MicroRNA‑141 inhibits epithelial‑mesenchymal transition, and ovarian cancer cell migration and invasion

MicroRNA Expression Profiles in Human Samples and Cell Lines Revealed Nine miRNAs Associated with Cisplatin Resistance in High-Grade Serous Ovarian Cancer

Metastasis and drug resistance are major contributors to cancer-related fatalities worldwide. In ovarian cancer (OC), a staggering 70% develop resistance to the front-line therapy, cisplatin. Despite proposed mechanisms, the molecular events driving cisplatin resistance remain unclear. Dysregulated microRNAs (miRNAs) play a role in OC initiation, progression, and chemoresistance, yet few studies have compared miRNA expression in OC samples and cell lines. This study aimed to identify key miRNAs involved in the cisplatin resistance of high-grade-serous-ovarian-cancer (HGSOC), the most common gynecological malignancy. MiRNA expression profiles were conducted on RNA isolated from formalin-fixed-paraffin-embedded human ovarian tumor samples and HGSOC cell lines. Nine miRNAs were identified in both sample types. Targeting these with oligonucleotide miRNA inhibitors (OMIs) reduced proliferation by more than 50% for miR-203a, miR-96-5p, miR-10a-5p, miR-141-3p, miR-200c-3p, miR-182-5p, miR-183-5p, and miR-1206. OMIs significantly reduced migration for miR-183-5p, miR-203a, miR-296-5p, and miR-1206. Molecular pathway analysis revealed that the nine miRNAs regulate pathways associated with proliferation, invasion, and chemoresistance through PTEN, ZEB1, FOXO1, and SNAI2. High expression of miR-1206, miR-10a-5p, miR-141-3p, and miR-96-5p correlated with poor prognosis in OC patients according to the KM plotter database. These nine miRNAs could be used as targets for therapy and as markers of cisplatin response.

The inhibitory role of microRNA-141-3p in human cutaneous melanoma growth and metastasis through the fibroblast growth factor 13-mediated mitogen-activated protein kinase axis

Human cutaneous melanoma (CM) is a highly invasive malignancy arising from melanocytes, and accompanied by ever-increasing incidence and mortality rates worldwide. Interestingly, microRNAs (miRNAs) possess the ability to regulate CM cell biological functions, resulting in the aggressive progression of CM. Nevertheless, a comprehensive understanding of the underlying mechanism remains elusive. Accordingly, the current study sought to elicit the functional role of miR-141-3p in human CM cells in association with fibroblast growth factor 13 (FGF13) and the MAPK pathway. First, miR-141-3p expression patterns were detected in human CM tissues and cell lines, in addition to the validation of the targeting relationship between miR-141-3p and FGF13. Subsequently, loss- and gain-of-function studies of miR-141-3p were performed to elucidate the functional role of miR-141-3p in the malignant features of CM cells. Intriguingly, our findings revealed that FGF13 was highly expressed, whereas miR-141-3p was poorly expressed in the CM tissues and cells. Further analysis highlighted FGF13 as a target gene of miR-141-3p. Meanwhile, overexpression of miR-141-3p inhibited the proliferative, invasive, and migratory abilities of CM cells, while enhancing their apoptosis accompanied by downregulation of FGF13 and the MAPK pathway-related genes. Collectively, our findings highlighted the inhibitory effects of miR-141-3p on CM cell malignant properties via disruption of the FGF13-dependent MAPK pathway, suggesting a potential target for treating human CM.

Interactions between circRNAs and miR-141 in Cancer: From Pathogenesis to Diagnosis and Therapy

The function of non-coding RNAs (ncRNAs) in the pathogenesis and development of cancer is indisputable. Molecular mechanisms underlying carcinogenesis involve the aberrant expression of ncRNAs, including circular RNAs (circRNAs), and microRNAs (miRNAs). CircRNAs are a class of single-stranded, covalently closed RNAs responsible for maintaining cellular homeostasis through their diverse functions. As a part of the competing endogenous RNA (ceRNAs) network, they play a central role in the regulation of accessibility of miRNAs to their mRNA targets. The interplay between these molecular players is based on the primary role of circRNAs that act as miRNAs sponges, and the circRNA/miRNA imbalance plays a central role in different pathologies including cancer. Herein, we present the latest state of knowledge about interactions between circRNAs and miR-141, a well-known member of the miR-200 family, in malignant transformation, with emphasis on the biological role of circRNA/miR-141/mRNA networks as a future target for novel anti-cancer therapies.

Deregulated miRNA clusters in ovarian cancer: Imperative implications in personalized medicine

Ovarian cancer (OC) is one of the most common and fatal types of gynecological cancer. OC is usually detected at the advanced stages of the disease, making it highly lethal. miRNAs are single-stranded, small non-coding RNAs with an approximate size ranging around 22 nt. Interestingly, a considerable proportion of miRNAs are organized in clusters with miRNA genes placed adjacent to one another, getting transcribed together to result in miRNA clusters (MCs). MCs comprise two or more miRNAs that follow the same orientation during transcription. Abnormal expression of the miRNA cluster has been identified as one of the key drivers in OC. MC exists both as tumor-suppressive and oncogenic clusters and has a significant role in OC pathogenesis by facilitating cancer cells to acquire various hallmarks. The present review summarizes the regulation and biological function of MCs in OC. The review also highlights the utility of abnormally expressed MCs in the clinical management of OC.

Epigenomic reprogramming in iAs-mediated carcinogenesis

Arsenic is a naturally occurring metal carcinogen found in the Earth's crust. Millions of people worldwide are chronically exposed to arsenic through drinking water and food. Exposure to inorganic arsenic has been implicated in many diseases ranging from acute toxicities to malignant transformations. Despite the well-known deleterious health effects of arsenic exposure, the molecular mechanisms in arsenic-mediated carcinogenesis are not fully understood. Since arsenic is non-mutagenic, the mechanism by which arsenic causes carcinogenesis is via alterations in epigenetic-regulated gene expression. There are two possible ways by which arsenic may modify the epigenome-indirectly through an arsenic-induced generation of reactive oxygen species which then impacts chromatin remodelers, or directly through interaction and modulation of chromatin remodelers. Whether directly or indirectly, arsenic modulates epigenetic gene regulation and our understanding of the direct effect of this modulation on chromatin structure is limited. In this chapter we will discuss the various ways by which inorganic arsenic affects the epigenome with consequences in health and disease.

The role of miR-200 family in the regulation of hallmarks of cancer

MiRNAs are short non-coding RNAs that regulate gene expression post-transcriptionally contributing to the development of different diseases including cancer. The miR-200 family consists of five members, miR-200a, miR-200b, miR-200c, miR-141, and miR-429. Their expression is dysregulated in cancer tissue and their level is altered in the body fluids of cancer patients. Moreover, the levels of miR-200 family members correlate with clinical parameters such as cancer patients' survival which makes them potentially useful as diagnostic and prognostic biomarkers. MiRNAs can act as either oncomiRs or tumor suppressor miRNAs depending on the target genes and their role in the regulation of key oncogenic signaling pathways. In most types of cancer, the miR-200 family acts as tumor suppressor miRNA and regulates all features of cancer. In this review, we summarized the expression pattern of the miR-200 family in different types of cancer and their potential utility as biomarkers. Moreover, we comprehensively described the role of miR-200 family members in the regulation of all hallmarks of cancer proposed by Hanahan and Weinberg with the focus on the epithelial-mesenchymal transition, invasiveness, and metastasis of tumor cells.

Differential expression and role of miR-200 family in multiple tumors

microRNA (miRNA) can maintain the homeostasis of the human by participating in the regulation of cell proliferation, apoptosis, differentiation, and metabolism. During the entire stage of tumorigenesis, miRNA can maintain the heterogeneity of cancer stem cells by regulating the formation and metastasis of the tumor, which leads to chemotherapy resistance. miR-200 family consists of five members, which can regulate the proliferation, invasion, and migration of cancer cells by inhibiting the transcription of downstream genes (including zinc finger E-box binding homeobox 1 and 2, E-cadherin, N-cadherin, transforming growth factor-β, and cancer stem cell related-proteins). Meanwhile, Long non-coding RNA can bind to miR-200s to regulate the proliferation and apoptosis of cancer cells. Besides, the expression of the miR-200 family can affect the mechanism of chemotherapy resistance.

LncRNA SLC16A1-AS1 is upregulated in hepatocellular carcinoma and predicts poor survival

BACKGROUND

Long non-coding RNAs (LncRNAs) are broadly transcribed in the genome of human and animals, they play critical roles in cellular process, and participate in the progression of multiple diseases, including cancer. SLC16A1-AS1 is a tumor suppressive lncRNA in lung cancer. This study aimed to investigate the involvement of lncRNA SLC16A1-AS1 in hepatocellular carcinoma (HCC).

METHOD

A total of 64 HCC patients were subjected to biopsy to obtain paired HCC and non-tumor tissues. Expression of SLC16A1-AS1 and miR-141 in paired tissues was determined by RT-qPCR. Correlations were analyzed by linear regression. Overexpression of SLC16A1-AS1 and miR-141 were achieved in HCC cells to explore the interactions between them. The methylation of the gene encoding miR-141 in HCC cells was detected by methylation-specific PCR (MSP). CCK-8 assay was performed for cell proliferation assay.

RESULTS

SLC16A1-AS1 was upregulated in HCC and its high expression levels predicted poor survival of HCC patients. Expression levels of miR-141 were lower in HCC patients and were inversely correlated with the expression levels of SLC16A1-AS1. In HCC cells, overexpression of SLC16A1-AS1 led to downregulation of miR-141, while overexpression of miR-141 did not regulate the expression of SLC16A1-AS1. In addition, overexpression of SLC16A1-AS1 led to increased methylation of miR-141. And overexpression of SLC16A1-AS1 attenuated the inhibitory effects of miR-141 on HCC cell proliferation.

CONCLUSION

SLC16A1-AS1 is upregulated in HCC and predicts poor survival. In addition, SLC16A1-AS1 may downregulate miR-141 through methylation to promote cancer cell proliferation.

circST6GALNAC6 suppresses bladder cancer metastasis by sponging miR-200a-3p to modulate the STMN1/EMT axis

Bladder cancer (BCa) is an aggressive malignancy because of its distant metastasis and high recurrence rate. Circular RNAs (circRNAs) exert critical regulatory functions in cancer progression. However, the expression patterns and roles of circRNAs in BCa have not been well investigated. In this study, we first screened circRNA expression profiles using a circRNA microarray of paired BCa and normal tissues, and the expression of circST6GALNAC6 was confirmed by qRT-PCR and fluorescence in situ hybridization (FISH). MTT, colony formation and Transwell assays were performed to measure cell proliferation, migration and invasion. We investigated the regulatory effect of circST6GALNAC6 on miRNA and its target genes to explore the potential regulatory mechanisms of circST6GALNAC6 by chromatin immunoprecipitation (ChIP), RNA immunoprecipitation (RIP), MS2-tagged RNA affinity purification (MS2-TRAP), immunofluorescence (IF) and dual luciferase activity assays. A nude mouse xenograft model was used to examine the functions of circST6GALNAC6/STMN1 in tumour metastasis in vivo. We found that 881 circRNAs were significantly dysregulated in BCa tissues compared to normal tissues. circST6GALNAC6(hsa_circ_0088708) was downregulated in BCa tissues and cells. Overexpression of circST6GALNAC6 effectively inhibited the cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) in vitro and suppressed BCa metastasis in vivo. Mechanistically, we showed that the SP1 transcription factor, which binds to the circST6GALNAC6 mRNA transcript, activates circST6GALNAC6 transcription. Next, we verified that circST6GALNAC6 serves as a sponge that directly binds miR-200a-3p to regulate stathmin (STMN1) expression. Furthermore, we found that STMN1 is involved in circST6GALNAC6/miR-200a-3p axis-regulated BCa EMT and metastasis. Thus, our findings indicate an important underlying mechanism in BCa metastasis by which SP1-induced circST6GALNAC6 sponges miR-200a-3p to promote STMN1/EMT signalling. This mechanism could provide pivotal potential prognostic biomarkers and therapeutic targets for BCa.

The Role of microRNAs in Epithelial Ovarian Cancer Metastasis

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and the major cause of death is mainly attributed to metastasis. MicroRNAs (miRNAs) are a group of small non-coding RNAs that exert important regulatory functions in many biological processes through their effects on regulating gene expression. In most cases, miRNAs interact with the 3′ UTRs of target mRNAs to induce their degradation and suppress their translation. Aberrant expression of miRNAs has been detected in EOC tumors and/or the biological fluids of EOC patients. Such dysregulation occurs as the result of alterations in DNA copy numbers, epigenetic regulation, and miRNA biogenesis. Many studies have demonstrated that miRNAs can promote or suppress events related to EOC metastasis, such as cell migration, invasion, epithelial-to-mesenchymal transition, and interaction with the tumor microenvironment. In this review, we provide a brief overview of miRNA biogenesis and highlight some key events and regulations related to EOC metastasis. We summarize current knowledge on how miRNAs are dysregulated, focusing on those that have been reported to regulate metastasis. Furthermore, we discuss the role of miRNAs in promoting and inhibiting EOC metastasis. Finally, we point out some limitations of current findings and suggest future research directions in the field.

Arsenic-Induced Carcinogenesis: The Impact of miRNA Dysregulation

Arsenic is a toxic metalloid widely present in the earth's crust, and is a proven human carcinogen. Chronic arsenic exposure mainly through drinking water causes skin, lung, and urinary bladder cancers, and is associated with liver, prostate, and kidney cancers, cardiovascular and neurological disorders, and diabetes. Several modes of action have been suggested in arsenic carcinogenesis. However, the molecular etiology of arsenic-induced cancer remains unclear. Recent evidence clearly indicates that gene expression modifications induced by arsenic may involve epigenetic alterations, including miRNA dysregulation. Many miRNAs have been implicated in different human cancers as a consequence of losses and or gains of miRNA function that contribute to cancer development. Progress in identifying miRNA dysregulation induced by arsenic has been made using different approaches and models. The present review discusses the recent data regarding dysregulated expression of miRNA in arsenic-induced malignant transformation in vitro, gaps in current understanding and deficiencies in current models for arsenic-induced carcinogenesis, and future directions of research that would improve our knowledge regarding the mechanisms involved in arsenic-induced carcinogenesis.

MicroRNA profiling of pancreatic ductal adenocarcinoma (PDAC) reveals signature expression related to lymph node metastasis

Lymph node (LN) metastasis occurs frequently in pancreatic ductal adenocarcinoma (PDAC), representing an advanced disease stage and independently predicting patient survival. Current nodal staging is inadequate preoperatively and even less so postoperatively, and molecular biomarkers are needed to improve prognostication and selection of therapy. Recent data have suggested important roles of miRNAs in PDAC tumorigenesis and progression. The aim of the present study was to identify miRNA expression signature for nodal spread in PDAC patients. Using PDAC human tissue specimens, we identified 39 miRNAs which were differently expressed in LN positive compared to LN negative PDAC samples. Of them, six miRNAs have been reported to play a role in cancer invasion and metastasis. A high versus low six- miRNA signature score was predictive of LN metastasis in the PDAC validation cohort. We demonstrated a similar expression pattern of four out of the six miRNAs in the plasma of PDAC patients. The results of our in-vitro studies revealed that miR-141 and miR-720 are involved in the process of epithelial to mesenchymal-transition in PDAC. These miRNAs significantly inhibited in vitro proliferation, migration and invasion of PDAC cells as evidence by gain- and loss- of function studies, specifically, via ZEB-1 and TWIST1 transcription factors, as well as through the activation of the MAP4K4/JNK signaling pathway.