miR-503 suppresses metastasis of hepatocellular carcinoma cell by targeting PRMT1

PRMT1-Mediated SWI/SNF Complex Recruitment via SMARCC1 Drives IGF2BP2 Transcription to Enhance Carboplatin Resistance in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a malignancy with poor prognosis and chemotherapy resistance. Here, protein arginine methyltransferase 1 (PRMT1) is identified as a key driver of carboplatin (CBP) resistance in HNSCC. Analyses of clinical samples, cell lines, patient-derived organoids, and xenograft models reveal that PRMT1 promotes tumor growth and CBP resistance through a novel, methyltransferase-independent mechanism. Conditional PRMT1 knockout suppresses tumorigenesis and enhances CBP sensitivity in vivo, highlighting its essential role in HNSCC progression. Mechanistically, PRMT1 recruits the SWI/SNF chromatin remodeling complex via direct interaction with SMARCC1, leading to the transcriptional activation of insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2), which enhances CBP resistance and tumor growth. Notably, this function is independent of PRMT1's enzymatic activity, distinguishing it from its well-established roles in arginine methylation. Furthermore, pre-B-cell leukemia homeobox 2 (PBX2) is identified as an upstream transcriptional activator that binds the PRMT1 promoter, driving its overexpression and reinforcing this oncogenic network. Clinically, high PBX2, PRMT1, SMARCC1, and IGF2BP2 expression correlates with malignant progression and poor prognosis in HNSCC patients. This study uncovers a previously unrecognized non-catalytic function of PRMT1 and highlights the PBX2-PRMT1-SWI/SNF-IGF2BP2 axis as a potential therapeutic target for overcoming CBP resistance in HNSCC.

MicroRNA as Key Players in Hepatocellular Carcinoma: Insights into Their Role in Metastasis

Liver cancer or hepatocellular carcinoma (HCC) remains the most common cancer in global epidemiology. Both the frequency and fatality of this malignancy have shown an upward trend over recent decades. Liver cancer is a significant concern due to its propensity for both intrahepatic and extrahepatic metastasis. Liver cancer metastasis is a multifaceted process characterized by cell detachment from the bulk tumor, modulation of cellular motility and invasiveness, enhanced proliferation, avoidance of the immune system, and spread either via lymphatic or blood vessels. MicroRNAs (miRNAs) are small non-coding ribonucleic acids (RNAs) playing a crucial function in the intricate mechanisms of tumor metastasis. A number of miRNAs can either increase or reduce metastasis via several mechanisms, such as control of motility, proliferation, attack by the immune system, cancer stem cell properties, altering the microenvironment, and the epithelial-mesenchymal transition (EMT). Besides, two other types of non-coding RNAs, such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) can competitively bind to endogenous miRNAs. This competition results in the impaired ability of the miRNAs to inhibit the expression of the specific messenger RNAs (mRNAs) that are targeted. Increasing evidence has shown that the regulatory axis comprising circRNA/lncRNA-miRNA-mRNA is correlated with the regulation of HCC metastasis. This review seeks to present a thorough summary of recent research on miRNAs in HCC, and their roles in the cellular processes of EMT, invasion and migration, as well as the metastasis of malignant cells. Finally, we discuss the function of the lncRNA/circRNA-miRNA-mRNA network as a crucial modulator of carcinogenesis and the regulation of signaling pathways or genes that are relevant to the metastasis of HCC. These findings have the potential to offer valuable insight into the discovery of novel therapeutic approaches for management of liver cancer metastasis.

Metformin suppresses gastric cancer progression by disrupting the STAT1-PRMT1 axis

Gastric cancer (GC) is a common form of cancer and the leading cause of cancer-related deaths worldwide. Chemotherapy is the primary treatment for patients with unresectable or partially resectable GC. However, its adverse effects and chemoresistance greatly restrict its applicability and efficacy. Although HER2-targeted therapy and immunotherapy have been successfully used for GC treatment, their beneficial population is limited. To expand the range of cancer treatments, drug repurposing has emerged as a promising strategy. In this study, we evaluated the potential of Metformin, an oral anti-hyperglycemic agent, to suppress GC progression both in vivo and in vitro. Functional investigations showed that Metformin significantly inhibits GC proliferation and migration. Furthermore, we discovered that Metformin bound and disrupted STAT1 phosphorylation, inhibiting PRMT1 expression and consequently GC progression. In conclusion, our study not only provides further evidence for the anti-GC role of Metformin but also identifies the direct target mediating the tumor-inhibitory effects of Metformin in GC.

PRMT1 promotes Warburg effect by regulating the PKM2/PKM1 ratio in non-small cell lung cancer

Abnormal epigenetic modifications are involved in the regulation of Warburg effect in tumor cells. Protein arginine methyltransferases (PRMTs) mediate arginine methylation and have critical functions in cellular responses. PRMTs are deregulated in a variety of cancers, but their precise roles in Warburg effect in cancer is largely unknown. Experiments from the current study showed that PRMT1 was highly expressed under conditions of glucose sufficiency. PRMT1 induced an increase in the PKM2/PKM1 ratio through upregulation of PTBP1, in turn, promoting aerobic glycolysis in non-small cell lung cancer (NSCLC). The PRMT1 level in p53-deficient and p53-mutated NSCLC remained relatively unchanged while the expression was reduced in p53 wild-type NSCLC under conditions of glucose insufficiency. Notably, p53 activation under glucose-deficient conditions could suppress USP7 and further accelerate the polyubiquitin-dependent degradation of PRMT1. Melatonin, a hormone that inhibits glucose intake, markedly suppressed cell proliferation of p53 wild-type NSCLC, while a combination of melatonin and the USP7 inhibitor P5091 enhanced the anticancer activity in p53-deficient NSCLC. Our collective findings support a role of PRMT1 in the regulation of Warburg effect in NSCLC. Moreover, combination treatment with melatonin and the USP7 inhibitor showed good efficacy, providing a rationale for the development of PRMT1-based therapy to improve p53-deficient NSCLC outcomes.

FBXO7 ubiquitinates PRMT1 to suppress serine synthesis and tumor growth in hepatocellular carcinoma

Cancer cells are often addicted to serine synthesis to support growth. How serine synthesis is regulated in cancer is not well understood. We recently demonstrated protein arginine methyltransferase 1 (PRMT1) is upregulated in hepatocellular carcinoma (HCC) to methylate and activate phosphoglycerate dehydrogenase (PHGDH), thereby promoting serine synthesis. However, the mechanisms underlying PRMT1 upregulation and regulation of PRMT1-PHGDH axis remain unclear. Here, we show the E3 ubiquitin ligase F-box-only protein 7 (FBXO7) inhibits serine synthesis in HCC by binding PRMT1, inducing lysine 37 ubiquitination, and promoting proteosomal degradation of PRMT1. FBXO7-mediated PRMT1 downregulation cripples PHGDH arginine methylation and activation, resulting in impaired serine synthesis, accumulation of reactive oxygen species (ROS), and inhibition of HCC cell growth. Notably, FBXO7 is significantly downregulated in human HCC tissues, and inversely associated with PRMT1 protein and PHGDH methylation level. Overall, our study provides mechanistic insights into the regulation of cancer serine synthesis by FBXO7-PRMT1-PHGDH axis, and will facilitate the development of serine-targeting strategies for cancer therapy.

PRMT1 Integrates Immune Microenvironment and Fatty Acid Metabolism Response in Progression of Hepatocellular Carcinoma

Background

Protein arginine methyltransferase (PRMT) family members have important roles in cancer processes. However, its functions in the regulation of cancer immunotherapy of hepatocellular carcinoma (HCC) are incompletely understood. This study aimed to investigate the roles of PRMT1 in HCC.

Methods

Single-cell RNA sequencing (scRNA-seq) and clinicopathological data were obtained and used to explore the diagnostic and prognostic value, cellular functions and roles in immune microenvironment regulation of PRMT1 in HCC. The functions of PRMT1 were explored using Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO), as well as gene set enrichment analysis (GSEA). TIMER and CIBERSORT were used to analyze the relationships between PRMT1 expression and immune cell infiltration. The STRING database was used to construct a protein-protein interaction (PPI) network.

Results

PRMT1 was aberrantly expressed in HCC, which high expression was associated with tumor progression, worse overall survival (OS) and disease-free survival (DFS) of patients with HCC. PRMT1 was also associated with immune cell infiltration. Moreover, it was specifically expressed in immune cells, including exhausted CD8 T cells, B cells, and mono/macro cells in patients with immunotherapy. The expression of immune checkpoints was significantly increased in the high-PRMT1 expression groups of HCC patients. Regarding biological mechanisms, cell viability, migration and invasion, and the expression of genes related to fatty acid metabolism were suppressed in PRMT1 knockdown HCC cells. Moreover, genes co-expressed with PRMT1 were involved in the fatty acid metabolic process and enriched in fatty and drug-induced liver disease.

Conclusion

Taken together, these results indicate that PRMT1 might exert its oncogenic effects via immune microenvironment regulation and fatty acid metabolism in HCC. Our finding will provide a foundation for further studies and indicate a potential clinical therapeutic target for liver cancer.

Downregulation of miR-503-5p Promotes the Development of Pancreatic Cancer by Targeting Cyclin E2

This study aimed to elucidate the role of microRNA-503 (miR-503) in pancreatic cancer (PC) progression and the underlying regulatory mechanisms. We acquired miR-503-3p and miR-503-5p expression data along with survival times of PC and normal samples from the UCSC Xena database. Using the t-test, we compared the expression of miR-503-3p and miR-503-5p between PC and normal samples, and evaluated their prognostic significance via Kaplan-Meier survival analysis. The expression of miR-503-5p in PC cells was detected by quantitative PCR. We subsequently overexpressed miR-503-5p in PC cells and examined cell viability, apoptosis, and migration through CCK8 assay, flow cytometry, and Transwell assay, respectively. Potential functional targets were identified using miRTarBase and validated by dual-luciferase reporter assay. Both miR-503-3p and miR-503-5p expression were found to be downregulated in PC; however, only miR-503-5p was linked to cancer prognosis based on public data. In vitro experiments demonstrated that overexpression of miR-503-5p substantially decreased cell viability, induced apoptosis, caused G0/G1 arrest, and inhibited cell migration. miR-503-5p was found to target cyclin E2 (CCNE2), and overexpression of CCNE2 could counteract the effects of miR-503-5p on PC cells. Conclusion: The downregulation of miR-503-5p enhances the progression of PC by targeting CCNE2. The detection of miR-503-5p expression may provide valuable insights for the prevention and prognostic evaluation of PC.

The protein arginine methyltransferase family (PRMTs) regulates metastases in various tumors: From experimental study to clinical application

Tumor metastasis is the leading cause of mortality among advanced cancer patients. Understanding its mechanisms and treatment strategies is vital for clinical application. Arginine methylation, a post-translational modification catalyzed by protein arginine methyltransferases (PRMTs), is implicated in diverse physiological processes and disease progressions. Previous research has demonstrated PRMTs' involvement in tumor occurrence, progression, and metastasis. This review offers a comprehensive summary of the relationship between PRMTs, prognosis, and metastasis in various cancers. Our focus centers on elucidating the molecular mechanisms through which PRMTs regulate tumor metastasis. We also discuss relevant clinical trials and effective PRMT inhibitors, including chemical compounds, long non-coding RNA (lncRNA), micro-RNA (miRNA), and nanomaterials, for treating tumor metastasis. While a few studies present conflicting results, the overall trajectory suggests that inhibiting arginine methylation exhibits promise in curtailing tumor metastasis across various cancers. Nonetheless, the underlying mechanisms and molecular interactions are diverse. The development of inhibitors targeting arginine methylation, along with the progression of clinical trials, holds substantial potential in the field of tumor metastasis, meriting sustained attention.

The Significant Role of microRNAs in Gliomas Angiogenesis: A Particular Focus on Molecular Mechanisms and Opportunities for Clinical Application

MicroRNAs (miRNAs) are non-coding RNAs with only 20-22 nucleic acids that inhibit gene transcription and translation by binding to mRNA. MiRNAs have a diverse set of target genes and can alter most physiological processes, including cell cycle checkpoints, cell survival, and cell death mechanisms, affecting the growth, development, and invasion of various cancers, including gliomas. So optimum management of miRNA expression is essential for preserving a normal biological environment. Due to their small size, stability, and capability of specifically targeting oncogenes, miRNAs have emerged as a promising marker and new biopharmaceutical targeted therapy for glioma patients. This review focuses on the most common miRNAs associated with gliomagenesis and development by controlling glioma-determining markers such as angiogenesis. We also summarized the recent research about miRNA effects on signaling pathways, their mechanistic role and cellular targets in the development of gliomas angiogenesis. Strategies for miRNA-based therapeutic targets, as well as limitations in clinical applications, are also discussed.

FOXM1 promotes TGF-β2-induced injury of human lens epithelial cells by up regulating VEGFA expression

OBJECTIVE

To explore whether Fork head box protein M1 (FOXM1) is involved in TGF-β2-induced injury of human lens epithelial cells and its related mechanism.

METHODS

Human lens epithelium samples from cataract patients and healthy controls were collected. A cellular epithelial injury model was established by treating HLE-B3 cells with TGF-β2. QPCR, immunoblot assays were performed to detect the levels of FOXM1 in human cataract samples and the lens epithelial injury cell model. FOXM1 siRNA and pcDNA3.1-FOXM1 plasmids were transfected into the cells to knockdown and overexpress FOXM1, respectively. MTT and wound closure and transwell assays were performed to analyze cell proliferation and migration in HLE-B3 cells. Immunoblot assays were also conducted to detect the effects of FOXM1 on EMT, VEGFA and MAPK/ERK signaling.

RESULTS

We found high expression of FOXM1 in lens tissues of cataract patients. Silencing of FOXM1 in TGF-β2-induced HLE-B3 cells suppressed cell proliferation, migration, and the EMT process. Mechanistically, we found that downregulation of FOXM1 inhibited the VEGFA/MAPK signaling pathway in TGF-β2-induced HLE-B3 cells.

CONCLUSION

FOXM1 promoted TGF-β2-induced injury of human lens epithelial cells (hLECs) by promoting VEGFA expression. FOXM1 could be a potential drug target for the treatment of ocular diseases.

Value of biomarkers in epithelial-mesenchymal transition models of liver cancer under different interventions: a meta-analysis

Aim: A meta-analysis was conducted to evaluate the effectiveness of crucial biomarkers in HepG2 cells during epithelial-mesenchymal transformation induced by multiple interventions. Methods: PubMed, Web of Science, Embase, China National Knowledge Infrastructure, Chinese Biomedical Literature Database, Wan Fang Data and VIP databases were systematically searched from inception to 14 June 2020, by two independent reviewers. Results: A total of 58 studies were included in the meta-analysis. E-cadherin, N-cadherin and vimentin performed well under medicinal interventions. E-cadherin worked well under genetic interventions. E-cadherin and N-cadherin also performed significantly well under tumor microenvironment interventions. Under ncRNA interventions, the expression of E-cadherin significantly changed. Conclusion: Different sets of biomarkers should be selected under various interventions based on their performance.

Interaction of lncRNA MIR100HG with hnRNPA2B1 facilitates m6A-dependent stabilization of TCF7L2 mRNA and colorectal cancer progression

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is a process linked to metastasis and drug resistance with non-coding RNAs (ncRNAs) playing pivotal roles. We previously showed that miR-100 and miR-125b, embedded within the third intron of the ncRNA host gene MIR100HG, confer resistance to cetuximab, an anti-epidermal growth factor receptor (EGFR) monoclonal antibody, in colorectal cancer (CRC). However, whether the MIR100HG transcript itself has a role in cetuximab resistance or EMT is unknown.

METHODS

The correlation between MIR100HG and EMT was analyzed by curating public CRC data repositories. The biological roles of MIR100HG in EMT, metastasis and cetuximab resistance in CRC were determined both in vitro and in vivo. The expression patterns of MIR100HG, hnRNPA2B1 and TCF7L2 in CRC specimens from patients who progressed on cetuximab and patients with metastatic disease were analyzed by RNAscope and immunohistochemical staining.

RESULTS

The expression of MIR100HG was strongly correlated with EMT markers and acted as a positive regulator of EMT. MIR100HG sustained cetuximab resistance and facilitated invasion and metastasis in CRC cells both in vitro and in vivo. hnRNPA2B1 was identified as a binding partner of MIR100HG. Mechanistically, MIR100HG maintained mRNA stability of TCF7L2, a major transcriptional coactivator of the Wnt/β-catenin signaling, by interacting with hnRNPA2B1. hnRNPA2B1 recognized the N6-methyladenosine (m⁶A) site of TCF7L2 mRNA in the presence of MIR100HG. TCF7L2, in turn, activated MIR100HG transcription, forming a feed forward regulatory loop. The MIR100HG/hnRNPA2B1/TCF7L2 axis was augmented in specimens from CRC patients who either developed local or distant metastasis or had disease progression that was associated with cetuximab resistance.

CONCLUSIONS

MIR100HG and hnRNPA2B1 interact to control the transcriptional activity of Wnt signaling in CRC via regulation of TCF7L2 mRNA stability. Our findings identified MIR100HG as a potent EMT inducer in CRC that may contribute to cetuximab resistance and metastasis by activation of a MIR100HG/hnRNPA2B1/TCF7L2 feedback loop.

Epi-miRNAs: Regulators of the Histone Modification Machinery in Human Cancer

Cancer is a leading cause of death and disability worldwide. Epigenetic deregulation is one of the most critical mechanisms in carcinogenesis and can be classified into effects on DNA methylation and histone modification. MicroRNAs are small noncoding RNAs involved in fine-tuning their target genes after transcription. Various microRNAs control the expression of histone modifiers and are involved in a variety of cancers. Therefore, overexpression or downregulation of microRNAs can alter cell fate and cause malignancies. In this review, we discuss the role of microRNAs in regulating the histone modification machinery in various cancers, with a focus on the histone-modifying enzymes such as acetylases, deacetylases, methyltransferases, demethylases, kinases, phosphatases, desumoylases, ubiquitinases, and deubiquitinases. Understanding of microRNA-related aberrations underlying histone modifiers in pathogenesis of different cancers can help identify novel therapeutic targets or early detection approaches that allow better management of patients or monitoring of treatment response.

Novel oncogenes and tumor suppressor genes in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a very deadly disease. HCC initiation and progression involve multiple genetic events, including the activation of proto-oncogenes and disruption of the function of specific tumor suppressor genes. Activation of oncogenes stimulates cell growth and survival, while loss-of-function mutations of tumor suppressor genes result in unrestrained cell growth. In this review, we summarize the new findings that identified novel proto-oncogenes and tumor suppressors in HCC over the past five years. These findings may inspire the development of novel therapeutic strategies to improve the outcome of HCC patients.

Structure, Activity, and Function of PRMT1

PRMT1, the major protein arginine methyltransferase in mammals, catalyzes monomethylation and asymmetric dimethylation of arginine side chains in proteins. Initially described as a regulator of chromatin dynamics through the methylation of histone H4 at arginine 3 (H4R3), numerous non-histone substrates have since been identified. The variety of these substrates underlines the essential role played by PRMT1 in a large number of biological processes such as transcriptional regulation, signal transduction or DNA repair. This review will provide an overview of the structural, biochemical and cellular features of PRMT1. After a description of the genomic organization and protein structure of PRMT1, special consideration was given to the regulation of PRMT1 enzymatic activity. Finally, we discuss the involvement of PRMT1 in embryonic development, DNA damage repair, as well as its participation in the initiation and progression of several types of cancers.

Protein arginine methyltransferases and hepatocellular carcinoma: A review

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Protein arginine methylation is essential in multiple biological processes.

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The family of PRMTs is a novel regulator of liver diseases.

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Deregulation of PRMTs is correlated with HCC prognosis and clinical features.

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PRMTs play a vital role in HCC malignancy, immune responses and metabolism.

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PRMTs may represent druggable targets as novel strategies for HCC therapy.

Hepatocellular carcinoma (HCC) is one of the most frequently diagnosed cancers with a high mortality rate worldwide. The complexity of HCC initiation and progression poses a great challenge to the diagnosis and treatment. An increasing number of studies have focused on the emerging roles of protein arginine methylation in cancers, including tumor growth, invasion, metastasis, metabolism, immune responses, chemotherapy sensitivity, etc. The family of protein arginine methyltransferases (PRMTs) is the most important proteins that mediate arginine methylation. The deregulation of PRMTs’ expression and functions in cancers have been gradually unveiled, and many PRMTs inhibitors are in preclinical and clinical investigations now. This review focuses predominantly on the aberrant expression of PRMTs, underlying mechanisms, as well as their potential applications in HCC, and provide novel insights into HCC therapy.

HCV Proteins Modulate the Host Cell miRNA Expression Contributing to Hepatitis C Pathogenesis and Hepatocellular Carcinoma Development

Simple Summary

According to the last estimate by the World Health Organization (WHO), more than 71 million individuals have chronic hepatitis C worldwide. The persistence of HCV infection leads to chronic hepatitis, which can evolve into liver cirrhosis and ultimately into hepatocellular carcinoma (HCC). Although the pathogenic mechanisms are not fully understood, it is well established that an interplay between host cell factors, including microRNAs (miRNA), and viral components exist in all the phases of the viral infection and replication. Those interactions establish a complex equilibrium between host cells and HCV and participate in multiple mechanisms characterizing hepatitis C pathogenesis. The present review aims to describe the role of HCV structural and non-structural proteins in the modulation of cellular miRNA during HCV infection and pathogenesis.

Abstract

Hepatitis C virus (HCV) genome encodes for one long polyprotein that is processed by cellular and viral proteases to generate 10 polypeptides. The viral structural proteins include the core protein, and the envelope glycoproteins E1 and E2, present at the surface of HCV particles. Non-structural (NS) proteins consist of NS1, NS2, NS3, NS4A, NS4B, NS5a, and NS5b and have a variable function in HCV RNA replication and particle assembly. Recent findings evidenced the capacity of HCV virus to modulate host cell factors to create a favorable environment for replication. Indeed, increasing evidence has indicated that the presence of HCV is significantly associated with aberrant miRNA expression in host cells, and HCV structural and non-structural proteins may be responsible for these alterations. In this review, we summarize the recent findings on the role of HCV structural and non-structural proteins in the modulation of host cell miRNAs, with a focus on the molecular mechanisms responsible for the cell re-programming involved in viral replication, immune system escape, as well as the oncogenic process. In this regard, structural and non-structural proteins have been shown to modulate the expression of several onco-miRNAs or tumor suppressor miRNAs.

Silencing circRNA LRP6 down-regulates PRMT1 to improve the streptozocin-induced pancreatic β-cell injury and insulin secretion by sponging miR-9-5p

Due to the sedentary lifestyles of people, the number of obese people is increasing alarmingly, which leads to the high prevalence of diabetes mellitus (DM). It was reported that circularRNA (circRNA) LRP6 was upregulated in HG-treated mesangial cells, and it could regulate high glucose-induced cell injury via sponging miR-205. Thus, the aim of this study was to explore the underlying pathogenesis of DM. Streptozocin (STZ) was used to stimulate the in vitro model of pancreatic β-cell injury. Then, quantitative reverse transcription polymerase chain reaction (RT-qPCR) and methyl thiazolyl tetrazolium (MTT) assay were used to evaluate the expression of circLRP6 and the cell viability in STZ-challenged INS-1 cells, respectively. After knocking down circLRP6, the cell viability and apoptosis were respectively measured by MTT and TdT-mediated dUTP nick-end labeling (TUNEL) staining, and insulin release and oxidative stress were respectively measured by enzyme-linked immunosorbent assay (ELISA) and corresponding kits. After the interactions among circLRP6, PRMT1, and miR-9-5p were predicted and confirmed, the above mentioned assays were conducted again. The expression of circLRP6 was elevated while cell viability was decreased after INS-1 cells were exposed to STZ. Silencing circLRP6 resulted in an increase in the cell viability, a decrease in the cell apoptosis, together with more insulin release. The circLRP6/miR-9-5p/PRMT1 regulatory network was then confirmed, which affected the cell viability, apoptosis, insulin release, and oxidative stress in STZ-challenged INS-1 cells. In conclusion, this study first provides evidence that the circLRP6/miR-9-5p/PRMT1 regulatory network can affect STZ-induced cell viability, oxidative stress, and insulin secretion in INS-l cells, which can further impact the progression of diabetes.

Arginine methylation: the promise of a 'silver bullet' for brain tumours?

Despite intense research efforts, our pharmaceutical repertoire against high-grade brain tumours has not been able to increase patient survival for a decade and life expectancy remains at less than 16 months after diagnosis, on average. Inhibitors of protein arginine methyltransferases (PRMTs) have been developed and investigated over the past 15 years and have now entered oncology clinical trials, including for brain tumours. This review collates recent advances in the understanding of the role of PRMTs and arginine methylation in brain tumours. We provide an up-to-date literature review on the mechanisms for PRMT regulation. These include endogenous modulators such as alternative splicing, miRNA, post-translational modifications and PRMT-protein interactions, and synthetic inhibitors. We discuss the relevance of PRMTs in brain tumours with a particular focus on PRMT1, -2, -5 and -8. Finally, we include a future perspective where we discuss possible routes for further research on arginine methylation and on the use of PRMT inhibitors in the context of brain tumours.

Systematic review and meta-analysis of the prognostic significance of microRNAs related to metastatic and EMT process among prostate cancer patients

The ability of tumor cells to spread from their origin place and form secondary tumor foci is determined by the epithelial-mesenchymal transition process. In epithelial tumors such as prostate cancer (PCa), the loss of intercellular interactions can be observed as a change in expression of polarity proteins. Epithelial cells acquire ability to migrate, what leads to the formation of distal metastases. In recent years, the interest in miRNA molecules as potential future treatment options has increased. In tumor microenvironment, miRNAs have the ability to regulate signal transduction pathways, where they can act as suppressors or oncogenes. MiRNAs are secreted by cancer cells, and the changes in their expression levels are closely related to a cancer progression, including epithelial-mesenchymal transition. These molecules offer new diagnostic and therapeutic possibilities. Therapeutics which make use of synthesized RNA fragments and mimic or block miRNAs affected in PCa, may lead to inhibition of tumor progression and even disease re-emission. Based on appropriate qualification criteria, we conducted a selection process to identify scientific articles describing miRNAs and their relation to epithelial-mesenchymal transition in PCa patients. The studies were published in English on Pubmed, Scopus and the Web of Science before August 08, 2019. Hazard ratios (HRs) and 95% confidence intervals (CI) as well as total Gleason score were used to assess the concordance between miRNAs and presence of metastases. A total of 13 studies were included in our meta-analysis, representing 1608 PCa patients and 15 miRNA molecules. Our study clarifies a relationship between the clinicopathological features of PCa and the aberrant expression of several miRNA as well as the complex mechanism of miRNA molecules involvement in the induction and promotion of the metastatic mechanism in PCa.

PRMT1 expression predicts sensitivity to platinum-based chemotherapy in patients with ovarian serous carcinoma

Patients with ovarian serous carcinoma are generally diagnosed at an advanced disease stage. The standard treatment for these patients is maximal debulking surgery followed by platinum-taxane combination chemotherapy. Despite initially responding well, more than half of patients become refractory to first-line chemotherapy. Upregulation of protein arginine methyltransferase 1 (PRMT1) expression has been demonstrated to methylate apoptosis signal-regulated kinase 1 and inhibit its activity, thereby contributing to chemoresistance. The present study investigated the association between PRMT1 expression and sensitivity to platinum-based chemotherapy in 51 patients with ovarian serous carcinoma (International Federation of Gynecology and Obstetrics stages III and IV), and the effect of RNA interference-mediated downregulation of PRMT1 on the sensitivity of ovarian cancer cells to cisplatin and carboplatin in vitro. Immunohistochemistry of tumor specimens was used to compare the expression levels of PRMT1, a Cell Counting Kit-8 assay and small interfering RNA transfection were performed for chemosensitivity assays, and reverse transcription-quantitative PCR was used to examine PRMT1 mRNA expression. Patients were divided into platinum-sensitive (n=26) and platinum-resistant (n=25) groups. PRMT1 expression was significantly lower in the platinum-sensitive group than in the platinum-resistant group (P=0.019). When patients were categorized according to PRMT1 expression, those in the low PRMT1 expression group were more sensitive to platinum-based chemotherapy than those in the high PRMT1 expression group (P=0.01). Additionally, in vitro experiments revealed that suppression of PRMT1 expression by siRNA significantly increased the sensitivity of human ovarian serous carcinoma cells to cisplatin and carboplatin (P<0.05). In conclusion, PRMT1 expression could predict sensitivity to platinum-based chemotherapy in patients with ovarian serous carcinoma.

Hepigenetics: A Review of Epigenetic Modulators and Potential Therapies in Hepatocellular Carcinoma

Hepatocellular carcinoma is the fifth most common cancer worldwide and the second most lethal, following lung cancer. Currently applied therapeutic practices rely on surgical resection, chemotherapy and radiotherapy, or a combination thereof. These treatment options are associated with extreme adversities, and risk/benefit ratios do not always work in patients' favor. Anomalies of the epigenome lie at the epicenter of aberrant molecular mechanisms by which the disease develops and progresses. Modulation of these anomalous events poses a promising prospect for alternative treatment options, with an abundance of felicitous results reported in recent years. Herein, the most recent epigenetic modulators in hepatocellular carcinoma are recapitulated on.

The microRNA-424/503 cluster: A master regulator of tumorigenesis and tumor progression with paradoxical roles in cancer

MicroRNAs (miRNAs) are a group of non-coding RNAs that play a crucial role in post-transcriptional gene regulation and act as indispensable mediators in several critical biological processes, including tumorigenesis, tissue homeostasis, and regeneration. MiR-424 and miR-503 are intragenic miRNAs that are clustered on human chromosome Xq26.3. Previous studies have reported that both miRNAs are dysregulated and play crucial but paradoxical roles in tumor initiation and progression, involving different target genes and molecular pathways. Moreover, these two miRNAs are concomitantly expressed in several cancer cells, indicating a coordinating function as a cluster. In this review, the roles and regulatory mechanisms of miR-424, miR-503, and miR-424/503 cluster are summarized in different types of cancers.

Protein arginine methylation promotes therapeutic resistance in human pancreatic cancer

Pancreatic cancer is a lethal disease with limited treatment options for cure. A high degree of intrinsic and acquired therapeutic resistance may result from cellular alterations in genes and proteins involved in drug transportation and metabolism, or from the influences of cancer microenvironment. Mechanistic basis for therapeutic resistance remains unclear and should profoundly impact our ability to understand pancreatic cancer pathogenesis and its effective clinical management. Recent evidences have indicated the importance of epigenetic changes in pancreatic cancer, including posttranslational modifications of proteins. We will review new knowledge on protein arginine methylation and its consequential contribution to therapeutic resistance of pancreatic cancer, underlying molecular mechanism, and clinical application of potential strategies of its reversal.

PRMT6 promotes endometrial cancer via AKT/mTOR signaling and indicates poor prognosis

Arginine methylation plays essential roles in post-transcriptional modification and signal transduction. Dysregulation of protein arginine methyltransferases (PRMTs) has been reported in human cancers, yet the expression and biological function of PRMT6 in endometrial cancer (EMC) remains unclear. Here, we show that PRMT6 is upregulated in EMC and exhibits oncogenic activities via activation of AKT/mTOR pathway. The expression of PRMT6 in EMC is much higher than that in the adjacent nontumorous tissues. Elevated PRMT6 expression is significantly associated with higher histological tumor grade and unfavorable prognosis in two independent cohorts consisting of a total of 564 patients with EMC. In vitro data demonstrate that PRMT6 expression was identified as a downstream target of miR-372-3p. Ectopic expression of miR-372-3p downregulates PRMT6. Overexpression of PRMT6 promotes EMC cell proliferation and migration, whereas knockdown of PRMT6 leads to opposite phenotypes. Mechanistically, PRMT6 induces the phosphorylation of AKT and mTOR in EMC cells. Inhibition of AKT/mTOR signaling by MK2206 or rapamycin attenuates the PRMT6-mediated EMC progression. In clinical samples, high expression of PRMT6 was correlated to low expression of miR-372-3p and high expression of phosphorylated AKT. Collectively, our findings suggest PRMT6 may function as an oncogene to promote tumor progression, and be of prognostic value to predict disease-free survival of patients with EMC. The newly identified miR-372-3p/PRMT6/AKT/mTOR axis represents a new promising target for EMC management.

miR-503 Inhibits Proliferation, Migration, And Angiogenesis Of Glioma By Acting On VEGFA Through Targeting LRIG2

Background

Glioma is a common malignant tumor of the human central nervous system, and the pathological characteristics include invasive growth, angiogenesis, and so on. Ectopic expression of miR-503 works as a critical factor in cancer cell proliferation, migration, and capillary-like tube formation. The potential mechanisms of miR-503 in angiogenesis of glioma cells are still not reported.

Methods

The expression levels of miR-503, LRIG2, and VEGFA mRNA and protein were performed by quantitative reverse transcription-PCR or Western blot assay. Dual-Luciferase reporter gene assay was used to determine the interaction between miR-503 and LRIG2. The concentration of VEGFA was measured using the ELISA method. The cell proliferation, migration, and angiogenesis of cocultured HCMEC/D3 cells were analyzed by MTT assay, transwell detection, and tube formation assay, respectively.

Results

The expression levels of LRIG2 and VEGFA were reduced in glioma cells with miR-503 overexpression and enhanced with miR-503 inhibition. Moreover, cell proliferation, migration, and angiogenesis of cocultured HCMEC/D3 cells were alleviated with miR-503 mimics transfection. VEGFA and miR-503 inhibitor promoted cell proliferation, cell migration, and angiogenesis. Luciferase reporter gene assay revealed that miR-503 could directly target LRIG2. Furthermore, knockdown of LRIG2 or addition of VEGF inhibitor bevacizumab could abrogate the effect of miR-503 inhibitor on VEGFA expression, as well as the promotion of cell proliferation, migration, and angiogenesis.

Conclusion

MiR-503 mediated LRIG2 suppression and regulated the expression of VEGFA, thereby reducing cell proliferation, migration, and angiogenesis of glioma cells. These results provide new insight into the action mechanism of miR-503-modulated signaling pathway in angiogenesis of glioma cells.

MicroRNA-503 Inhibits Non-Small Cell Lung Cancer Progression By Targeting PDK1/PI3K/AKT Pathway

OBJECTIVES

The aim of the study was to study the role of dysregulated expression of a microRNA (miRNA), miR-503, in non-small-cell lung cancer (NSCLC) and investigate the underlying mechanism.

METHODS

Quantitative real-time PCR (qRT-PCR) and in situ hybridization staining (ISH) were used to evaluate the expression level of miR-503 in NSCLC tissues and paired adjacent tissues. CCK-8, colony formation and flow cytometry were performed to explore the effects of miR-503 overexpression on cell proliferation, colony formation and apoptosis. Cells with miR-503 overexpression were used to initiate xenograft models. Dual luciferase reporter assay, qRT-PCR, immunohistochemistry and Western blotting were conducted to investigate the interaction of miR-503 and its potential target.

RESULTS

Significantly downregulated miR-503 was found in NSCLC tumor tissues and cell lines. miR-503 overexpression significantly inhibited NSCLC cell proliferation, migration and invasion. PDK1 was predicted as the direct targets of miR-503. PDK1 overexpression reversed the inhibitory effects of miR-503 on biological functions, while PDK1 silencing significantly counteracted miR-503 inhibitor-induced pro-tumor effects in A549 cells. Mechanistically, upregulation of miR-503 inhibited PDK1 expression and subsequently caused the inactivation of PI3K/AKT pathway.

CONCLUSION

Our results suggest that miR-503 inhibits NSCLC progression by targeting PDK1/PI3K/AKT pathway, potentiating the use of miR-503 as a biomarker and therapeutic target for NSCLC.

PRMT1 promotes pancreatic cancer growth and predicts poor prognosis

BACKGROUND

Protein arginine methyltransferase 1 (PRMT1) is the founding member of the PRMT family of proteins, whose members catalyze methylation of arginine residues in various proteins. Although several studies have reported upregulation of PRMT1 in various cancer types, the expression pattern and the underlying mechanism of PRMT1 action in pancreatic ductal adenocarcinoma (PDAC) are still unclear.

METHODS

Immunohistochemistry staining as well as RT-PCR was used to determine the expression pattern of PRMT1 in clinical PDAC samples. Lentivirus packaging and transfection were employed to construct cell lines with PRMT1 overexpression or knockdown. MTT and crystal violet assays were used to determine the proliferation rates of PDAC cells. β-catenin transcription activity was measured using a TOPFlash assay. PRMT1 binding to the promoter region of CTNNB1 was determined by ChIP-qPCR assay.

RESULTS

Elevated PRMT1 expression was found in PDAC tissue samples compared to noncancerous normal tissues in 41 patients using a real-time PCR assay and in 90 patients using a tissue microarray (TMA) in conjunction with immunohistochemistry. Analysis of the PRMT1 expression data and PDAC clinical features revealed that PRMT1 expression was significantly correlated with PDAC tumor size and prognosis in postoperative patients. Additional functional experiments revealed that PRMT1 expression promoted the growth of pancreatic cancer-derived cells, both in vitro and in vivo. Mechanistically, we found that PRMT1 increased the cellular β-catenin level. We also found that PRMT1 and β-catenin were co-expressed in TCGA and GTEx datasets containing 370 samples.

CONCLUSIONS

Collectively, our study provides novel insight into the expression and function of PRMT1 in PDAC and indicates that PRMT1 may serve as a therapeutic target for treating patients with pancreatic ductal adenocarcinoma.

The regulation, functions and clinical relevance of arginine methylation

Methylation of arginine residues by protein arginine methyltransferases (PRMTs) is involved in the regulation of fundamental cellular processes, including transcription, RNA processing, signal transduction cascades, the DNA damage response and liquid-liquid phase separation. Recent studies have provided considerable advances in the development of experimental tools and the identification of clinically relevant PRMT inhibitors. In this review, we discuss the regulation of PRMTs, their various cellular roles and the clinical relevance of PRMT inhibitors for the therapy of neurodegenerative diseases and cancer.

MicroRNA-503 serves an oncogenic role in retinoblastoma progression by directly targeting PTPN12

Numerous studies have demonstrated that microRNAs (miRNAs or miRs) are abnormally expressed in retinoblastoma (RB). miRNAs may serve a role in oncogene or tumor-suppressor activity in RB genesis and development by modulating various biological processes. miRNAs therefore, may be effective therapeutic targets for miRNA-based therapy in patients with RB. Recently it has been revealed that miR-503 may serve a role in various types of human cancer. However, the expression and functional roles of miR-503 are rarely reported in RB. In the current study, the expression of miR-503 was significantly upregulated in RB tissues and cell lines. In addition, Cell Counting Kit-8 and in vitro invasion assays were performed to assess cell proliferation and invasion, respectively. The results of the present study revealed that miR-503 inhibition impeded RB in vitro cell proliferation and invasion. Furthermore, protein tyrosine phosphatase nonreceptor type 12 (PTPN12) was demonstrated to be a direct target gene of miR-503 in RB cells. PTPN12 overexpression also led to the downregulation of miR-503 in RB cell proliferation and invasion. PTPN12 knockdown could therefore abrogate the effects of miR-503 downregulation in RB cells. In conclusion, the results demonstrated that miR-503 may serve a role in RB oncogenic activity progression by directly targeting PTPN12. Therefore, miR-503 may be a target for effective therapy in patients with RB.

PRMTs and miRNAs: functional cooperation in cancer and beyond

Epigenetic modulators play pivotal roles in directing gene expression for the maintenance of normal cellular functions. However, when these modulators are aberrantly regulated, this can result in a variety of disease states, including cancer. One class of epigenetic regulators, protein arginine methyltransferases (PRMTs), have been shown to play critical roles in disease through methylation of arginine residues (R) on histone or non-histone proteins. Quite different from PRMTs, microRNAs (miRNAs) belong to the family of modulators known as noncoding RNAs (ncRNA) that act to regulate gene expression via RNA-mediated gene silencing. Importantly, miRNAs are frequently dysregulated and contribute to the progression of cancer and other conditions, including neurological and cardiovascular diseases. Recently, numerous studies have shown that miRNAs and other epigenetic enzymes can co-regulate each other. This review highlights multiple nodes of interaction between miRNAs and PRMTs and also discusses how this interplay might open up promising opportunities for drug development for the treatment of cancer and other diseases.

Protein arginine methyltranferase-1 induces ER stress and epithelial-mesenchymal transition in renal tubular epithelial cells and contributes to diabetic nephropathy

BACKGROUND

In this study, we examined the association of PRMT1 with ER stress and epithelial-mesenchymal transition (EMT), two critical pathogenic mechanisms leading to DN development, in proximal tubular epithelial cells (PTECs).

METHODS

The level of PRMT1 was compared between the serum from DN patients and healthy individuals by ELISA, and between renal tissues of DN mice and normal mice using RT-qPCR and immunohistochemistry. Using high-glucose-treated PTEC cell line, HK2 cells as the model system, the significance of PRMT1 in ER stress and EMT was assessed by shRNA targeting PRMT1 (sh-PRMT1) and/or by overexpressing PRMT1. Mechanistic studies focused on three major pathways controlling ER stress: protein kinase R-like ER kinase (PERK), inositol requiring-1α (IRE1α), and activating transcription factor 6 (ATF6).

RESULTS

PRMT1 was up-regulated in the serum of DN patients and renal tissues of DN mice. High glucose administration induced elevation of PRMT1 expression in HK2 cells in vitro, accompanied with ER stress and EMT activation. PRMT1 knockdown attenuated high glucose-induced ER stress and apoptosis by inactivating PERK and ATF6, but not IRE1α. PRMT1 activated ATF6 by recruiting H4R3me2as to the promoter. Furthermore, PRMT1-induced ER stress was concomitant with the activation of an EMT-like state. Specifically, inhibition of ATF6, but not PERK blocked PRMT1-induced EMT in high-glucose-treatment HK2 cells.

CONCLUSIONS

By activating ER stress, PRMT1 essentially regulates the apoptosis and EMT of PTECs in response to diabetic milieu. Thus, targeting PRMT1 may alleviate both tissue injury and renal fibrosis, and thus benefit the treatment of DN.

Downregulation of PRMT1 promotes the senescence and migration of a non-MYCN amplified neuroblastoma SK-N-SH cells

Protein arginine methyltransferase 1 (PRMT1) catalyzing the formation of asymmetric dimethylarginines has been implicated in cancer development, metastasis, and prognosis. In this study, we investigated the effects of low PRMT1 levels on a non-MYCN amplified neuroblastoma SK-N-SH cell line. Stable PRMT1-knockdown (PRMT1-KD) cells showed reduced growth rates and cell cycle arrest at G₂/M. They also exhibited senescent phenotypes and increased p53 expression. p21 and PAI-1, which are two p53 downstream targets critical for senescence, were significantly induced in SK-N-SH cells subjected to either PRMT1-KD or inhibitor treatment. The induction was suppressed by a p53 inhibitor and marginal in a p53-null SK-N-AS cell line, suggesting dependence on p53. In general, the DNA damage and ROS levels of the PRMT1-KD SK-N-SH cells were slightly increased. Their migration activity also increased with the induction of PAI-1. Thus, PRMT1 downregulation released the repression of cellular senescence and migration activity in SK-N-SH cells. These results might partially explain the poor prognostic outcome of low PRMT1 in a non-MYCN-amplified cohort and indicate the multifaceted complexity of PRMT1 as a biological regulator of neuroblastoma.

microRNAs: Key players in virus-associated hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is known as one of the major health problems worldwide. Pathological analysis indicated that a variety of risk factors including genetical (i.e., alteration of tumor suppressors and oncogenes) and environmental factors (i.e., viruses) are involved in beginning and development of HCC. The understanding of these risk factors could guide scientists and clinicians to design effective therapeutic options in HCC treatment. Various viruses such as hepatitis B virus (HBV) and hepatitis C virus (HCV) via targeting several cellular and molecular pathways involved in HCC pathogenesis. Among various cellular and molecular targets, microRNAs (miRNAs) have appeared as key players in HCC progression. miRNAs are short noncoding RNAs which could play important roles as oncogenes or tumor suppressors in several malignancies such as HCC. Deregulation of many miRNAs (i.e., miR-222, miR-25, miR-92a, miR-1, let-7f, and miR-21) could be associated with different stages of HCC. Besides miRNAs, exosomes are other particles which are involved in HCC pathogenesis via targeting different cargos, such as DNAs, RNAs, miRNAs, and proteins. In this review, we summarize the current knowledge of the role of miRNAs and exosomes as important players in HCC pathogenesis. Moreover, we highlighted HCV- and HBV-related miRNAs which led to HCC progression.

MicroRNA-205 is downregulated in hepatocellular carcinoma and inhibits cell growth and metastasis via directly targeting vascular endothelial growth factor A

MicroRNAs (miRs) are an emerging class of non-coding, endogenous and small RNA molecules that serve important functions in tumorigenesis and development. The present study investigated the expression, functions and molecular mechanism underlying miR-205 in hepatocellular carcinoma. miR-205 was downregulated in hepatocellular carcinoma tissues and cell lines. Ectopic miR-205 expression suppressed hepatocellular carcinoma cell proliferation, migration and invasion in vitro. In addition, vascular endothelial growth factor A (VEGFA) was identified as a functional downstream target of miR-205 in hepatocellular carcinoma. Furthermore, knockdown of VEGFA revealed the same functions with miR-205 overexpression in hepatocellular carcinoma cells. These results provided evidence that miR-205 served important functions in the inhibition of hepatocellular carcinoma cells growth and metastasis via directly targeting VEGFA, which indicated that miR-205 may have therapeutic value for hepatocellular carcinoma.

PRMT9 promotes hepatocellular carcinoma invasion and metastasis via activating PI3K/Akt/GSK-3β/Snail signaling

Protein arginine methyltransferases (PRMT) catalyze protein arginine methylation and play an important role in many biological processes. Aberrant PRMT expression in tumor cells has been documented in several common cancer types; however, its precise contribution to hepatocellular carcinoma (HCC) cell invasion and metastasis is not fully understood. In this study, we identified a new oncogene, PRMT9, whose overexpression strongly promotes HCC invasion and metastasis. PRMT9 expression was detected more frequently in HCC tissues than in adjacent noncancerous tissues. PRMT9 overexpression was significantly correlated with hepatitis B virus antigen (HBsAg) status, vascular invasion, poor tumor differentiation and advanced TNM stage. Patients with higher PRMT9 expression had a shorter survival time and higher recurrence rate. PRMT9 expression was an independent and significant risk factor for survival after curative resection. Functional studies demonstrated that PRMT9 increased HCC cell invasion and lung metastasis. Knocking down PRMT9 with short hairpin RNA (shRNA) inhibited HCC cell invasion. Further investigations found that PRMT9 increased cell migration and invasion through epithelial-mesenchymal transition (EMT) by regulating Snail expression via activation of the PI3K/Akt/GSK-3β/Snail signaling pathway. In clinical HCC samples, PRMT9 expression was positively associated with Snail expression and was negatively associated with E-cadherin expression. In conclusion, our study demonstrated that PRMT9 is an oncogene that plays an important role in HCC invasion and metastasis through EMT by regulating Snail expression via activation of the PI3K/Akt/GSK-3β/Snail signaling pathway. Thus, PRMT9 may serve as a candidate prognostic biomarker and a potential therapeutic target.

Transcription and microRNA Profiling of Cultured Human Tympanic Membrane Epidermal Keratinocytes

The human tympanic membrane (TM) has a thin outer epidermal layer which plays an important role in TM homeostasis and ear health. The specialised cells of the TM epidermis have a different physiology compared to normal skin epidermal keratinocytes, displaying a dynamic and constitutive migration that maintains a clear TM surface and assists in regeneration. Here, we characterise and compare molecular phenotypes in keratinocyte cultures from TM and normal skin. TM keratinocytes were isolated by enzymatic digestion and cultured in vitro. We compared global mRNA and microRNA expression of the cultured cells with that of human epidermal keratinocyte cultures. Genes with either relatively higher or lower expression were analysed further using the biostatistical tools g:Profiler and Ingenuity Pathway Analysis. Approximately 500 genes were found differentially expressed. Gene ontology enrichment and Ingenuity analyses identified cellular migration and closely related biological processes to be the most significant functions of the genes highly expressed in the TM keratinocytes. The genes of low expression showed a marked difference in homeobox (HOX) genes of clusters A and C, giving the TM keratinocytes a strikingly low HOX gene expression profile. An in vitro scratch wound assay showed a more individualised cell movement in cells from the tympanic membrane than normal epidermal keratinocytes. We identified 10 microRNAs with differential expression, several of which can also be linked to regulation of cell migration and expression of HOX genes. Our data provides clues to understanding the specific physiological properties of TM keratinocytes, including candidate genes for constitutive migration, and may thus help focus further research.

Novel prognostic marker PRMT1 regulates cell growth via downregulation of CDKN1A in HCC

Hepatocellular carcinoma (HCC) is a major type of liver cancer caused by the hepatitis B and C viruses, alcohol and exposure to aflatoxin. For HCC treatment, anticancer drugs have been widely used, but drug resistance in advanced HCC is an important problem, resulting in a continuous need for novel therapeutic targets. Therefore, in this study, we established a screening pipeline based on RNA-seq to screen novel therapeutic/prognostic targets in HCC and identified PRMT1 (Protein Arginine Methyltransferase 1). In the prognostic analysis, the overexpression of PRMT1 was clearly associated with poor prognosis in a number of HCC patient cohorts. Moreover, after PRMT1 knockdown, HCC cell lines exhibited cell growth and spheroid formation suppression, an increase in Sub-G1 cells by FACS analysis, and enrichment of the cell cycle pathway via functional enrichment analysis. With these results, we demonstrated that PRMT1 could be a novel prognostic marker and therapeutic target for HCC therapy.

Arginine Methylation: The Coming of Age

Arginine methylation is a common post-translational modification functioning as an epigenetic regulator of transcription and playing key roles in pre-mRNA splicing, DNA damage signaling, mRNA translation, cell signaling, and cell fate decision. Recently, a wealth of studies using transgenic mouse models and selective PRMT inhibitors helped define physiological roles for protein arginine methyltransferases (PRMTs) linking them to diseases such as cancer and metabolic, neurodegenerative, and muscular disorders. This review describes the recent molecular advances that have been uncovered in normal and diseased mammalian cells.

MiR-503 modulates epithelial-mesenchymal transition in silica-induced pulmonary fibrosis by targeting PI3K p85 and is sponged by lncRNA MALAT1

Silicosis is a kind of chronic, progressive and incurable lung fibrotic diseases with largely unknown and complex pathogenesis and molecular mechanisms. Mounting evidence suggests that microRNAs (miRNAs, miRs) are involved in the pathogenesis of silicosis. Our previous study based on miRNA microarray had shown that the expression levels of miR-503 were down-regulated in mouse lung tissues of silica-induced pulmonary fibrosis. Here, we validated the decreased expression of miR-503 in the fibrotic mouse lung tissues, human bronchial epithelial cells (HBE) and human lung adenocarcinoma A549 cells which were exposed to silica. In addition, overexpressed miR-503 inhibited silica-induced pulmonary fibrosis by attenuating the severity and the distribution of lesions in vivo and limiting the process of epithelial-mesenchymal transition (EMT) in vitro. Our molecular study further demonstrated that PI3K p85 is one of the target genes of miR-503 and the downstream molecules (Akt, mTOR and Snail) are tightly associated with EMT. Furthermore, the up-regulated lncRNA Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), acted as a competing endogenous RNA (ceRNA), can directly bound to miR-503, which indicated that lncRNA MALAT1 may modulate the expression of miR-503 thus triggering the activation of downstream fibrotic signaling pathways. Taken together, our data suggested that MALAT1-miR-503-PI3K/Akt/mTOR/Snail pathway plays critical roles in silica-induced pulmonary fibrosis.

PRMT1 expression is elevated in head and neck cancer and inhibition of protein arginine methylation by adenosine dialdehyde or PRMT1 knockdown downregulates proliferation and migration of oral cancer cells

Protein arginine methylation is a post-translational modification that has been implicated in signal transduction, gene transcription, DNA repair and RNA processing. Overexpression or deregulation of protein arginine methyltransferases (PRMTs) have been reported to be associated with various cancers but have not been studied in head and neck cancer (HNC). We investigated the involvement of the modification in HNC using oral cancer cell lines (SAS, OECM-1 and HSC-3) and an immortalized normal oral cells (S-G). The expression levels of the predominant PRMT1 were generally consistent with the levels of asymmetric dimethylarginine (ADMA), highest in SAS and OECM1, then S-G and low in HSC-3. Upon the treatment with an indirect methyltransferase inhibitor adenosine dialdehyde (AdOx), the ADMA levels in SAS and OECM1, but not that in S-G and HSC-3, decreased significantly. SAS and OECM with high ADMA levels grew faster than HSC-3 and S-G. The growth rate of the fast growing SAS and OECM, but not that of the other two cell lines, decreased significantly upon AdOx treatment. The migration activity of SAS and HSC-3, two cell lines with migration ability also decreased after the AdOx treatment. Immunohistochemical analyses of specimens from typical HNC patients showed strong PRMT1 expression in the tumor cells compared with neighboring normal cells. Knockdown of PRMT1 in SAS cells decreased the levels of PRMT1 and ADMA-containing proteins significantly. These cells showed decreased growth rate, reduced migration activity but increased expression of the epithelial marker E-cadherin. The present study thus provides fundamental background for evaluation of the PRMT1 gene as the therapeutic targets of HNC.

MiR-646 inhibited cell proliferation and EMT-induced metastasis by targeting FOXK1 in gastric cancer

Background:

MiR-646 has been reported to be aberrantly expressed in human cancers. However, the underlying molecular mechanisms of action of miR-646 in gastric cancer (GC) have not yet been investigated.

Methods:

In vitro function of miR-646 in GC was evaluated using EdU assay, plate colony formation assay, and matrigel invasion assay. Real-time PCR or western blotting was performed to detect miR-646 and FOXK1 expressions. In vivo tumour growth and metastasis were conducted in nude mice.

Results:

MiR-646 expression was downregulated in GC tissues compared with adjacent normal tissues. Low miR-646 expression is associated with malignant progression. Transient transfection of GC cells with miR-646 inhibited their growth and migration. Moreover, miR-646 influenced the expression of epithelial–mesenchymal transition (EMT)-associated proteins. TGF-β1 treatment significantly suppressed the expression of miR-646 and overexpression of this microRNA counteracted the influence of the TGF-β1-induced EMT phenotype. In terms of the underlying mechanism, miR-646 directly targeted FOXK1. In vivo, it inhibited the FOXK1-mediated proliferation and EMT-induced metastasis. Consistently, inverse correlations were also observed between the expression of miR-646 and FOXK1 in human GC tissue samples. Furthermore, miR-646 regulated Akt/mTOR signalling after FOXK1.

Conclusions:

miR-646 inhibited GC cell proliferation and the EMT progression in GC cells by targeting FOXK1.

MicroRNA-592 targets IGF-1R to suppress cellular proliferation, migration and invasion in hepatocellular carcinoma

MicroRNAs (miRs) can function as tumor suppressors or oncogenes in different types of human malignancy, and may provide an effective therapy for cancer. The expression and functions of miR-592 have previously been studied in relation to cancer. However, the expression and potential functions of miR-592 in hepatocellular carcinoma (HCC) are still unknown. Using quantitative polymerase chain reaction, MTT assays, cellular migration and invasion assays, bioinformatics software, western blot analysis and dual-luciferase report assays, the present study explored the expression and roles of miR-592 in HCC. It was identified that miR-592 was significantly downregulated in HCC tissues and cell lines. The statistical analysis revealed that low expression of miR-592 was evidently associated with tumor node metastasis stage and lymph node metastasis. Additionally, the present study provided the first evidence that miR-592 was likely to directly target the insulin-like growth factor 1 receptor in vitro. The present results indicated that miR-592 could be investigated as an efficacious therapeutic target for HCC in the future.

PRMT8 demonstrates variant-specific expression in cancer cells and correlates with patient survival in breast, ovarian and gastric cancer

Recent emphasis has been placed on the role of epigenetic regulators and epigenetic marks as biomarkers for cancer diagnosis and prognosis, and as therapeutic targets for treatment. One such class of regulators is the protein arginine methyltransferase (PRMT) family. The present study examined available curated data regarding the expression and alteration of one of the least studied PRMT family members, PRMT8, in various types of cancer and cancer cell lines. Publicly available cancer data on PRMT8 expression were examined using the Human Protein Atlas and the Kaplan-Meier Plotter, and reverse transcription-polymerase chain reaction was used to screen a selection of human cell lines for variant-specific PRMT8 expression. High levels of PRMT8 expression in breast, ovarian and cervical cancer was observed. Additionally, in patients with breast and ovarian cancer, high PRMT8 expression was correlated with increased patient survival, whereas in gastric cancer, high PRMT8 expression was correlated with decreased patient survival. The present study also investigated the expression of PRMT8 variant 2, a novel transcript variant recently identified in our laboratory, in various cancer cell lines. Variant-specific expression of PRMT8 in numerous distinct cancer cell lines derived from different tissues, including the expression of the novel PRMT8 variant 2 in U87MG glioblastoma cells was demonstrated. The present study proposes the possibility of PRMT8 as a cancer biomarker, based on the high level of PRMT8 expression in various types of cancer, particularly in tissues that would not normally be expected to express PRMT8, and on the correlation of PRMT8 and patient lifespan in several cancer types. Variant-specific expression of PRMT8 in diverse cancer cell lines suggests the possibility of alternate PRMT8 isoforms to have diverse effects on cancer cell phenotypes.

Decreased miR-503 expression in gastric cancer is inversely correlated with serum carcinoembryonic antigen and acts as a potential prognostic and diagnostic biomarker

Background

Altered expression of miR-503 has been linked to human carcinogenesis. In this present study, we aimed to detect the potential for miR-503 as a novel biomarker for gastric cancer (GC) patients.

Materials and methods

The relative mRNA level of miR-503 in serum and tissue of 68 GC patients and serum of 32 healthy volunteers was determined by real-time reverse transcription quantitative polymerase chain reaction.

Results

The miR-503 level was significantly lower in the tissue and serum of GC than their counterparts (all P<0.01). Downregulation of miR-503 was found to be corrected with more aggressive tumor. Patients in the high-miR-503 group showed significantly better overall survival compared to the low-miR-503 group (P=0.021). The serum miR-503 level in GC was inversely correlated with carcinoembryonic antigen (CEA) (r=−0.624, P<0.001). Furthermore, the area under the receiver operating characteristic curve for miR-503 discriminating GC patients from healthy individuals was 0.889 (P=0.006), with a sensitivity of 96.8% and a specificity of 79.4%, higher than that of CEA (area under the receiver operating characteristic curve =0.681, P=0.048).

Conclusion

The present study suggests that the expression level of miR-503 may serve as prognostic and diagnostic biomarker for GC.

Biomarker MicroRNAs for Diagnosis, Prognosis and Treatment of Hepatocellular Carcinoma: A Functional Survey and Comparison

Hepatocellular Carcinoma (HCC) is one of the most common malignant tumors with high incidence and mortality rate. Precision and effective biomarkers are therefore urgently needed for the early diagnosis and prognostic estimation. MicroRNAs (miRNAs) are important regulators which play functions in various cellular processes and biological activities. Accumulating evidence indicated that the abnormal expression of miRNAs are closely associated with HCC initiation and progression. Recently, many biomarker miRNAs for HCC have been identified from blood or tissues samples, however, the universality and specificity on clinicopathological features of them are less investigated. In this review, we comprehensively surveyed and compared the diagnostic, prognostic, and therapeutic roles of HCC biomarker miRNAs in blood and tissues based on the cancer hallmarks, etiological factors as well as ethnic groups, which will be helpful to the understanding of the pathogenesis of biomarker miRNAs in HCC development and further provide accurate clinical decisions for HCC diagnosis and treatment.