study attempted to reveal the clinical utility of ctDNA in lung cancer treatment., Methods: Recurrent or metastatic non-small cell lung cancer (NSCLC) patients were prospectively enrolled in this study. Tumor tissue and serial blood samples were obtained from newly diagnosed patients (Cohort A) or patients treated with targeted therapy (Cohort B) and targeted gene panel sequencing was conducted to identify tumor mutational profiles., Results: At the time of diagnosis, patients in Cohort A with a high cell-free DNA (cfDNA) concentration had poorer overall survival than those with a low cfDNA concentration. The sensitivity and precision of ctDNA analysis in pre-treatment patients compared with those of tissue sequencing were 58.4% and 61.5%, respectively. Known lung cancer-associated variants of oncogenic driver genes, including EGFR and KRAS , and tumor suppressor genes, including TP53 and APC , were frequently detected in the ctDNA of the patients (76.9%). An association between smoking and TP53 mutation status was observed in both tissues and ctDNA (P=0.005 and 0.037, respectively). In addition, the EGFR T790M resistance mutation was detected solely from the ctDNA of two patients after treatment with an EGFR tyrosine kinase inhibitor., Conclusions: ctDNA may be a reliable prognostic biomarker with an additional role in treating patients with lung cancer. Further analyses are necessary to understand the properties of ctDNA and widen its clinical use., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tlcr.amegroups.com/article/view/10.21037/tlcr-22-912/coif). Sungjae Kim and NJK are employees of Macrogen Inc. The other authors have no conflicts of interest to declare., (2023 Translational Lung Cancer Research. All rights reserved.)
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- 2023
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11. ClinPharmSeq: A targeted sequencing panel for clinical pharmacogenetics implementation.
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Lee SB, Shin JY, Kwon NJ, Kim C, and Seo JS
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- Alleles, Genotype, Haplotypes, Whole Genome Sequencing methods, High-Throughput Nucleotide Sequencing methods, Pharmacogenetics methods
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The accurate identification of genetic variants contributing to therapeutic drug response or adverse effects is the first step in implementation of precision drug therapy. Targeted sequencing has recently become a common methodology for large-scale studies of genetic variation thanks to its favorable balance between low cost, high throughput, and deep coverage. Here, we present ClinPharmSeq, a targeted sequencing panel of 59 genes with associations to pharmacogenetic (PGx) phenotypes, as a platform to explore the relationship between drug response and genetic variation, both common and rare. For validation, we sequenced DNA from 64 ethnically diverse Coriell samples with ClinPharmSeq to call star alleles (haplotype patterns) in 27 genes using the bioinformatics tool PyPGx. These reference samples were extensively characterized by multiple laboratories using PGx testing assays and, more recently, whole genome sequencing. We found that ClinPharmSeq can consistently generate deep-coverage data (mean = 274x) with high uniformity (30x or above = 94.8%). Our genotype analysis identified a total of 185 unique star alleles from sequencing data, and showed that diplotype calls from ClinPharmSeq are highly concordant with that from previous publications (97.6%) and whole genome sequencing (97.9%). Notably, all 19 star alleles with complex structural variation including gene deletions, duplications, and hybrids were recalled with 100% accuracy. Altogether, these results demonstrate that the ClinPharmSeq platform offers a feasible path for broad implementation of PGx testing and optimization of individual drug treatments., Competing Interests: The authors have declared that no competing interests exist.
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- 2022
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12. Evaluation of low-pass genome sequencing in polygenic risk score calculation for Parkinson's disease.
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Kim S, Shin JY, Kwon NJ, Kim CU, Kim C, Lee CS, and Seo JS
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- Adult, Aged, Chromosome Mapping, Female, Genome-Wide Association Study, Genotype, Humans, Male, Middle Aged, Parkinson Disease pathology, Polymorphism, Single Nucleotide genetics, Risk Factors, Genetic Predisposition to Disease, Multifactorial Inheritance genetics, Parkinson Disease genetics, Whole Genome Sequencing statistics & numerical data
- Abstract
Background: Low-pass sequencing (LPS) has been extensively investigated for applicability to various genetic studies due to its advantages over genotype array data including cost-effectiveness. Predicting the risk of complex diseases such as Parkinson's disease (PD) using polygenic risk score (PRS) based on the genetic variations has shown decent prediction accuracy. Although ultra-LPS has been shown to be effective in PRS calculation, array data has been favored to the majority of PRS analysis, especially for PD., Results: Using eight high-coverage WGS, we assessed imputation approaches for downsampled LPS data ranging from 0.5 × to 7.0 × . We demonstrated that uncertain genotype calls of LPS diminished imputation accuracy, and an imputation approach using genotype likelihoods was plausible for LPS. Additionally, comparing imputation accuracies between LPS and simulated array illustrated that LPS had higher accuracies particularly at rare frequencies. To evaluate ultra-low coverage data in PRS calculation for PD, we prepared low-coverage WGS and genotype array of 87 PD cases and 101 controls. Genotype imputation of array and downsampled LPS were conducted using a population-specific reference panel, and we calculated risk scores based on the PD-associated SNPs from an East Asian meta-GWAS. The PRS models discriminated cases and controls as previously reported when both LPS and genotype array were used. Also strong correlations in PRS models for PD between LPS and genotype array were discovered., Conclusions: Overall, this study highlights the potentials of LPS under 1.0 × followed by genotype imputation in PRS calculation and suggests LPS as attractive alternatives to genotype array in the area of precision medicine for PD., (© 2021. The Author(s).)
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- 2021
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13. Genomic landscape of extraordinary responses in metastatic breast cancer.
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Lim SM, Kim E, Jung KH, Kim S, Koo JS, Kim SI, Park S, Park HS, Park BW, Cho YU, Kim JY, Paik S, Kwon NJ, Kim GM, Kim JH, Kim MH, Jeon MK, Kim S, and Sohn J
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- Adult, Animals, Female, Genomics, High-Throughput Nucleotide Sequencing, Humans, Middle Aged, Exome Sequencing, Breast Neoplasms genetics, DNA Copy Number Variations, Genome, Human, INDEL Mutation, Polymorphism, Single Nucleotide
- Abstract
Extreme responders to anticancer therapy are rare among advanced breast cancer patients. Researchers, however, have yet to investigate treatment responses therein on the whole exome level. We performed whole exome analysis to characterize the genomic landscape of extreme responders among metastatic breast cancer patients. Clinical samples were obtained from breast cancer patients who showed exceptional responses to anti-HER2 therapy or hormonal therapy and from those who did not. Matched breast tumor tissue (somatic DNA) and blood samples (germline DNA) were collected from a total of 30 responders and 15 non-responders. Whole exome sequencing using Illumina HiSeq2500 was performed for all 45 patients (90 samples). Somatic single nucleotide variants (SNVs), indels, and copy number variants (CNVs) were identified for the genomes of each patient. Group-specific somatic variants and mutational burden were statistically analyzed. Sequencing of cancer exomes for all patients revealed 1839 somatic SNVs (1661 missense, 120 nonsense, 43 splice-site, 15 start/stop-lost) and 368 insertions/deletions (273 frameshift, 95 in-frame), with a median of 0.7 mutations per megabase (range, 0.08 to 4.2 mutations per megabase). Responders harbored a significantly lower nonsynonymous mutational burden (median, 26 vs. 59, P = 0.02) and fewer CNVs (median 13.6 vs. 97.7, P = 0.05) than non-responders. Multivariate analyses of factors influencing progression-free survival showed that a high mutational burden and visceral metastases were significantly related with disease progression. Extreme responders to treatment for metastatic breast cancer are characterized by fewer nonsynonymous mutations and CNVs.
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- 2021
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14. Publisher Correction: Analysis of the serial circulating tumor cell count during neoadjuvant chemotherapy in breast cancer patients.
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Gwark S, Kim J, Kwon NJ, Kim KY, Kim Y, Lee CH, Kim YH, Kim MS, Hong SW, Choi MY, Jeon BH, Chang S, Yu J, Park JY, Lee HJ, Lee SB, Chung IY, Ko BS, Kim HJ, Lee JW, Son BH, Ahn JH, Jung KH, Kim SB, Gong GY, and Ahn SH
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- 2021
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15. Analysis of the serial circulating tumor cell count during neoadjuvant chemotherapy in breast cancer patients.
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Gwark S, Kim J, Kwon NJ, Kim KY, Kim Y, Lee CH, Kim YH, Kim MS, Hong SW, Choi MY, Jeon BH, Chang S, Yu J, Park JY, Lee HJ, Lee SB, Chung IY, Ko BS, Kim HJ, Lee JW, Son BH, Ahn JH, Jung KH, Kim SB, Gong GY, and Ahn SH
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- Adult, Aged, Biomarkers, Tumor metabolism, Breast Neoplasms blood, Cell Count, Chemotherapy, Adjuvant, Disease-Free Survival, Estrogen Receptor alpha metabolism, Female, Follow-Up Studies, Humans, MCF-7 Cells, Microscopy, Fluorescence, Middle Aged, Neoadjuvant Therapy, Neoplasm Recurrence, Local blood, Neoplasm, Residual blood, Neoplasm, Residual drug therapy, Prognosis, Receptor, ErbB-2 metabolism, Recurrence, Treatment Outcome, Triple Negative Breast Neoplasms blood, Breast Neoplasms drug therapy, Neoplasm Recurrence, Local pathology, Neoplastic Cells, Circulating pathology, Triple Negative Breast Neoplasms drug therapy
- Abstract
We evaluated the prognostic implications of the circulating tumor cell (CTC) count in non-metastatic, HER2-negative breast cancer patients who failed to achieve pathologic complete response (pCR) after neoadjuvant chemotherapy (NCT). A total of 173, non-metastatic breast cancer patients treated with NCT were prospectively enrolled. CTCs were obtained from blood drawn pre-NCT and post-NCT using a SMART BIOPSY SYSTEM isolation kit (Cytogen Inc., Seoul, Korea) with immunofluorescence staining. Excluding 26 HER2-positive patients, Relapse-free survival (RFS) and overall survival (OS) related to the CTC count and the association of the CTC count with the treatment response to given therapy were analyzed in 147 HER2-negative patients. Among 147 HER2-negative patients, 28 relapses (19.0%) and 13 deaths (8.8%, all breast cancer-specific) were observed during a median follow-up of 37.3 months. One hundred and seven patients (72.8%) were hormone receptor-positive, and 40 patients (27.2%) had triple-negative breast cancer (TNBC). One or more CTCs were identified in 88 of the 147 patients (59.9%) before NCT and 77 of the 134 patients (52.4%) after NCT. In the entire HER2-negative patient cohort, the initial nodal status was the most significant factor influencing RFS and OS. In TNBC, 11 patients (27.5%) achieved pCR and patients that failed to achieve pCR with ≥ 5 CTCs after NCT, showed worse RFS (HR, 10.66; 95% CI, 1.80-63.07; p = 0.009) and OS (HR, 14.00; 95% CI, 1.26-155.53; p = 0.032). The patients with residual tumor and a high number of the CTCs after NCT displayed the worse outcome. These findings could provide justification to launch a future, well designed trial with longer follow-up data to obtain regulatory approval for clinical use of the assay, especially for the ER-positive, HER2-negative breast cancer subset.
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- 2020
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16. The Clinical Significance of RAS, PIK3CA, and PTEN Mutations in Non-Small Cell Lung Cancer Using Cell-Free DNA.
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Chang WJ, Sung JS, Lee SY, Kang EJ, Kwon NJ, Kim HM, Shin SW, Choi JY, Choi YJ, Kim JW, Park KH, and Kim YH
- Abstract
Mutations in the EGFR gene downstream signaling pathways may cause receptor-independent pathway activation, making tumors unresponsive to EGFR inhibitors. However, the clinical significance of RAS, PIK3CA or PTEN mutations in NSCLC is unclear. In this study, patients who were initially diagnosed with NSCLC or experienced recurrence after surgical resection were enrolled, and blood samples was collected. Ultra-deep sequencing analysis of cfDNA using Ion AmpliSeq Cancer Hotspot Panel v2 with Proton platforms was conducted. RAS/PIK3CA/PTEN mutations were frequently detected in cfDNA in stage IV NSCLC (58.1%), and a high proportion of the patients (47.8%) with mutations had bone metastases at diagnosis. The frequency of RAS/PIK3CA/PTEN mutations in patients with activating EGFR mutation was 61.7%. The median PFS for EGFR-TKIs was 15.1 months in patients without RAS/PIK3CA/PTEN mutations, and 19.9 months in patients with mutations ( p = 0.549). For patients with activating EGFR mutations, the overall survival was longer in patients without RAS/PIK3CA/PTEN mutations (53.8 months vs. 27.4 months). For the multivariate analysis, RAS/PIK3CA/PTEN mutations were independent predictors of poor prognosis in patients with activating EGFR mutations. In conclusion, RAS, PIK3CA and PTEN mutations do not hamper EGFR-TKI treatment outcome; however, they predict a poor OS when activating EGFR mutations coexist.
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- 2020
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17. A newly developed capture-based sequencing panel for genomic assay of lung cancer.
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Im SW, Chae J, Jang SS, Choi J, Yun J, Cha S, Kwon NJ, Jeon YK, Hwang Y, Kim M, Kim TM, Kim DW, Kim JI, and Kim YT
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- Cell Line, Tumor, DNA Copy Number Variations, Data Accuracy, Genes, Neoplasm, Genomic Structural Variation, Humans, INDEL Mutation, Lung Neoplasms diagnosis, Lung Neoplasms metabolism, Polymorphism, Single Nucleotide, Precision Medicine, Sensitivity and Specificity, High-Throughput Nucleotide Sequencing methods, Lung Neoplasms genetics, Mutation, Neoplasm Proteins genetics, Polymorphism, Genetic, Sequence Analysis, DNA methods
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Background: The increase in genetic alterations targeted by specific chemotherapy in lung cancer has led to the need for universal use of more comprehensive genetic testing, which has highlighted the development of a lung cancer diagnostic panel using next-generation sequencing., Objective: We developed a hybridization capture-based massively parallel sequencing assay named Friendly, Integrated, Research-based, Smart and Trustworthy (FIRST)-lung cancer panel (LCP), and evaluated its performance., Methods: FIRST-LCP comprises 64 lung cancer-related genes to test for various kinds of genetic alterations including single nucleotide variations (SNVs), insertions and deletions (indels), copy number variations (CNVs), and structural variations. To assess the performance of FIRST-LCP, we compiled test sets using HapMap samples or tumor cell lines with disclosed genetic information, and also tested our clinical lung cancer samples whose genetic alterations were known by conventional methods., Results: FIRST-LCP accomplished high sensitivity (99.4%) and specificity (100%) of the detection of SNVs. High precision was also achieved, with intra- or inter-run concordance rate of 0.99, respectively. FIRST-LCP detected indels and CNVs close to the expected allele frequency and magnitude, respectively. Tests with samples from lung cancer patients also identified all SNVs, indels and fusions., Conclusion: Based on the current state of the art, continuous application of the panel design and analysis pipeline following up-to-date knowledge could ensure precision medicine for lung cancer patients.
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- 2020
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18. Virus Isolation from the First Patient with SARS-CoV-2 in Korea.
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Park WB, Kwon NJ, Choi SJ, Kang CK, Choe PG, Kim JY, Yun J, Lee GW, Seong MW, Kim NJ, Seo JS, and Oh MD
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- Adult, COVID-19, Female, Humans, Microscopy, Electron, Transmission, Phylogeny, Republic of Korea, SARS-CoV-2, Betacoronavirus genetics, Betacoronavirus isolation & purification, Coronavirus Infections diagnosis, Oropharynx virology, Pneumonia, Viral diagnosis, Whole Genome Sequencing
- Abstract
Novel coronavirus (SARS-CoV-2) is found to cause a large outbreak started from Wuhan since December 2019 in China and SARS-CoV-2 infections have been reported with epidemiological linkage to China in 25 countries until now. We isolated SARS-CoV-2 from the oropharyngeal sample obtained from the patient with the first laboratory-confirmed SARS-CoV-2 infection in Korea. Cytopathic effects of SARS-CoV-2 in the Vero cell cultures were confluent 3 days after the first blind passage of the sample. Coronavirus was confirmed with spherical particle having a fringe reminiscent of crown on transmission electron microscopy. Phylogenetic analyses of whole genome sequences showed that it clustered with other SARS-CoV-2 reported from Wuhan., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2020 The Korean Academy of Medical Sciences.)
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- 2020
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19. Development of a LC-MS/MS method for determination of propofol-glucuronide in hair and preliminary study on relationships between dose and hair concentration.
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Kwon NJ, Kim HJ, Cho S, Lee MA, and Han E
- Subjects
- Adult, Chromatography, Liquid, Female, Forensic Toxicology, Glucuronides administration & dosage, Humans, Hypnotics and Sedatives administration & dosage, Male, Middle Aged, Propofol administration & dosage, Substance-Related Disorders diagnosis, Tandem Mass Spectrometry, Young Adult, Glucuronides analysis, Hair chemistry, Hypnotics and Sedatives analysis, Propofol analysis, Substance Abuse Detection methods
- Abstract
Propofol abuse has been reported worldwide, suggesting the need to establish analytical methods for human biological samples to investigate the abuse of propofol. This study aimed to investigate the relationship between dose and hair concentration using a simple and rapid analytical method developed and validated in this study. In the sample preparation, hair samples were washed with distilled water and methanol and extracted in methanol during 16h at room temperature. After centrifugation and evaporation, the residue was reconstituted and filtered through a 0.22μm membrane filter before LC-MS/MS analysis. The precursor-to-product ion transitions were 353 → 175, 113 for propofol glucuronide and m/z 370 → 175, 113 for internal standard(propofol glucuronide-d
17 ). The calibration curves were satisfactory (R2 =0.9997) and the limits of detection and quantification were 2 and 5pg/mg, respectively. In addition, this study collected the history of propofol use from subjects using a questionnaire and analyzed subjects' hair samples using a validated analytical method. As a result, the concentrations of propofol glucuronide ranged from 7 to 122pg/mg (mean : 51pg/mg). There were cases of positive relationships, but generally there was no correlation between dose and hair concentration., (Copyright © 2019 Elsevier B.V. All rights reserved.)- Published
- 2020
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20. The clinical impact of family history of cancer in female never-smoker lung adenocarcinoma.
- Author
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Lee Y, Jeon JH, Goh SH, Roh H, Yun JY, Kwon NJ, Choi JH, Yang HC, Kim MS, Lee JM, Lee GK, and Han JY
- Subjects
- Adenocarcinoma of Lung diagnosis, Adenocarcinoma of Lung therapy, Adult, Aged, Aged, 80 and over, Biomarkers, Tumor, Combined Modality Therapy, Female, Gene Frequency, Humans, Kaplan-Meier Estimate, Medical History Taking, Middle Aged, Mutation, Neoplasm Staging, Prognosis, Public Health Surveillance, Republic of Korea epidemiology, Risk Assessment, Risk Factors, Smoking adverse effects, Adenocarcinoma of Lung epidemiology, Adenocarcinoma of Lung etiology, Disease Susceptibility, Non-Smokers
- Abstract
Objectives: Accumulating evidence reveals the association between the risk of never-smoker lung cancer and family history of cancer. However, the clinicogenomic effect of family history of cancer in never-smoker lung cancer remains unknown., Material and Methods: We screened 3,241 lung cancer patients who (a) underwent curative resection at National Cancer Center (Goyang, Korea) between 2001-2014, and (b) completed a pre-designed interview about family/smoking history at the time of diagnosis and identified 604 female never smoker lung adenocarcinoma. A positive family history of cancer [categorized as pulmonary cancer (FH-PC) or non-pulmonary cancer (FH-NPC)] was defined as a self-reported history of cancer in first-degree relatives. Survival data were followed up until January 2017. Multiplexed targeted next-generation sequencing was performed for genetic profiling., Results: Of 604 patients, 29.1% (n = 176) had a FH, including 132 (21.9%) with FH-NPC and 44 (7.3%) with FH-PC. Patients with the FH-NPC had a higher proportion of young patients (≤45 years) than those without the FH-NPC (FH-NPC, FH-PC, and no FH; 13.6%, 2.3%, and 8.2%, respectively; P = 0.032). Patients with the FH-NPC had an increased risk of recurrence (hazard ratio [HR]: 1.90; 95% confidence interval [CI]: 1.40-2.56; P<0.001) and death (HR: 1.67; 95% CI: 1.18-2.37; P=0.004). In contrast, the FH-PC had no prognostic effect on recurrence (HR: 1.23; 95% CI: 0.71-2.15; P = 0.456) and death (HR: 0.93; 95% CI: 0.45-1.91; P=0.838). Among three driver oncogene alterations, EGFR mutation was significantly associated with the FH-PC (53.8%, 84.1%, and 65.8%, respectively; P = 0.016), ALK/ROS1/RET fusions was significantly associated with the FH-NPC (13.7%, 0.0%, and 5.0%, respectively; P = 0.004), but KRAS mutation was not associated with any type of the FH (13.8% vs. 6.0% vs. 7.8%, respectively; P = 0.288)., Conclusion: The type of family history of cancer was associated with distinct clinocogenomic subtypes and prognosis of never-smoker lung adenocarcinoma., (Copyright © 2019 Elsevier B.V. All rights reserved.)
- Published
- 2019
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21. Web-based Korean maximum residue limit evaluation tools: an applied example of maximum residue limit evaluation for trichlorfon in fishery products.
- Author
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Kang HS, Kwon NJ, Jeong J, Lee K, and Lee H
- Subjects
- Agriculture, Animals, Drug Residues standards, Fisheries statistics & numerical data, Food, Food Additives, Food Contamination legislation & jurisprudence, Food Contamination statistics & numerical data, Food Supply, Humans, Internet, Pesticide Residues, Republic of Korea, Trichlorfon standards, Veterinary Drugs standards, World Health Organization, Drug Residues analysis, Environmental Policy legislation & jurisprudence, Trichlorfon analysis, Veterinary Drugs analysis
- Abstract
To ensure public safety against veterinary drug residues in food products from animal sources, maximum residue limits (MRLs) should be established by scientific evidence and a transparent estimation process. The Joint Food and Agriculture Organization (FAO)/World Health Organization (WHO) Expert Committee on Food Additives (JECFA) developed an Excel workbook-based tool for MRLs evaluation in 2003. In this study, we developed a web-based tool for MRL evaluation, called Korean MRL evaluation tools (KMET). While KMET used algorithms of JECFA workbook, it added some databases (e.g., Korean food consumption database) and provided additional functions (e.g., selection of target marker residue). Web-based KMET enabled regulatory policy makers to update the database. All input data and output results related to MRL evaluation based on residue depletion and food consumption datasets were archived and provided overall processes from the initial depletion data entry to MRL establishment with user-friendly interface. Our results demonstrated the stepwise processes whereby MRL for trichlorfon in the muscle of Paralichthys olivaceus was established with functional descriptions of KMET. MRL for trichlorfon derived from KMET was proposed and notified by the Ministry of Food and Drug Safety in 2018.
- Published
- 2019
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22. A review on the abuse of three NPS (synthetic cannabinoids, kratom, poppers) among youths in Asia.
- Author
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Bae K, Kwon NJ, and Han E
- Subjects
- Asia, Cannabinoids adverse effects, Humans, Illicit Drugs adverse effects, Substance-Related Disorders epidemiology, Synthetic Drugs adverse effects
- Abstract
Abuse of new psychoactive substances (NPSs) among youths is increasing at an unprecedented rate all over the world. In Asia, abuse of synthetic cannabinoids (SCs), kratom, and poppers has been reported, but up to date information related to abuse of these three NPSs is lacking. This literature review focuses on the recent abuse of these three NPS among Asian youth. Many studies have been conducted to investigate the abuse statuses of SCs in Asian youth in Turkey, Japan, and Korea, and many cases of kratom abuse have been reported in Malaysia and Thailand. In addition, concerns have been expressed about the use of kratom in combination with other substances by teenagers. Popper abuse has been reported among many young people in Asia, including Korea and China, and many studies on popper abuse have focused on men who have sex with men in China and Malaysia. Since NPS abuse can have severe adverse effects and create social problems, there is a continuing need to investigate NPS abuse status continuously among young people., (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Published
- 2018
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23. Development of nutritional risk assessment platform in Korea.
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Lee H, Kwon NJ, Kim Y, and Han E
- Subjects
- Adolescent, Adult, Child, Child, Preschool, Computer Simulation, Diet, Eating, Humans, Infant, Nutritional Status, Recommended Dietary Allowances, Republic of Korea, Risk Assessment, Young Adult, Databases, Factual, Nutrition Assessment
- Abstract
Risk assessment has been used to prevent health problems associated with eating habits in response to increased interest in a balanced diet. For nutritional risk assessment (NRA), it is important to 1) consider personal nutrition status based on year-round dietary intake, 2) organize core datasets such as food composition, intake, and health based guidance value (HBGV) datasets with public confidence, and 3) assess and predict the effects by using the computerized NRA tool. Our research staff constructed an integrated database system by compiling and organizing core datasets produced sporadically by different organizations and with different formats and developed a nutritional exposure and risk assessment system called Nutri-Risk (NUTRItional RISK assessment platform), which contained the database. Nutri-Risk is not only capable of NRA, but also contains additional data service functions. Here, the compilations and organization of an integrated database are outlined. In addition, the overall architectures of Nutri-Risk and dietary modeling are described and predictive simulation functions to support the regulatory decisions related to nutritional fortification or reduction policy were demonstrated., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2018
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24. Cancer panel analysis of circulating tumor cells in patients with breast cancer.
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Lee CH, Lee SJ, Choi SH, Ahn SH, Son BH, Lee JW, Yu JH, Kwon NJ, Lee WC, Yang KS, Lee DH, Han DY, Choi MS, Park PS, Lee HK, Kim MS, Lee J, and Jeon BH
- Abstract
Liquid biopsy using circulating tumor cells (CTCs) is a noninvasive and repeatable procedure, and is therefore useful for molecular assays. However, the rarity of CTCs remains a challenge. To overcome this issue, our group developed a novel technology for the isolation of CTCs on the basis of cell size difference. The present study isolated CTCs from patients with breast cancer using this method, and then used these cells for cancer gene panel analysis. Blood samples from eight patients with breast cancer were collected, and CTCs were enriched using size-based filtration. Enriched CTCs were counted using immunofluorescent staining with an epithelial cell adhesion molecule (EpCAM) and CD45 antibodies. CTC genomic DNA was extracted, amplified, and screened for mutations in 400 genes using the Ion AmpliSeq Comprehensive Cancer Panel. White blood cells (WBCs) from the same patient served as a negative control, and mutations in CTCs and WBCs were compared. EpCAM
+ cells were detected in seven out of eight patients, and the average number of EpCAM+ cells was 8.6. The average amount of amplified DNA was 32.7 µg, and the percentage of reads mapped to any targeted region relative to all reads mapped to the reference was 98.6%. The detection rate of CTC-specific mutations was 62.5%. The CTC-specific mutations were enhancer of zeste polycomb repressive complex 2 subunit, notch 1, AT-rich interaction domain 1A, serine/threonine kinase 11, fms related tyrosine kinase 3, MYCN proto-oncogene, bHLH transcription factor, APC, WNT signaling pathway regulator, and phosphatase and tensin homolog. The technique used by the present study was demonstrated to be effective at isolating CTCs at a sufficiently high purity for genomic analysis, and supported the use of comprehensive cancer panel analysis as a potential application for precision medicine.- Published
- 2018
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25. A commentary on the effects of methamphetamine and the status of methamphetamine abuse among youths in South Korea, Japan, and China.
- Author
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Kwon NJ and Han E
- Subjects
- Adolescent, Adolescent Behavior psychology, Amphetamine-Related Disorders complications, Blood Pressure drug effects, Body Temperature drug effects, Cardiotoxicity etiology, Central Nervous System Stimulants adverse effects, China epidemiology, Cognition Disorders chemically induced, Dopamine Uptake Inhibitors adverse effects, Humans, Japan epidemiology, Methamphetamine analysis, Republic of Korea epidemiology, Wastewater chemistry, Amphetamine-Related Disorders epidemiology, Methamphetamine adverse effects
- Abstract
Methamphetamine (MA) abuse continues in East Asia and shows an increasing trend among youths in South Korea, Japan, and China. Although the negative effects of MA abuse on youth are considered as significant problems, few studies have been conducted on the topic in these countries. This paper focuses on the effects of MA on the human body and current MA abuse among youths in South Korea, Japan, and China. To investigate the negative effects of MA on the human body, we searched the keywords "MA," "human," and "effect" for studies published from 2013 to 2017. MA activates the neurotransmitter system and the central nervous system, and when used at high dosage or for long term, MA can cause severe neurotoxicity and cardiovascular problems. Online networks contribute to MA abuse by sharing methods for preparing synthetic MA. Despite efforts to reduce MA abuse, social crimes associated with its abuse continue and numbers of illegal MA users are increasing steadily in Korea, Japan, and China. In young users, diverse factors associated with drug addiction, such as curiosity and peer effect, lead to MA abuse and its attendant personal and social problems., (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Published
- 2018
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26. Detection of somatic variants and EGFR mutations in cell-free DNA from non-small cell lung cancer patients by ultra-deep sequencing using the ion ampliseq cancer hotspot panel and droplet digital polymerase chain reaction.
- Author
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Sung JS, Chong HY, Kwon NJ, Kim HM, Lee JW, Kim B, Lee SB, Park CW, Choi JY, Chang WJ, Choi YJ, Lee SY, Kang EJ, Park KH, and Kim YH
- Abstract
Highly sensitive genotyping assays can detect mutations in cell-free DNA (cfDNA) from cancer patients, reflecting the biology of each patient's cancer. Because circulating tumor DNA comprises a small, variable fraction of DNA circulating in the blood, sensitive parallel multiplexing tests are required to determine mutation profiles. We prospectively examined the clinical utility of ultra-deep sequencing analysis of cfDNA from 126 non-small cell lung cancer (NSCLC) patients using the Ion AmpliSeq Cancer Hotspot Panel v2 (ICP) and validated these findings with droplet digital polymerase chain reaction (ddPCR). ICP results were compared with tumor tissue genotyping (TTG) results and clinical outcomes. A total of 853 variants were detected, with a median of four variants per patient. Overall concordance of ICP and TTG analyses was 90% for EGFR exon 19 deletion and 88% for the L858R mutation. Of 34 patients with a well-defined EGFR activating mutation defined based on the results of ICP and TTG, 31 (81.6%) showed long-term disease control with EGFR TKI treatment. Of 56 patients treated with an EGFR tyrosine kinase inhibitor (TKI), the presence of the de novo T790M mutation was confirmed in 28 (50%). Presence of this de novo mutation did not have a negative effect on EGFR TKI treatment. Ultra-deep sequencing analysis of cfDNA using ICP combined with confirmatory ddPCR was effective at defining driver genetic changes in NSCLC patients. Comprehensive analysis of tumor DNA and cfDNA can increase the specificity of molecular diagnosis, which could translate into tailored treatment., Competing Interests: CONFLICTS OF INTEREST H.Y. Chong, N. Kwon, H.M. Kim, and C.W. Park are employees of Macrogen Inc., Seoul, Republic of Korea. Other than the employment, there are no potential conflicts of interest such as external board membership, ownership, or stockholding.
- Published
- 2017
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27. Cancer gene panel analysis of cultured circulating tumor cells and primary tumor tissue from patients with breast cancer.
- Author
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Hwang E, Uh JH, Lee HS, Lee CH, Lee SJ, Ahn SH, Son BH, Lee JW, Yu JH, Kwon NJ, Lee WC, Yang KS, Choi SH, Kim MS, Lee J, and Jeon BH
- Abstract
Although numerous effective therapies have improved the survival rate of patients with breast cancer, a number of patients present with tumor recurrence and metastasis. A liquid biopsy of circulating tumor cells (CTC) is a non-invasive method to obtain tumor cells and may be used as substitute for a tumor tissue biopsy. The present study focuses on determining whether CTC culture is an optimal method of obtaining sufficient amounts of CTCs for molecular analysis. The current study demonstrates a method of isolating and culturing CTCs from patients with breast cancer and the construction of a molecular profile of cultured cells using the Ion AmpliSeq Cancer Gene Panel V2. Gene mutations that were observed in cultured CTCs were compared with those observed in primary tumor tissues. CTCs were isolated and cultured from the blood of six patients with breast cancer. Mutations from the Catalogue Of Somatic Mutation In Cancer (COSMIC) were detected in Platelet-Derived Growth Factor Receptor Alpha, MET (also known as Hepatocyte Growth Factor Receptor), Phosphatase and Tensin Homolog, Harvey Rat Sarcoma Viral Oncogene Homolog, SWI/SNF Related, Matrix Associated, Actin Dependent Regulator of Chromatin Subfamily B Member 1, Cyclin Dependent Kinase Inhibitor 2A and MutL Homolog 1 genes in 5/6 samples. A comparison between mutations detected in cultured CTCs and mutations detected in primary tumor tissues demonstrated that a large number of mutations that were identified in CTCs were also detected in primary tumor tissues. The results from the current study describe a novel cell culture approach that may be used to obtain an optimal number of CTCs for molecular analysis. This novel approach is able to be used as a tool for liquid biopsy during breast cancer treatment.
- Published
- 2017
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28. Evaluation of a novel approach to circulating tumor cell isolation for cancer gene panel analysis in patients with breast cancer.
- Author
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Lee SJ, Lee CH, Choi SH, Ahn SH, Son BH, Lee JW, Yu JH, Kwon NJ, Lee WC, Yang KS, Lee DH, Han DY, Choi MS, Park PS, Lee HK, Kim MS, Lee J, and Jeon BH
- Abstract
Liquid biopsy isolation of circulating tumor cells (CTCs) allows the genomic analysis of CTCs, which is useful in the determination of personalized cancer therapy. In the present study, CTCs from patients with breast cancer were enriched and successfully analyzed using cancer gene panel analysis. Blood samples from 11 patients with breast cancer were collected and CTCs enriched for using size-based filtration. The enriched CTCs were analyzed using immunofluorescence staining with antibodies directed against epithelial cell adhesion molecule (EpCAM) and cluster of differentiation 45. The genomic DNA of CTCs was extracted, amplified and 50 genes screened for mutations using the Ion AmpliSeq™ Cancer Hotspot Panel v2. EpCAM staining detected CTCs in 10/11 patients and the average CTC count was 3.9 in 5 ml blood. The average purity of enriched CTCs was 14.2±29.4% and the average amount of amplified DNA was 28.6±11.9 µg. Catalogue Of Somatic Mutations In Cancer mutations were detected in the CTCs and included IDH2, TP53, NRAS, IDH1, PDGFRA, HRAS, STK11, EGFR, PTEN, MLH1, PIK3CA, CDKN2A, KIT and SMARCB1. In conclusion, a novel size-based filtration approach for the isolation of CTCs was evaluated and successfully applied for the genomic analysis of CTCs from patients with breast cancer.
- Published
- 2017
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29. Analysis of Fifty Hotspot Mutations of Lung Squamous Cell Carcinoma in Never-smokers.
- Author
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Lee HY, Lee SH, Won JK, Lee DS, Kwon NJ, Choi SM, Lee J, Lee CH, Lee SM, Yim JJ, Yoo CG, Kim YW, Han SK, and Park YS
- Subjects
- AMP-Activated Protein Kinase Kinases, Aged, Carcinoma, Squamous Cell genetics, Carcinoma, Squamous Cell mortality, ErbB Receptors genetics, Female, Humans, Lung Neoplasms genetics, Lung Neoplasms mortality, Male, Middle Aged, Mutation, Neoplasm Staging, PTEN Phosphohydrolase genetics, Protein Serine-Threonine Kinases genetics, Proto-Oncogene Proteins c-kit genetics, Retrospective Studies, Smoking, Survival Rate, Tumor Suppressor Protein p53 genetics, ras Proteins genetics, Carcinoma, Squamous Cell pathology, Lung Neoplasms pathology
- Abstract
Smoking is the major risk factor for lung squamous cell carcinoma (SCC), although a small number of lung SCCs occurs in never-smokers. The purpose of this study was to compare 50 hotspot mutations of lung SCCs between never-smokers and smokers. We retrospectively reviewed the medical records of patients newly diagnosed with lung SCC between January 1, 2011 and December 31, 2013 in the Seoul National University Hospital. Formalin-fixed, paraffin-embedded tumor samples were used for analysis of hotspot mutations. Fifty cancer-related genes in never-smokers were compared to those in ever-smokers. Of 379 lung SCC patients, 19 (5.0%) were never-smokers. The median age of these 19 patients was 67 years (interquartile range 57-73 years), and 10 of these patients were women (52.5%). The incidence rates of stage I, II, III, and IV disease in this group were 26.4%, 5.3%, 31.6%, and 36.8%, respectively, and sequencing was performed successfully in 14 cases. In the 26 lung SCC tumor samples (12 from never-smokers and 14 from ever-smokers) sequenced using personal genome machine, the most common mutations were in TP53 (75.0%), RAS (66.7%), and STK11 (33.3%), but mutations were also found in EGFR, KIT, and PTEN. The distribution of hotspot mutations in never-smokers was similar to that in ever-smokers. There was no significant difference in overall survival between the 2 groups. The 50 hotspot mutations of lung SCC in never-smokers were similar to those of ever-smokers., Competing Interests: The authors have no potential conflicts of interest to disclose.
- Published
- 2017
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30. Illegal use patterns, side effects, and analytical methods of ketamine.
- Author
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Han E, Kwon NJ, Feng LY, Li JH, and Chung H
- Subjects
- Anesthetics, Dissociative analysis, Anesthetics, Dissociative pharmacology, Forensic Toxicology, Gas Chromatography-Mass Spectrometry, Hair chemistry, Humans, Ketamine analysis, Ketamine pharmacology, Anesthetics, Dissociative adverse effects, Ketamine adverse effects, Substance Abuse Detection, Substance-Related Disorders diagnosis
- Abstract
In Asian countries, such as China, Taiwan, and Hong Kong, ketamine (KT) is one of the most prevalent illicit use drugs. KT is regulated by various drug-related laws in many countries, such as Korea, Taiwan, China, U.S.A, Netherlands, UK, Australia, Mexico, and Canada. This review research explored pharmacology and side effects of KT, the illicit use patterns of KT, the analytical methods of KT in biological samples, and the concentrations of KT from abusers and non-abusers. Many side effects of KT have been reported mental and physical problems. Although many studies conducted various analytical methods for KT, this research focused on the urine and hair analysis and compared some parameters of samples, instruments, columns, extraction methods, internal standards, LOD/LOQ levels, metabolites, NK/K ratio, cut off values, and m/z values. Our research also compared the concentrations of KT in biological samples from abusers and non-abusers. Many rapid and precise analytical methods for illegal KT use are needed to be developed and applied to real samples. To minimize and prevent harm from KT, the authorities and appropriate agencies require a careful assessment, evaluation, early identification, and surveillance of KT users in both clinical and social settings. In addition, there is a need to construct a stricter legislative management and provide preventive education to younger individuals because illegal KT use is relatively common among the young populations., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)
- Published
- 2016
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31. Negative regulation and developmental competence in Aspergillus.
- Author
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Lee MK, Kwon NJ, Lee IS, Jung S, Kim SC, and Yu JH
- Subjects
- Amino Acid Sequence, Aspergillus fumigatus genetics, Aspergillus fumigatus physiology, Aspergillus nidulans physiology, Gene Deletion, Models, Genetic, Reproduction, Asexual genetics, Sequence Homology, Amino Acid, Species Specificity, Spores, Fungal growth & development, Aspergillus nidulans genetics, Fungal Proteins genetics, Gene Expression Regulation, Developmental, Gene Expression Regulation, Fungal, Spores, Fungal genetics
- Abstract
Asexual development (conidiation) in the filamentous fungus Aspergillus nidulans is governed by orchestrated gene expression. The three key negative regulators of conidiation SfgA, VosA, and NsdD act at different control point in the developmental genetic cascade. Here, we have revealed that NsdD is a key repressor affecting the quantity of asexual spores in Aspergillus. Moreover, nullifying both nsdD and vosA results in abundant formation of the development specific structure conidiophores even at 12 h of liquid culture, and near constitutive activation of conidiation, indicating that acquisition of developmental competence involves the removal of negative regulation exerted by both NsdD and VosA. NsdD's role in repressing conidiation is conserved in other aspergilli, as deleting nsdD causes enhanced and precocious activation of conidiation in Aspergillus fumigatus or Aspergillus flavus. In vivo NsdD-DNA interaction analyses identify three NsdD binding regions in the promoter of the essential activator of conidiation brlA, indicating a direct repressive role of NsdD in conidiation. Importantly, loss of flbC or flbD encoding upstream activators of brlA in the absence of nsdD results in delayed activation of brlA, suggesting distinct positive roles of FlbC and FlbD in conidiation. A genetic model depicting regulation of conidiation in A. nidulans is presented.
- Published
- 2016
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32. Next-generation sequencing reveals somatic mutations that confer exceptional response to everolimus.
- Author
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Lim SM, Park HS, Kim S, Kim S, Ali SM, Greenbowe JR, Yang IS, Kwon NJ, Lee JL, Ryu MH, Ahn JH, Lee J, Lee MG, Kim HS, Kim H, Kim HR, Moon YW, Chung HC, Kim JH, Kang YK, and Cho BC
- Subjects
- Adult, Aged, Aged, 80 and over, Carcinoma, Renal Cell drug therapy, Class I Phosphatidylinositol 3-Kinases, Class Ib Phosphatidylinositol 3-Kinase genetics, Female, Head and Neck Neoplasms drug therapy, High-Throughput Nucleotide Sequencing, Humans, Kidney Neoplasms drug therapy, Male, Middle Aged, Mutation genetics, Phosphatidylinositol 3-Kinases genetics, Polymorphism, Single Nucleotide genetics, Sarcoma drug therapy, Stomach Neoplasms drug therapy, TOR Serine-Threonine Kinases antagonists & inhibitors, Thyroid Neoplasms drug therapy, Tuberous Sclerosis Complex 1 Protein, Tuberous Sclerosis Complex 2 Protein, Tumor Suppressor Proteins genetics, Young Adult, Adenocarcinoma drug therapy, Antineoplastic Agents therapeutic use, Drug Resistance, Neoplasm genetics, Everolimus therapeutic use, Lacrimal Apparatus pathology, Neurofibromin 1 genetics, TOR Serine-Threonine Kinases genetics, Tumor Suppressor Protein p53 genetics
- Abstract
Background: Given the modest responses to everolimus, a mTOR inhibitor, in multiple tumor types, there is a pressing need to identify predictive biomarkers for this drug. Using targeted ultra-deep sequencing, we aimed to explore genomic alterations that confer extreme sensitivity to everolimus., Results: We collected formalin-fixed paraffin-embedded tumor/normal pairs from 39 patients (22 with exceptional clinical benefit, 17 with no clinical benefit) who were treated with everolimus across various tumor types (13 gastric cancers, 15 renal cell carcinomas, 2 thyroid cancers, 2 head and neck cancer, and 7 sarcomas). Ion AmpliSeqTM Comprehensive Cancer Panel was used to identify alterations across all exons of 409 target genes. Tumors were sequenced to a median coverage of 552x. Cancer genomes are characterized by 219 somatic single-nucleotide variants (181 missense, 9 nonsense, 7 splice-site) and 22 frameshift insertions/deletions, with a median of 2.1 mutations per Mb (0 to 12.4 mutations per Mb). Overall, genomic alterations with activating effect on mTOR signaling were identified in 10 of 22 (45%) patients with clinical benefit and these include MTOR, TSC1, TSC2, NF1, PIK3CA and PIK3CG mutations. Recurrently mutated genes in chromatin remodeling genes (BAP1; n = 2, 12%) and receptor tyrosine kinase signaling (FGFR4; n = 2, 12%) were noted only in patients without clinical benefit., Conclusions: Regardless of different cancer types, mTOR-pathway-activating mutations confer sensitivity to everolimus. Targeted sequencing of mTOR pathway genes facilitates identification of potential candidates for mTOR inhibitors.
- Published
- 2016
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33. Characterization of the aodA, dnmA, mnSOD and pimA genes in Aspergillus nidulans.
- Author
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Leiter É, Park HS, Kwon NJ, Han KH, Emri T, Oláh V, Mészáros I, Dienes B, Vincze J, Csernoch L, Yu JH, and Pócsi I
- Subjects
- Aspergillus nidulans genetics, Aspergillus nidulans metabolism, Biodegradation, Environmental, Dynamins metabolism, Fungal Proteins genetics, Fungal Proteins metabolism, Gene Expression Regulation, Fungal, Mitochondria metabolism, Mitochondrial Proteins metabolism, Mutation, Oxidative Stress, Oxidoreductases metabolism, Plant Proteins metabolism, Podospora genetics, Podospora growth & development, Podospora metabolism, Protease La metabolism, Superoxide Dismutase metabolism, Aspergillus nidulans growth & development, Dynamins genetics, Mitochondrial Proteins genetics, Oxidoreductases genetics, Plant Proteins genetics, Protease La genetics, Superoxide Dismutase genetics
- Abstract
Mitochondria play key roles in cellular energy generation and lifespan of most eukaryotes. To understand the functions of four nuclear-encoded genes predicted to be related to the maintenance of mitochondrial morphology and function in Aspergillus nidulans, systematic characterization was carried out. The deletion and overexpression mutants of aodA, dnmA, mnSOD and pimA encoding alternative oxidase, dynamin related protein, manganese superoxide dismutase and Lon protease, respectively, were generated and examined for their growth, stress tolerances, respiration, autolysis, cell death, sterigmatocystin production, hyphal morphology and size, and mitochondrial superoxide production as well as development. Overall, genetic manipulation of these genes had less effect on cellular physiology and ageing in A. nidulans than that of their homologs in another fungus Podospora anserina with a well-characterized senescence. The observed interspecial phenotypic differences can be explained by the dissimilar intrinsic stabilities of the mitochondrial genomes in A. nidulans and P. anserina. Furthermore, the marginally altered phenotypes observed in A. nidulans mutants indicate the presence of effective compensatory mechanisms for the complex networks of mitochondrial defense and quality control. Importantly, these findings can be useful for developing novel platforms for heterologous protein production, or on new biocontrol and bioremediation technologies based on Aspergillus species.
- Published
- 2016
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34. Isolation of Middle East Respiratory Syndrome Coronavirus from a Patient of the 2015 Korean Outbreak.
- Author
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Park WB, Kwon NJ, Choe PG, Choi SJ, Oh HS, Lee SM, Chong H, Kim JI, Song KH, Bang JH, Kim ES, Kim HB, Park SW, Kim NJ, and Oh MD
- Subjects
- Animals, Chlorocebus aethiops, Coronavirus Infections epidemiology, Disease Outbreaks, Humans, Microscopy, Electron, Middle East Respiratory Syndrome Coronavirus classification, Middle East Respiratory Syndrome Coronavirus genetics, Middle East Respiratory Syndrome Coronavirus ultrastructure, Phylogeny, Polymerase Chain Reaction, RNA, Viral analysis, RNA, Viral chemistry, RNA, Viral metabolism, Republic of Korea epidemiology, Sequence Analysis, RNA, Vero Cells, Coronavirus Infections diagnosis, Coronavirus Infections virology, Middle East Respiratory Syndrome Coronavirus isolation & purification
- Abstract
During the 2015 outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) in Korea, 186 persons were infected, resulting in 38 fatalities. We isolated MERS-CoV from the oropharyngeal sample obtained from a patient of the outbreak. Cytopathic effects showing detachment and rounding of cells were observed in Vero cell cultures 3 days after inoculation of the sample. Spherical virus particles were observed by transmission electron microscopy. Full-length genome sequence of the virus isolate was obtained and phylogenetic analyses showed that it clustered with clade B of MERS-CoV.
- Published
- 2016
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35. Phase II clinical and exploratory biomarker study of dacomitinib in recurrent and/or metastatic esophageal squamous cell carcinoma.
- Author
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Kim HS, Kim SM, Kim H, Pyo KH, Sun JM, Ahn MJ, Park K, Keam B, Kwon NJ, Yun HJ, Kim HG, Chung IJ, Lee JS, Lee KH, Kim DJ, Lee CG, Hur J, Chung H, Park JC, Shin SK, Lee SK, Kim HR, Moon YW, Lee YC, Kim JH, Paik S, and Cho BC
- Subjects
- Aged, Aged, 80 and over, Antineoplastic Agents adverse effects, Biomarkers, Tumor antagonists & inhibitors, Carcinoma, Squamous Cell genetics, Carcinoma, Squamous Cell mortality, Carcinoma, Squamous Cell pathology, DNA Mutational Analysis, Disease Progression, Disease-Free Survival, ErbB Receptors antagonists & inhibitors, ErbB Receptors genetics, Esophageal Neoplasms genetics, Esophageal Neoplasms mortality, Esophageal Neoplasms pathology, Esophageal Squamous Cell Carcinoma, Female, Humans, Kaplan-Meier Estimate, Male, Middle Aged, Mutation, Patient Selection, Precision Medicine, Protein Kinase Inhibitors adverse effects, Quinazolinones adverse effects, Republic of Korea, Time Factors, Treatment Outcome, Antineoplastic Agents therapeutic use, Biomarkers, Tumor genetics, Carcinoma, Squamous Cell drug therapy, Esophageal Neoplasms drug therapy, Neoplasm Recurrence, Local, Protein Kinase Inhibitors therapeutic use, Quinazolinones therapeutic use
- Abstract
The purpose of this study was to investigate the clinical activity, safety and predictive biomarkers of dacomitinib, an irreversible pan-HER inhibitor, in patients with recurrent or metastatic esophageal squamous cell carcinoma (R/M-ESCC). Patients, whose diseases were not amenable to curative treatment and had progressed on platinum-based chemotherapy, were treated with dacomitinib 45 mg/day. The primary endpoint was objective response rate by RECISTv 1.1. Predictive biomarker analyses included the characterization of somatic mutations and gene expression using the Ion Torrent AmpliSeq Cancer Hotspot Panel and Nanostring nCounter, and investigation of their relationship with clinical outcomes. Of the 48 evaluable patients, 6 (12.5%) achieved partial responses and 29 (60.4%) had stable disease. The median response duration was 7.1 months. The median progression free survival (PFS) and overall survival (OS) was 3.3 months (95% CI, 2.4-4.3 months) and 6.4 months (95% CI, 4.4-8.4 months). Adverse events were mostly grade 1-2. Gene set enrichment analysis revealed that ERBB signaling pathway is significantly enriched in patients with PFS ≥ 4 months (n = 12) than PFS < 4 months (n = 21) (p < 0.001). Upregulation of ERBB signaling pathway was significantly associated with longer PFS (5.0 vs. 2.9 months, P = 0.016) and OS (10.0 vs. 4.8 months, P = 0.022). The most frequent mutations were TP53 (61%) followed by CDKN2A (8%), MLH1 (8%), FLT3 (8%) and EGFR (8%). Dacomitinib demonstrated clinical efficacy with manageable toxicity in platinum-failed R/M-ESCC. Screening of ERBB pathway-related gene expression profiles may help identify patients who are most likely benefit from dacomitinib.
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- 2015
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36. γ-Glutamyl transpeptidase (GgtA) of Aspergillus nidulans is not necessary for bulk degradation of glutathione.
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Spitzmüller Z, Kwon NJ, Szilágyi M, Keserű J, Tóth V, Yu JH, Pócsi I, and Emri T
- Subjects
- Aspergillus nidulans genetics, Carbon metabolism, Enzyme Activation genetics, Gene Deletion, Genes, Fungal genetics, Glucose metabolism, Glutathione metabolism, Homeostasis, Hyphae enzymology, Oxidation-Reduction, gamma-Glutamyltransferase genetics, Aspergillus nidulans enzymology, gamma-Glutamyltransferase metabolism
- Abstract
Aspergillus nidulans exhibited high γ-glutamyl transpeptidase (γGT) activity in both carbon-starved and carbon-limited cultures. Glucose repressed, but casein peptone increased γGT production. Null mutation of creA did not influence γGT formation, but the functional meaB was necessary for the γGT induction. Deletion of the AN10444 gene (ggtA) completely eliminated the γGT activity, and the mRNA levels of ggtA showed strong correlation with the observed γGT activities. While ggtA does not contain a canonical signal sequence, the γGT activity was detectable both in the fermentation broth and in the hyphae. Deletion of the ggtA gene did not prevent the depletion of glutathione observed in carbon-starved and carbon-limited cultures. Addition of casein peptone to carbon-starved cultures lowered the formation of reactive species (RS). Deletion of ggtA could hinder this decrease and resulted in elevated RS formation. This effect of γGT on redox homeostasis may explain the reduced cleistothecia formation of ΔggtA strains in surface cultures.
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- 2015
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37. Phase II clinical and exploratory biomarker study of dacomitinib in patients with recurrent and/or metastatic squamous cell carcinoma of head and neck.
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Kim HS, Kwon HJ, Jung I, Yun MR, Ahn MJ, Kang BW, Sun JM, Kim SB, Yoon DH, Park KU, Lee SH, Koh YW, Kim SH, Choi EC, Koo DH, Sohn JH, Kim B, Kwon NJ, Yun HJ, Lee MG, Lee JH, Kim TM, Kim HR, Kim JH, Paik S, and Cho BC
- Subjects
- Adult, Aged, Aged, 80 and over, Antineoplastic Agents administration & dosage, Antineoplastic Agents adverse effects, Biomarkers, Carcinoma, Squamous Cell genetics, Carcinoma, Squamous Cell mortality, Cluster Analysis, Female, Gene Dosage, Gene Expression Profiling, Head and Neck Neoplasms genetics, Head and Neck Neoplasms mortality, Humans, Male, Middle Aged, Mutation, Neoplasm Metastasis, Neoplasm Recurrence, Local, Prognosis, Protein Kinase Inhibitors administration & dosage, Protein Kinase Inhibitors adverse effects, Quinazolinones administration & dosage, Quinazolinones adverse effects, Retreatment, Risk Factors, Squamous Cell Carcinoma of Head and Neck, Treatment Outcome, Antineoplastic Agents therapeutic use, Carcinoma, Squamous Cell drug therapy, Carcinoma, Squamous Cell pathology, Head and Neck Neoplasms drug therapy, Head and Neck Neoplasms pathology, Protein Kinase Inhibitors therapeutic use, Quinazolinones therapeutic use
- Abstract
Purpose: The goals of this study were to investigate the clinical activity, safety, and biomarkers of dacomitinib, an irreversible tyrosine kinase inhibitor of EGFR, HER2, and HER4, in recurrent and/or metastatic squamous cell carcinoma of the head and neck (R/M-SCCHN)., Experimental Design: Patients were eligible if the diseases were not amenable to curative treatment and had progressed on platinum-based chemotherapy, and were treated with dacomitinib 45 mg/day. The primary endpoint was objective response rate by RECISTv1.1. Exploratory analysis included the characterization of somatic mutation, gene copy number, gene expression, p16(INK4A) expression by IHC, and investigation of their relationship with clinical outcomes., Results: Forty-eight patients were evaluable for efficacy and toxicity. Ten patients (20.8%) had partial responses and 31 patients (65%) had stable diseases. The median progression-free survival (PFS) and overall survival (OS) were 3.9 months [95% confidence interval (CI), 2.9-5.0] and 6.6 months (95% CI, 5.4-10.3). Adverse events were mostly grade 1-2. Mutations in the PI3K pathway (PIK3CA, PTEN) and high expression of inflammatory cytokines (IL6, IL8, IL1A, IL1B, IL4, and TNF) were significantly associated with shorter PFS (2.9 vs. 4.9 months without mutations, P = 0.013; 2.8 vs. 9.9 months with low expression, P = 0.004). Those harboring PI3K pathway mutations or high inflammatory cytokine expression had shorter median OS (6.1 vs. 12.5 months lacking PI3K pathway mutations and with low inflammatory cytokine expression, P = 0.005)., Conclusions: Dacomitinib demonstrated clinical efficacy with manageable toxicity in platinum-failed R/M-SCCHN patients. Screening of PI3K pathway mutation and inflammatory cytokine expression may help identify which R/M-SCCHN patients are likely to gain benefit from dacomitinib., (©2014 American Association for Cancer Research.)
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- 2015
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38. Hydroxypropyl cyclic β-(1 → 2)-D-glucans and epichlorohydrin β-cyclodextrin dimers as effective carbohydrate-solubilizers for polycyclic aromatic hydrocarbons.
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Choi JM, Jeong D, Piao J, Kim K, Nguyen AB, Kwon NJ, Lee MK, Lee IS, Yu JH, and Jung S
- Subjects
- Polycyclic Aromatic Hydrocarbons isolation & purification, Solubility, Water chemistry, beta-Glucans isolation & purification, Dimerization, Epichlorohydrin chemistry, Polycyclic Aromatic Hydrocarbons chemistry, beta-Cyclodextrins chemistry, beta-Glucans chemistry
- Abstract
The removal of polycyclic aromatic hydrocarbons by soil washing using water is extremely difficult due to their intrinsic hydrophobic nature. In this study, the effective aqueous solubility enhancements of seven polycyclic aromatic hydrocarbons by chemically modified hydroxypropyl rhizobial cyclic β-(1 → 2)-D-glucans and epichlorohydrin β-cyclodextrin dimer have been investigated for the first time. In the presence of hydroxypropyl cyclic β-(1 → 2)-D-glucans, the solubility of benzo[a]pyrene is increased up to 38 fold of its native solubility. The solubility of pyrene and phenanthrene dramatically increased up to 160 and 359. Coronene, chrysene, perylene, and fluoranthene also show an increase of 11, 23, 23, and 97 fold, respectively, of enhanced solubility by complexation with synthetic epichlorohydrin β-cyclodextrin dimer. The physicochemical properties of the complex are characterized by Fourier-transform infrared spectra and differential scanning calorimetry. Utilizing a scanning electron microscopy, the morphological structures of native benzo[a]pyrene, pyrene, phenanthrene, coronene, chrysene, perylene, fluoranthene and their complex with novel carbohydrate-solubilizers are studied. These results elucidate that polycyclic aromatic hydrocarbons are able to form an efficient complex with hydroxypropyl cyclic β-(1 → 2)-D-glucans and β-cyclodextrin dimer, suggesting the potential usage of chemically modified novel carbohydrate-solubilizers., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2015
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39. NsdD is a key repressor of asexual development in Aspergillus nidulans.
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Lee MK, Kwon NJ, Choi JM, Lee IS, Jung S, and Yu JH
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- Aspergillus nidulans genetics, Aspergillus nidulans metabolism, Fungal Proteins genetics, Gene Dosage, Gene Expression Regulation, Fungal, Sterigmatocystin biosynthesis, Aspergillus nidulans physiology, Fungal Proteins metabolism, Reproduction, Asexual
- Abstract
Asexual development (conidiation) of the filamentous fungus Aspergillus nidulans occurs via balanced activities of multiple positive and negative regulators. For instance, FluG (+) and SfgA (-) govern upstream regulation of the developmental switch, and BrlA (+) and VosA (-) control the progression and completion of conidiation. To identify negative regulators of conidiation downstream of FluG-SfgA, we carried out multicopy genetic screens using sfgA deletion strains. After visually screening >100,000 colonies, we isolated 61 transformants exhibiting reduced conidiation. Responsible genes were identified as AN3152 (nsdD), AN7507, AN2009, AN1652, AN5833, and AN9141. Importantly, nsdD, a key activator of sexual reproduction, was present in 10 independent transformants. Furthermore, deletion, overexpression, and double-mutant analyses of individual genes have led to the conclusion that, of the six genes, only nsdD functions in the FluG-activated conidiation pathway. The deletion of nsdD bypassed the need for fluG and flbA∼flbE, but not brlA or abaA, in conidiation, and partially restored production of the mycotoxin sterigmatocystin (ST) in the ΔfluG, ΔflbA, and ΔflbB mutants, suggesting that NsdD is positioned between FLBs and BrlA in A. nidulans. Nullifying nsdD caused formation of conidiophores in liquid submerged cultures, where wild-type strains do not develop. Moreover, the removal of both nsdD and vosA resulted in even more abundant development of conidiophores in liquid submerged cultures and high-level accumulation of brlA messenger (m)RNA even at 16 hr of vegetative growth. Collectively, NsdD is a key negative regulator of conidiation and likely exerts its repressive role via downregulating brlA.
- Published
- 2014
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40. The use of open source electronic health records within the federal safety net.
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Goldwater JC, Kwon NJ, Nathanson A, Muckle AE, Brown A, and Cornejo K
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- American Recovery and Reinvestment Act, Federal Government, Interviews as Topic, United States, Electronic Health Records, Ownership
- Abstract
Objective: To conduct a federally funded study that examines the acquisition, implementation and operation of open source electronic health records (EHR) within safety net medical settings, such as federally qualified health centers (FQHC)., Methods and Materials: The study was conducted by the National Opinion Research Center (NORC) at the University of Chicago from April to September 2010. The NORC team undertook a comprehensive environmental scan, including a literature review, a dozen key informant interviews using a semistructured protocol, and a series of site visits to West Virginia, California and Arizona FQHC that were currently using an open source EHR., Results: Five of the six sites that were chosen as part of the study found a number of advantages in the use of their open source EHR system, such as utilizing a large community of users and developers to modify their EHR to fit the needs of their provider and patient communities, and lower acquisition and implementation costs as compared to a commercial system., Discussion: Despite these advantages, many of the informants and site visit participants felt that widespread dissemination and use of open source was restrained due to a negative connotation regarding this type of software. In addition, a number of participants stated that there is a necessary level of technical acumen needed within the FQHC to make an open source EHR effective., Conclusions: An open source EHR provides advantages for FQHC that have limited resources to acquire and implement an EHR, but additional study is needed to evaluate its overall effectiveness.
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- 2014
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41. Open source electronic health records and chronic disease management.
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Goldwater JC, Kwon NJ, Nathanson A, Muckle AE, Brown A, and Cornejo K
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- Access to Information, Chronic Disease, Disease Management, Humans, Hypertension therapy, Medical Records Systems, Computerized, Organizational Innovation, Ownership, Surveys and Questionnaires, United States, Community Health Centers organization & administration, Diabetes Mellitus therapy, Electronic Health Records
- Abstract
Objective: To study and report on the use of open source electronic health records (EHR) to assist with chronic care management within safety net medical settings, such as community health centers (CHC)., Methods and Materials: The study was conducted by NORC at the University of Chicago from April to September 2010. The NORC team undertook a comprehensive environmental scan, including a literature review, a dozen key informant interviews using a semistructured protocol, and a series of site visits to CHC that currently use an open source EHR., Results: Two of the sites chosen by NORC were actively using an open source EHR to assist in the redesign of their care delivery system to support more effective chronic disease management. This included incorporating the chronic care model into an CHC and using the EHR to help facilitate its elements, such as care teams for patients, in addition to maintaining health records on indigent populations, such as tuberculosis status on homeless patients., Discussion: The ability to modify the open-source EHR to adapt to the CHC environment and leverage the ecosystem of providers and users to assist in this process provided significant advantages in chronic care management. Improvements in diabetes management, controlled hypertension and increases in tuberculosis vaccinations were assisted through the use of these open source systems., Conclusions: The flexibility and adaptability of open source EHR demonstrated its utility and viability in the provision of necessary and needed chronic disease care among populations served by CHC.
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- 2014
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42. Predictive efficacy of low burden EGFR mutation detected by next-generation sequencing on response to EGFR tyrosine kinase inhibitors in non-small-cell lung carcinoma.
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Kim HS, Sung JS, Yang SJ, Kwon NJ, Jin L, Kim ST, Park KH, Shin SW, Kim HK, Kang JH, Kim JO, Park JY, Choi JE, Yoon H, Park CK, Yang KS, Seo JS, and Kim YH
- Subjects
- Aged, Carcinoma, Non-Small-Cell Lung enzymology, Carcinoma, Non-Small-Cell Lung pathology, Female, Genomics instrumentation, Humans, Kaplan-Meier Estimate, Lung Neoplasms enzymology, Lung Neoplasms genetics, Lung Neoplasms pathology, Male, Oligonucleotides, Peptide Nucleic Acids, Polymerase Chain Reaction, Protein Kinase Inhibitors pharmacology, Treatment Outcome, Carcinoma, Non-Small-Cell Lung drug therapy, Carcinoma, Non-Small-Cell Lung genetics, DNA Mutational Analysis methods, ErbB Receptors genetics, Lung Neoplasms drug therapy, Mutation genetics, Protein Kinase Inhibitors therapeutic use
- Abstract
Direct sequencing remains the most widely used method for the detection of epidermal growth factor receptor (EGFR) mutations in lung cancer; however, its relatively low sensitivity limits its clinical use. The objective of this study was to investigate the sensitivity of detecting an epidermal growth factor receptor (EGFR) mutation from peptide nucleic acid-locked nucleic acid polymerase chain reaction (PNA-LNA PCR) clamp and Ion Torrent Personal Genome Machine (PGM) techniques compared to that by direct sequencing. Furthermore, the predictive efficacy of EGFR mutations detected by PNA-LNA PCR clamp was evaluated. EGFR mutational status was assessed by direct sequencing, PNA-LNA PCR clamp, and Ion Torrent PGM in 57 patients with non-small cell lung cancer (NSCLC). We evaluated the predictive efficacy of PNA-LNA PCR clamp on the EGFR-TKI treatment in 36 patients with advanced NSCLC retrospectively. Compared to direct sequencing (16/57, 28.1%), PNA-LNA PCR clamp (27/57, 47.4%) and Ion Torrent PGM (26/57, 45.6%) detected more EGFR mutations. EGFR mutant patients had significantly longer progressive free survival (14.31 vs. 21.61 months, P = 0.003) than that of EGFR wild patients when tested with PNA-LNA PCR clamp. However, no difference in response rate to EGFR TKIs (75.0% vs. 82.4%, P = 0.195) or overall survival (34.39 vs. 44.10 months, P = 0.422) was observed between the EGFR mutations by direct sequencing or PNA-LNA PCR clamp. Our results demonstrate firstly that patients with EGFR mutations were detected more frequently by PNA-LNA PCR clamp and Ion Torrent PGM than those by direct sequencing. EGFR mutations detected by PNA-LNA PCR clamp may be as a predicative factor for EGFR TKI response in patients with NSCLC.
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- 2013
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43. Gβ-like CpcB plays a crucial role for growth and development of Aspergillus nidulans and Aspergillus fumigatus.
- Author
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Kong Q, Wang L, Liu Z, Kwon NJ, Kim SC, and Yu JH
- Subjects
- Aspergillus fumigatus metabolism, Aspergillus nidulans metabolism, Fungal Proteins metabolism, Gene Expression Regulation, Fungal, Heterotrimeric GTP-Binding Proteins genetics, Heterotrimeric GTP-Binding Proteins metabolism, Mutation, Mycotoxins biosynthesis, Phenotype, Spores, Fungal genetics, Spores, Fungal growth & development, Aspergillus fumigatus genetics, Aspergillus fumigatus growth & development, Aspergillus nidulans genetics, Aspergillus nidulans growth & development, Fungal Proteins genetics
- Abstract
Growth, development, virulence and secondary metabolism in fungi are governed by heterotrimeric G proteins (G proteins). A Gβ-like protein called Gib2 has been shown to function as an atypical Gβ in Gpa1-cAMP signaling in Cryptococcus neoformans. We found that the previously reported CpcB (cross pathway control B) protein is the ortholog of Gib2 in Aspergillus nidulans and Aspergillus fumigatus. In this report, we further characterize the roles of CpcB in governing growth, development and toxigenesis in the two aspergilli. The deletion of cpcB results in severely impaired cellular growth, delayed spore germination, and defective asexual sporulation (conidiation) in both aspergilli. Moreover, CpcB is necessary for proper expression of the key developmental activator brlA during initiation and progression of conidiation in A. nidulans and A. fumigatus. Somewhat in accordance with the previous study, the absence of cpcB results in the formation of fewer, but not micro-, cleistothecia in A. nidulans in the presence of wild type veA, an essential activator of sexual development. However, the cpcB deletion mutant cleistothecia contain no ascospores, validating that CpcB is required for progression and completion of sexual fruiting including ascosporogenesis. Furthermore, unlike the canonical GβSfaD, CpcB is not needed for the biosynthesis of the mycotoxin sterigmatocystin (ST) as the cpcB null mutant produced reduced amount of ST with unaltered STC gene expression. However, in A. fumigatus, the deletion of cpcB results in the blockage of gliotoxin (GT) production. Further genetic analyses in A. nidulans indicate that CpcB may play a central role in vegetative growth, which might be independent of FadA- and GanB-mediated signaling. A speculative model summarizing the roles of CpcB in conjunction with SfaD in A. nidulans is presented.
- Published
- 2013
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44. The putative guanine nucleotide exchange factor RicA mediates upstream signaling for growth and development in Aspergillus.
- Author
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Kwon NJ, Park HS, Jung S, Kim SC, and Yu JH
- Subjects
- Aspergillus fumigatus genetics, Aspergillus fumigatus metabolism, Aspergillus nidulans genetics, Aspergillus nidulans metabolism, DNA, Fungal genetics, Databases, Genetic, Fungal Proteins genetics, GTP-Binding Proteins genetics, GTP-Binding Proteins metabolism, Gene Deletion, Gene Expression Regulation, Fungal, Genes, Fungal, Genetic Complementation Test, Guanine Nucleotide Exchange Factors genetics, Phylogeny, Protein Interaction Mapping, Protein Serine-Threonine Kinases genetics, Protein Serine-Threonine Kinases metabolism, RNA, Fungal genetics, RNA, Messenger genetics, RNA, Messenger metabolism, Reproduction, Asexual, Spores, Fungal genetics, Spores, Fungal growth & development, Spores, Fungal metabolism, Two-Hybrid System Techniques, Aspergillus fumigatus growth & development, Aspergillus nidulans growth & development, Fungal Proteins metabolism, Guanine Nucleotide Exchange Factors metabolism, Signal Transduction
- Abstract
Heterotrimeric G proteins (G proteins) govern growth, development, and secondary metabolism in various fungi. Here, we characterized ricA, which encodes a putative GDP/GTP exchange factor for G proteins in the model fungus Aspergillus nidulans and the opportunistic human pathogen Aspergillus fumigatus. In both species, ricA mRNA accumulates during vegetative growth and early developmental phases, but it is not present in spores. The deletion of ricA results in severely impaired colony growth and the total (for A. nidulans) or near (for A. fumigatus) absence of asexual sporulation (conidiation). The overexpression (OE) of the A. fumigatus ricA gene (AfricA) restores growth and conidiation in the ΔAnricA mutant to some extent, indicating partial conservation of RicA function in Aspergillus. A series of double mutant analyses revealed that the removal of RgsA (an RGS protein of the GanB Gα subunit), but not sfgA, flbA, rgsB, or rgsC, restored vegetative growth and conidiation in ΔAnricA. Furthermore, we found that RicA can physically interact with GanB in yeast and in vitro. Moreover, the presence of two copies or OE of pkaA suppresses the profound defects caused by ΔAnricA, indicating that RicA-mediated growth and developmental signaling is primarily through GanB and PkaA in A. nidulans. Despite the lack of conidiation, brlA and vosA mRNAs accumulated to normal levels in the ΔricA mutant. In addition, mutants overexpressing fluG or brlA (OEfluG or OEbrlA) failed to restore development in the ΔAnricA mutant. These findings suggest that the commencement of asexual development requires unknown RicA-mediated signaling input in A. nidulans.
- Published
- 2012
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45. The small molecular mass antifungal protein of Penicillium chrysogenum--a mechanism of action oriented review.
- Author
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Hegedus N, Leiter E, Kovács B, Tomori V, Kwon NJ, Emri T, Marx F, Batta G, Csernoch L, Haas H, Yu JH, and Pócsi I
- Subjects
- Antifungal Agents chemistry, Antifungal Agents metabolism, Apoptosis, Calcium metabolism, Fungal Proteins chemistry, Fungal Proteins metabolism, Models, Molecular, Molecular Weight, Penicillium chrysogenum growth & development, Protein Conformation, Signal Transduction, Spores, Fungal growth & development, Spores, Fungal metabolism, Antifungal Agents pharmacology, Fungal Proteins pharmacology, Penicillium chrysogenum metabolism
- Abstract
The β-lactam producing filamentous fungus Penicillium chrysogenum secretes a 6.25 kDa small molecular mass antifungal protein, PAF, which has a highly stable, compact 3D structure and is effective against a wide spectrum of plant and zoo pathogenic fungi. Its precise physiological functions and mode of action need to be elucidated before considering possible biomedical, agricultural or food technological applications. According to some more recent experimental data, PAF plays an important role in the fine-tuning of conidiogenesis in Penicillium chrysogenum. PAF triggers apoptotic cell death in sensitive fungi, and cell death signaling may be transmitted through two-component systems, heterotrimeric G protein coupled signal transduction and regulatory networks as well as via alteration of the Ca(2+) -homeostasis of the cells. Possible biotechnological applications of PAF are also outlined in the review., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2011
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46. Extracellular proteinase formation in carbon starving Aspergillus nidulans cultures--physiological function and regulation.
- Author
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Szilágyi M, Kwon NJ, Bakti F, M-Hamvas M, Jámbrik K, Park H, Pócsi I, Yu JH, and Emri T
- Subjects
- Aspergillus nidulans genetics, Aspergillus nidulans metabolism, Autolysis, Culture Media chemistry, Gene Deletion, Aspergillus nidulans enzymology, Aspergillus nidulans physiology, Carbon metabolism, Gene Expression Regulation, Fungal, Peptide Hydrolases metabolism
- Abstract
Extracellular proteinase formation in carbon depleted cultures of the model filamentous fungus Aspergillus nidulans was studied to elucidate its regulation and possible physiological function. As demonstrated by gene deletion, culture optimization, microbial physiological and enzymological experiments, the PrtA and PepJ proteinases of A. nidulans did not appear to play a decisive role in the autolytic decomposition of fungal cells under the conditions we tested. However, carbon starvation induced formation of the proteinases observable in autolytic cultures. Similar to other degradative enzymes, production of proteinase was regulated by FluG-BrlA asexual developmental signaling and modulated by PacC-dependent pH-responsive signaling. Under the same carbon starved culture conditions, alterations of CreA, MeaB or heterotrimeric G protein mediated signaling pathways caused less significant changes in the formation of extracellular proteinases. Taken together, these results indicate that while the accumulation of PrtA and PepJ is tightly coupled to the initiation of autolysis, they are not essential for autolytic cell wall degradation in A. nidulans. Thus, as Aspergillus genomes contain a large group of genes encoding proteinases with versatile physiological functions, selective control of proteinase production in fungal cells is needed for the improved industrial use of fungi., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2011
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47. Characterization of the developmental regulator FlbE in Aspergillus fumigatus and Aspergillus nidulans.
- Author
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Kwon NJ, Shin KS, and Yu JH
- Subjects
- Aspergillus fumigatus genetics, Aspergillus fumigatus metabolism, Aspergillus nidulans genetics, Aspergillus nidulans metabolism, Fungal Proteins genetics, Gene Expression Regulation, Fungal, Spores, Fungal genetics, Spores, Fungal growth & development, Spores, Fungal metabolism, Transcription Factors genetics, Aspergillus fumigatus growth & development, Aspergillus nidulans growth & development, Fungal Proteins metabolism, Gene Expression Regulation, Developmental, Genes, Regulator, Transcription Factors metabolism
- Abstract
Several upstream developmental activators control asexual development (conidiation) in Aspergillus. In this study, we characterize one of such activators called flbE in Aspergillus fumigatus and Aspergillus nidulans. The predicted FlbE protein is composed of 222 and 201 aa in A. fumigatus and A. nidulans, respectively. While flbE is transiently expressed during early phase of growth in A. nidulans, it is somewhat constitutively expressed during the lifecycle of A. fumigatus. The deletion of flbE causes reduced conidiation and delayed expression of brlA and vosA in both species. Moreover, FlbE is necessary for salt-induced development in liquid submerged culture in A. fumigatus. The A. nidulans flbE null mutation is fully complemented by A. fumigatus flbE, indicating a functional conservancy of FlbE in Aspergillus. Both the deletion and overexpression of flbE in A. nidulans result in developmental defects, enhanced autolysis, precocious cell death, and delayed expression of brlA/vosA, suggesting that balanced activity of FlbE is crucial for proper growth and development. Importantly, the N-terminal portion of FlbE exhibits the trans-activation ability in yeast, whereas the C-terminal half negatively affects its activity. Site-directed mutagenesis of certain conserved N-terminal amino acids abolishes the ability of trans-activation, overexpression-induced autolysis, and complementing the null mutation. Finally, overexpression of flbD, but not flbB or flbC, restores conidiation in A. nidulans ΔflbE, generally supporting the current genetic model for developmental regulation., (Copyright © 2010 Elsevier Inc. All rights reserved.)
- Published
- 2010
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48. The extracellular β-1,3-endoglucanase EngA is involved in autolysis of Aspergillus nidulans.
- Author
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Szilágyi M, Kwon NJ, Dorogi C, Pócsi I, Yu JH, and Emri T
- Subjects
- Aspergillus nidulans genetics, Autolysis genetics, Cellulase genetics, Chitinases metabolism, Gene Expression Regulation, Fungal, Hydrolases metabolism, Mutation, Aspergillus nidulans enzymology, Autolysis enzymology, Cellulase metabolism
- Abstract
Aims: To elucidate the roles of the β-1,3-endoglucanase EngA in autolysis of the filamentous fungus Aspergillus nidulans and to identify the common regulatory elements of autolytic hydrolases., Methods and Results: A β-1,3-endoglucanase was purified from carbon-starving cultures of A. nidulans. This enzyme is found to be encoded by the engA gene (locus ID: AN0472.3). Functional and gene-expression studies demonstrated that EngA is involved in the autolytic cell wall degradation resulting from carbon starvation of the fungus. Moreover, regulation of engA is found to be dependent on the FluG/BrlA asexual sporulation signalling pathway in submerged culture. The deletion of either engA or chiB (encoding an endochitinase) caused highly reduced production of hydrolases in general., Conclusions: The β-1,3-endoglucanase EngA plays a pivotal role in fungal autolysis, and activities of both EngA and ChiB are necessary to orchestrate the expression of autolytic hydrolases. The production of cell wall-degrading enzymes was coordinately controlled in a highly sophisticated and complex manner., Significance and Impact of the Study: No information was available on the autolytic glucanase(s) of the euascomycete A. nidulans. This study demonstrates that EngA is a key element in fungal autolysis, and normal activities of both EngA and ChiB are crucial for balanced production of hydrolases., (© 2010 The Authors. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology.)
- Published
- 2010
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49. Pathologic nodal evaluation improves prognostic accuracy in Merkel cell carcinoma: analysis of 5823 cases as the basis of the first consensus staging system.
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Lemos BD, Storer BE, Iyer JG, Phillips JL, Bichakjian CK, Fang LC, Johnson TM, Liegeois-Kwon NJ, Otley CC, Paulson KG, Ross MI, Yu SS, Zeitouni NC, Byrd DR, Sondak VK, Gershenwald JE, Sober AJ, and Nghiem P
- Subjects
- Adult, Aged, Aged, 80 and over, Consensus, Databases, Factual, Female, Follow-Up Studies, Humans, Lymph Nodes pathology, Male, Middle Aged, Neoplasm Staging standards, Prognosis, Reproducibility of Results, Survival Analysis, Carcinoma, Merkel Cell mortality, Carcinoma, Merkel Cell pathology, Neoplasm Staging methods, Skin Neoplasms mortality, Skin Neoplasms pathology
- Abstract
Background: The management of Merkel cell carcinoma (MCC) has been complicated by a lack of detailed prognostic data and by the presence of conflicting staging systems., Objective: We sought to determine the prognostic significance of tumor size, clinical versus pathologic nodal evaluation, and extent of disease at presentation and thereby derive the first consensus staging/prognostic system for MCC., Methods: A total of 5823 prospectively enrolled MCC cases from the National Cancer Data Base had follow-up data (median 64 months) and were used for prognostic analyses., Results: At 5 years, overall survival was 40% and relative survival (compared with age- and sex-matched population data) was 54%. Among all MCC cases, 66% presented with local, 27% with nodal, and 7% with distant metastatic disease. For cases presenting with local disease only, smaller tumor size was associated with better survival (stage I, ≤2 cm, 66% relative survival at 5 years; stage II, >2 cm, 51%; P < .0001). Patients with clinically local-only disease and pathologically proven negative nodes had better outcome (76% at 5 years) than those who only underwent clinical nodal evaluation (59%, P < .0001)., Limitations: The National Cancer Data Base does not capture disease-specific survival. Overall survival for patients with MCC was therefore used to calculate relative survival based on matched population data., Conclusion: Although the majority (68%) of patients with MCC in this nationwide cohort did not undergo pathologic nodal evaluation, this procedure may be indicated in many cases as it improves prognostic accuracy and has important treatment implications for those found to have microscopic nodal involvement., (Copyright © 2010 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
50. FlbC is a putative nuclear C2H2 transcription factor regulating development in Aspergillus nidulans.
- Author
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Kwon NJ, Garzia A, Espeso EA, Ugalde U, and Yu JH
- Subjects
- Amino Acid Sequence, Aspergillus nidulans genetics, Cell Nucleus chemistry, Conserved Sequence, DNA, Fungal genetics, DNA, Fungal metabolism, Fungal Proteins genetics, Gene Deletion, Gene Expression Profiling, Hyphae growth & development, Molecular Sequence Data, Promoter Regions, Genetic, Protein Binding, RNA, Messenger biosynthesis, RNA, Messenger genetics, Sequence Alignment, Spores, Fungal growth & development, Transcription Factors genetics, Aspergillus nidulans growth & development, Aspergillus nidulans metabolism, Fungal Proteins metabolism, Transcription Factors metabolism
- Abstract
Asexual development (conidiation) in Aspergillus is governed by multiple regulators. Here, we characterize the upstream developmental activator FlbC in Aspergillus nidulans. flbC mRNA is detectable throughout the life cycle, at relatively high levels during vegetative growth, early asexual and late sexual developmental phases. The deletion of flbC causes a delay/reduction in conidiation, brlA and vosA expression, and conidial germination. While overexpression of flbC (OEflbC) does not elaborate conidiophores, it inhibits hyphal growth and activates expression of brlA, abaA and vosA, but not wetA. FlbC is conserved in filamentous Ascomycetes containing two C(2) H(2) zinc fingers at the C-terminus and a putative activation domain at the N-terminus. FlbC localizes in the nuclei of both hyphae and developmental cells. Localization and expression of FlbC are not affected by the absence of FlbB or FlbE, and vice versa. Importantly, overexpression of flbC causes growth inhibition and activation of abaA and vosA in the absence of brlA and abaA respectively. In vitro DNA-binding assay reveals that FlbC binds to the brlA, abaA and vosA, but not the wetA, promoters. In summary, FlbC is a putative nuclear transcription factor necessary for proper activation of conidiation, and its balanced activity is crucial for governing growth and development in A. nidulans., (© 2010 Blackwell Publishing Ltd.)
- Published
- 2010
- Full Text
- View/download PDF
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