DNA methylation mediated silencing of microRNA-145 is a potential prognostic marker in patients with lung adenocarcinoma

Crosstalk between miRNAs and DNA Methylation in Cancer

miRNAs are some of the most well-characterized regulators of gene expression. Integral to several physiological processes, their aberrant expression often drives the pathogenesis of both benign and malignant diseases. Similarly, DNA methylation represents an epigenetic modification influencing transcription and playing a critical role in silencing numerous genes. The silencing of tumor suppressor genes through DNA methylation has been reported in many types of cancer and is associated with tumor development and progression. A growing body of literature has described the crosstalk between DNA methylation and miRNAs as an additional layer in the regulation of gene expression. Methylation in miRNA promoter regions inhibits its transcription, while miRNAs can target transcripts and subsequently regulate the proteins responsible for DNA methylation. Such relationships between miRNA and DNA methylation serve an important regulatory role in several tumor types and highlight a novel avenue for potential therapeutic targets. In this review, we discuss the crosstalk between DNA methylation and miRNA expression in the pathogenesis of cancer and describe how miRNAs influence DNA methylation and, conversely, how methylation impacts the expression of miRNAs. Finally, we address how these epigenetic modifications may be leveraged as biomarkers in cancer.

A Systematic Review of Progress toward Unlocking the Power of Epigenetics in NSCLC: Latest Updates and Perspectives

Epigenetic research has the potential to improve our understanding of the pathogenesis of cancer, specifically non-small-cell lung cancer, and support our efforts to personalize the management of the disease. Epigenetic alterations are expected to have relevance for early detection, diagnosis, outcome prediction, and tumor response to therapy. Additionally, epi-drugs as therapeutic modalities may lead to the recovery of genes delaying tumor growth, thus increasing survival rates, and may be effective against tumors without druggable mutations. Epigenetic changes involve DNA methylation, histone modifications, and the activity of non-coding RNAs, causing gene expression changes and their mutual interactions. This systematic review, based on 110 studies, gives a comprehensive overview of new perspectives on diagnostic (28 studies) and prognostic (25 studies) epigenetic biomarkers, as well as epigenetic treatment options (57 studies) for non-small-cell lung cancer. This paper outlines the crosstalk between epigenetic and genetic factors as well as elucidates clinical contexts including epigenetic treatments, such as dietary supplements and food additives, which serve as anti-carcinogenic compounds and regulators of cellular epigenetics and which are used to reduce toxicity. Furthermore, a future-oriented exploration of epigenetic studies in NSCLC is presented. The findings suggest that additional studies are necessary to comprehend the mechanisms of epigenetic changes and investigate biomarkers, response rates, and tailored combinations of treatments. In the future, epigenetics could have the potential to become an integral part of diagnostics, prognostics, and personalized treatment in NSCLC.

DNA methylation and cancer: transcriptional regulation, prognostic, and therapeutic perspective

DNA methylation is one among the major grounds of cancer progression which is characterized by the addition of a methyl group to the promoter region of the gene thereby causing gene silencing or increasing the probability of mutations; however, in bacteria, methylation is used as a defense mechanism where DNA protection is by addition of methyl groups making restriction enzymes unable to cleave. Hypermethylation and hypomethylation both pose as leading causes of oncogenesis; the former being more frequent which occurs at the CpG islands present in the promoter region of the genes, whereas the latter occurs globally in various genomic sequences. Reviewing methylation profiles would help in the detection and treatment of cancers. Demethylation is defined as preventing methyl group addition to the cytosine DNA base which could cause cancers in case of global hypomethylation, however, upon further investigation; it could be used as a therapeutic tool as well as for drug design in cancer treatment. In this review, we have studied the molecules that induce and enzymes (DNMTs) that bring about methylation as well as comprehend the correlation between methylation with transcription factors and various signaling pathways. DNA methylation has also been reviewed in terms of how it could serve as a prognostic marker and the various therapeutic drugs that have come into the market for reversing methylation opening an avenue toward curing cancers.

Epigenetic regulation of MIR145 core promoter controls miR-143/145 cluster in bladder cancer progression and treatment outcome

Owing to its highly heterogeneous molecular landscape, bladder cancer (BlCa) is still characterized by non-personalized treatment and lifelong surveillance. Motivated by our previous findings on miR-143/145 value in disease prognosis, we have studied the underlying epigenetic regulation of the miR-143/145 cluster in BlCa. Expression and DNA methylation of miR-143/145 cluster were analyzed in our screening (n = 162) and The Cancer Genome Atlas Urothelial Bladder Carcinoma (TCGA-BLCA; n = 412) cohorts. Survival analysis was performed using tumor relapse and progression as clinical endpoints for non-muscle-invasive bladder cancer (NMIBC; TaT1), while disease progression and patients' death were used for muscle-invasive bladder cancer (MIBC; T2-T4). TCGA-BLCA served as validation cohort. Bootstrap analysis was carried out for internal validation, while decision curve analysis was used to evaluate clinical benefit. TCGA-BLCA and screening cohorts highlighted MIR145 core promoter as the pivotal, epigenetic regulatory region on cluster's expression. Lower methylation of MIR145 core promoter was associated with aggressive disease phenotype, higher risk for NMIBC short-term progression, and poor MIBC survival. MIR145 methylation-fitted multivariate models with established disease markers clearly enhanced patients' risk stratification and prediction of treatment outcome. MIR145 core promoter methylation was identified as a potent epigenetic regulator of miR-143/145 cluster, supporting modern personalized risk stratification and management in BlCa.

Long Noncoding RNA LINC02470 Sponges MicroRNA-143-3p and Enhances SMAD3-Mediated Epithelial-to-Mesenchymal Transition to Promote the Aggressive Properties of Bladder Cancer

Simple Summary

Long noncoding RNAs (lncRNAs) were proposed as novel tumor prognostic markers, including for predicting bladder cancer progression, and the competing endogenous RNA (ceRNA) hypothesis conceived an accessible entry point to discover potential lncRNA candidates. This study indicated that LINC02470 promotes bladder cancer cell viability, migration, invasion, and in vivo tumorigenicity by sponging miR-143-3p and consequently rescuing SMAD3 translation to activate the TGF-β-induced EMT process. These data demonstrate that the LINC02470–miR-143-3p–SMAD3 ceRNA axis directly regulates the major transcription factor of TGF-β signaling, SMAD3, thereby inducing the EMT process in bladder cancer and enhancing the aggressiveness of bladder cancer cells.

Abstract

Bladder cancer progression and metastasis have become major threats in clinical practice, increasing mortality and therapeutic refractoriness; recently, epigenetic dysregulation of epithelial-to-mesenchymal transition (EMT)-related signaling pathways has been explored. However, research in the fields of long noncoding RNA (lncRNA) and competing endogenous RNA (ceRNA) regulation in bladder cancer progression is just beginning. This study was designed to determine potential EMT-related ceRNA regulation in bladder cancer progression and elucidate the underlying mechanisms that provoke aggressiveness. After screening the intersection of bioinformatic pipelines, LINC02470 was identified as the most upregulated lncRNA during bladder cancer initiation and progression. Both in vitro and in vivo biological effects indicated that LINC02470 promotes bladder cancer cell viability, migration, invasion, and tumorigenicity. On a molecular level, miR-143-3p directly targets and reduces both LINC02470 and SMAD3 RNA expression. Therefore, the LINC02470–miR-143-3p–SMAD3 ceRNA axis rescues SMAD3 translation upon LINC02470 sponging miR-143-3p, and SMAD3 consequently activates the TGF-β-induced EMT process. In conclusion, this is the first study to demonstrate that LINC02470 plays a pivotally regulatory role in the promotion of TGF-β-induced EMT through the miR-143-3p/SMAD3 axis, thereby aggravating bladder cancer progression. Our study warrants further investigation of LINC02470 as an indicatively prognostic marker of bladder cancer.

Epstein-Barr Virus Infection Alone or Jointly with Human Papillomavirus Associates with Down-Regulation of miR-145 in Oral Squamous-Cell Carcinoma

Down-regulation of tumor-suppressive miR-145 has been reported in various malignancies, including oral squamous-cell carcinoma (OSCC) that is influenced by several factors, including Epstein-Barr virus (EBV) and human papillomavirus (HPV). Oncoviruses can modulate the expression of cellular microRNAs. Therefore, we sought to investigate the association of miR-145 down-regulation in OSCC with EBV and/or HPV infection, which might be a possible mechanism of these viruses in oral carcinogenesis. Herein, prevalence of EBV, HPV, and their co-infection was significantly higher in tumors than normal tissues of OSCC. EBV infection alone or jointly with HPV was significantly associated with down-regulation of miR-145 in tumors compared with normal adjacent tissues. In cell lines infected with EBV or HPV, miR-145 was also down-regulated. Consistently, methylation of miR-145 was significantly greater in tumors, and well correlated with increased expression of DNMT3B, which was influenced by infection with EBV and HPV. In cell lines, only EBV infection was associated with increased expression of DNMT3B. Moreover, the level of EBV-LMP1 mRNA in tumors was negatively correlated with miR-145 and positively correlated with DNMT3B. Therefore, EBV alone or jointly with HPV is associated with down-regulation of miR-145 and may influence on miR-145 promoter methylation through the induction of DNMT3B in OSCC.

Epigenetic Regulation of microRNAs in Cancer: Shortening the Distance from Bench to Bedside

Cancer is a complex disease involving alterations of multiple processes, with both genetic and epigenetic features contributing as core factors to the disease. In recent years, it has become evident that non-coding RNAs (ncRNAs), an epigenetic factor, play a key role in the initiation and progression of cancer. MicroRNAs, the most studied non-coding RNAs subtype, are key controllers in a myriad of cellular processes, including proliferation, differentiation, and apoptosis. Furthermore, the expression of miRNAs is controlled, concomitantly, by other epigenetic factors, such as DNA methylation and histone modifications, resulting in aberrant patterns of expression upon the occurrence of cancer. In this sense, aberrant miRNA landscape evaluation has emerged as a promising strategy for cancer management. In this review, we have focused on the regulation (biogenesis, processing, and dysregulation) of miRNAs and their role as modulators of the epigenetic machinery. We have also highlighted their potential clinical value, such as validated diagnostic and prognostic biomarkers, and their relevant role as chromatin modifiers in cancer therapy.

MicroRNAs: Key Regulators in Lung Cancer

Noncoding RNAs have emerged as key regulators of the genome upon gene expression profiling and genome-wide sequencing. Among these noncoding RNAs, microRNAs are short noncoding RNAs that regulate a plethora of functions, biological processes and human diseases by targeting the messenger RNA stability through 3'UTR binding, leading to either mRNA cleavage or translation repression, depending on microRNA-mRNA complementarity degree. Additionally, strong evidence has suggested that dysregulation of miRNAs contribute to the etiology and progression of human cancers, such as lung cancer, the most common and deadliest cancer worldwide. Indeed, by acting as oncogenes or tumor suppressors, microRNAs control all aspects of lung cancer malignancy, including cell proliferation, survival, migration, invasion, angiogenesis, cancer stem cells, immune-surveillance escape, and therapy resistance; and their expressions are often associated with clinical parameters. Moreover, several deregulated microRNAs in lung cancer are carried by exosomes, microvesicles and secreted in body fluids, mainly the circulation where they conserve their stable forms. Subsequently, seminal efforts have been focused on extracellular microRNAs levels as noninvasive diagnostic and prognostic biomarkers in lung cancer. In this review, focusing on recent literature, we summarize the deregulation, mechanisms of action, functions and highlight clinical applications of miRNAs for better management and design of future lung cancer targeted therapies.

Epigenetic silencing of microRNA-199a-5p promotes the proliferation of non-small cell lung cancer cells by increasing AKAP1 expression

MicroRNA (miR)-199a-5p expression is downregulated in a variety of malignancies, including non-small cell lung cancer (NSCLC), and its low expression is associated with a poor prognosis. However, to the best of our knowledge, the mechanism underlying miR-199a-5p downregulation in NSCLC and its target effectors remain to be elucidated. The present study revealed the downregulation of miR-199a-5p expression in NSCLC tissues and cell lines compared with in para-carcinoma tissues and a lung epithelial cell line. Further experiments indicated that the methylation levels of the miR-199a promoter were markedly higher in NSCLC tissues compared with in para-carcinoma tissues. The DNA methyltransferase inhibitor 5-Aza-2′-deoxycytidine markedly increased the expression levels of miR-199a-5p in NSCLC cells. Furthermore, it was identified that miR-199a-5p mimics transfection decreased the expression levels of A-kinase anchoring protein 1 (AKAP1) at both the mRNA and protein levels by targeting the 3′ untranslated region of AKAP1 mRNA. The in vitro experiments demonstrated that miR-199a-5p overexpression inhibited the proliferation and tumorigenicity of NSCLC cells, whereas overexpression of AKAP1 partially recovered the malignant phenotypes, suggesting that AKAP1 may be a downstream effector targeted by miR-199a-5p. Collectively, the present findings indicated that miR-199a-5p may be a novel regulator of AKAP1, and that miR-199a-5p may be a potential tumor suppressor in NSCLC.

The Microrna-143/145 Cluster in Tumors: A Matter of Where and When

The establishment and spreading of cancer involve the acquirement of many biological functions including resistance to apoptosis, enhanced proliferation and the ability to invade the surrounding tissue, extravasate from the primary site, survive in circulating blood, and finally extravasate and colonize distant organs giving origin to metastatic lesions, the major cause of cancer deaths. Dramatic changes in the expression of protein coding genes due to altered transcription factors activity or to epigenetic modifications orchestrate these events, intertwining with a microRNA regulatory network that is often disrupted in cancer cells. microRNAs-143 and -145 represent puzzling players of this game, with apparently contradictory functions. They were at first classified as tumor suppressive due to their frequently reduced levels in tumors, correlating with cell survival, proliferation, and migration. More recently, pro-oncogenic roles of these microRNAs have been described, challenging their simplistic definition as merely tumor-suppressive. Here we review their known activities in tumors, whether oncogenic or onco-suppressive, and highlight how their expression and functions are strongly dependent on their complex regulation downstream and upstream of cytokines and growth factors, on the cell type of expression and on the specific tumor stage.

Investigating the epi-miRNome: identification of epi-miRNAs using transfection experiments

Aim: Growing evidence shows a strong interplay between post-transcriptional regulation, mediated by miRNAs (miRs) and epigenetic regulation. Nevertheless, the number of experimentally validated miRs (called epi-miRs) involved in these regulatory circuitries is still very small. Material & methods: We propose a pipeline to prioritize candidate epi-miRs and to identify potential epigenetic interactors of any given miR starting from miR transfection experiment datasets. Results & conclusion: We identified 34 candidate epi-miRs: 19 of them are known epi-miRs, while 15 are new. Moreover, using an in-house generated gene expression dataset, we experimentally proved that a component of the polycomb-repressive complex 2, the histone methyltransferase enhancer of zeste homolog 2 (EZH2), interacts with miR-214, a well-known prometastatic miR in melanoma and breast cancer, highlighting a miR-214-EZH2 regulatory axis potentially relevant in tumor progression.

Long Non-coding RNA LINC00628 Interacts Epigenetically with the LAMA3 Promoter and Contributes to Lung Adenocarcinoma

Long non-coding RNAs (lncRNAs) have emerged as key regulators of cellular progress in lung adenocarcinoma. In this study, to identify cancer-related lncRNAs and genes, we screened for those lncRNAs that were differentially expressed in lung adenocarcinoma, which revealed LINC00628 overexpression and low expression of laminin subunit alpha 3 (LAMA3). This was further validated in the cancerous tissues from patients diagnosed with lung adenocarcinoma. Thereafter, we explored the functional relevance of LINC00628 and LAMA3 in lung adenocarcinoma by analyzing the recruitment of DNA methyltransferase (DNMT) and the cellular processes of lung adenocarcinoma cells following treatments that induced LINC00628 overexpression or LINC00628 silencing or with 5-azacytidine (5-Aza, a DNMT inhibitor). The results showed that LINC00628 silencing decreased cell proliferation, migration, and invasion as well as the drug resistance of lung adenocarcinoma cells to vincristine (VCR). The results were opposite in the cells with LAMA3 demethylation induced by 5-Aza treatment. Further research indicated that LINC00628 recruited DNMT1, DNMT3A, and DNMT3B to promote the methylation of LAMA3 promoter, thereby decreasing its expression. Moreover, an in vivo experiment was performed in nude mice to assess the tumor growth ability and drug resistance of human lung adenocarcinoma cells. It was observed that LINC00628 silencing or 5-Aza treatment inhibited the in vivo tumor growth ability of the human lung adenocarcinoma cells and reduced their resistance to VCR. Altogether, our results provide evidence of a mechanism by which LINC00628 silencing exerts an inhibitory role in lung adenocarcinoma by modulating the DNA methylation of LAMA3, indicative of a novel molecular target for treatment of lung adenocarcinoma patients showing resistance to VCR.

Exploration of bladder cancer-associated methylated miRNAs by methylated DNA immunoprecipitation sequencing

BACKGROUND

The current study aimed to explore the association between two epigenomic components, miRNA and DNA methylation, in bladder cancer (BC).

METHODS

Eight paired samples of tumor tissue and matched adjacent normal tissues from BC patients were subjected to methylated DNA immunoprecipitation sequencing and sRNA-Seq for differentially methylated miRNA genes and differential miRNA analysis. The miRNAs regulated by DNA methylation were screened and their functions involved in BC were analyzed using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) as well as a miRNA-mRNA interaction network.

RESULTS

The methylation levels of 212 genes were different between tumors and normal tissues with specific enrichment at transcription initiation and termination sites. Among these genes, 154 were hypermethylated and 58 were hypomethylated. GO and KEGG pathway enrichment analysis indicated that differentially methylated miRNA genes were mainly enriched in tumor-associated GO terms and signaling pathways. Pairwise statistical analysis of MeDIP-Seq and sRNA-Seq data showed that there are 154 and 165 candidate methylation-regulated genes in tumors and normal tissues, respectively. Notably, an interaction network indicated that the miRNAs regulated by methylation regulated a broad range of mRNAs associated with cancer development and progression. In particular, the most differentially expressed miRNAs were validated by qRT-PCR, such that miR-145-5p was downregulated and miR-182-5p was upregulated in patients with bladder cancer.

CONCLUSION

A large number of miRNA genes were modified by methylation in BC. Identification of changes in the expression of these miRNAs provides a great deal of important information for BC diagnosis.

miR‑146a‑5p targets TCSF and influences cell growth and apoptosis to repress NSCLC progression

Several studies have indicated that microRNAs (miRs) mediate multiple pathways associated with tumorigenesis and progression. Our preliminary study experimentally verified that miR-146a-5p has a role in the biological behavior of non-small cell lung cancer (NSCLC) cells. To perform further investigation of miR-146a-5p, the present study evaluated miR-146a-5p by targeting its downstream gene tumor collagenase stimulatory factor (TCSF) to influence cell viability, proliferation and apoptosis in NSCLC. Online sequence prediction, a thorough search of the open source database The Cancer Genome Atlas (TCGA), immunohistochemistry (IHC) of TCSF in clinical lung cancer tissues, and a dual-luciferase assay, as well as assays to test viability, proliferation and apoptosis in vitro, were conducted to explain the targeted regulation association between miR-146a-5p and TCSF in NSCLC. The miRanda and TargetScanHuman database revealed that TCSF and miR-146a-5p had target binding sites. A luciferase reporter assay demonstrated that miR-146a-5p and TCSF did have complementary sequences (P<0.05). From the TCGA database, TCSF was highly expressed in lung adenocarcinoma and lung squamous cell carcinoma tissues when compared with normal lung tissues (P<0.05). Furthermore, the protein level of TCSF in cancerous lung tissues was determined by IHC, and it was concluded that TCSF protein was also upregulated in NSCLC tissues (P<0.001). A significant difference was identified following in vitro experiments for the NSCLC cell line A549, which revealed that miR-146a-5p and TCSF regulated cell viability, proliferation and apoptosis. In conclusion, the present study verified the target action association between TCSF and miR-146a-5p with high throughput data analysis and experimental results in NSCLC.

DNA methylation-mediated silencing of miR-204 is a potential prognostic marker for papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy and its incidence has increased over the last few decades. The molecular mechanisms underlying PTC tumorigenesis and progression are still unclear.

PATIENTS AND METHODS

The microRNA (miRNA) expression patterns of PTC were revealed by miRNA microarray analysis and validated with The Cancer Genome Atlas (TCGA) data. Promoter DNA methylation rates of miR-204 were analyzed by Agena Methylation MassAR-RAY analysis and validated with TCGA data. The underlying molecular mechanisms of miR-204 involved in PTC were studied by bioinformatics analyses.

RESULTS

A total of 181 differentially expressed miRNAs (89 downregulated and 92 upregulated miRNAs) between PTC and normal tissues were detected in this study. We identified miR-204 as one of the most significantly downregulated miRNAs in PTC. Downregulation of miR-204 was related to PTC extrathyroidal extension, high T-stage, lymph metastasis, BRAF V600E mutation, and aggressive tall cell variant. The Agena MassARRAY results indicated that 12 CpG sites located at the promoter of miR-204 were hypermethylated in PTC tissues compared to normal tissues. The promoter methylation rates of miR-204 in PTC were negatively correlated with the expression levels of miR-204 and its host gene TRPM3. Downregulated miR-204 expression was related to several important pathways and mechanisms involved in tumorigenesis and progression.

CONCLUSION

Promoter DNA methylation-silenced miR-204 could serve as a potential diagnostic biomarker of PTC. Downregulation of miR-204 may play an important role in PTC via its involvement in many tumor-related pathways. Novel target genes and putative mechanisms of miR-204 in PTC need to be further validated.

MicroRNA-181a Functions as an Oncogene in Gastric Cancer by Targeting Caprin-1

MicroRNA-181a (miRNA-181a) is a multifaceted miRNA implicated in various cellular processes, particularly in cell fate determination and cellular invasion. It is frequently expressed aberrantly in human tumors and shows opposing functions in different types of cancers. In this study, we found that miRNA-181a is overexpressed in Gastric cancer (GC) tissues. Clinical and pathological analyses revealed that the expression of miRNA-181a is correlated with tumor size, lymph node metastasis, distant metastasis, and TNM stage. Kaplan-Meier analysis indicated that overexpression of miRNA-181a is associated with poor overall survival of patients with GC. Moreover, miRNA-181a is overexpressed in GC cells, and downregulation of miRNA-181a induced cell apoptosis and suppressed the proliferation, invasion, and metastasis of GC cells both in vitro and in vivo. Target prediction and luciferase reporter assay showed that caprin-1 was a direct target of miRNA-181a. Downregulation of caprin-1 expression resulted in a converse change with miRNA-181a in GC. Spearman’s correlation test confirmed that the expression of miRNA-181a expression was inversely correlated with that of caprin-1 in GC cells. Furthermore, the expression of caprin-1 increased after downregulation of miRNA-181a in the GC cells. Caprin-1 siRNA can rescue the oncogenic effect of miRNA-181a on GC cell proliferation, apoptosis, migration, and invasion. These findings suggest that miRNA-181a directly inhibits caprin-1 and promotes GC development. miRNA-181a could be a target for anticancer drug development.

The Prognostic Value and Regulatory Mechanisms of microRNA-145 in Various Tumors: A Systematic Review and Meta-analysis of 50 Studies

Acting as an important tumor-related miRNA, the clinical significance and underlying mechanisms of miR-145 in various malignant tumors have been investigated by numerous studies. This study aimed to comprehensively estimate the prognostic value and systematically illustrate the regulatory mechanisms of miR-145 based on all eligible literature.Relevant studies were acquired from multiple online databases. Overall survival (OS) and progression-free survival (PFS) were used as primary endpoints. Detailed subgroup analyses were performed to decrease the heterogeneity among studies and recognize the prognostic value of miR-145. All statistical analyses were performed with RevMan software version 5.3 and STATA software version 14.1. A total of 48 articles containing 50 studies were included in the meta-analysis. For OS, the pooled results showed that low miR-145 expression in tumor tissues was significantly associated with worse OS in patients with various tumors [HR = 1.70; 95% confidence interval (CI), 1.46-1.99; P < 0.001). Subgroup analysis based on tumor type showed that the downregulation of miR-145 was associated with unfavorable OS in colorectal cancer (HR = 2.17; 95% CI, 1.52-3.08; P < 0.001), ovarian cancer (HR = 2.15; 95% CI, 1.29-3.59; P = 0.003), gastric cancer (HR = 1.78; 95% CI, 1.35-2.36; P < 0.001), glioma (HR = 1.65; 95% CI, 1.30-2.10; P < 0.001), and osteosarcoma (HR = 2.28; 95% CI, 1.50-3.47; P < 0.001). For PFS, the pooled results also showed that the downregulation of miR-145 was significantly associated with poor PFS in patients with multiple tumors (HR = 1.39; 95% CI, 1.16-1.67; P < 0.001), and the subgroup analyses further identified that the low miR-145 expression was associated with worse PFS in patients with lung cancer (HR = 1.97; 95% CI, 1.25-3.09; P = 0.003) and those of Asian descent (HR = 1.50; 95% CI, 1.23-1.82; P < 0.001). For the regulatory mechanisms, we observed that numerous tumor-related transcripts could be targeted by miR-145-5p or miR-145-3p, as well as the expression and function of miR-145-5p could be regulated by multiple molecules.This meta-analysis indicated that downregulated miR-145 in tumor tissues or peripheral blood predicted unfavorable prognostic outcomes for patients suffering from various malignant tumors. In addition, miR-145 was involved in multiple tumor-related pathways and the functioning of significant biological effects. miR-145 is a well-demonstrated tumor suppressor, and its expression level is significantly correlated with the prognosis of patients with multiple malignant tumors.

Hypermethylation of the Micro-RNA 145 Promoter Is the Key Regulator for NLRP3 Inflammasome-Induced Activation and Plaque Formation

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miR-145 in vessels decreases with plaque progression.

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DNMT1 and TET2 dynamic imbalance leads to miR-145 promoter hypermethylation.

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Reduction of miR-145 activates NLRP3 inflammasome through CD137/NFATc1 signaling.

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DNMT1 and TET2 could be promising therapeutic candidates for atherosclerosis in the future.

Two major issues are involved in clinical atherosclerosis treatment. First, there are no significant clinical markers for early diagnosis of atherosclerosis. Second, the plaque will not regress once it initiates even if the risk factors are removed. In this paper, the research shows that the hypermethylation level of the microRNA 145 (miR-145) promoter is related to a DNMT1 and TET2 dynamic imbalance. The reduction of miR-145 causes NLRP3 (nucleotide-binding oligomerization domain-like receptor protein 3) inflammasome activation through CD137/NFATc1 signaling. These findings could be a potential target for plaque regression in the future.

Promoter Methylation-Regulated miR-145-5p Inhibits Laryngeal Squamous Cell Carcinoma Progression by Targeting FSCN1

Laryngeal squamous cell carcinoma (LSCC) is a common form of head and neck cancer with poor prognosis. However, the mechanism underlying the pathogenesis of LSCC remains unclear. Here, we demonstrated increased expression of fascin actin-bundling protein 1 (FSCN1) and decreased expression of microRNA-145-5p (miR-145-5p) in a clinical cohort of LSCC. Luciferase assay revealed that miR-145-5p is a negative regulator of FSCN1. Importantly, low miR-145-5p expression was correlated with TNM (tumor, node, metastasis) status and metastasis. Moreover, cases with low miR-145-5p/high FSCN1 expression showed poor prognosis, and these characteristics together served as independent prognostic indicators of survival. Gain- and loss-of-function studies showed that miR-145-5p overexpression or FSCN1 knockdown inhibited LSCC migration, invasion, and growth by suppressing the epithelial-mesenchymal transition along with inducing cell-cycle arrest and apoptosis. Additionally, hypermethylation of the miR-145-5p promoter suggested that repression of miR-145-5p arises through epigenetic inactivation. LSCC tumor growth in vivo could be inhibited by using miR-145-5p agomir or FSCN1 small interfering RNA (siRNA), which highlights the potential for clinical translation. Collectively, our findings indicate that miR-145-5p plays critical roles in inhibiting the progression of LSCC by suppressing FSCN1. Both miR-145-5p and FSCN1 are important potential prognostic markers and therapeutic targets for LSCC.

DNA methylation biomarkers for the occurrence of lung adenocarcinoma from TCGA data mining

The development of lung cancer is a combination of multifactor, multistage, and multiple genetic alterations processes. DNA methylation is an important factor. Currently, the study on the genome-scale epigenetic modification for studying the pathogenesis of lung cancer is still lacking. Here, we aimed to identify the epigenetic modifications of lung cancer, thus to provide scientific basis for the personalized medicine, and research of classification screening for lung adenocarcinoma patients. The DNA methylation data, and the corresponding clinical information of lung adenocarcinoma samples were extracted from the Cancer Genome Atlas (TCGA) database. We explored the association of DNA methylation and gene transcription expression of lung adenocarcinoma by identifying the differentially expressed genes, DNA methylated locis, functional gene clusters, and the relevant genes associated with the survival. We identified 17 differentially expressed genes which had differentially methylated locis, 4 functional gene clusters regulated by methylation, and 522 genes, which were relevant to the survival time of patients. Our study suggested that methylation controlled the gene expression in a variety of ways, which had high/low expression and hyper-/hypo-methylation. Genes of different methylation status showed the different survival curve. The genes and methylated locis identified in this study could be potential biomarkers and therapeutic targets for lung adenocarcinoma.

DNA methylation mediated silencing of microRNA-874 is a promising diagnosis and prognostic marker in breast cancer

MicroRNA-874 (miR-874) is downregulated in several human cancers and has been suggested to be a tumor suppressor gene. However, the molecular mechanism of miR-874 downregulation in breast cancer has not been well elucidated. Here we aimed to study the aberrant hyper-methylation of CpG sites with the utility of miR-874 downreregulation in breast cancer and evaluate the clinical function of miR-874 as a prognostic marker. The miR-874 expressions in cells and tissues of two breast cancer lines were measured by real-time PCR. The DNA methylation status of the miR-874 promoter region in 19 pairs of breast cancer and adjacent normal samples was analyzed with Sequenom EpiTYPER MassArray. To evaluate whether miR-874 is a potential prognostic marker in breast cancer, we also explored the clinical long-time follow-up records from The Cancer Genome Atlas (TCGA). We found miR-874 expression was downregulated in 47 pairs of breast cancer tissues. Moreover, univariate and multivariate analysis revealed miR-874 expression may be a prognostic biomarker of overall survival in breast cancer patients. Preconditioning with 5-Aza-CdR in two cell lines elevated miR-874 expressions. The data from Sequenom EpiTYPER MassArray showed that DNA methylation of the promoter region of miR-874 was upregulated and accompanied by decreased miR-874 expression, which was further confirmed by TCGA. After comprehensive considerations, we think miR-874, which might be served as a prognostic biomarker, is mediated by DNA methylation.

Genetic variants in regulatory regions of microRNAs are associated with lung cancer risk

Genetic variants in regulatory regions of some miRNAs might be associated with lung cancer risk and survival. We performed a case-control study including 1341 non-small cell lung cancer (NSCLC) cases and 1982 controls to evaluate the associations of 7 potentially functional polymorphisms in several differently expressed miRNAs with NSCLC risk. Each SNP was also tested for the association with overall survival of 1001 NSCLC patients. We identified that rs9660710 in miR-200b/200a/429 cluster and rs763354 in miR-30a were significantly associated with NSCLC risk [odds ratio (OR) = 1.17, 95% confidence interval (CI) = 1.06–1.30, P = 0.002; OR = 0.88, 95% CI = 0.80–0.98, P = 0.017; respectively]. However, no significant association between variants and NSCLC death risk was observed in survival analysis. Functional annotation showed that both rs9660710 and rs763354 were located in regulatory elements in lung cancer cells. Compared to normal tissues, miR-200a-3p, miR-200a-5p, miR-200b-3p, miR-200b-5p and miR-429 were significantly increased in The Cancer Genome Atlas (TCGA) Lung Adenocarcinoma (LUAD) tumors, whereas miR-30a-3p and miR-30a-5p were significantly decreased in tumors (all P < 0.05). Furthermore, we observed that rs9660710 is an expression quantitative trait locus (eQTL) or methylation eQTL for miR-429 expression in TCGA normal tissues. Our results indicated that rs9660710 in miR-200b/200a/429 cluster and rs763354 in miR-30a might modify the susceptibility to NSCLC.

Epigenetically regulated miR-145 suppresses colon cancer invasion and metastasis by targeting LASP1

MiR-145 is a tumor-suppressive microRNA that participates in the malignant progression of colorectal cancer (CRC). Although miR-145 has been reported to inhibit proliferation and to induce apoptosis of CRC cells, the reports about its role in invasion and metastasis are controversial. The regulation of miR-145 its own expression also requires further elucidation. In this study, we firstly found that miR-145 is markedly downregulated in the metastatic tumors of CRC patients. Then through gain- and loss-of function studies, we demonstrated that miR-145 suppresses the invasion and metastasis of CRC cells. We also provided experimental evidences which include direct binding assays and verifications on tissue specimens to confirm that LIM and SH3 protein 1 (LASP1) is a direct target of miR-145. Furthermore, we identified the core promoter regions of miR-145 and observed the cooperation between histone methylation and transcription factors through binding to these core promoter regions to regulate the expression of miR-145 in CRC cells. Our study provides an insight into the regulatory network in CRC cells, thus offering new targets for treating CRC patients.

Epigenetics and MicroRNAs in Cancer

The ability to reprogram the transcriptional circuitry by remodeling the three-dimensional structure of the genome is exploited by cancer cells to promote tumorigenesis. This reprogramming occurs because of hereditable chromatin chemical modifications and the consequent formation of RNA-protein-DNA complexes that represent the principal actors of the epigenetic phenomena. In this regard, the deregulation of a transcribed non-coding RNA may be both cause and consequence of a cancer-related epigenetic alteration. This review summarizes recent findings that implicate microRNAs in the aberrant epigenetic regulation of cancer cells.

Passenger strand of miR-145-3p acts as a tumor-suppressor by targeting MYO1B in head and neck squamous cell carcinoma

Analysis of the microRNA (miRNA) expression signature of head and neck squamous cell carcinoma (HNSCC) based on RNA sequencing showed that dual strands of pre-miR-145 (miR-145-5p, guide strand; and miR-145-3p, passenger strand) were significantly reduced in cancer tissues. In miRNA biogenesis, passenger strands of miRNAs are degraded and have no biological activities in cells. The aims of this study were to investigate the functional significance of the passenger strand of miR-145 and to identify miR-145-3p-regulated oncogenic genes in HNSCC cells. Expression levels of miR-145-5p and miR-145-3p were significantly downregulated in HNSCC tissues and cell lines (SAS and HSC3 cells). Ectopic expression of miR-145-3p inhibited cancer cell proliferation, migration and invasion, similar to miR-145-5p, in HNSCC cells. Myosin 1B (MYO1B) was directly regulated by miR-145-3p, and knockdown of MYO1B by siRNA inhibited cancer cell aggressiveness. Overexpression of MYO1B was confirmed in HNSCC clinical specimens by analysis of protein and mRNA levels. Interestingly, high expression of MYO1B was associated with poor prognosis in patients with HNSCC by analysis of The Cancer Genome Atlas database (p=0.00452). Our data demonstrated that the passenger strand of miR-145 acted as an antitumor miRNA through targeting MYO1B in HNSCC cells. The involvement of dual strands of pre-miR-145 (miR-145-5p and miR-145-3p) in the regulation of HNSCC pathogenesis is a novel concept in present RNA research.

MicroRNA‑21 increases cell viability and suppresses cellular apoptosis in non‑small cell lung cancer by regulating the PI3K/Akt signaling pathway

MicroRNA (miRNA/miR), a type of non‑coding RNA molecule, is able to inhibit the expression of target genes at multiple stagess. There are 800‑1,000 known miRNAs in the human genome, which serve important roles in cell proliferation, differentiation, apoptosis and migration. Previous studies have demonstrated that the expression of miR‑21 is upregulated in numerous types of malignant tumor, and that miR‑21 participates in the occurrence and development of tumors via complex regulatory mechanisms. The present study aimed to investigate the association between miR‑21 expression, cell viability and apoptosis in a lung cancer cell line, and to elucidate the potential mechanisms. miR‑21 or small interfering RNA against miR‑21 were transfected into A549 non‑small cell lung cancer cells. The mRNA expression of miR‑21 was confirmed. Cell viability and apoptosis were examined using MTT and flow cytometric assays, respectively. The expression of certain apoptosis‑associated proteins was detected by western blotting. The results of the present study demonstrated that miR‑21 was able to increase the proliferation of A549 cells by inhibiting cellular apoptosis. miR‑21 inhibited apoptosis by modulating the activation of the phosphatidylinositol 3‑kinase/Rac‑α serine/threonine protein kinase (Akt) pathway in A549 cells. Correspondingly, inhibition of Akt decreased the apoptosis of A549 cells in miR‑21 siRNA‑treated cells. Therefore, the results of the present study demonstrated that miR‑21 increased cell viability by inhibiting apoptosis, through regulation of Akt activation. The present study demonstrated that miR‑21 may be involved in the progression of lung cancer and may be a novel therapeutic target for the disease.

MicroRNAs: A novel potential biomarker for diagnosis and therapy in patients with non-small cell lung cancer

BACKGROUND

Lung cancer is still one of the most serious causes of cancer-related deaths all over the world. MicroRNAs (miRNAs) are defined as small non-coding RNAs which could play a pivotal role in post-transcriptional regulation of gene expression. Increasing evidence demonstrated dysregulation of miRNA expression associates with the development and progression of NSCLC.

AIMS

To emphasize a variety of tissue-specific miRNAs, circulating miRNAs and miRNA-derived exosomes could be used as potential diagnostic and therapeutic biomarkers in NSCLC patients.

MATERIALS & METHODS

In the current review, we paid attention to the significant discoveries of preclinical and clinical studies, which performed on tissue-specific miRNA, circulating miRNA and exosomal miRNA. The related studies were obtained through a systematic search of Pubmed, Web of Science, Embase.

RESULTS

A variety of tissue-specific miRNAs and circulating miRNAs with high sensitivity and specificity which could be used as potential diagnostic and therapeutic biomarkers in NSCLC patients. In addition, we emphasize that the miRNA-derived exosomes become novel diagnostic biomarkers potentially in these patients with NSCLC.

CONCLUSION

MiRNAs have emerged as non-coding RNAs, which have potential to be candidates for the diagnosis and therapy of NSCLC.

miR-145-5p inhibits epithelial-mesenchymal transition via the JNK signaling pathway by targeting MAP3K1 in non-small cell lung cancer cells

Lung cancer is one of the most common types of tumors and the leading cause of cancer-associated mortality in the world. Additionally, non-small cell lung cancer (NSCLC) accounts for ~80% of all lung cancer cases. Epithelial-mesenchymal transition (EMT) is an important cell biological process, which is associated with cancer migration, metastasis, asthma and fibrosis in the lung. In the present study, it was revealed that miR-145-5p was able to suppress EMT by inactivating the c-Jun N-terminal kinase (JNK) signaling pathway in NSCLC cells. Mitogen-activated protein kinase kinase kinase 1 (MAP3K1) was predicted and confirmed to be a novel target of miR-145-5p. Overexpression of MAP3K1 was able to reverse the inhibition of EMT induced by miR-145-5p via the JNK signaling pathway. Overall, the results revealed that miR-145-5p inhibits EMT via the JNK signaling pathway by targeting MAP3K1 in NSCLC cells.

CDCA2 promotes lung adenocarcinoma cell proliferation and predicts poor survival in lung adenocarcinoma patients

Cell division cycle associated 2(CDCA2) is overexpressed in neuroblastoma and oral squamous cell carcinoma, and its overexpression positively correlates to tumor progression. However, the biological and clinical significance of CDCA2 in lung adenocarcinoma(LAC) has never been investigated. We determined the expression profile and clinical significance of CDCA2 using The Cancer Genome Atlas(TCGA) and tissue microarray(TMA). Furthermore, we explored the biological function of CDCA2 both in vitro and in vivo. A great upregulation of CDCA2 was observed in LAC tissues compared with adjacent normal tissues. Importantly, Cox regression analysis indicated that high level of CDCA2 was an independent risk factor for overall survival(OS) in LAC patients (TCGA: HR = 1.720, p = 0.004; TMA: HR = 1.971, p = 0.023). Inhibition of CDCA2 suppressed the proliferation of LAC cells via G1 phase arrest by downregulating cyclin E1(CCNE1), while overexpression of CDCA2 promoted LAC cells proliferation by upregulating CCNE1. Moreover, the oncogenic activity of CDCA2 was also confirmed in vivo. In conclusion, CDCA2 promotes proliferation of LAC cells and predicts poor prognosis in LAC patients. CDCA2 might play a significant role in LAC progression.

Epithelial-to-Mesenchymal Transition and MicroRNAs in Lung Cancer

Despite major advances, non-small cell lung cancer (NSCLC) remains the major cause of cancer-related death in developed countries. Metastasis and drug resistance are the main factors contributing to relapse and death. Epithelial-to-mesenchymal transition (EMT) is a complex molecular and cellular process involved in tissue remodelling that was extensively studied as an actor of tumour progression, metastasis and drug resistance in many cancer types and in lung cancers. Here we described with an emphasis on NSCLC how the changes in signalling pathways, transcription factors expression or microRNAs that occur in cancer promote EMT. Understanding the biology of EMT will help to define reversing process and treatment strategies. We will see that this complex mechanism is related to inflammation, cell mobility and stem cell features and that it is a dynamic process. The existence of intermediate phenotypes and tumour heterogeneity may be debated in the literature concerning EMT markers, EMT signatures and clinical consequences in NSCLC. However, given the role of EMT in metastasis and in drug resistance the development of EMT inhibitors is an interesting approach to counteract tumour progression and drug resistance. This review describes EMT involvement in cancer with an emphasis on NSCLC and microRNA regulation.

Impact of novel miR-145-3p regulatory networks on survival in patients with castration-resistant prostate cancer

BACKGROUND

Despite recent advancements, metastatic castration-resistant prostate cancer (CRPC) is not considered curative. Novel approaches for identification of therapeutic targets of CRPC are needed.

METHODS

Next-generation sequencing revealed 945-1248 miRNAs from each lethal mCRPC sample. We constructed miRNA expression signatures of CRPC by comparing the expression of miRNAs between CRPC and normal prostate tissue or hormone-sensitive prostate cancer (HSPC). Genome-wide gene expression studies and in silico analyses were carried out to predict miRNA regulation and investigate the functional significance and clinical utility of the novel oncogenic pathways regulated by these miRNAs in prostate cancer (PCa).

RESULTS

Based on the novel miRNA expression signature of CRPC, miR-145-5p and miR-145-3p were downregulated in CRPC. By focusing on miR-145-3p, which is a passenger strand and has not been well studied in previous reports, we showed that miR-145-3p targeted 4 key molecules, i.e., MELK, NCAPG, BUB1, and CDK1, in CPRC. These 4 genes significantly predicted survival in patients with PCa.

CONCLUSIONS

Small RNA sequencing for lethal CRPC and in silico analyses provided novel therapeutic targets for CRPC.

Demethylation of the MIR145 promoter suppresses migration and invasion in breast cancer

miR-145 has been implicated in the progression of breast cancer. Here, we report that its expression is decreased in breast cancer specimens and cell lines and that this low level of expression is associated with DNA methylation of its gene, MIR145. Methylation of MIR145 has previously been correlated with cell migration and invasion, both in vivo and in vitro. We found that demethylation of MIR145 reactivates miR-145 and contributes to the anti-cancer properties of 5-aza-2'-deoxyazacytidine (5-AzaC). Therefore, miR-145 is a potentially valuable biomarker for breast cancer.