Search

Background: Gastric cancer (GC) stands out as one of the most prevalent malignancies affecting the digestive system, characterized by a substantial incidence rate and mortality. Maternal embryonic leucine zipper kinase (MELK) has been implicated in the advancement of various cancer types and the modulation of the tumor microenvironment. This study aims to delve into the involvement of MELK in chemoresistance and the tumor microenvironment of GC. Methods: The MELK expression was detected using quantitative real-time polymerase chain reaction (qRT-PCR), western blotting and immunohistochemistry. Lentiviral transfection was employed to establish stable cell lines with either overexpressed or silenced MELK. The impact of MELK on the chemoresistance of GC cells and the polarization of macrophages was investigated through in vitro and in vivo functional assays. Additionally, the correlation between MELK and the cytokines colony-stimulating factor 1 (CSF-1), as well as stromal macrophages, was analysed. The prognostic significance of MELK, CSF-1, and CD206 expression levels in clinical samples was further investigated. Results: MELK was found to be highly expressed in chemoresistant GC cells and tissues. Furthermore, both in vitro and in vivo assays indicated that MELK overexpression conferred chemoresistance in GC cells. Additionally, MELK overexpression was observed to induce M2 macrophage polarization via the CSF-1/JAK2/STAT3 pathway, thereby contributing to chemoresistance within the tumor microenvironment. The expression of MELK in GC tissues from neoadjuvant chemotherapy patients correlated positively with CSF-1 and CD206. Moreover, patients with higher expression levels of MELK, CSF-1, or CD206 exhibited significantly shorter OS and DFS rates. Conclusions: Our investigation underscores the critical role of MELK in promoting chemoresistance and inducing M2 macrophage polarization in GC. It proposes novel targets and methods for the treatment of GC, as well as prognostic factors for neoadjuvant chemotherapy. [ABSTRACT FROM AUTHOR]

Accumulating evidence indicates that microRNAs (miRNAs) have a vital effect on the pathogenesis of psoriasis. This study is conducted to investigate the potential involvement of miR-181a-5p and miR-181b-5p in the proliferation of HaCaT keratinocytes. Cell viability and proliferation were evaluated respectively in this study using the CCK-8 and the 5-ethynyl-2’-deoxyuridine (EdU) assays. The expression of Maternal Embryonic Leucine Zipper Kinase (MELK) and Keratin 16 (KRT16) mRNA and protein in tissues and cells was assessed using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. The Luciferase reporter system analyzes the connection between miR-181a-5p/miR-181b-5p and MELK. The results showed that miR-181a/b-5p expression was downregulated in the psoriasis lesions and negatively regulated the proliferation of keratinocytes. MELK was directly targeted by miR-181a-5p/miR-181b-5p. In addition, HaCaT keratinocytes proliferation was inhibited by knockdown of MELK while promoted dramatically by MELK overexpression. Notably, miR-181a/b-5p mimics could attenuate the effects of MELK in keratinocytes. In conclusion, our research findings suggested miR-181a-5p and miR-181b-5p negatively regulate keratinocyte proliferation by targeting MELK, providing potential diagnostic biomarkers and therapeutic targets for psoriasis. [ABSTRACT FROM AUTHOR]

Abstract Background Gastric cancer (GC) stands out as one of the most prevalent malignancies affecting the digestive system, characterized by a substantial incidence rate and mortality. Maternal embryonic leucine zipper kinase (MELK) has been implicated in the advancement of various cancer types and the modulation of the tumor microenvironment. This study aims to delve into the involvement of MELK in chemoresistance and the tumor microenvironment of GC. Methods The MELK expression was detected using quantitative real-time polymerase chain reaction (qRT-PCR), western blotting and immunohistochemistry. Lentiviral transfection was employed to establish stable cell lines with either overexpressed or silenced MELK. The impact of MELK on the chemoresistance of GC cells and the polarization of macrophages was investigated through in vitro and in vivo functional assays. Additionally, the correlation between MELK and the cytokines colony-stimulating factor 1 (CSF-1), as well as stromal macrophages, was analysed. The prognostic significance of MELK, CSF-1, and CD206 expression levels in clinical samples was further investigated. Results MELK was found to be highly expressed in chemoresistant GC cells and tissues. Furthermore, both in vitro and in vivo assays indicated that MELK overexpression conferred chemoresistance in GC cells. Additionally, MELK overexpression was observed to induce M2 macrophage polarization via the CSF-1/JAK2/STAT3 pathway, thereby contributing to chemoresistance within the tumor microenvironment. The expression of MELK in GC tissues from neoadjuvant chemotherapy patients correlated positively with CSF-1 and CD206. Moreover, patients with higher expression levels of MELK, CSF-1, or CD206 exhibited significantly shorter OS and DFS rates. Conclusions Our investigation underscores the critical role of MELK in promoting chemoresistance and inducing M2 macrophage polarization in GC. It proposes novel targets and methods for the treatment of GC, as well as prognostic factors for neoadjuvant chemotherapy.

Abstract Breast cancer (BC) is a leading cause of global cancer-related mortality in women, necessitating accurate tumor classification for timely intervention. Molecular and histological factors, including PAM50 classification, estrogen receptor α (ERα), breast cancer type 1 susceptibility protein (BRCA1), progesterone receptor (PR), and HER2 expression, contribute to intricate BC subtyping. In this work, through a combination of bioinformatic and wet lab screenings, followed by classical signal transduction and cell proliferation methods, and employing multiple BC cell lines, we identified enhanced sensitivity of ERα-positive BC cell lines to ALK and MELK inhibitors, inducing ERα degradation and diminishing proliferation in specific BC subtypes. MELK inhibition attenuated ERα transcriptional activity, impeding E2-induced gene expression, and hampering proliferation in MCF-7 cells. Synergies between MELK inhibition with 4OH-tamoxifen (Tam) and ALK inhibition with HER2 inhibitors revealed potential therapeutic avenues for ERα-positive/PR-positive/HER2-negative and ERα-positive/PR-negative/HER2-positive tumors, respectively. Our findings propose MELK as a promising target for ERα-positive/PR-positive/HER2-negative BC and highlight ALK as a potential focus for ERα-positive/PR-negative/HER2-positive BC. The synergistic anti-proliferative effects of MELK with Tam and ALK with HER2 inhibitors underscore kinase inhibitors’ potential for selective treatment in diverse BC subtypes, paving the way for personalized and effective therapeutic strategies in BC management.

Purpose: In our previous study, Developmental endothelial locus-1 (Del-1) was a promising predictive marker for breast cancer. However, the downstream targets of Del-1 remain unknown. Here, we sought to discover a druggable target downstream of Del-1 and investigate the mechanism by which it regulates the course of breast cancer. Methods: To investigate Del-1 downregulation effect on breast cancer, we performed transcriptome analysis using RNA sequencing of Del-1 knockdowned MDA-MB-231 cell line Plus, to investigate the expression of Del-1 and Maternal embryonic leucine zipper kinase (MELK), mRNA levels in eight different triple-Negative Breast Cancer (TNBC) cell lines were analyzed. High-throughput sequencing was performed on total RNA isolated. OTS167 was used for MELK inhibition. The effects of MELK on cell proliferation and invasion were determined using the MTT and Matrigel transwell assays. Furthermore, we examined MELK expression in breast cancer tissue. Results: Del-1 and MELK mRNA expression levels were significantly higher in the TNBC cell lines, MDA-MB-468, HCC-1806, and MBA-MB-231. Knocking down Del-1 with siRNA in HCC-1806 and MBA-MB-231 cells significantly decreased MELK expression and thus suggested a possible relationship between Del-1 and MELK. In MDA-MB-468 cells, a basal-like 1 TNBC cell line, OTS167 significantly inhibited breast cancer cell proliferation and promoted cell apoptosis. To further investigate the relationship between Del-1 and MELK, dual inhibition of both Del-1 and MELK was performed, which significantly reduced the viability of MDA-MB-468 and MBA-MB-231 cells. Conclusion: We found that MELK acts downstream of Del-1 and is a promising druggable target, especially in basal-like and mesenchymal stem-like subtype. [ABSTRACT FROM AUTHOR]

We tried to elucidate the possible roles of maternal embryonic leucine pull chain kinase (MELK) in lung adenocarcinoma (LUAD) growth and metastasis. Differentially expressed genes in LUAD samples were analysed by the GEPIA database. Clinical tissue samples and cells were collected for MELK, EZH2 and LATS2 expression determination. Co‐IP assay was used to verify the interaction between EZH2 and MELK; CHX tracking assay and ubiquitination assay detected the degradation of MELK on EZH2 ubiquitination. ChIP assay detected the enrichment of EZH2 and H3K27me3 on the LATS2 promoter region. LUAD cells were selected for in vitro validation, and the tumorigenic ability of LUAD cells was also observed in a transplantation tumour model of LUAD nude mice. MELK and EZH2 were highly expressed in LUAD samples, while LATS2 was lowly expressed. MELK interacted with EZH2 to inhibit its ubiquitination degradation; EZH2 elevated H3K27me3 modification in the LATS2 promoter to lower LATS2 expression. Silencing MELK or EZH2 or overexpressing LATS2 restrained LUAD cell proliferation and invasion, and facilitated their apoptosis. Silencing MELK or EZH2 or overexpressing LATS2 suppressed tumour formation in nude mice. This study demonstrated that MELK aggravated LUAD by upregulating EZH2 and downregulating LATS2. [ABSTRACT FROM AUTHOR]

Maternal Embryonic Leucine Zipper Kinase (MELK) has been studied intensively in recent years due to its overexpression in multiple cancers. However, the cell biology of MELK remains less characterized despite its well-documented association with mitosis. Here we report a distinctive pattern of human MELK that translocates from the cytoplasm to cell cortex within 3 min of anaphase onset. The cortex association lasts about 30 min till telophase. The spatiotemporal specific localization of MELK depends on the interaction between its Threonine-Proline (TP) rich domain and kinase associated 1 (KA1) domain, which is regulated by CDK1 kinase and PP4 protein phosphatase. KA1 domains are known to regulate kinase activities through various intramolecular interactions. Our results revealed a new role for KA1 domain to control subcellular localization of a protein kinase.

Background: Circular RNAs (circRNAs) are involved in the progression of colon cancer (CC). This study aimed to examine the role of a new circRNA circ_0101050 in CC. Methods: Dual-luciferase reporter and RNA immunoprecipitation analyses were performed to validate the target relationships among maternal embryonic leucine zipper kinase (MELK), microRNA (miR)-140–3 p, and circ_0101050. Expression levels were calculated using western blotting and/or quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Western blotting was performed to evaluate the relative expression of Bcl-2 and Bax proteins to determine cell death. Cell Counting Kit-8 (CCK-8) and colony formation assays were performed to determine the proliferative potential of CC cells. The migration rate of CC cells was evaluated using wound healing assays. Tumor formation tests were performed to determine the effect of circ_0101050 on tumor development in vivo. Results: Elevated levels of circ_0101050 and MELK were observed in CC. By inhibiting circ 0,101,050 or MELK, CC cell proliferation and migration were inhibited, but CC cell apoptosis was promoted. Silencing circ_0101050 also inhibited CC growth in vivo. We also found that miR-140–3 p was downregulated, which alleviated the repressive effects of circ_0101050 knockdown on proliferating and migrating CC cells, as well as the stimulating effect on apoptosis. In addition, the absence of MELK alleviated the effects of miR-140–3 p downregulation, which enhanced CC cell malignancy. Conclusions: Circ_0101050 exacerbates malignant phenotypes in CC by targeting the miR-140–3 p/MELK axis. These findings suggested that the circ_0101050/miR-140–3 p/MELK network may be a prospective target for CC treatment.

Maternal embryonic leucine zipper kinase (MELK) is a serine-threonine kinase. Several studies have revealed its role as a regulator in the tumorigenesis of various cancers. Consequently, MELK has been considered as an attractive therapeutic target for cancer management. Herein, we report pharmacophore models extracted from crystallographic complexes of potent ligands bound to MELK protein. The resulting models were evaluated by Receiver Operating Characteristic (ROC) analysis, and the best models were employed as search queries to screen the national cancer institute for potent inhibitors. The anti-MELK bioactivities of acquired hits were evaluated in vitro. Moreover, best anti-MELK hits were further evaluated against lung and cervical cancer cells (A549 and HeLa, respectively) using cell viability MTT assay. The enzymatic assay identified six potent hits with IC50 values ranging from nanomolar to low micromolar values. The most active hit showed anti-MELK IC50 of 134.6 nM. Likewise, these hits significantly inhibited the growth of tested cancer cell lines. Interestingly, four of the identified inhibitors have chemical scaffolds that are notably different from those of reported MELK inhibitors. This study highlights the use of X-ray crystallographic structures to boost the drug discovery process. [ABSTRACT FROM AUTHOR]

Background: Cancer is a multifactorial disease and the second leading cause of human deaths worldwide. So far, the underlying mechanisms of cancer have not been yet fully elucidated. Methods: By using TCGA expression data, we determine the pathogenic roles of the maternal embryonic leucine zipper kinase (MELK) gene in various human cancers in this study. For this purpose, different online databases and tools (UALCAN, Kaplan–Meier (KM) plotter, TNMplot, GENT2, GEPIA, HPA, cBioPortal, STRING, Enrichr, TIMER, Cytoscape, DAVID, MuTarget, and CTD) were used. Results: MELK gene expression was analyzed in a total of 24 human cancers and was found notably up-regulated in all the 24 analyzed tumor tissues relative to controls. Moreover, across a few specific cancers, including kidney renal clear cell carcinoma (KIRC), stomach adenocarcinoma (STAD), lung adenocarcinoma (LUAD), and liver hepatocellular carcinoma (LIHC) patients, MELK up-regulation was observed to be correlated with the shorter survival duration and metastasis. This valuable information highlighted that MELK plays a significant role in the development and progression of these four cancers. Based on clinical variables, MELK higher expression was also found in KIRC, STAD, LUAD, and LIHC patients with different clinical variables. Gene ontology and pathway analysis outcomes showed that MELK-associated genes notably co-expressed with MELK and belongs to a variety of diverse biological processes, molecular functions, and pathways. MELK expression was also correlated with promoter methylation levels, genetic alterations, other mutant genes, tumor purity, CD8+ T, and CD+4 T immune cells infiltrations in KIRC, STAD, LUAD, and LIHC. Conclusion: This pan-cancer study revealed the diagnostic and prognostic roles of MELK across four different cancers. [ABSTRACT FROM AUTHOR]

Background: Patients with clear cell renal cell carcinoma (ccRCC), which is the most commonly diagnosed subtype of renal cell carcinoma, are at risk of tumor metastasis and recrudescence. Previous research has shown that oxidative stress can induce tumorigenesis in many cancers and can be a target of cancer treatment. Despite these findings, little progress has been made understanding in the association of oxidative stress-related genes (OSRGs) with ccRCC. Methods: In vitro experiments were conducted with MTT survival assays, qRT‒PCR, apoptosis assays, cell cycle assays, ROS assays, and IHC staining. Results: In our study, 12 differentially expressed oxidative stress-related genes (DEOSGs) and related transcription factors (TFs) that are relevant to overall survival (OS) were screened, and their mutual regulatory networks were constructed with data from the TCGA database. Moreover, we constructed a risk model of these OSRGs and performed clinical prognostic analysis and validation. Next, we performed protein–protein interaction (PPI) network analysis and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of MELK, PYCR1, and PML. A tissue microarray also verified the high expression of MELK and PYCR1 in ccRCC. Finally, in vitro cellular experiments demonstrated that knockdown of MELK or PYCR1 significantly inhibited ccRCC cell proliferation by causing cell apoptosis and inducing cell cycle arrest in the G1 phase. Intracellular ROS levels were elevated after these two genes were knocked down. Conclusion: Our results revealed the potential DEORGs to be used in ccRCC prognostic prediction and identified two biomarkers, named PYCR1 and MELK, which regulated the proliferation of ccRCC cells by affecting ROS levels. Furthermore, PYCR1 and MELK could be promising targets for predicting the progression and prognosis of ccRCC, thereby serving as new targets for medical treatments. [ABSTRACT FROM AUTHOR]

Maternal embryonic leucine-zipper kinase (MELK) plays a significant role in cell cycle progression, mitosis, cell migration, cell renewal, gene expression, embryogenesis, proliferation, apoptosis, and spliceosome assembly. In addition, MELK is known to be overexpressed in multiple types of cancer and is associated with cancer proliferation. Tumorigenesis shares many similarities with wound healing, in which the rate of cell proliferation is a critical factor. Therefore, this study aimed to determine the involvement of MELK in the regulation of cell division in two cell types involved in this process, namely fibroblasts and keratinocytes. We examined how temporal overexpression of wild-type and kinase-dead MELK kinase variants affect the rate of proliferation, viability, cell cycle, and phosphorylation state of other kinases involved in these processes, such as ERK1/2, AKT1, MAPK9, p38, and p53. We explored if MELK could be used as a therapeutic stimulator of accelerated wound healing via increased proliferation. We observed that aberrant expression of MELK results in abnormal proliferation, altered cell cycle distribution, and decreased viability of the cells, which challenge the utility of MELK in accelerated wound healing. Our results indicate that, at least in healthy cells, any deviation from precisely controlled MELK expression is harmful to fibroblasts and keratinocytes. [ABSTRACT FROM AUTHOR]

Skin wounds remain a significant problem for the healthcare system, affecting the clinical outcome, patients' quality of life, and financial costs. Reduced wound healing times would improve clinical, economic, and social aspects for both patients and the healthcare system. Skin wound healing has been studied for years, but effective therapy that leads to accelerated wound healing remains to be discovered. This study aimed to evaluate the potential of MELK silencing to accelerate wound healing. A vectorless, transient knockdown of the MELK gene using siRNA was performed in a murine skin wound model. The wound size, total collagen, type 3 collagen, vessel size, vessel number, cell proliferation, cell apoptosis, number of mast cells, and immune infiltration by CD45, CD11b, CD45, and CD8a cells were evaluated. We observed that treatment with MELK siRNA leads to significantly faster wound closing associated with increased collagen deposition. [ABSTRACT FROM AUTHOR]

Objective: Glioma accounts for the vast majority of primary brain tumors with inevitable recurrence and poor prognosis. Maternal embryonic leucine zipper kinase (MELK) is overexpressed in multiple human tumors and could activate a variety of oncogenic-associated signal pathways. However, its role in the glioma microenvironment is still largely unknown. Methods: We collected the RNA sequence data and clinical information of gliomas from the Chinese Glioma Genome Atlas (CGGA), The Cancer Genome Atlas (TCGA), and the Gene Expression Omnibus (GEO) databases, and investigated MELK expression and its correlation with clinicopathologic features and prognosis in glioma. Moreover, the relationship between MELK expression and immune cell infiltration in the tumor microenvironment of gliomas was explored through single-sample gene set enrichment analysis (ssGSEA) and CIBERSORT. In addition, gene set enrichment analysis (GSEA) and Metascape online analysis were performed to find out signaling pathways enriched by differentially expressed genes (DEGs) between high- and low-MELK expression groups. Finally, immunohistochemistry was performed to validate our findings. Results: Data analysis of CGGA and GEO datasets showed that MELK was significantly upregulated in gliomas than in normal brain tissues, and MELK expression was obviously correlated with clinicopathologic features, including age, WHO grade, histological subtype, IDH mutant status, 1p19q codeletion status, and PRS type. Stratified analysis, Cox regression analysis, and nomogram model revealed that high expression of MELK predicted poor survival; hence, MELK could serve as an independent prognostic biomarker for glioma. Moreover, results from enrichment pathway analysis indicated that the immune system process, angiogenesis, apoptosis, cell cycle, and other oncogenic-related signal pathways were significantly enriched between high- and low-MELK expression groups. Immune infiltration analysis demonstrated that increased MELK expression was significantly correlated with higher immune scores, higher fractions of immunocytes (T cells, NK cells resting, macrophages, resting mast cells, and neutrophils), and higher expression levels of immune checkpoints (B7-H3, CTLA4, LAG3, PD-1, PD-L1, and TIM3). Finally, immunohistochemistry analysis validated our findings that high expression of MELK relates to increased malignancy and poor prognosis of glioma. Conclusion: Our findings identified that MELK could act as an independent prognostic indicator and potential immunotherapy target for glioma. In conclusion, these findings suggested that DDOST mediated the immunosuppressive microenvironment of gliomas and could be an important biomarker in diagnosing and treating gliomas. [ABSTRACT FROM AUTHOR]

Maternal embryonic leucine zipper kinase (MELK), a member of the AMP-related serine-threonine kinase family, has been involved in regulating many cellular events, and aberrant MELK expression is associated with tumorigenesis and malignant progression in various cancers. More and more studies have found that MELK plays an essential regulatory role in tumor multidrug resistance or radio resistance. MELK inhibitors can also improve drug resistance caused by a gene mutation. These findings remind us that MELK could be a chemo- or radio-sensitizing target. However, it has also been found that most experiments on MELK rely on non-selective RNAi and small molecule reagents, which makes the results questionable, and thus the development of selective MELK inhibitors is still necessary. In this review, we summarized the identified regulatory pathways of MELK in tumor resistance and reclassified MELK inhibitors from a structural perspective. In addition, we discovered the glycosylation modification site of the MELK protein and discussed the possibility of continuing to develop small molecule inhibitors targeting the glycosylation modification site. These provide new strategies for developing selective MELK inhibitors and understanding the essential biological role of MELK in cancer.

Maternal embryonic leucine-zipper kinase (MELK) plays a significant role in cell cycle progression, mitosis, cell migration, cell renewal, gene expression, embryogenesis, proliferation, apoptosis, and spliceosome assembly. In addition, MELK is known to be overexpressed in multiple types of cancer and is associated with cancer proliferation. Tumorigenesis shares many similarities with wound healing, in which the rate of cell proliferation is a critical factor. Therefore, this study aimed to determine the involvement of MELK in the regulation of cell division in two cell types involved in this process, namely fibroblasts and keratinocytes. We examined how temporal overexpression of wild-type and kinase-dead MELK kinase variants affect the rate of proliferation, viability, cell cycle, and phosphorylation state of other kinases involved in these processes, such as ERK1/2, AKT1, MAPK9, p38, and p53. We explored if MELK could be used as a therapeutic stimulator of accelerated wound healing via increased proliferation. We observed that aberrant expression of MELK results in abnormal proliferation, altered cell cycle distribution, and decreased viability of the cells, which challenge the utility of MELK in accelerated wound healing. Our results indicate that, at least in healthy cells, any deviation from precisely controlled MELK expression is harmful to fibroblasts and keratinocytes.

Colorectal cancer (CRC) is a malignant cancer with an increasing incidence. Circular RNA (circRNA) is recently found to participate in the regulation of CRC progression. However, the role of circ_0007031 in CRC malignant progression remains elusive. 50 CRC patients were implicated in this study. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the RNA expression of circ_0007031, microRNA-485-3p (miR-485-3p) and maternal embryonic leucine zipper kinase (MELK). Western blot analysis was conducted to determine protein expression. Cell viability and proliferation were demonstrated by cell counting kit-8 and 5-Ethynyl-29-deoxyuridine (EdU) assays, respectively. Cell cycle and apoptosis were investigated by flow cytometry analysis. The interaction among circ_0007031, miR-485-3p and MELK was predicted by online databases, and identified by dual-luciferase reporter assay. Mouse model assay was conducted to reveal the effect of circ_0007031 on tumor formation in vivo. Circ_0007031 and MELK expression were obviously increased, while miR-485-3p expression was decreased in CRC tissues and cells compared with normal colorectal tissues or cells. Circ_0007031 knockdown repressed proliferation, whereas induced cell arrest at G0/G1 phase and apoptosis. On the opposite, circ_0007031 overexpression promoted cell proliferation and induced cell arrest at S phase. Additionally, miR-485-3p inhibitors attenuated circ_0007031 silencing-mediated CRC cell malignancy. MiR-485-3p was unveiled to regulate CRC cell processes via targeting MELK. Circ_0007031 controlled MELK expression via interacting with miR-485-3p. Furthermore, circ_0007031 contributed to tumor formation in vivo. Circ_0007031 knockdown repressed CRC malignant progression by reducing MELK expression through associating with miR-485-3p, suggesting that circ_0007031 was a potential target for the therapy of CRC. [ABSTRACT FROM AUTHOR]

Abstract Background Non-small cell lung cancer (NSCLC) is a major histological subtype of lung cancer with high mortality and morbidity. A substantial amount of evidence demonstrates long non-coding RNAs (lncRNA) as critical regulators in tumorigeneis and malignant progression of human cancers. The oncogenic role of BBOX1 anti-sense RNA 1 (BBOX1-AS1) has been reported in several tumors. As yet, the potential functions and mechanisms of BBOX1-AS1 in NSCLC are obscure. Methods The gene and protein expression was detected by qRT-PCR and western blot. Cell function was determined by CCK-8, colony forming, would healing and transwell assays. Bioinformatics tools, ChIP assays, dual luciferase reporters system and RNA pull-down experiments were used to examine the interaction between molecules. Subcutaneous tumor models in nude mice were established to investigate in vivo NSCLC cell behavior. Results BBOX1-AS1 was highly expressed in NSCLC tissues and cells. High BBOX1-AS1 expression was associated with worse clinical parameters and poor prognosis. BBOX1-AS1 up-regulation was induced by transcription factor KLF5. BBOX1-AS1 deficiency resulted in an inhibition of cell proliferation, migration, invasion and EMT in vitro. Also, knockdown of BBOX1-AS1 suppressed NSCLC xenograft tumor growth in mice in vivo. Mechanistically, BBOX1-AS1 acted act as a competetive “sponge” of miR-27a-5p to promote maternal embryonic leucine zipper kinase (MELK) expression and activate FAK signaling. miR-27a-5p was confirmed as a tumor suppressor in NSCLC. Moreover, BBOX1-AS1-induced increase of cell proliferation, migration, invasion and EMT was greatly reversed due to the overexpression of miR-27a-5p. In addition, the suppressive effect of NSCLC progression owing to BBOX1-AS1 depletion was abated by the up-regulation of MELK. Consistently, BBOX1-AS1-mediated carcinogenicity was attenuated in NSCLC after treatment with a specific MELK inhibitor OTSSP167. Conclusions KLF5-induced BBOX1-AS1 exerts tumor-promotive roles in NSCLC via sponging miR-27a-5p to activate MELK/FAK signaling, providing the possibility of employing BBOX1-AS1 as a therapeutic target for NSCLC patients.

Background: Evaluation of cancer cervix prognosis is highly needed for novel targeted therapy and improved outcomes. Nucleolar and spindle associated protein 1 (NUSAP1) is a novel biomarker that has roles in spindle formation and mitotic progression. Maternal embryonic leucine zipper kinase (MELK) is involved in cell cycle control and carcinogenesis. The L1 cell adhesion molecule (L1-CAM) plays an essential role in cell migration. This study aimed to investigate NUSAP1, MELK, and L1CAM immunohistochemical expression in cancer cervix tissues and detect their prognostic roles. Method: In this prospective cohort study, we evaluated NUSAP1, MELK, and L1CAM expressions of sections from 62 cervical carcinoma cases using immunohistochemistry. Results: NUSAP1, MELK, and L1CAM expression correlated with tumor high grade, advanced FIGO stage, poor survival rates, and higher recurrence rate after successful therapy (p

Background: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world with high morbidity and mortality. Identifying specific molecular markers that can predict HCC prognosis is extremely important. MELK has been reported to play key roles in several types of human cancers and predict poor prognosis. This study was aimed to explore the impact of MELK on HCC.Methods: A pan-cancer analysis of MELK was conducted by The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) data. The prognosis of MELK in various cancers was analyzed in GEPIA. Then, a ceRNA network of MELK was constructed based on the comprehensive consideration of the expression analysis, the correlation analysis, and the survival analysis by R software. The correlation of MELK and immune cell infiltration was analyzed by TIMER and CIBERSORT. Then, the overall survival of differentially expressed immune cells was conducted. The correlation of MELK and immune checkpoints expression was analyzed by GEPIA.Results: MELK was overexpressed in 14 types of human cancers, and its expression was significantly higher than that in both unmatched and paired normal samples in HCC. Higher MELK expression was correlated with poorer survival and advanced clinical stage, topography (T) stage, and histological grade. The univariate and multivariate Cox regression analyses showed that MELK was an independent risk factor for poor prognosis in HCC. Then, we constructed a ceRNA network consisting of MELK, miR-101-3p, and two lncRNAs (SNHG1 and SNHG6) after evaluating the expression and impact on prognosis in HCC of these RNAs. TIMER and CIBERSORT databases indicated that MELK was correlated with various immune cells including B cells, CD8+ T cells, CD4+ T cells, macrophage, neutrophil, and dendritic cells in HCC. Of them, B cells, CD4+ T cells, macrophage, and neutrophil were related to the prognosis of HCC. In addition, MELK was significantly positively correlated with the immune checkpoint genes.Conclusions: MELK may be a novel potential biomarker for predicting prognosis and immunotherapy efficacy in patients with HCC. Our study may provide new molecular and therapeutic strategies for the treatment of HCC patients.

Skin wounds remain a significant problem for the healthcare system, affecting the clinical outcome, patients’ quality of life, and financial costs. Reduced wound healing times would improve clinical, economic, and social aspects for both patients and the healthcare system. Skin wound healing has been studied for years, but effective therapy that leads to accelerated wound healing remains to be discovered. This study aimed to evaluate the potential of MELK silencing to accelerate wound healing. A vectorless, transient knockdown of the MELK gene using siRNA was performed in a murine skin wound model. The wound size, total collagen, type 3 collagen, vessel size, vessel number, cell proliferation, cell apoptosis, number of mast cells, and immune infiltration by CD45, CD11b, CD45, and CD8a cells were evaluated. We observed that treatment with MELK siRNA leads to significantly faster wound closing associated with increased collagen deposition.

Maternal embryonic leucine zipper kinase (MELK) is a highly conserved serine/threonine kinase initially found to be expressed in a wide range of early embryonic cellular stages, and as a result has been implicated in embryogenesis and cell cycle control. Recent evidence has identified a broader spectrum of tissue expression pattern for this kinase than previously appreciated. MELK is expressed in several human cancers and stem cell populations. Unique spatial and temporal patterns of expression within these tissues suggest that MELK plays a prominent role in cell cycle control, cell proliferation, apoptosis, cell migration, cell renewal, embryogenesis, oncogenesis, and cancer treatment resistance and recurrence. These findings have important implications for our understanding of development, disease, and cancer therapeutics. Furthermore understanding MELK signaling may elucidate an added dimension of stem cell control.

Maternal embryonic leucine zipper kinase (MELK) is frequently overexpressed in cancer, but the role of MELK in cancer is still poorly understood. MELK was shown to have roles in many cancer-associated processes including tumor growth, chemotherapy resistance, and tumor recurrence. To determine whether the frequent overexpression of MELK can be exploited in therapy, we performed a high-throughput screen using a library of Saccharomyces cerevisiae mutants to identify genes whose functions become essential when MELK is overexpressed. We identified two such genes: LAG2 and HDA3. LAG2 encodes an inhibitor of the Skp, Cullin, F-box containing (SCF) ubiquitinligase complex, while HDA3 encodes a subunit of the HDA1 histone deacetylase complex. We find that one of these synthetic lethal interactions is conserved in mammalian cells, as inhibition of a human homolog of HDA3 (Histone Deacetylase 4, HDAC4) is synthetically toxic in MELK overexpression cells. Altogether, our work identified a novel potential drug target for tumors that overexpress MELK. [ABSTRACT FROM AUTHOR]

Hongchun Li,1 Miao Chen,2 Zhuying Yang,3 Qinxian Wang,1 Jiesheng Wang,1 Dong Jin,1 Xiuyun Yang,1 Fuxing Chen,1 Xiumin Zhou,4 Kexue Luo1 1Department of Cadre Health, Tongde Hospital of Zhejiang Province, Hangzhou 310012, Zhejiang, People’s Republic of China; 2Department of Oncology, Tongde Hospital of Zhejiang Province, Hangzhou 310012, Zhejiang, People’s Republic of China; 3Department of Gastroenterology, Tongde Hospital of Zhejiang Province, Hangzhou 310012, Zhejiang, People’s Republic of China; 4Department of Pharmacy, Tongde Hospital of Zhejiang Province, Hangzhou 310012, Zhejiang, People’s Republic of ChinaCorrespondence: Kexue LuoDepartment of Cadre Health, Tongde Hospital of Zhejiang Province, 234 Gucui Road, Hangzhou 310012, Zhejiang, People’s Republic of ChinaTel +86 571 89972437Email tdyylke521@163.comIntroduction: Pancreatic cancer (PC) is one of the leading causes of cancer, with the lowest 5-year survival rate of all cancer types. Given the fast metastasis of PC and its resistance to surgery, radiotherapy, chemotherapy, and combinations thereof, it is imperative to develop more effective anti-PC drugs. Phillygenin (PHI) has been reported to exert anti-cancer, anti-bacterial, and anti‐inflammatory properties. However, the mechanism of PHI in the development of PC is still unclear.Methods: The cytotoxicity of PHI in pancreatic cancer cells was evaluated by MTT assay, and clonogenic assay was used to test the anti-proliferation of PHI. The pro-apoptotic effect of PHI was detected by flow cytometry analysis. The changes of epithelial–mesenchymal transition (EMT) in pancreatic cancer cells treated with PHI were determined by Western blot. Transwell assay was used to test the migration and invasion of PC cells after treatment with PHI. Molecular docking was used to predict the potential binding site of candidate target with PHI.Results: PHI could inhibit the proliferation, migration, and EMT of PC cells (PANC-1 and SW1990) and induce its apoptosis. Analysis of the Cancer Genome Atlas database indicated that elevated MELK levels correlated with poor overall survival (OS) and disease-free survival (DFS) of PC patients. In addition, molecular modeling showed that PHI may potentially target the catalytic domain of maternal embryonic leucine zipper kinase (MELK). Overexpression of MELK muted the anti-PC effects of PHI.Conclusion: PHI holds promise as a potent candidate drug for the treatment of PC via targeted MELK.Keywords: pancreatic cancer, phillygenin, MELK, proliferation, EMT, apoptosis

Background: Circular RNAs (circRNAs) are involved in the progression of colon cancer (CC). This study aimed to examine the role of a new circRNA circ_0101050 in CC., Methods: Dual-luciferase reporter and RNA immunoprecipitation analyses were performed to validate the target relationships among maternal embryonic leucine zipper kinase (MELK), microRNA (miR)-140-3 p, and circ_0101050. Expression levels were calculated using western blotting and/or quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Western blotting was performed to evaluate the relative expression of Bcl-2 and Bax proteins to determine cell death. Cell Counting Kit-8 (CCK-8) and colony formation assays were performed to determine the proliferative potential of CC cells. The migration rate of CC cells was evaluated using wound healing assays. Tumor formation tests were performed to determine the effect of circ_0101050 on tumor development in vivo., Results: Elevated levels of circ_0101050 and MELK were observed in CC. By inhibiting circ 0,101,050 or MELK, CC cell proliferation and migration were inhibited, but CC cell apoptosis was promoted. Silencing circ_0101050 also inhibited CC growth in vivo. We also found that miR-140-3 p was downregulated, which alleviated the repressive effects of circ_0101050 knockdown on proliferating and migrating CC cells, as well as the stimulating effect on apoptosis. In addition, the absence of MELK alleviated the effects of miR-140-3 p downregulation, which enhanced CC cell malignancy., Conclusions: Circ_0101050 exacerbates malignant phenotypes in CC by targeting the miR-140-3 p/MELK axis. These findings suggested that the circ_0101050/miR-140-3 p/MELK network may be a prospective target for CC treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

The ubiquitin-proteasome pathway is an important protein quality control system involved in intracellular homeostasis. To achieve intracellular homeostasis, proteins that are misfolded as a result of translational errors or genetic mutations must be eliminated by the ubiquitin-proteasome pathway. In our previous publications, we determined that 4T1 breast and B16F10 melanoma cancer cells have differential levels of resistance to proteasome inhibitors. Again, in the previous studies, we reported that 4T1 cell cultures, despite being p53-mutant, underwent apoptosis as a result of bortezomib treatment. The first goal of this study was to verify the resistance levels of parental and resistant PC3 prostate cancer cells to bortezomib using WST-1 test. As a result of treatment with different bortezomib concentrations for 48 h, the IC50 value of the parental cells was determined as 32.8 nM and that of the resistant cells was determined as 346 nM. This result showed that the resistant cells were at least 10.5 times more resistant. In addition, to determine whether the resistance gained was reversible or not, the cells were passaged in a medium without bortezomib for one month. The IC50 value determination by WST-1 test showed that the resistant PC3 cells gained an irreversible bortezomib resistance phenotype. The results of the 3D spheroid experiment showed that the 3D spheroid diameter of resistant cells was significantly higher than that of the parental cells. The studies conducted with Western blot showed that ERK1 MAPK T202 phosphorylation and the conversion of autophagy marker LC3-I to LC3-II were significantly increased in parental cells as compared to the resistant cells. Finally, the results showed that while both maternal embryonic leucine zipper kinase (MELK) inhibitor OTSSP167 and Ca2+ chelator BAPTA-AM (also an inhibitor of the expression of antiapoptotic protein GRP78) are promising agents for cancer cells resistant to the proteasome inhibitors, CDK2 inhibitor CVT-313 was found ineffective in both parental and the resistant cells. [ABSTRACT FROM AUTHOR]

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a group of chronic recurrent and incurable gastrointestinal diseases with an unknown etiology that leads to a high risk of developing colitis-associated colorectal cancer (CRC). In this study, we measured the expression characteristics of MELK in IBD and CRC tissues and explored the regulatory effect of OTSSP167 (a MELK-selective inhibitor) on the mice models of colitis and colitis-associated carcinogenesis and analyzed the specific molecular mechanisms. DSS-induced colitis and colitis-associated carcinogenesis (CAC) model were treated with MELK inhibitor OTSSP167 then the fight against effect of OTSSP167 in the clinical symptoms of colitis and CAC was measured. In addition, underlying mechanism of OTSSP167 treatment in vitro and vivo including anti -ferroptosis and anti-inflammatory response effect was further explored. We found that pharmacological inhibition of MELK was indicated to significantly alleviate the inflammatory response in mice with colitis, reduce intestinal damage, and effectively inhibit the occurrence and progression of colitis-propelled carcinogenesis, which was closely related to the regulation of gut microbial composition, and OTSSP167-mediated fecal microbiota transplantation effectively alleviated DSS-induced colitis. In addition, OTSSP167 treatment obviously inhibited ferroptosis in the intestinal tissue and suppressed macrophage infiltration and M1 polarization, which reduced the secretion of pro-inflammatory factors. Further exploration of the molecular mechanism revealed that OTSSP167 inhibited AKT/IKK/P65 and ERK/IKK/P65 signaling cascades both in vivo and in vitro, which may help alleviate intestinal inflammation and control the occurrence of cancer. Our findings lay a theoretical foundation for the use of OTSSP167 as a treatment for IBD and its inhibition of the occurrence of colitis-associated carcinogenesis; additionally, MELK may be a potentially effective target molecule, thus providing more options for clinical treatment. [Display omitted] • OTSSP167 effectively alleviated the inflammatory response in colitis mice and inhibited colitis-propelled carcinogenesis. • Inhibiting ferroptosis in epithelial cells is important for OTSSP167 exerting anti-colitis and anti-carcinogenesis effects. • OTSSP167 also reduced macrophage infiltration, M1 polarization and pro-inflammatory factors secretion in intestinal tissues. • The protective effect of OTSSP167 on mice with colitis is also closely related to the rebalance of intestinal microbiota. • OTSSP167 exerts anti-colitis and anti-tumor effects through suppressing the AKT/IKK/P65 axis and ERK/IKK/P65 axis. [ABSTRACT FROM AUTHOR]

Background: Non-small cell lung cancer (NSCLC) is a major histological subtype of lung cancer with high mortality and morbidity. A substantial amount of evidence demonstrates long non-coding RNAs (lncRNA) as critical regulators in tumorigeneis and malignant progression of human cancers. The oncogenic role of BBOX1 anti-sense RNA 1 (BBOX1-AS1) has been reported in several tumors. As yet, the potential functions and mechanisms of BBOX1-AS1 in NSCLC are obscure. Methods: The gene and protein expression was detected by qRT-PCR and western blot. Cell function was determined by CCK-8, colony forming, would healing and transwell assays. Bioinformatics tools, ChIP assays, dual luciferase reporters system and RNA pull-down experiments were used to examine the interaction between molecules. Subcutaneous tumor models in nude mice were established to investigate in vivo NSCLC cell behavior. Results: BBOX1-AS1 was highly expressed in NSCLC tissues and cells. High BBOX1-AS1 expression was associated with worse clinical parameters and poor prognosis. BBOX1-AS1 up-regulation was induced by transcription factor KLF5. BBOX1-AS1 deficiency resulted in an inhibition of cell proliferation, migration, invasion and EMT in vitro. Also, knockdown of BBOX1-AS1 suppressed NSCLC xenograft tumor growth in mice in vivo. Mechanistically, BBOX1-AS1 acted act as a competetive "sponge" of miR-27a-5p to promote maternal embryonic leucine zipper kinase (MELK) expression and activate FAK signaling. miR-27a-5p was confirmed as a tumor suppressor in NSCLC. Moreover, BBOX1-AS1-induced increase of cell proliferation, migration, invasion and EMT was greatly reversed due to the overexpression of miR-27a-5p. In addition, the suppressive effect of NSCLC progression owing to BBOX1-AS1 depletion was abated by the up-regulation of MELK. Consistently, BBOX1-AS1-mediated carcinogenicity was attenuated in NSCLC after treatment with a specific MELK inhibitor OTSSP167. Conclusions: KLF5-induced BBOX1-AS1 exerts tumor-promotive roles in NSCLC via sponging miR-27a-5p to activate MELK/FAK signaling, providing the possibility of employing BBOX1-AS1 as a therapeutic target for NSCLC patients. [ABSTRACT FROM AUTHOR]

Background: Evaluation of cancer cervix prognosis is highly needed for novel targeted therapy and improved outcomes. Nucleolar and spindle associated protein 1 (NUSAP1) is a novel biomarker that has roles in spindle formation and mitotic progression. Maternal embryonic leucine zipper kinase (MELK) is involved in cell cycle control and carcinogenesis. The L1 cell adhesion molecule (L1-CAM) plays an essential role in cell migration. This study aimed to investigate NUSAP1, MELK, and L1CAM immunohistochemical expression in cancer cervix tissues and detect their prognostic roles. Method: In this prospective cohort study, we evaluated NUSAP1, MELK, and L1CAM expressions of sections from 62 cervical carcinoma cases using immunohistochemistry. Results: NUSAP1, MELK, and L1CAM expression correlated with tumor high grade, advanced FIGO stage, poor survival rates, and higher recurrence rate after successful therapy (P<0.001). Conclusion: Expression of NUSAP1, MELK, and L1CAM in cancer cervix was associated with poor prognosis. [ABSTRACT FROM AUTHOR]

Following wounding, endogenously secreted TGFβs drive resident and bone marrow-derived cells to convert into α-smooth actin (SMA)-rich, contractile myofibroblasts. The TGFβ effect is initiated by the phosphorylation of SMADs 2 and 3 (SMAD2/3). This event has been referred to as the canonical response to TGFβ. TGFβ also elicits other responses viewed as parallel events not directly connected to the SMAD activation, and thus referred to as noncanonical. A recognized response is the phosphorylation of the -activated kinase (TAK1/MAP3K), an upstream component of the mitogen-activated protein kinase (MAPK) cascade. We have now examined the relationship between these two effects of TGFβ1 at their earliest stages. The bulk of the studies were carried out with primary fibroblasts derived from the human cornea. The results' widespread relevance was confirmed in critical experiments with dermal-, and Tenon's capsule-derived fibroblasts. Cells were treated with kinase inhibitors or targeting siRNAs followed by induction by 2 ng/ml TGFβ1, and/or 10 ng/ml TNF-α. Cells were collected after 1 to 30 min for Western blot analysis and assayed for the accumulation of phosphorylated TAK1, ASK1, JNK1/2, p38, HPS27, MELK, SMAD2/3, and GAPDH. The effect of the kinase inhibitors on α-SMA expression and α-SMA stress fiber organization was also tested. For the immediate response to TGFβ1 we found that a) activation of the MAPK pathway was completed within 1 min after the addition of TGFβ1; b) phosphorylation of JNK1/2 was fully dependent on TAK1 and ASK1 activity, c) phosphorylation of MELK was fully dependent on JNK1/2 activity; d) phosphorylation of ASK1 depends on MELK activity, indicating the existence of an ASK1-MELK positive activation feedback loop; e) phosphorylation of SMAD2/3 started only after a 5 min period and reached a nadir after 10–15 min, f) the latter phosphorylation was fully blocked by inhibition of TAK1, ASK1, JNK1/2, and MELK, and siRNA-driven MELK downregulation; g) the inhibitors equally blocked the α-SMA protein expression, stress fiber development, and cell morphology changes at 72 h. These results demonstrate that the activation of the canonical pathway is fully subordinate to the activity of the MAPK pathway, challenging the concept of canonical and noncanonical TGFβ pathways and that SMAD2/3 activation is mediated by MELK, a kinase not previously associated with rapid pharmacological responses. • The current finding leads to a novel view of the signal transduction events induced by TGFβ1. • SMAD2/3 phosphorylation in response to TGFβ1 is characterized by a delayed response involving a 5-min silent period. • The phosphorylation of SMAD2/3 in response to TGFβ1 is characterized by a delayed response involving a 5-min silent period. • It consists of a single coordinated event where p.SMAD2/3 generation is fully dependent on the pre-activation of MAPKs. • Activated MELK is absolutely essential for the phosphorylation of SMAD2/3 and the development of myofibroblasts. [ABSTRACT FROM AUTHOR]

Background: Psoriasis is a chronic inflammatory skin disease. However, the influence of the TOP2A and MELK genes on psoriasis remains unclear., Methods: Psoriasis datasets GSE166388 and GSE181318 were downloaded from the Gene Expression Omnibus (GEO) database generated from GPL570 and GPL22120. Differential gene expression (DEGs) was identified. Functional enrichment analysis, gene set enrichment analysis (GSEA), weighted gene co-expression network analysis (WGCNA), and immune infiltration analysis were conducted. The protein-protein interaction (PPI) network was constructed and analyzed. Gene expression heat map was generated. The most relevant diseases associated with core genes were determined through comparison with the Comparative Toxicogenomics Database (CTD) website. TargetScan was used to select miRNAs regulating central DEGs., Results: A total of 773 DEGs were identified. According to Gene Ontology (GO) analysis, they were mainly enriched in mitochondrial gene expression, oxidative phosphorylation, mitochondrial envelope, mitochondria and ribosome. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that target cells were mainly enriched in metabolic pathways, proteasome, and oxidative phosphorylation. Seven core genes (TOP2A, NUF2, MELK, ASPM, DLGAP5, CCNA2, DEPDC1B) were obtained. The gene expression heatmap showed high expression of core genes (TOP2A, MELK) in psoriasis samples, while DEPDC1B, CCNA2, DLGAP5, NUF2, ASPM were lowly expressed in psoriasis samples. CTD analysis found that TOP2A and MELK were related to skin neoplasms, skin diseases, psoriasis, erythema, dermatitis, and infections., Conclusion: TOP2A and MELK genes are highly expressed in psoriasis, and higher expression of TOP2A and MELK genes is associated with poorer prognosis.

The balance between T helper 1 (Th1) and T helper 2 (Th2) has a critical function in determining intratumoral immune response and anti-PD-1 immunotherapy. The level of maternal embryonic leucine zipper kinase (MELK) is reported to correlate with infiltration of immune cells in cancers, but the underlying molecular mechanism is not clarified. In the present study, we aimed to elucidate the potential function of MELK in cervical cancer. We found that MELK was upregulated and played an oncogenic role in cervical cancer. MELK overexpression shifted Th1/Th2 balance toward Th2 predisposition in mouse cervical tumors in vivo and naive T cells from human PBMCs in vitro , whereas MELK knockdown exhibited opposite effects. MELK overexpression activated NF-κB signaling and promoted IL-6 secretion by cervical cancer cells. Depletion of IL-6 by neutralization antibodies abrogated the influence of MELK on Th1/Th2 balance. In addition, MELK modulated the antitumor activity of cytotoxic CD8 + T cells in cervical tumors, but depletion of Th2 cells by IL-4 neutralization abrogated this effect. Finally, MELK overexpression conferred tolerance to PD-1 blockade in cervical tumors, whereas targeting MELK by OTSSP167 significantly enhanced PD-1 blockade efficiency. Our data elucidated a novel role of MELK in regulating Th1/Th2 balance and anti-PD-1 immunotherapy in cervical cancer., Competing Interests: The authors declare no competing interests., (© 2024 The Author(s).)

Objective: Maternal embryonic leucine zipper kinase (MELK) is receiving an attention as a therapeutic target in various types of cancers. In this study, we aimed to evaluate the prognostic significance of MELK expression in ovarian cancer using clinical samples, and assessed the efficacy of a small molecule MELK inhibitor, OTS167, using patient-derived ovarian cancer cells as well as cell lines. Methods: Expression levels of MELK in 11 ovarian cancer cell lines were confirmed by western blotting. Inhibitory concentration of OTS167 was determined by colorimetric assay. MELK messenger RNA (mRNA) expression was evaluated in 228 ovarian cancer patients by quantitative polymerase chain reaction. Growth inhibition of OTS167 was also evaluated using freshly-isolated primary ovarian cancer cells including spheroid formation condition. Results: MELK mRNA expression was significantly higher in ovarian cancer than in normal ovaries (p<0.001), and high MELK mRNA expression was observed in patients with advanced stage, positive ascites cytology and residual tumor size. Patients with high MELK mRNA expression showed shorter progression-free survival (p=0.001). Expression of MELK was also confirmed in 10 of 11 ovarian cancer cell lines tested, and the half maximal inhibitory concentration of MELK inhibitor, OTS167, ranged from 9.3 to 60 nM. Additionally, OTS167 showed significant growth inhibitory effect against patient-derived ovarian cancer cells, regardless of their tumor locations, histologic subtypes and stages. Conclusions: We demonstrated MELK as both a prognostic marker and a therapeutic target for ovarian cancer using clinical ovarian cancer samples. MELK inhibition by OTS167 may be an effective approach to treat ovarian cancer patients. [ABSTRACT FROM AUTHOR]

Maternal embryonic leucine zipper kinase (MELK), is an adenosine monophosphate-activated protein kinase-related kinase that serves important roles in tumourigenesis in multiple malignant tumours. However, to the best of our knowledge, the effect of MELK in lung adenocarcinoma (LUAD) has not been elucidated. The present study aimed to explore the clinical significance of MELK in the prognosis of LUAD. Data from Oncomine, Gene Expression Profiling Interactive Analysis (GEPIA) and The Cancer Genome Atlas (TCGA) were selected to predict the differential mRNA expression levels of MELK mRNA in LUAD and normal tissues. Subsequently, LUAD and adjacent normal tissue samples were collected from 75 patients with the disease, and immunohistochemistry was used to detect the protein expression of MELK. In addition, the Kaplan-Meier Plotter database, GEPIA and TCGA were used to verify the effect of MELK expression on clinical prognosis in patients with LUAD. MELK was significantly upregulated in LUAD tissues compared with that in normal tissues based on Oncomine, GEPIA and TCGA data (P<0.05). In addition, the results from immunohistochemistry demonstrated that the MELK protein level in LUAD tissues was significantly higher compared with that in matched normal tissues (P<0.05). Prognostic analysis performed using the Kaplan-Meier plotter, GEPIA and TCGA suggested that the expression of MELK was negatively associated with the overall survival time of patients with LUAD (P<0.05). In conclusion, MELK was highly expressed in LUAD based on bioinformatics and immunohistochemistry analysis, and increased expression of MELK was associated with a poor patient prognosis. MELK may serve as a potential diagnostic marker and therapeutic target for LUAD. [ABSTRACT FROM AUTHOR]

Background: Glioma has the chief type of primary brain tumors worldwide. The glioma may be controlled by regulators including some lncRNAs, miRNAs, and proteins. Objective: Our study aims to discover the underlying mechanism for lncPCAT19/miR-142-5p/MELK axis in glioma progression. Methods: The clinical samples were from patients with gliomas in our Hospital. Hematoxylin–eosin staining (H&E) was applied to determine the clinical pathological changes. Real time PCR was performed to measure the levels of lncPCAT19, miR-142-5p, MELK, and expression of other genes. Western blot was conducted to detect the protein level of MELK. RIP assay was performed to analyze the interaction between lncPCAT19 and miR-142-5p, and dual-luciferase reporter assay was used to determine the binding site between lncPCAT19 and miR-142-5p. CCK-8, colony formation assay, flow cytometry, and trans-well assay were carried out to confirm cell proliferation, colony formation, apoptosis, and invasion, respectively. Results: LncPCAT19 was increased in cancer tissues. Then, lncPCAT19 could interact with and down-regulate miR-142-5p. Knockdown of lncPCAT19 distinctly inhibited tumor growth in vivo. Interfering lncPCAT19/overexpression of miR-142-5p decreased glioma cell proliferation, colony formation and invasion, and promoted cell apoptosis by down-regulating expression of Cyclin B1, CDK2, N-cadherin, Bcl-2, and by up-regulating expression of Bax and E-cadherin. Moreover, overexpression of lncPCAT19 overturned tumor-suppressing role of miR-142-5p in cells. Additionally, lncPCAT19 and miR-142-5p synergistically regulated expression of MELK. In conclusion, lncPCAT19 enhanced glioma development via increasing MELK by performing as a sponge of miR-142-5p. Conclusions: LncPCAT19 promotes glioma progression by sponging miR-142-5p to upregulate MELK levels. Thus, lncPCAT19/miR-142-5p/MELK signaling would be a potential target for glioma treatment. [ABSTRACT FROM AUTHOR]

Maternal embryo leucine zipper kinase (MELK) has a higher expression level in a variety of cancers and involved in progression of colorectal cancer. The MELK expression levels in colorectal cancer tissues and cells were detected by RT-qPCR. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and transwell assays were used to examine the effect of the MELK konckdown on the proliferation, migration and invasion of colorectal cancer cells. Western blot analysis was used to detect the protein level of MELK and the downstream signaling pathways related proteins. Our findings indicated that MELK expression in colorectal cancer tissues was significantly higher than that in para-carcinoma tissues. Knockdown of MELK with shRNA had strong inhibition effects on the proliferation, migration and invasion of colorectal cancer cells. MELK knockdown could also decrease the phosphorylation level of AKT through FAK/Src pathway. Our results indicated downregulation of MELK retarded the progression of CRC by inhibition of the phosphorylation level of AKT through inactivating FAK/Src pathways. Therefore, MELK has the potential to be explored as a new therapeutic target and knockdown can be used as a potential treatment strategy for colorectal cancer. [ABSTRACT FROM AUTHOR]

Uterine leiomyosarcoma (ULMS) is the most lethal gynecologic malignancy with few therapeutic options. Chemoresistance prevails as a major hurdle in treating this malignancy, yet the mechanism of chemoresistance remains largely unclear. In this study, we certified MELK as a poor prognostic marker through bioinformatic analysis of the GEO database. Cellular experiments in vitro revealed that MELK played an essential role in ULMS cells' chemoresistance and that a high expression of MELK could lead to doxorubicin resistance. mRNA profiling uncovered the pathways that MELK was involved in which led to doxorubicin resistance. MELK was found to affect ULMS cells' chemoresistance through an anti-apoptotic mechanism via the JAK2/STAT3 pathway. miRNA profiling also revealed that upregulated MELK could induce the decrease of miRNA-34a (regulated by JAK2/STAT3 pathway). We detected that MELK overexpression could induce M2 macrophage polarization via the miR-34a/JAK2/STAT3 pathway, contributing to doxorubicin chemoresistance in the tumor microenvironment. OTSSP167, a MELK inhibitor, may increase ULMS sensitivity to doxorubicin. Our investigation could propose novel targets for early diagnosis and precision therapy in ULMS patients.

Esophageal squamous cell carcinoma (ESCC) is a common gastrointestinal malignancy and is one of the most important cause of cancer related mortalities in the world. However, there is no clinically effective targeted therapeutic drugs for ESCC due to lack of valuable molecular therapeutic targets. In the present study, we investigated the biological function and molecular mechanisms of maternal embryonic leucine zipper kinase (MELK) in ESCC. The expression of MELK mRNA and protein was determined in cell lines and clinical samples of ESCC. MTT, focus formation and soft agar assays were carried out to measure cell proliferation and colony formation. Wound healing and transwell assays were used to assess the capacity of tumor cell migration and invasion. Nude mice models of subcutaneous tumor growth and lung metastasis were performed to examine the function of MELK in tumorigenecity and metastasis of ESCC cells. High expression of MELK was observed in ESCC cell line and human samples, especially in the metastatic tumor tissues. Moreover, overexpression of MELK promoted cell proliferation, colony formation, migration and invasion, and increased the expression and enzyme activity of MMP-2 and MMP-9 in ESCC cells. More importantly, enhanced expression of MELK greatly accelerated tumor growth and lung metastasis of ESCC cells in vivo. In contrast, knockdown of MELK by lentiviral shRNA resulted in an opposite effect both in vitro and in animal models. Mechanistically, MELK facilitated the phosphorylation of FOXM1, leading to activation of its downstream targets (PLK1, Cyclin B1, and Aurora B), and thereby promoted tumorigenesis and metastasis of ESCC cells. In conclusion, MELK enhances tumorigenesis, migration, invasion and metastasis of ESCC cells via activation of FOXM1 signaling pathway, suggesting MELK is a potential therapeutic target for ESCC patients, even those in an advanced stage.

Abstract Background Previous studies showed sanguinarine induced apoptosis in CRC cells but did not define the underlying mechanisms. The purpose of this work was to determine the in vivo and in vitro effects of sanguinarine on CRC tumors and to elucidate the mechanism in regulating the intrinsic apoptosis. Methods Cell viability of CRC cell lines treated with sanguinarine was measured by MTT assay. Apoptotic cells stained with Annexin V and 7-AAD were detected by flow cytometry. Mitochondrial membrane potential and reactive oxygen species (ROS) were analyzed by JC-1 and DCFH-DA staining, respectively. The in vitro kinase activity of MELK was analyzed by using HTRF® KinEASE™-STK kit. The expression of proteins were determined using Western blotting and immunohistochemistry. Co-immunoprecipitation and immunofluorecence were used to study the interaction between STRAP and MELK. The anti-neoplastic effect of sanguinarine was observed in vivo in an orthotopic CRC model. Results Sanguinarine decreased the tumor size in a dose-dependent manner in orthotopical colorectal carcinomas through intrinsic apoptosis pathway in BALB/c-nu mice. It significantly increased cleavage of caspase 3 and PARP in implanted colorectal tissues. Sanguinarine increased mitochondrial ROS and triggered mitochondrial outer membrane permeabilization in multiple colorectal cancer (CRC) cell lines. NAC pretreatment lowered ROS level and downregulated apoptosis induced by sanguinarine. The intrinsic apoptosis induced by sanguinarine was Bax-dependent. The elevated expression and association between serine-threonine kinase receptor-associated protein (STRAP) and maternal embryonic leucine zipper kinase (MELK) were observed in Bax positive cells but not in Bax negative cells. Sanguinarine dephosphorylated STRAP and MELK and disrupted the association between them in HCT116 and SW480 cells. The expression and association between STRAP and MELK were also attenuated by sanguinarine in the tumor tissues. Importantly, we found that STRAP and MELK were overexpressed and highly phosphorylated in colorectal adenocarcinomas and their expression were significantly correlated with tumor stages. Furthermore, the expression of MELK, but not STRAP, was associated with lymph node metastasis. Conclusions Sanguinarine dephosphorelates STRAP and MELK and disassociates the interaction between them to trigger intrinsic apoptosis. Overexpression of STRAP and MELK may be markers of CRC and their disassociation may be a determinant of therapeutic efficacy.

Uterine leiomyosarcoma (ULMS) is the most lethal gynecologic malignancy with few therapeutic options. Chemoresistance prevails as a major hurdle in treating this malignancy, yet the mechanism of chemoresistance remains largely unclear. In this study, we certified MELK as a poor prognostic marker through bioinformatic analysis of the GEO database. Cellular experiments in vitro revealed that MELK played an essential role in ULMS cells' chemoresistance and that a high expression of MELK could lead to doxorubicin resistance. mRNA profiling uncovered the pathways that MELK was involved in which led to doxorubicin resistance. MELK was found to affect ULMS cells' chemoresistance through an anti-apoptotic mechanism via the JAK2/STAT3 pathway. miRNA profiling also revealed that upregulated MELK could induce the decrease of miRNA-34a (regulated by JAK2/STAT3 pathway). We detected that MELK overexpression could induce M2 macrophage polarization via the miR-34a/JAK2/STAT3 pathway, contributing to doxorubicin chemoresistance in the tumor microenvironment. OTSSP167, a MELK inhibitor, may increase ULMS sensitivity to doxorubicin. Our investigation could propose novel targets for early diagnosis and precision therapy in ULMS patients. [ABSTRACT FROM AUTHOR]

Esophageal squamous cell carcinoma (ESCC) is a common gastrointestinal malignancy and is one of the most important cause of cancer related mortalities in the world. However, there is no clinically effective targeted therapeutic drugs for ESCC due to lack of valuable molecular therapeutic targets. In the present study, we investigated the biological function and molecular mechanisms of maternal embryonic leucine zipper kinase (MELK) in ESCC. The expression of MELK mRNA and protein was determined in cell lines and clinical samples of ESCC. MTT, focus formation and soft agar assays were carried out to measure cell proliferation and colony formation. Wound healing and transwell assays were used to assess the capacity of tumor cell migration and invasion. Nude mice models of subcutaneous tumor growth and lung metastasis were performed to examine the function of MELK in tumorigenecity and metastasis of ESCC cells. High expression of MELK was observed in ESCC cell line and human samples, especially in the metastatic tumor tissues. Moreover, overexpression of MELK promoted cell proliferation, colony formation, migration and invasion, and increased the expression and enzyme activity of MMP-2 and MMP-9 in ESCC cells. More importantly, enhanced expression of MELK greatly accelerated tumor growth and lung metastasis of ESCC cells in vivo. In contrast, knockdown of MELK by lentiviral shRNA resulted in an opposite effect both in vitro and in animal models. Mechanistically, MELK facilitated the phosphorylation of FOXM1, leading to activation of its downstream targets (PLK1, Cyclin B1, and Aurora B), and thereby promoted tumorigenesis and metastasis of ESCC cells. In conclusion, MELK enhances tumorigenesis, migration, invasion and metastasis of ESCC cells via activation of FOXM1 signaling pathway, suggesting MELK is a potential therapeutic target for ESCC patients, even those in an advanced stage. [ABSTRACT FROM AUTHOR]

We aimed to investigate the biological function of MELK and the therapeutic potential of OTSSP167 in human bladder cancer (BCa). First, we observed overexpression of MELK in BCa cell lines and tissues and found that it was associated with higher tumour stage and tumour grade, which was consistent with transcriptome analysis. High expression of MELK was significantly correlated with poor prognosis in BCa patients, and MELK was found to have a role in the cell cycle, the G1/S transition in mitosis, and DNA repair and replication. Furthermore, BCa cells presented significantly decreased proliferation capacity following silencing of MELK or treatment with OTSSP167 in vitro and in vivo. Functionally, reduction in MELK or treatment of cells with OTSSP167 could induce cell cycle arrest and could suppress migration. In addition, these treatments could activate phosphorylation of ATM and CHK2, which would be accompanied by down‐regulated MDMX, cyclin D1, CDK2 and E2F1; however, p53 and p21 would be activated. Opposite results were observed when MELK expression was induced. Overall, MELK was found to be a novel oncogene in BCa that induces cell cycle arrest via the ATM/CHK2/p53 pathway. OTSSP167 displays potent anti‐tumour activities, which may provide a new molecule‐based strategy for BCa treatment. [ABSTRACT FROM AUTHOR]

Abstract Background MicroRNAs are considered as potential regulators in various biological pathways and contribute to the diagnosis and prognosis of cancers. MicroRNA-214-3p (miR-214-3p) was proved to be correlated with various cancers in recent studies. However, the biological functions of miR-214-3p in hepatocellular carcinoma (HCC) and its association with the prognosis of HCC after liver transplantation are still unevaluated. Here we intended to elucidate the functional implication of miR-214-3p in regulation of cell proliferation and apoptosis and its potential prediction of clinical prognosis of HCC patients. Methods Expressions of miR-214-3p in 98 HCC patients and three HCC cell lines were detected by quantitative reverse transcription PCR (qRT-PCR) to explore the association of miR-214-3p expression and clinicopathological characteristics. The effects of miR-214-3p on cell proliferation and apoptosis were examined by proliferation and flow cytometry assay, respectively. The direct target gene of miR-214-3p was also detected by luciferase reporter assay. Results The effects of miR-214-3p on cell proliferation and apoptosis were examined by proliferation and flow cytometry assay, respectively. The direct target gene of miR-214-3p was also detected by luciferase reporter assay. The results showed that miR-214-3p expression was downregulated in primary HCC samples compared with normal liver tissues, and was decreased in HCC recurrence species compared with non-recurrence controls (P = 0.001). Low miR-214-3p level was associated with poor overall survival (OS) (Log rank P = 0.003) and recurrence-free survival (RFS) (Log rank P = 0.007). Moreover, miR-214-3p precursor transfection resulted in decreased cell proliferation, cell cycle arrest at G1 phase, and enhanced cell apoptosis in HepG2 and HUH-7 cells. Further investigation showed that miR-214-3p could regulate its target gene maternal embryonic leucine zipper kinase (MELK) by directly binding to MELK-3′-UTR. Conclusions miR-214-3p suppresses HCC progression by directly down-regulating MELK expression, indicating a potential therapeutic target for the treatment and prognosis of HCC patients.