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Currently, a reliable serum biomarker for hepatocellular carcinoma (HCC) has not been established, particularly for early‐stage HCC (single tumor 0.8. In our validation study, serum exo‐miR‐4661‐5p could diagnose HCC in all stages (AUROC = 0.917), even in early stage (AUROC = 0.923), with a greater accuracy than other candidate serum exo‐miRs and serum AFP. The panel composed of exo‐miR‐4661‐5p and exo‐miR‐4746‐5p was identified as the most accurate biomarker for early‐stage HCC (AUROC = 0.947, 95% confidence interval = 0.889‐0.980, sensitivity = 81.8%, and specificity = 91.7%). In conclusion, exo‐miR‐4661‐5p–based serum panel is a promising diagnostic marker for early‐stage HCC., The present study derived potential serum exosomal microRNA panels for hepatocellular carcinoma (HCC) using a systematic, genome‐wide biomarker discovery approach. Serum exosomal microRNA‐4661‐5p–based panel is a potent diagnostic biomarker for early stage HCC and could also be used as a prognostic indicator in patients with HCC.

Reverse transcription-quantitative (RT-q) PCR is the most feasible and useful technique for identifying and evaluating cancer biomarkers; however, the method requires suitable reference genes for gene expression analysis. The aim of the present study was to identify the most suitable reference gene for the normalization of relative gene expression in human hepatocellular carcinoma (HCC) tissue and blood samples. First, 14 candidate reference genes were selected through a systematic literature search. The expression levels of these genes (ACTB, B2M, GAPDH, GUSB, HMBS, HPRT1, PGK1, PPIA, RPLP0, RPL13A, SDHA, TBP, TFRC and YWHAZ) were evaluated using human multistage HCC transcriptome data (dataset GSE114564), which included normal liver (n=15), chronic hepatitis (n=20), liver cirrhosis (n=10), and early (n=18) and advanced HCC (n=45). From the 14 selected genes, five genes, whose expression levels were stable in all liver disease statuses (ACTB, GAPDH, HMBS, PPIA and RPLP0), were further assessed using RT-qPCR in 40 tissues (20 paired healthy tissues and 20 tissues from patients with HCC) and 40 blood samples (20 healthy controls and 20 samples from patients with HCC). BestKeeper statistical algorithms were used to identify the most stable reference genes, of which HMBS was found to be the most stable in both HCC tissues and blood samples. Therefore, the results of the present study suggest HMBS as a promising reference gene for the normalization of relative RT-qPCR techniques in HCC-related studies.

Exosomal microRNAs (exo-miRs) contribute to cancer metastasis. To identify pro-metastatic circulating exo-miRs in hepatocellular carcinoma (HCC), next-generation sequencing-based plasma exo-miR profiles of 14 patients with HCC (eight non-metastatic and six with metastasis within 1 year of follow-up) were analyzed. Sixty-one miRs were significantly overexpressed among patients with metastatic HCC. Candidate miRs were selected through integrative analyses of two different public expression datasets, GSE67140 and The Cancer Genome Atlas liver hepatocellular carcinoma (TCGA_LIHC). Integrative analyses revealed 3 of 61 miRs (miR-106b-5p, miR-1307-5p, and miR-340-5p) commonly overexpressed both in metastasis and vascular invasion groups, with prognostic implications. Validation was performed using stored blood samples of 150 patients with HCC. Validation analysis showed that circulating exo-miR-1307-5p was significantly overexpressed in the metastasis group (p = 0.04), as well as in the vascular invasion and tumor recurrence groups. Circulating exo-miR-1307-5p expression was significantly correlated with tumor stage progression (p &lt, 0.0001). Downstream signaling pathways of miR-1307 were predicted using TargetScan and Ingenuity Pathway Analysis. On comprehensive bioinformatics analysis, the downstream pathway of miR-1307-5p, promoting epithelial&ndash, mesenchymal transition (EMT), showed SEC14L2 and ENG downregulation. Our results show that circulating exo-miR-1307-5p promotes metastasis and helps predict metastasis in HCC, and SEC14L2 and ENG are target tumor suppressor genes of miR-1307 that promote EMT.

Liquid biopsy can provide a strong basis for precision medicine. We aimed to identify novel single-nucleotide variants (SNVs) in circulating tumor DNA (ctDNA) in patients with hepatocellular carcinoma (HCC). Deep sequencing of plasma-derived ctDNA from 59 patients with HCC was performed using a panel of 2924 SNVs in 69 genes. In 55.9% of the patients, at least one somatic mutation was detected. Among 25 SNVs in 12 genes, four frequently observed SNVs, MLH1 (13%), STK11 (13%), PTEN (9%), and CTNNB1 (4%), were validated using droplet digital polymerase chain reaction with ctDNA from 62 patients with HCC. Three candidate SNVs were detected in 35.5% of the patients, with a frequency of 19% for MLH1 chr3:37025749T>A, 11% for STK11 chr19:1223126C>G, and 8% for PTEN chr10:87864461C>G. The MLH1 and STK11 SNVs were also confirmed in HCC tissues. The presence of the MLH1 SNV, in combination with an increased ctDNA level, predicted poor overall survival among 107 patients. MLH1 chr3:37025749T>A SNV detection in ctDNA is feasible, and thus, ctDNA can be used to detect somatic mutations in HCC. Furthermore, the presence or absence of the MLH1 SNV in ctDNA, combined with the ctDNA level, can predict the prognosis of patients with HCC.

Hepatocellular carcinoma (HCC) has a high rate of cancer recurrence (up to 70%) in patients who undergo surgical resection. We investigated prognostic gene signatures for predicting HCC recurrence using in silico gene expression analysis. Recurrence-associated gene candidates were chosen by a comparative analysis of gene expression profiles from two independent whole-transcriptome datasets in patients with HCC who underwent surgical resection. Five promising candidate genes, CETN2, HMGA1, MPZL1, RACGAP1, and SNRPB were identified, and the expression of these genes was evaluated using quantitative reverse transcription PCR in the validation set (n = 57). The genes CETN2, HMGA1, RACGAP1, and SNRPB, but not MPZL1, were upregulated in patients with recurrent HCC. In addition, the combination of HMGA1 and MPZL1 demonstrated the best area under the curve (0.807, 95% confidence interval [CI] = 0.681–0.899) for predicting HCC recurrence. In terms of clinicopathological correlation, CETN2, MPZL1, RACGAP1, and SNRPB were upregulated in patients with microvascular invasion, and the expression of MPZL1 and SNRPB was increased in proportion to the Edmonson tumor differentiation grade. Additionally, overexpression of CETN2, HMGA1, and RACGAP1 correlated with poor overall survival (OS) and disease-free survival (DFS) in the validation set. Finally, Cox regression analysis showed that the expression of serum alpha-fetoprotein and RACGAP1 significantly affected OS, whereas platelet count, microvascular invasion, and HMGA1 expression significantly affected DFS. In conclusion, HMGA1 and RACGAP1 may be potential prognostic biomarkers for predicting the recurrence of HCC after surgical resection.

The roles of chromatin remodelers and their underlying mechanisms of action in cancer remain unclear. In this study, SMARCB1, known initially as a bona fide tumor suppressor gene, was investigated in liver cancer. SMARCB1 was highly upregulated in patients with liver cancer and was associated with poor prognosis. Loss- and gain-of-function studies in liver cells revealed that SMARCB1 loss led to reduced cell proliferation, wound healing capacity, and tumor growth in vivo. Although upregulated SMARCB1 appeared to contribute to switch/sucrose nonfermentable (SWI/SNF) complex stability and integrity, it did not act using its known pathways antagonism with EZH2 or association between TP53 or AMPK. SMARCB1 knockdown induced a mild reduction in global H3K27 acetylation, and chromatin immunoprecipitation sequencing of SMARCB1 and acetylated histone H3K27 antibodies before and after SMARCB1 loss identified Nucleoporin210 (NUP210) as a critical target of SMARCB1, which bound its enhancer and changed H3K27Ac enrichment and downstream gene expression, particularly cholesterol homeostasis and xenobiotic metabolism. Notably, NUP210 was not only a putative tumor supporter involved in liver cancer but also acted as a key scaffold for SMARCB1 and P300 to chromatin. Furthermore, SMARCB1 deficiency conferred sensitivity to doxorubicin and P300 inhibitor in liver cancer cells. These findings provide insights into mechanisms underlying dysregulation of chromatin remodelers and show novel associations between nucleoporins and chromatin remodelers in cancer. Significance: This study reveals a novel protumorigenic role for SMARCB1 and describes valuable links between nucleoporins and chromatin remodelers in cancer by identifying NUP210 as a critical coregulator of SMARCB1 chromatin remodeling activity.

// Sung Kyung Choi 1, * , Kurinji Pandiyan 2, 3, * , Jung Woo Eun 4 , Xiaojing Yang 2 , Seong Hwi Hong 1 , Suk Woo Nam 4 , Peter A. Jones 5 , Gangning Liang 2 and Jueng Soo You 1, 6 1 Department of Biochemistry, School of Medicine, Konkuk University, Seoul, Korea 2 Departments of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA 3 Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, MD, USA 4 Department of Pathology, College of Medicine, The Catholic University, Seoul, Korea 5 Van Andel Research Institute, Grand Rapids, MI, USA 6 Research Institute of Medical Science, KonKuk University School of Medicine, Seoul, Korea * These authors contributed equally to this work Correspondence to: Jueng Soo You, email: jsyou@kku.ac.kr Keywords: epigenetic landscape, EMT, DNA methylation, chromatin accessibility, TRIM29 Received: August 01, 2017 Accepted: September 22, 2017 Published: October 09, 2017 ABSTRACT Epithelial to mesenchymal transition (EMT) is a key trans-differentiation process, which plays a critical role in physiology and pathology. Although gene expression changes in EMT have been scrutinized, study of epigenome is in its infancy. To understand epigenetic changes during TWIST-driven EMT, we used the AcceSssIble assay to study DNA methylation and chromatin accessibility in human mammary epithelial cells (HMECs). The DNA methylation changes were found to have functional significance in EMT – i.e. methylated genes were enriched for E-box motifs that can be recognized by TWIST, at the promoters suggesting a potential targeting phenomenon, whereas the demethylated regions were enriched for pro-metastatic genes, supporting the role of EMT in metastasis. TWIST-induced EMT triggers alterations in chromatin accessibility both independent of and dependent on DNA methylation changes, primarily resulting in closed chromatin conformation. By overlapping the genes, whose chromatin structure is changed during early EMT and a known “core EMT signature”, we identified 18 driver candidate genes during EMT, 14 upregulated and 4 downregulated genes with corresponding chromatin structure changes. Among 18 genes, we focused on TRIM29 as a novel marker of EMT. Although loss of TRIM29 is insufficient to suppress CDH, it is enough to induce CDH2 and VIM. Gene functional annotation analysis shows the involvement of TRIM29 in epidermal development, cell differentiation and cell migration. Taken together, our results provide a robust snapshot of chromatin state during human EMT and identify TRIM29 as a core mediator of EMT.

// Jung Woo Eun 1 , Hee Doo Yang 1 , Soo Hyun Kim 2 , Sungyoup Hong 3 , Kyu Nam Park 2 , Suk Woo Nam 1 and Sikyoung Jeong 3 1 Department of Pathology, Functional RNomics Research Center, Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 2 Department of Emergency Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 3 Department of Emergency Medicine, College of Medicine, The Catholic University of Korea, Daejeon, Republic of Korea Correspondence to: Sikyoung Jeong, email: // Keywords : peripheral blood transcriptome, molecular signature, neurological prognosis, cardiac arrest, cerebral performance category, Pathology Section Received : October 27, 2016 Accepted : January 19, 2017 Published : January 28, 2017 Abstract Background: Early prognostication of neurological outcome in comatose patients after cardiac arrest (CA) is important for devising patient treatment strategies. However, there is still a lack of sensitive and specific biomarkers for easy identification of these patients. We evaluated whether molecular signatures from blood of CA patients might help to improve the prediction of neurological outcome. Methods: We examined 22 comatose patients resuscitated after CA and obtained peripheral blood samples 48 hours after CA. To identify novel blood biomarkers, we aimed to measure neurological outcomes according to the Cerebral Performance Category (CPC) score at 6 months after CA and to determine blood transcriptome-based molecular signature of poor neurological outcome group. Results: According to the CPC score, 10 patients exhibited a CPC score of one and 12 patients, a CPC score four to five. Blood transcriptomics revealed differently expressed profiles between the good outcome group and poor outcome group. A total of 150 genes were down-regulated and 237 genes were up-regulated in the poor neurological outcome group compared with good outcome group. From the blood transcriptome-based signatures, we identified that MAPK3, BCL2 and AKT1 were more specific and sensitive diagnostic biomarkers in poor neurological outcome with an area under the curve of 0.867 ( p

BACKGROUND/AIM Fibroblast growth factor (FGF), vascular endothelial growth factor, and hepatocyte growth factor play a critical role in the pathogenesis of hepatocellular carcinoma (HCC). MATERIALS AND METHODS We assessed nine single nucleotide polymorphisms (SNPs) in the FGF1, FGF2, FGF receptor (FGFR)-2, Flt-1, and c-MET genes in 245 HCC patients and 483 chronic hepatitis B virus (HBV) carriers without HCC. RESULTS Kaplan-Meier analysis showed that patients with the FGF2 rs308447 TT genotype had shorter overall survival than patients with the CC or CT genotype (p=0.016) and that FGF2 rs308379 A allele carriers had shorter overall survival than patients with the TT genotype (p=0.020). CONCLUSION Multivariate Cox proportional analysis revealed that the FGF2 rs308379 A allele (hazard ratio(HR)=1.663, p=0.004) and advanced tumor stage (HR=3.430, p

H2A.Z is a highly conserved H2A variant, and two distinct H2A.Z isoforms, H2A.Z.1 and H2A.Z.2, have been identified as products of two non-allelic genes, H2AFZ and H2AFV. H2A.Z has been reported to be overexpressed in breast, prostate and bladder cancers, but most studies did not clearly distinguish between isoforms. One recent study reported a unique role for the H2A.Z isoform H2A.Z.2 as a driver of malignant melanoma. Here we first report that H2A.Z.1 plays a pivotal role in the liver tumorigenesis by selectively regulating key molecules in cell cycle and epithelial-mesenchymal transition (EMT). H2AFZ expression was significantly overexpressed in a large cohort of hepatocellular carcinoma (HCC) patients, and high expression of H2AFZ was significantly associated with their poor prognosis. H2A.Z.1 overexpression was demonstrated in a subset of human HCC and cell lines. H2A.Z.1 knockdown suppressed HCC cell growth by transcriptional deregulation of cell cycle proteins and caused apoptotic cell death of HCC cells. We also observed that H2A.Z.1 knockdown reduced the metastatic potential of HCC cells by selectively modulating epithelial-mesenchymal transition regulatory proteins such as E-cadherin and fibronectin. In addition, H2A.Z.1 knockdown reduced the in vivo tumor growth rate in a mouse xenograft model. In conclusion, our findings suggest the oncogenic potential of H2A.Z.1 in liver tumorigenesis and that it plays established role in accelerating cell cycle transition and EMT during hepatocarcinogenesis. This makes H2A.Z.1 a promising target in liver cancer therapy.

The interleukin-7 receptor (IL7R) is generally expressed in immune cells and is critical in survival, development and homeostasis in the immune system. Advanced genome-wide cancer studies have reported that IL7R is genetically amplified in human esophageal squamous cell carcinoma (ESCC), however, the exact role of IL7R in ESCC has not been investigated. In the present study, it was found that IL7R was overexpressed in ESCC cohorts and the loss of IL7R induced anti-oncogenic effects in ESCC cell lines. A small panel of epigenetic drugs were screened for their ability to downregulate the expression of IL7R. Unexpectedly, apicidin, a histone deacetylase (HDAC) inhibitor, effectively downregulated the expression of IL7R in a dose-dependent manner at an early time-point, as determined by quantitative polymerase chain reaction and IL7R immunostaining, and did not require de novo protein synthesis. Of note, apicidin induced the acetylation of Forkhead box-containing protein, O subfamily 1, which acts as a repressor at the IL7R promoter, accompanied with depleted active histone modifications based on chromatin immunoprecipitation assay. Taken together, these results demonstrated that targeting oncogenic IL7R in ESCC by HDAC inhibitors may be a valuable therapeutic approach.

// Hun-Jun Park 1, * , Ji Heon Noh 2, 3, * , Jung Woo Eun 2, 3, * , Yoon-Seok Koh 1 , Suk Min Seo 1 , Won Sang Park 2 , Jung Young Lee 2 , Kiyuk Chang 1 , Ki Bae Seung 1 , Pum-Joon Kim 1 , Suk Woo Nam 2, 3, 4 1 Department of Cardiology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 2 Department of Pathology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 3 Functional RNomics Research Center, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 4 Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea * These authors have contributed equally to this work Correspondence to: Suk Woo Nam, e-mail: swnam@catholic.ac.kr Pum-Joon Kim, e-mail: bjheart@catholic.ac.kr Keywords: ST-segment-elevation myocardial infarction, peripheral blood transcriptome, molecular signature, diagnostic biomarkers Received: March 25, 2015 Accepted: May 04, 2015 Published: May 18, 2015 ABSTRACT Blood transcriptome reflects the status of diseases, and characteristic molecular signature provides a novel window on gene expression preceding acute coronary events. We aim to determine blood transcriptome-based molecular signature of acute coronary syndrome (ACS), and to identify novel serum biomarkers for early stage ST-segment-elevation myocardial infarction (STEMI). We obtained peripheral blood from the patients with ACS who visited emergency department within 4 hours after the onset of chest pain: STEMI ( n = 10), Non-ST-segment-elevation MI (NSTEMI, n = 10) and unstable angina (UA, n = 11). Blood transcriptome scans revealed that a characteristic gene expression change exists in STEMI, resulting in 531 outlier genes as STEMI molecular signature (Welch’s t test, P < 0.05). Another analysis with a set of blood samples of patients with STEMI ( n = 7) before and 7 days after the primary percutaneous coronary intervention ( n = 7) and normal control ( n = 10) evidenced that STEMI molecular signature directly reflects the onset of STEMI pathogenesis. From the two sets of transcriptome-based STEMI signatures, we identified 10 genes encoding transmembrane or secretory proteins that are highly expressed in STEMI. We validated blood protein expression levels of these 10 putative biomarkers in 40 STEMI and 32 healthy subjects by ELISA. Data suggested that PGLYRP1, IRAK3 and VNN3 are more specific and sensitive diagnostic biomarkers for STEMI than traditional CK-MB or troponin. Blood transcriptome scans of ACS evidenced early stage molecular markers for STEMI. Here, we report novel biomarkers to diagnose STEMI at emergency department in hospitals by a simple ELISA method.

Mutations of the HRPT2 gene, which are respon- sible for hyperparathyroidism-jaw tumor (HPT-JT) syndrome, have been implicated in the development of a high propor- tion of parathyroid carcinomas. The aim of this study was to investigate differences in expression of the most important genes connected with parathyroid carcinoma between HPT-JT syndrome due to an HRPT2 splicing mutation, normal parathyroid tissue and sporadic parathyroid adenoma. Total RNAs were extracted from parathyroid carcinoma in HPT-JT syndrome harbouring HRPT2 splicing mutation or sporadic parathyroid adenoma and normal parathyroid gland, and subjected to Illumina DASL-based gene expression assay. Unsupervised hierarchical clustering analysis was used to compare gene expression in HPT-JT syndrome, sporadic parathyroid adenoma and normal parathyroid glands. We identified differentially regulated genes in HPT-JT syndrome and sporadic parathyroid adenoma relative to normal para- thyroid glands using a combination of Welch's t-test and fold-change analysis. Quantitative PCR, RT-PCR and IHC were used for validation. Sixteen genes differentially regu- lated in the parathyroid carcinoma were associated with signal pathways, MAPK, regulation of actin cytoskeleton, prostate cancer and apoptosis. FGFR1 expression was confirmed to be significantly upregulated by validation experiments. Our gene expression profiling experiments suggest that upregulated FGFR1 expression appears to be associated with parathyroid carcinoma in HPT-JT syndrome due to an HRPT2 splicing mutation.

Aberrant regulation of histone deacetylase 2 (HDAC2) contributes to malignant progression in various cancers, but the underlying mechanism leading to the activation of oncogenic HDAC2 remains unknown. In this study, we show that HDAC2 expression is upregulated in a large cohort of patients with human hepatocellular carcinoma, and that high expression of HDAC2 was significantly associated with poor prognosis of patients with hepatocellular carcinoma. We found that mTORC1/NF-κBp50 signaling is necessary for the growth factor–induced HDAC2 and is sustained in hepatocellular carcinoma, but not in normal hepatic cells. Growth factor–induced mTORC1 activates the nuclear translocation of NF-κBp50, where it binds to the intragenic sequences of the HDAC2 gene and promotes its transcription. Hepatocellular carcinoma tissues derived from chemical-induced mouse and rat liver cancer models validated that mTORC1 activation and NF-κBp50 nuclear translocation are essential for the transcriptional activation of oncogenic HDAC2 in hepatocellular carcinoma. In addition, we demonstrate that HDAC2 is required to maintain mTORC1 activity by stabilizing the mTOR/RAPTOR complex. Elevated expression of HDAC2 triggers a positive feedback loop that activates AKT phosphorylation via the transcriptional modulation of phosphoinositide signaling molecules. Bioinformatics analysis of HDAC2 signature and immunoblot analysis of mesenchymal genes also evidenced that HDAC2 plays a role in the malignant behavior of tumor cells by Snail induction and simultaneously E-cadherin suppression in hepatocellular carcinoma cells. These findings establish a molecular mechanism responsible for the activation of oncogenic HDAC2, which explains how growth factor–induced HDAC2 maintains mitogenic signaling and function during hepatocellular malignant progression and provide a novel strategy for therapeutic intervention in liver cancer. Cancer Res; 74(6); 1728–38. ©2014 AACR.

Patients with HPV-positive oropharyngeal cancer show better tumor response to radiation or chemotherapy than patients with HPV-negative cancer. HPV oncoprotein E6 binds and degrades a typically wild-type p53 protein product. However, HPV16 infection and p53 mutation infrequently coexist in a subset of HNSCCs. The purpose of this study was to investigate the mechanisms through which tumor biology and molecular genetic mechanisms change when two HPV-negative, p53-mutated oropharyngeal cell lines (YD8, non-disruptive p53 mutation; YD10B, disruptive p53 mutation) derived from patients with a history of heavy smoking are transfected with HPV E6 and E7 oncogenes in vitro. Transfection with HPV E6 and E7 oncogenes in YD8, reduced the abundance of proteins encoded by tumor suppressor genes, such as p-p53 and p-Rb. Cell proliferative activity was increased in the cells transfected with E6E7 compared to cells transfected with vector alone (P=0.09), whereas the invasiveness of E6E7-transfected cells was significantly reduced (P=0.02). cDNA microarray of the transfected cells with E6E7 showed significant changes in mRNA expression in several signaling pathways, including focal adhesion, JAK-STAT signaling pathway, cell cycle and p53 signaling pathway. Regarding the qPCR array for the p53 signaling pathway, the mRNA expression of STAT1 was remarkably upregulated by 6.47-fold (P

Aberrant regulation of histone deacetylase 2 (HDAC2) was reported for gastric cancers. However, responsive cancer genes in disease onset and progression are less understood. HDAC2 expression was studied by quantitative RT-PCR and Western blotting. The functional consequences of HDAC2 knockdown on cell-cycle regulation, programmed cell death, and gene target identification was investigated by flow cytometry, Western blotting, electron microscopy, anchorage-independent colony formation, and cell migration assay and by whole-genome microarray. Therapeutic efficacy of HDAC2 knockdown was determined in nude mice with small hairpin expressing human gastric cancer cells. Epigenetic regulation of p16INK4a was studied by methylation-specific PCR and chromatin-IP to evidence HDAC2 or acetylated-histone-H4 binding at gene specific promoter sequences. HDAC2 gene and protein expression was significantly upregulated in different histopathologic grades of human gastric cancers and cancer cell lines. HDAC2 inactivation significantly reduced cell motility, cell invasion, clonal expansion, and tumor growth. HDAC2 knockdown-induced G1–S cell cycle arrest and restored activity of p16INK4a and the proapoptotic factors. This treatment caused PARP cleavage and hypophosphorylation of the Rb-protein, repressed cyclinD1, CDK4, and Bcl-2 expression and induced autophagic phenotype, that is, LC3B-II conversion. Some gastric tumors and cancer cells displayed p16INK4a promoter hypermethylation but treatment with 5-aza-deoxycitidine restored activity. With others the methylation status was unchanged. Here, chromatin-IP evidenced HDAC2 binding. Nonetheless, expression of p16INK4a was restored by HDAC2 knockdown with notable histone-H4-acetylation, as determined by chromatin-IP. Thus, p16INK4a is regulated by HDAC2. HDAC2 is a bona fide target for novel molecular therapies in gastric cancers. Mol Cancer Res; 11(1); 62–73. ©2012 AACR.

Deregulation of the epigenome component affects multiple pathways in the cancer phenotype since the epigenome acts at the pinnacle of the hierarchy of gene expression. Pioneering work over the past decades has highlighted that targeting enzymes or proteins involved in the epigenetic regulation is a valuable approach to cancer therapy. Very recent results demonstrated that inhibiting the epigenetic reader BRD4 has notable efficacy in diverse cancer types. We investigated the potential of BRD4 as a therapeutic target in liver malignancy. BRD4 was overexpressed in three different large cohort of hepatocellular carcinoma (HCC) patients as well as in liver cancer cell lines. BRD4 inhibition by JQ1 induced anti-tumorigenic effects including cell cycle arrest, cellular senescence, reduced wound healing capacity and soft agar colony formation in liver cancer cell lines. Notably, BRD4 inhibition caused MYC-independent large-scale gene expression changes in liver cancer cells. Serial gene expression analyses with SK-Hep1 liver cancer cells treated with JQ1 to delineate the key player of BRD4 inhibition identified E2F2 as the first line of downstream direct target of BRD4. Further experiments including chromatin immunoprecipitation (ChIP) assay and loss of function study confirmed E2F2 as key player of BRD4 inhibition. Overexpressed E2F2 is a crucial center of cell cycle regulation and high expression of E2F2 is significantly associated with poor prognosis of HCC patients. Our findings reveal BRD4-E2F2-cell cycle regulation as a novel molecular circuit in liver cancer and provide a therapeutic strategy and innovative insights for liver cancer therapies.

The putative tumor suppressor, DBC1 (deleted in breast cancer-1), was recently found to negatively regulate SIRT1 in vitro and in vivo, but the mechanism whereby DBC1 regulates SIRT1 in liver cancer remains to be elucidated. In this study, it was found that although the expression of DBC1 and SIRT1 was not aberrantly regulated in a large cohort of human hepatocellular carcinoma (HCC) patients, these proteins were highly overexpressed in a subset of HCC tissues compared with surrounding non-cancer tissues. In liver cancer, DBC1 and SIRT1 were found to be positively correlated. Inactivation of DBC1 or SIRT1 reduced SNU-182 (a liver cancer cell line) proliferation as determined by MTT viability assays. Notably, although DBC1 functions as a negative regulator of SIRT1 in A549 lung cancer cells since it suppresses the deacetylase activity of the p53 protein, it did not affect the p53 deacetylase activity of SIRT1 in SNU-182 cells. Taken together, we conclude that DBC1 is associated with SIRT1 in HCC, but that it does not inhibit SIRT1.

Histone deacetylase 6 (HDAC6) uniquely endows as tumor suppressor in liver tumorigenesis, but the underlying mechanisms leading to liver cancer are not fully understood. To identify the large-scale microRNA (miRNA) expression changes by HDAC6, we performed miRNA expression analysis in HDAC6-overexpressing Hep3B cells. From this, let-7i-5p was suggested as most highly associated miRNA with HDAC6 in liver cancer cells. We also found that let-7i-5p expression was up-regulated in a large cohort of HCC patients, and high expression of let-7i-5p was significantly associated with poor prognosis of HCC patients. Ectopic expression of antisense let-7i-5p (AS-let-7i-5p) caused cancer cell growth inhibition mediated by caspase-dependent cell death processing, and inhibited epithelial-mesenchymal transition (EMT) of liver cancer cells. Computational analysis suggested that thrombospondin-1 (TSP-1) is a specific target for let-7i-5p in liver cancer cells. Increased secretion of TSP1 was detected in AS-let-7i-5p transfected HCC cells. We found that partially purified TSP-1 from culture media (ppTSP-1) induced cellular death processing and simultaneously inhibited tumor angiogenesis and metastatic behavior of liver cancer cells. In addition, we observed that anti-TSP-1 antibody containing CD47 receptor binding motif (3F352) attenuated HDAC6, AS-let-7i-5p and TSP-1 effects on liver cancer cells. Furthermore, TSP-1 and ppTSP-1 treatments significantly enhanced macrophage phagocytosis through blocking CD47-dependent “Don't eat me” signal in liver cancer cells. Our findings suggest that HDAC6-let-7i-5p-TSP-1 signaling axis regulates CD47-dependent neoplastic and phagocytic behaviors of hepatocytes providing a novel target for the molecular treatment of liver malignancies. Citation Format: Hee Doo Yang, Jung Woo Eun, Qingyu Shen, Hyung Seok Kim, Sang Yean Kim, Suk Woo Nam. Histone deacetylase 6-let-7i-5p-thrombospondin-1 signaling axis suppresses CD47-dependent tumorigenic behavior of liver cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 522.

// Hyung Seok Kim 1,2,* , Kyo Sun Lee 3,* , Hyun Jin Bae 1,2 , Jung Woo Eun 1,2 , Qingyu Shen 1,2 , Se Jin Park 1,2 , Woo Chan Shin 1,2 , Hee Doo Yang 1,2 , Mijung Park 1,2 , Won Sang Park 1,2 , Yong-Koo Kang 3 and Suk Woo Nam 1,2,4 1 Lab of Oncogenomics, Department of Pathology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 2 Functional RNomics Research Center, The Catholic University of Korea, Seoul, Republic of Korea 3 Department of Orthopedic Surgery, College of Medicine, The Catholic University of Korea, Gyeonggi-do, Korea 4 Cancer Evolution Research Center, Catholic University of Korea, Seoul, Republic of Korea * These authors contributed equally to this work Correspondence to: Suk Woo Nam, email: // Keywords : Hepatocellular carcinoma, microRNA-31, CDK2, HDAC2, cell cycle Received : October 01, 2014 Accepted : February 04, 2015 Published : March 10, 2015 Abstract MicroRNA-31 (miR-31) is among the most frequently altered microRNAs in human cancers and altered expression of miR-31 has been detected in a large variety of tumor types, but the functional role of miR-31 still hold both tumor suppressive and oncogenic roles in different tumor types. MiR-31 expression was down-regulated in a large cohort of hepatocellular carcinoma (HCC) patients, and low expression of miR-31 was significantly associated with poor prognosis of HCC patients. Ectopic expression of miR-31 mimics suppressed HCC cell growth by transcriptional deregulation of cell cycle proteins. Additional study evidenced miR-31 directly to suppress HDAC2 and CDK2 expression by inhibiting mRNA translation in HCC cells. We also found that ectopic expression of miR-31 mimics reduced metastatic potential of HCC cells by selectively regulating epithelial-mesenchymal transition (EMT) regulatory proteins such as N-cadherin, E-cadherin, vimentin and fibronectin . HCC tissues derived from chemical-induced rat liver cancer models validated that miR-31 expression is significantly down-regulated, and that those cell cycle- and EMT-regulatory proteins are deregulated in rat liver cancer. Overall, we suggest that miR-31 functions as a tumor suppressor by selectively regulating cell cycle and EMT regulatory proteins in human hepatocarcinogenesis providing a novel target for the molecular treatment of liver malignancies.

Alternative splicing is one of the crucial mechanism that contribute to proteome diversity and, as reported, up to 90% of genes are alternatively spliced in human. In the last few years, a large number of mRNA isoforms revealed to contribute many cellular development and disease, including cancer. SF3B4 is one of six subunits of the splicing factor 3b (SF3b) complex which is an important protein complex in U2 snRNP super complex. In this study, we show that SF3B4 expression was overexpressed in a large cohort of human hepatocellular carcinoma (HCC) patients. SF3B4 knockdown caused G1/S cell cycle arrest by recovering p27 expression and simultaneously suppressing cyclins, and CDKs in liver cancer cell. Consistently, Spliceostatin A, a SF3b complex inhibitor, also suppressed liver cancer cell growth with similar effect on cell cycle regulation. In addition, sustained suppression of SF3B4 reduced the in vivo tumor growth rate in mouse xenograft models. Furthermore, SF3B4 knockdown repressed in vitro tumor cell motility and invasion of liver cancer cells. Notably, we observed that SF3B4 knockdown increased alternative transcript splicing event of a large number of genes in liver cancer cells. From this, we found that SF3B4 knockdown caused induction of wildtype KLF4 transcript expression, and thereby exerted anti-tumor growth effect on liver cancer cells. Indeed, ectopic expression of KLF4 mimicked SF3B4 knockdown effect on same cells. Our results suggest that aberrant regulation of SF3B4 contribute to malignant transformation and growth of liver cancer cells by repression of tumor suppressor via unmodulated alternative splicing activity during liver tumorigenesis. Citation Format: Qingyu Shen, Jung Woo Eun, Hyung Seok Kim, Hee Doo Yang, Sang Yean Kim, Suk Woo Nam. A subunit of splicing factor 3b, SF3B4, functions as driver of liver cancer via aberrant splicing activity on tumor suppressor KLF4 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4472. doi:10.1158/1538-7445.AM2017-4472

Recurrence and metastasis are a major challenge in the management of hepatocellular carcinoma (HCC) patients after HCC resection. In order to identify metastatic molecular signature, we performed comparative gene expression profiling analysis with recurred HCC tissues from HCC patients who underwent partial or total hepatectomy and non-metastatic primary HCC. From this, we were able to recapitulate molecular signatures associate with HCC recurrence, and found that TCIRG1 (T-Cell Immune Regulator 1) was one of the aberrantly overexpressed gene elements in recurred HCC patients with total hepatectomy. We then observed that TCIRG1 is significantly overexpressed in TCGA-LIHC (Liver Hepatocellular Carcinoma Dataset of The Cancer Genome Atlas), and high expression of TCIRG1 was significantly associated with poor prognosis of HCC patients in 5-year disease-free. TCIRG1 knockdown suppressed tumor cell growth and proliferation in Huh7 and SNU475, liver cancer cell lines. From flow cytometric analysis for cell cycle analysis and cell death, we observed that TCIRG1 knockdown caused a significant increase of G1/S phase, and also induced programmed cell death processing in liver cancer cells. TCIRG1 knockdown also reduced the metastatic potential of HCC cells by selectively regulating epithelial-mesenchymal transition (EMT) regulatory proteins, E-cadherin, N-cadherin, Vimentin, Fibronectin, Snail and Slug, in liver cancer cells. In addition, sustained expression of TCIRG1 in liver cancer cell line reduced tumor growth rate in mouse xenograft model. Moreover, targeted-disruption of TCIRG1 significantly attenuated the metastatic potential of ras-transformed NIH-3T3 cells in vitro and in vivo. In conclusion, our findings suggest that TCIRG1 functions as metastatic enhancing gene by modulating cellular growth, death, and EMT in liver cancer cells providing TCIRG1 as a therapeutic target for the treatment of liver malignancy and metastasis. Citation Format: Hee Doo Yang, Jung Woo Eun, Qingyu Shen, Hyung Seok Kim, Sang Yean Kim, Suk Woo Nam. TCIRG1, T-cell immune regulator 1, functions as a metastatic enhancing gene in liver tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3829. doi:10.1158/1538-7445.AM2017-3829

The aberrant regulation of histone deacetylase 6 (HDAC6) contributes to malignant progression in various types of cancer, but the mechanism underlying gastric carcinogenesis remains unknown. Aberrant HDAC6 overexpression was observed in a subset of human gastric cancer cells. HDAC6 knockdown caused the significant inhibition of gastric cancer cell growth without affecting the transition of cell cycles or the processing of cell death. We demonstrate that an increase in epidermal growth factor receptor (EGFR) signaling through decreased EGFR degradation was mediated by HDAC6 in gastric carcinogenesis. These results establish a molecular mechanism responsible for oncogenic HDAC6, explaining how EGFR signaling induced by the growth factor is sustained during the malignant progression of gastric cancer.

Nemo-like kinase (NLK), an evolutionarily conserved MAP kinase-related kinase, has been reported to be involved in the development of hepatocellular carcinoma (HCC), but the underlying mechanisms leading to oncogenic NLK are poorly understood. A comprehensive microRNA (miRNA) profiling analysis on human HCC tissues identified four downregulated miRNAs that may target NLK. Ectopic expression of miRNA mimics suggested that miR-101 could suppress NLK in HCC cells. Notably, ectopic miR-101 expression repressed cancer cell growth and proliferation and imitated NLK knockdown effect on HCC cells. In conclusion, we suggest that miR-101 functions as a tumor suppressor by regulating abnormal NLK activity in liver.

Hepatocellular carcinoma (HCC) is the fifth frequently diagnosed cancer and is the second leading cause of cancer death worldwide. Many groups have suggested possible clinical applications for liver cancer therapy but sorafenib, an orally-available kinase inhibitor, is the only standard systematic therapeutics for treatment of hepatocellular carcinoma. However, survival benefit of sorafenib is unsatisfactory due to high level heterogeneity of individual response. We previously reported that histone deacetylase 2 (HDAC2) was deregulated in HCC, and thereby contributed to liver tumorigenesis by enhancing mitotic and metastatic potential of transformed cells. Targeted-disruption of HDAC2 suppressed in vitro and in vivo tumorgigenic potential of HDAC2 in liver cancer. The goal of this study was to investigate whether both sorafenib treatment and HDAC2 inhibition elicit synergistic anti-tumor effect against HCC cells. Here, we showed that sorafenib effectively blocked ERK/MEK and AKT signaling pathway upon EGF stimulation in liver cancer cell lines. Also, we found that valproic acid (VPA), a selective inhibitor of histone deacetylase family I, and sorafenib treatment synergistically evoked liver cancer cell growth retardation. This effect was recapitulated by HDAC2 knockdown with sorafenib treatment and exhibited synergistic effect on apoptotic cell death of liver cancer cell lines, Hep3B and Huh7, compared to single treatment of sorafenib. Our data suggest that combined sorafenib treatment with HDAC2 targeting may provide more benefits toward HCC therapy providing a novel approach for future application in patients with advanced HCC. Citation Format: Hyung Seok Kim, Jung Woo Eun, Qingyu Shen, Woo Chan Shin, Hee Doo Yang, Sang Yeon Kim, Suk Woo Nam. Histone deacetylase 2 is a potential determinant of the sensitivity of hepatocellular carcinoma cells to sorafenib. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4810.

Aberrant regulation of histone deacetylase 2 (HDAC2) plays a pivotal role in the development of hepatocellular carcinoma (HCC), but, the underlying mechanism leading to HDAC2 overexpression is not well understood. We performed microRNA (miRNA) profiling analysis in a subset of HCCs, and identified four down-regulated miRNAs that may target HDAC2 in HCC. Ectopic expression of miRNA mimics evidenced that miR-145 suppresses HDAC2 expression in HCC cells. This treatment repressed cancer cell growth and recapitulated HDAC2 knockdown effects on HCC cells. In conclusion, we suggest that loss or suppression of miR-145 may cause aberrant overexpression of HDAC2 and promote HCC tumorigenesis.

Histone deacetylases (HDACs) are known to play a central role in the regulation of several cellular properties interlinked with the development and progression of cancer. Recently, HDAC1 has been reported to be overexpressed in hepatocellular carcinoma (HCC), but its biological roles in hepatocarcinogenesis remain to be elucidated. In this study, we demonstrated overexpression of HDAC1 in a subset of human HCCs and liver cancer cell lines. HDAC1 inactivation resulted in regression of tumor cell growth and activation of caspase-independent autophagic cell death, via LC3B-II activation pathway in Hep3B cells. In cell cycle regulation, HDAC1 inactivation selectively induced both p21(WAF1/Cip1) and p27(Kip1) expressions, and simultaneously suppressed the expression of cyclin D1 and CDK2. Consequently, HDAC1 inactivation led to the hypophosphorylation of pRb in G1/S transition, and thereby inactivated E2F/DP1 transcription activity. In addition, we demonstrated that HDAC1 suppresses p21(WAF1/Cip1) transcriptional activity through Sp1-binding sites in the p21(WAF1/Cip1) promoter. Furthermore, sustained suppression of HDAC1 attenuated in vitro colony formation and in vivo tumor growth in a mouse xenograft model. Taken together, we suggest the aberrant regulation of HDAC1 in HCC and its epigenetic regulation of gene transcription of autophagy and cell cycle components. Overexpression of HDAC1 may play a pivotal role through the systemic regulation of mitotic effectors in the development of HCC, providing a particularly relevant potential target in cancer therapy.

Histone deacetylase 2 (HDAC2) is crucial for embryonic development, affects cytokine signaling relevant for immune responses and is often significantly overexpressed in solid tumors; but little is known about its role in human hepatocellular carcinoma (HCC). In this study, we showed that targeted-disruption of HDAC2 resulted in reduction of both tumor cell growth and de novo DNA synthesis in Hep3B cells. We then demonstrated that HDAC2 regulated cell cycle and that disruption of HDAC2 caused G1/S arrest in cell cycle. In G1/S transition, targeted-disruption of HDAC2 selectively induced the expression of p16(INK4A) and p21(WAF1/Cip1), and simultaneously suppressed the expression of cyclin D1, CDK4 and CDK2. Consequently, HDAC2 inhibition led to the down-regulation of E2F/DP1 target genes through a reduction in phosphorylation status of pRb protein. In addition, sustained suppression of HDAC2 attenuated in vitro colony formation and in vivo tumor growth in a mouse xenograft model. Further, we found that HDAC2 suppresses p21(WAF1/Cip1) transcriptional activity via Sp1-binding site enriched proximal region of p21(WAF1/Cip1) promoter. In conclusion, we suggest that the aberrant regulation of HDAC2 may play a pivotal role in the development of HCC through its regulation of cell cycle components at the transcription level providing HDAC2 as a relevant target in liver cancer therapy.

The transforming growth factor receptor III (TGFbetaRIII) is the most abundant and essential TGF-beta binding protein that functions as a co-receptor with other receptors in TGF-beta signaling. In earlier studies, expression of TGFbetaRIII was reported to be decreased in a variety of human cancers. Functional assessment of TGFbetaRIII was performed in many previously studied cancers but not in hepatocellular carcinoma. Therefore, in this study, we investigated the expression and genetic alterations of TGFbetaRIII in hepatocellular carcinoma (HCC) by quantitative real-time PCR (qRT-PCR) and single-strand conformation polymorphism (SSCP) analysis. The qRT-PCR showed down-regulation of TGFbetaRIII in the tumor samples. To investigate whether genetic alterations mediated decreased expression of TGFbetaRIII, we performed mutation analysis of 67 human HCC tissues by SSCP and direct sequencing. We found five previously reported and one novel single nucleotide polymorphisms in exons 2, 3, 5, 13 and 14, but no mutations were detected. These polymorphisms were not associated with amino acid changes except for a base change found in exon 2 (TCC-->TTC, S15F). The loss of heterozygosity (LOH) analysis performed on 10 tumors and corresponding normal pairs, showed a low rate of LOH (2/10). The results of this study suggest that TGFbetaRIII is transcriptionally down-regulated in hepatocellular carcinoma. In addition, genetic alterations did not appear to be associated with the reduced expression level of TGFbetaRIII. To clarify the role of TGFbetaRIII in hepatocellular tumor development and progression, functional analysis is needed in future studies.

Many clinical studies of cancer patients have established that the most common reason behind changes in HDAC function is its overexpression. However, among HDACs in liver cancer, HDAC6, a cytoplasmic tubulin deacetylase, is uniquely endowed with a tumor suppressor, but the mechanism underlying HDAC6 inactivation has yet to be uncovered. In this study we show that genetic and epigenetic dysregulation was not part of the HDAC6 inactivation mechanism. Instead, microRNA-221-3p (miR-221) directly suppressed HDAC6 in hepatocellular carcinoma (HCC) cells. A comprehensive miRNA profiling analysis identified seven putative endogenous miRNAs that are significantly upregulated in HCC. Ectopic expression of miRNA mimics in Dicer knockdown cells evidenced miR-221 to suppress HDAC6 in HCC cells. Notably, targeted-disruption of miR-221 repressed cancer cell growth and proliferation, and it recapitulated HDAC6 overexpression effects in HCC cells. Our results also demonstrate that c-Met-mediated c-Jun NH2-terminal kinase (JNK)/c-Jun signaling induced miR-221 to suppress HDAC6 and was sustained in liver cancer cells but not in normal hepatic cells. In addition, cytokine-induced NF-κBp65 independently regulated miR-221, thereby suppressing HDAC6 expression in liver cancer cells. HCC tissues derived from chemical-induced rat liver cancer models validated that JNK/c-Jun activation and NF-kBp65 nuclear translocation are essential for the transcriptional activation of oncogenic miR-221 to repress tumor suppressor HDAC6 in HCC. In conclusion, our finding suggest that the functional loss or suppression of the tumor suppressor HDAC6 is caused by miR-221 through coordinated JNK/c-Jun- and NF-κB-signaling pathways during liver tumorigenesis, providing a novel target for the molecular treatment of liver malignancies. Citation Format: Hyung Seok Kim, Qingyu Shen, Jung Woo Eun, Woo Chan Shin, Hee Doo Yang, Won Sang Park, Joung Young Lee, Suk Woo Nam. JNK/c-Jun- and NF-κB-mediated microRNA-221 governs tumor suppressor HDAC6 to potentiate malignant progression of liver cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3111. doi:10.1158/1538-7445.AM2015-3111

Cytoplasmic deacetylase, histone deacetylase 6 (HDAC6) is a critical component of the lysomal protein degradation pathways. HDAC6 has been shown to be involved in carcinogenic transformation and to modulate the epithelial-mesenchymal transition in several cancers by way of the regulations of several critical cellular functions, but the biological roles in gastric carcinogenesis remains to be elucidated. In this study, we observed that HDAC6 is aberrantly over-expressed in a subset of gastric cancer, and that targeted-inactivation of HDC6 caused cell cycle and cell death pathways-independent growth inhibition. Additional experiments evidenced that ectopic overexpression of HDAC6 sustains epidermal growth factor receptor (EGFR) degradation in EGF-stimulated gastric cancer cells. In addition, we found that HDAC6 inactivation recovered rabaptin 5, a Rab5 interacting protein potentiating Rab5, a small GTPase that regulates early endocytic events. These findings suggest that aberrant overexpression of HDAC6 confers gastric cancer cells to sustain EGF-signaling by retardation of EGFR degradation by way of repression of rababtin-5, and HDAC6 is a bona fide target for therapeutic intervention in gastric cancers. Note: This abstract was not presented at the meeting. Citation Format: Se Jin Park, Hyun Jin Bae, Jung Woo Eun, Qinngyu Shen, Hyung Seok Kim, Woo Chan Shin, Won Sang Park, Jung Young Lee, Suk Woo Nam. Aberrant expression of HDAC6 sustains malignant progression by preventing epidermal growth factor receptor degradation in gastric cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5261. doi:10.1158/1538-7445.AM2014-5261

Epigenetic effector molecules are involved in many biological processes by regulating post-translational histone modification and DNA methylation. Recent evidence has suggested that several epigenetic effectors are aberrantly over-expressed in gastric cancer (GC). However, underlying regulatory mechanisms of those molecules are not completely understood. In this study, we identified miR-495-3p which regulates multiple epigenetic effectors through a comprehensive miRNA profiling analysis with in silico target prediction in GC. The down-regulation of miR-495-3p was demonstrated in a subset of GC tissue, revealing inverse correlation with expression levels of epigenetic effectors that were predicted to be targeted by miR-495-3p. Ectopic overexpression of miR-495-3p in GC cells suppressed protein expression and 3’-UTR (untranslated region) reporter luciferase activity of multiple epigenetic effectors including histone deacetylase 2 (HDAC2), SET and MYND domain-containing protein 3 (SMYD3), DNA methyltransferase 1 (DNMT1) and metastasis-associated protein1 (MTA1). Moreover, miR-495-3p attenuated cancer cell proliferation accompanied with LC3B-II conversion, PARP cleavage, p16INK4A expression and down-regulation of CDK4/6 and cyclin D1, which were implicated in autophagic cell death, apoptosis and cell cycle regulation, respectively. In addition, ectopically over-expressed miR-495-3p inhibits cell migration via suppressing epithelial-mesenchymal transition (EMT)-related molecules, Snail and SLUG. Taken together, we suggest that a loss or down-regulation of endogenous miR-495-3p triggers aberrant overexpression of multiple oncogenic epigenetic effector molecules, and thereby miR-495-3p functions as a tumor suppressor in gastric tumorigenesis. Citation Format: Min Gyu Kim, Seung Jin Kim, Hyun Jin Bae, Ji Heon Noh, Jeong Kyu Kim, Jung Woo Eun, Kwang Hwa Jung, Young Gyoon Chang, Qingyu Shen, Won Sang Park, Jung Young Lee, Suk Woo Nam. MicroRNA-495-3p functions as tumor suppressor by targeting multiple oncogenic epigenetic effector molecules in gastric cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5290. doi:10.1158/1538-7445.AM2013-5290 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

SIRT1 (Sirtuin 1) is the most well-known member of the class III histone deaceylase family which plays key roles in many cellular pathways by deacetylating or interacting with numerous non-histone proteins. Recent evidence has demonstrated that SIRT1 is up-regulated in a variety of human cancers and inhibition of SIRT1 expression or activity induces cancer cell growth retardation, cell cycle arrest and apoptosis. Although the functions of SIRT1 in cancer have been extensively studied, the underlying mechanisms of aberrant regulation of SIRT1 are not clearly understood. In the present study, we identified 5 microRNAs (miRNAs) that were significantly down-regulated in human hepatocellular carcinomas (HCCs) via large-scale miRNA expression analysis with computational prediction of miRNA targeting for SIRT1. Of these, it was found that miR-29c and miR-141 were directly able to suppress endogenous SIRT1 expression, but only miR-29c was able to recapitulate the effects of SIRT1 inactivation in HCC cells. In addition, the expression level of miR-29c was inversely correlated with SIRT1 protein expression levels in a subset of HCC tissues with their corresponding noncancerous tissue. The ectopic expressions of miR-29c in SNU-182 liver cancer cell lines suppressed cell growth and induced cell cycle arrest at G1-phase accompanied with the altered expressions of G1-related cellular components, such as CDK6, CDK2, cyclin D1, cyclin D3, phosphorylation of Rb and E2F1. Taken together, we suggest that loss or down-regulation of endogenous miR-29c causes aberrant overexpression of SIRT1 contributing oncogenic potential to the cells, and that a novel tumor suppression mechanism involving miR-29c may be amenable to epigenetic regulation in human HCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 179. doi:1538-7445.AM2012-179

The wnt/β-catenin signaling pathway regulates various aspects of development and plays important role in human carcinogenesis. Nemo-like kinase (NLK), which is mediator of wnt/β-catenin signaling pathway, phosphorylates T-cell factor/lymphoid enhancer factor (TCF/LEF) factor and inhibits interaction of β-catenin/TCF complex. Although, NLK is known to be a tumor suppressor in wnt/β-catenin signaling pathway of colon cancer, the other events occurring downstream of NLK pathways in other types of cancer remain unclear. In the present study, we identified that expression of NLK was significantly up-regulated in the HCCs compared to corresponding normal tissues in five selected tissue samples. Immunhistochemical analysis showed significant over-expression of NLK in the HCCs. Targeted-disruption of NLK suppressed cell growth and arrested cell-cycle transition. Suppression of NLK elicited anti-mitogenic properties of the Hep3B cells by simultaneous inhibition of cyclinD1 and CDK2. The results of this study suggest that NLK is aberrantly regulated in HCC, which might contribute to the mitogenic potential of tumor cells during the initiation and progression of hepatocellular carcinoma; this process appears to involve the induction of CDK2 and cyclin D1 and might provide a novel target for therapeutic intervention in patients with liver cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1079.