MiR-101 inhibits melanoma cell invasion and proliferation by targeting MITF and EZH2

Loss of miR-101-3p in melanoma stabilizes genomic integrity, leading to cell death prevention

Malignant melanoma remains the most lethal form of skin cancer, exhibiting poor prognosis after forming distant metastasis. Owing to their potential tumor-suppressive properties by regulating oncogenes and tumor suppressor genes, microRNAs are important player in melanoma development and progression. We defined the loss of miR-101-3p expression in melanoma cells compared with melanocytes and melanoblast-related cells as an early event in tumor development and aimed to understand the tumor suppressive role of miR-101-3p and its regulation of important cellular processes. Reexpression of miR-101-3p resulted in inhibition of proliferation, increase in DNA damage, and induction of apoptosis. We further determined the nuclear structure protein Lamin B1, which influences nuclear processes and heterochromatin structure, ATRX, CASP3, and PARP as an important direct target of miR-101-3p. RNA sequencing and differential gene expression analysis after miR-101-3p reexpression supported our findings and the importance of loss of mir-101-3p for melanoma progression. The validated functional effects are related to genomic instability, as recent studies suggest miRNAs plays a key role in mediating this cellular process. Therefore, we concluded that miR-101-3p reexpression increases the genomic instability, leading to irreversible DNA damage, which leads to apoptosis induction. Our findings suggest that the loss of miR-101-3p in melanoma serves as an early event in melanoma progression by influencing the genomic integrity to maintain the increased bioenergetic demand.

MicroRNA as a Diagnostic Tool, Therapeutic Target and Potential Biomarker in Cutaneous Malignant Melanoma Detection—Narrative Review

Melanoma is the most serious type of skin cancer, causing a large majority of deaths but accounting for only ~1% of all skin cancer cases. The worldwide incidence of malignant melanoma is increasing, causing a serious socio-economic problem. Melanoma is diagnosed mainly in young and middle-aged people, which distinguishes it from other solid tumors detected mainly in mature people. The early detection of cutaneous malignant melanoma (CMM) remains a priority and it is a key factor limiting mortality. Doctors and scientists around the world want to improve the quality of diagnosis and treatment, and are constantly looking for new, promising opportunities, including the use of microRNAs (miRNAs), to fight melanoma cancer. This article reviews miRNA as a potential biomarker and diagnostics tool as a therapeutic drugs in CMM treatment. We also present a review of the current clinical trials being carried out worldwide, in which miRNAs are a target for melanoma treatment.

Role of miRNA in Melanoma Development and Progression

Melanoma is one of the most aggressive and progressive skin cancers. It develops from normal pigment-producing cells known as melanocytes, so it is important to know the mechanism behind such transformations. The study of metastasis mechanisms is crucial for a better understanding the biology of neoplastic cells. Metastasis of melanoma, or any type of cancer, is a multi-stage process in which the neoplastic cells leave the primary tumour, travel through the blood and/or lymphatic vessels, settle in distant organs and create secondary tumours. MicroRNA (miRNA) can participate in several steps of the metastatic process. This review presents the role of miRNA molecules in the development and progression as well as the immune response to melanoma.

Immunomodulatory Properties of Human Breast Milk: MicroRNA Contents and Potential Epigenetic Effects

Infants who are exclusively breastfed in the first six months of age receive adequate nutrients, achieving optimal immune protection and growth. In addition to the known nutritional components of human breast milk (HBM), i.e., water, carbohydrates, fats and proteins, it is also a rich source of microRNAs, which impact epigenetic mechanisms. This comprehensive work presents an up-to-date overview of the immunomodulatory constituents of HBM, highlighting its content of circulating microRNAs. The epigenetic effects of HBM are discussed, especially those regulated by miRNAs. HBM contains more than 1400 microRNAs. The majority of these microRNAs originate from the lactating gland and are based on the remodeling of cells in the gland during breastfeeding. These miRNAs can affect epigenetic patterns by several mechanisms, including DNA methylation, histone modifications and RNA regulation, which could ultimately result in alterations in gene expressions. Therefore, the unique microRNA profile of HBM, including exosomal microRNAs, is implicated in the regulation of the genes responsible for a variety of immunological and physiological functions, such as FTO, INS, IGF1, NRF2, GLUT1 and FOXP3 genes. Hence, studying the HBM miRNA composition is important for improving the nutritional approaches for pregnancy and infant's early life and preventing diseases that could occur in the future. Interestingly, the composition of miRNAs in HBM is affected by multiple factors, including diet, environmental and genetic factors.

Reciprocal regulation of BRN2 and NOTCH1/2 signaling synergistically drives melanoma cell migration and invasion

Phenotypic plasticity drives cancer progression, impacts on treatment response and is a major driver of therapeutic resistance. In melanoma, a regulatory axis between the MITF and BRN2 transcription factors has been reported to promote tumor heterogeneity by mediating switching between proliferative and invasive phenotypes respectively. Despite strong evidence that subpopulations of cells that exhibit a BRN2^high/MITF^low expression profile switch to a predominantly invasive phenotype, the mechanisms by which this switch is propagated and promotes invasion remain poorly defined. We have found that a reciprocal relationship between BRN2 and NOTCH1/2 signaling exists in melanoma cells in vitro, within patient datasets and in vivo primary and metastatic human tumors that bolsters acquisition of invasiveness. Working through the epigenetic modulator EZH2, the BRN2-NOTCH1/2 axis is potentially a key mechanism by which the invasive phenotype is maintained. Given the emergence of agents targeting both EZH2 and NOTCH, understanding the mechanism through which BRN2 promotes heterogeneity may provide crucial biomarkers to predict treatment response to prevent metastasis.

MicroRNA Isoforms Contribution to Melanoma Pathogenesis

Cutaneous melanoma (CM) is the most lethal tumor among skin cancers, and its incidence is constantly increasing. A deeper understanding of the molecular processes guiding melanoma pathogenesis could improve diagnosis, treatment and prognosis. MicroRNAs play a key role in melanoma biology. Recently, next generation sequencing (NGS) experiments, designed to assess small-RNA expression, revealed the existence of microRNA variants with different length and sequence. These microRNA isoforms are known as isomiRs and provide an additional layer to the complex non-coding RNA world. Here, we collected data from NGS experiments to provide a comprehensive characterization of miRNA and isomiR dysregulation in benign nevi (BN) and early-stage melanomas. We observed that melanoma and BN express different and specific isomiRs and have a different isomiR abundance distribution. Moreover, isomiRs from the same microRNA can have opposite expression trends between groups. Using The Cancer Genome Atlas (TCGA) dataset of skin cancers, we analyzed isomiR expression in primary melanoma and melanoma metastasis and tested their association with NF1, BRAF and NRAS mutations. IsomiRs differentially expressed were identified and catalogued with reference to the canonical form. The reported non-random dysregulation of specific isomiRs contributes to the understanding of the complex melanoma pathogenesis and serves as the basis for further functional studies.

MicroRNA Signature in Melanoma: Biomarkers and Therapeutic Targets

Melanoma is the utmost fatal kind of skin neoplasms. Molecular changes occurring during the pathogenic processes of initiation and progression of melanoma are diverse and include activating mutations in BRAF and NRAS genes, hyper-activation of PI3K/AKT pathway, inactivation of p53 and alterations in CDK4/CDKN2A axis. Moreover, several miRNAs have been identified to be implicated in the biology of melanoma through modulation of expression of genes being involved in these pathways. In the current review, we provide a summary of the bulk of information about the role of miRNAs in the pathobiology of melanoma, their possible application as biomarkers and their emerging role as therapeutic targets for this kind of skin cancer.

MiR-101 reduces cell proliferation and invasion and enhances apoptosis in endometrial cancer via regulating PI3K/Akt/mTOR

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Microphthalmia-Associated Transcription Factor-Dependent Melanoma Cell Adhesion Molecule Activation Promotes Peritoneal Metastasis of Ovarian Cancer

Ovarian cancer (OvCa) is one of the leading causes of death due to its high metastasis rate to the peritoneum. Recurrent peritoneal tumors also develop despite the use of conventional platinum-based chemotherapies. Therefore, it is still important to explore the factors associated with peritoneal metastasis, as these predict the prognosis of patients with OvCa. In this study, we investigated the function of microphthalmia-associated transcription factor (MITF), which contributes to the development of melanoma, in epithelial ovarian cancer (OvCa). High MITF expression was significantly associated with a poor prognosis in OvCa. Notably, MITF contributed to the motility and invasion of OvCa cells, and specifically with their peri-mesothelial migration. In addition, MITF-positive cells expressed the melanoma cell adhesion molecule (MCAM/CD146), which was initially identified as a marker of melanoma progression and metastasis, and MCAM expression was regulated by MITF. MCAM was also identified as a significant prognostic factor for poor progression-free survival in patients with OvCa. Collectively, our results suggest that MITF is a novel therapeutic target that potentially promotes peritoneal metastasis of OvCa.

Regulating Methylation at H3K27: A Trick or Treat for Cancer Cell Plasticity

Properly timed addition and removal of histone 3 lysine 27 tri-methylation (H3K27me3) is critical for enabling proper differentiation throughout all stages of development and, likewise, can guide carcinoma cells into altered differentiation states which correspond to poor prognoses and treatment evasion. In early embryonic stages, H3K27me3 is invoked to silence genes and restrict cell fate. Not surprisingly, mutation or altered functionality in the enzymes that regulate this pathway results in aberrant methylation or demethylation that can lead to malignancy. Likewise, changes in expression or activity of these enzymes impact cellular plasticity, metastasis, and treatment evasion. This review focuses on current knowledge regarding methylation and de-methylation of H3K27 in cancer initiation and cancer cell plasticity.

The Emerging Roles of Heterochromatin in Cell Migration

Cell migration is a key process in health and disease. In the last decade an increasing attention is given to chromatin organization in migrating cells. In various types of cells induction of migration leads to a global increase in heterochromatin levels. Heterochromatin is required for optimal cell migration capabilities, since various interventions with heterochromatin formation impeded the migration rate of numerous cell types. Heterochromatin supports the migration process by affecting both the mechanical properties of the nucleus as well as the genetic processes taking place within it. Increased heterochromatin levels elevate nuclear rigidity in a manner that allows faster cell migration in 3D environments. Condensed chromatin and a more rigid nucleus may increase nuclear durability to shear stress and prevent DNA damage during the migration process. In addition, heterochromatin reorganization in migrating cells is important for induction of migration-specific transcriptional plan together with inhibition of many other unnecessary transcriptional changes. Thus, chromatin organization appears to have a key role in the cellular migration process.

Long non-coding RNA GAS5 accelerates oxidative stress in melanoma cells by rescuing EZH2-mediated CDKN1C downregulation

Background

The significance of long non-coding RNAs (lncRNAs) in mediating oxidative stress of cancers has been implicated recently. This study proposed a potential therapeutic target lncRNA growth arrest-specific transcript 5 (GAS5) for melanoma, due to its crucial role in oxidative stress and apoptosis of melanoma cells by regulating the enhancer of zeste homolog 2 (EZH2)-mediated CDKN1C expression.

Methods

The lncRNA GAS5 expression pattern was examined in melanoma tissues and cells. The correlation of lncRNA GAS5, EZH2, and CDKN1C with survival rate of melanoma patients was analyzed. In melanoma cell lines, lncRNA GAS5 expression was overexpressed or knocked down to clarify its effects on cell viability, apoptosis, and oxidative stress. The interaction between lncRNA GAS5 and EZH2 was examined by RIP and RNA pull-down assays followed by verification of the target relationship between EZH2 and CDKN1C.

Results

High expression of EZH2 and poor expression of lncRNA GAS5 and CDKN1C was observed in melanoma tissues and found to be correlated with the reduction in survival expectancy of melanoma patients. Overexpression of lncRNA GAS5 or CDKN1C or EZH2 knockdown could inhibit cell viability but enhance melanoma cell apoptosis and oxidative stress. Importantly, lncRNA GAS5 attenuated EZH2 expression by recruiting E2F4 to the EZH2 promoter region and knockdown of EZH2 upregulated CDKN1C expression by inhibiting the H3K27me3.

Conclusion

The evidence provided by our study highlighted the involvement of lncRNA GAS5 in the translational suppression of EZH2 as well as the upregulation of CDKN1C, resulting in the promotion of melanoma cell apoptosis and oxidative stress.

The miRNAs Role in Melanoma and in Its Resistance to Therapy

Melanoma is the less common but the most malignant skin cancer. Since the survival rate of melanoma metastasis is about 10–15%, many different studies have been carried out in order to find a more effective treatment. Although the development of target-based therapies and immunotherapeutic strategies has improved chances for patient survival, melanoma treatment still remains a big challenge for oncologists. Here, we collect recent data about the emerging role of melanoma-associated microRNAs (miRNAs) currently available treatments, and their involvement in drug resistance. We also reviewed miRNAs as prognostic factors, because of their chemical stability and resistance to RNase activity, in melanoma progression. Moreover, despite miRNAs being considered small conserved regulators with the limitation of target specificity, we outline the dual role of melanoma-associated miRNAs, as oncogenic and/or tumor suppressive factors, compared to other tumors.

Influence of miR-101 on proliferation of liver cancer cells through the MAPK/ERK signaling pathway

The expression of miR-101 in carcinoma and para-carcinoma tissues of patients with liver cancer was studied. The carcinoma and para-carcinoma tissues of 67 patients with liver cancer treated in Chinese PLA General Hospital were collected, and the expression of miR-101 in carcinoma and para-carcinoma tissues was detected via reverse transcription-polymerase chain reaction (RT-PCR). The liver cancer HepG2 cell line was transfected with miR-101 mimics. Moreover, the influence of miR-101 overexpression on the proliferation of liver cancer cells was detected via Cell Counting Kit-8 assay and colony formation assay. The proportion of Ki67-positive cells in the control group (NC group) and miR-101 overexpression group (miR-101 mimics group) was detected via Ki67 staining. The proportions of cells were detected via flow cytometry, and the predicted target gene Zeste2 enhancer (EZH2) was further verified via luciferase reporter gene assay and western blotting. The miR-101 overexpression significantly inhibited the colony formation and proliferation ability of liver cancer cells (P<0.05). The proportion of Ki67-positive cells in liver cancer cells was lower in miR-101 mimics group (P<0.05). The proportion of cells in G0/G1 phase was increased in miR-101 mimics group compared with that in NC group (P<0.05). The extracellular signal-regulated kinase (ERK)1/2 phosphorylation level in liver cancer cells was obviously suppressed in miR-101 mimics group (P<0.05). Therefore, the expression level of miR-101 declines in liver cancer tissues, and the miR-101 overexpression can inhibit the proliferation of liver cancer cells. The inhibitory effect of miR-101 on the proliferation of liver cancer cells may be related to its inhibition on the mitogen-activated protein kinase (MAPK)/ERK signaling pathway, and the inhibition on the MAPK/ERK may be mediated by the targeted inhibition of miR-101 on EZH2.

miR-101 regulates cell proliferation and apoptosis by targeting KDM1A in diffuse large B cell lymphoma

Background

miR-101 is reported to be associated with cell proliferation and apoptosis. However, it is unknown whether miR-101 expression affects cell proliferation and apoptosis in diffuse large B cell lymphoma (DLBCL). The aim of the present study was to investigate the expression of miR-101 and its effect on cell proliferation and apoptosis in DLBCL.

Methods

miR-101 expression was detected in 30 cases of patients with DLBCL and normal lymph node by qRT-PCR. Then, miR-101 expression was up-regulated and down-regulated in Originated Cell Line-Large Lymphoma 8 (OCL-LY8) cell line, respectively. MTT and flow cytometry assay were used to evaluate the effect of miR-101 on cell proliferation and apoptosis, respectively. As KDM1A was confirmed to be as a specific target of miR-101 by TargetScanHuman, the relationship between MiR-101 and KDM1A was further investigated.

Results

miR-101 expression in patients with DLBCL was significantly reduced compared those in normal lymph node (P<0.05). miR-101 expression was significantly associated with tumor size, clinical stage and International Prognostic Index (IPI) scores (P<0.05). In OCL-LY8 cell line, miR-101 down-regulation significantly promoted cell proliferation and suppressed cell apoptosis. Meanwhile, miR-101 up-regulation reversed this effect. In addition, miR-101 negatively regulated the expression of KDM1A. KDM1A down-regulation was oberved in normal tissues compared with those in DLBCL tissues, which inhibited cell proliferation and promoted cell apoptosis.

Conclusion

These data indicate that miR-101 regulates cell proliferation and apoptosis by targeting KDM1A, which provides a potential therapeutic for DLBCL patients.

MicroRNA-101-3p suppresses proliferation and migration in hepatocellular carcinoma by targeting the HGF/c-Met pathway

MicroRNAs are involved in each stage of tumor development. Activation of the hepatocyte growth factor (HGF)/c-Met axis facilitates the proliferation and migration of cancer cells, and the HGF/c-MET pathway provides potential targets for anticancer treatment. However, the interaction between HGF and miRNAs in hepatocellular carcinoma (HCC) remains unknown. Previous studies have shown that miR-101 is downregulated in various types of cancer and acts as a tumor suppressor, but the role of miR-101 in HCC has not yet been well defined. Here, we show that HGF is upregulated while microRNA-101-3p is significantly downregulated in the tumor tissues of HCC. By combining bioinformatics analysis and luciferase reporter assays, we demonstrated that HGF is a direct target of miR-101. In vitro experiments indicated that miR-101 inhibits the migration and proliferation of HCC cells by targeting the HGF/c-MET axis, and in vivo studies showed that overexpressed miR-101 dramatically suppresses tumor growth. Therefore, the present study identifies miR-101 as a negative regulator of HGF/c-MET and suggests that miRNAs can be used as targeted drugs for the clinical treatment of HCC.

Overexpression of miR-101-2 in donor cells improves the early development of Holstein cow somatic cell nuclear transfer embryos

Accumulating studies have suggested that microRNA play a part in regulating multiple cellular processes, such as cell proliferation, apoptosis, the cell cycle, and embryo development. This study explored the effects of miR-101-2 on donor cell physiological status and the development of Holstein cow somatic cell nuclear transfer (SCNT) embryos in vitro. Holstein cow bovine fetal fibroblasts (BFF) overexpressing miR-101-2 were used as donor cells to perform SCNT; then, cleavage rate, blastocyst rate, inner cell mass-to-trophectoderm ratio, and the expression of some development- and apoptosis-related genes in different groups were analyzed. The miR-101-2 suppressed the expression of inhibitor of growth protein 3 (ING3) at mRNA and protein levels, expedited cell proliferation, and decreased apoptosis in BFF, suggesting that ING3, a target gene of miR-101-2, is a potential player in this process. Moreover, by utilizing donor cells overexpressing miR-101-2, the development of bovine SCNT embryos in vitro was significantly enhanced; the apoptotic rate in SCNT blastocysts was reduced, and the inner cell mass-to-trophectoderm ratio and SOX2, POU5F1, and BCL2L1 expression significantly increased, whereas BAX and ING3 expression decreased. Collectively, these findings suggest that miR-101-2 promotes BFF proliferation and vitality, reduces their apoptosis, and improves the early development of SCNT embryos.

Interplay between small and long non-coding RNAs in cutaneous melanoma: a complex jigsaw puzzle with missing pieces

The incidence of cutaneous melanoma (CM) has increased in the past few decades. The biology of melanoma is characterized by a complex interaction between genetic, environmental and phenotypic factors. A greater understanding of the molecular mechanisms that promote melanoma cell growth and dissemination is crucial to improve diagnosis, prognostication, and treatment of CM. Both small and long non-coding RNAs (lncRNAs) have been identified to play a role in melanoma biology; microRNA and lncRNA expression is altered in transformed melanocytes and this in turn has functional effects on cell proliferation, apoptosis, invasion, metastasis, and immune response. Moreover, specific dysregulated ncRNAs were shown to have a diagnostic or prognostic role in melanoma and to drive the establishment of drug resistance. Here, we review the current literature on small and lncRNAs with a role in melanoma, with the aim of putting into some order this complex jigsaw puzzle.

miR-193b and miR-30c-1* inhibit, whereas miR-576-5p enhances melanoma cell invasion in vitro

In cancer cells, microRNAs (miRNAs) are often aberrantly expressed resulting in impaired mRNA translation. In this study we show that miR-193b and miR-30c-1^* inhibit, whereas miR-576-5p accelerates invasion of various human melanoma cell lines. Using Boyden chamber invasion assays the effect of selected miRNAs on the invasive capacity of various human melanoma cell lines was analyzed. Upon gene expression profiling performed on transfected A375 cells, CTGF, THBS1, STMN1, BCL9, RAC1 and MCL1 were identified as potential targets. For target validation, qPCR, Western blot analyses or luciferase reporter assays were applied. This study reveals opposed effects of miR-193b / miR-30c-1^* and miR-576-5p, respectively, on melanoma cell invasion and on expression of BCL9 and MCL1, possibly accounting for the contrasting invasive phenotypes observed in A375 cells transfected with these miRNAs. The miRNAs studied and their targets identified fit well into a model proposed by us explaining the regulation of invasion associated genes and the observed opposed phenotypes as a result of networked direct and indirect miRNA / target interactions. The results of this study suggest miR-193b and miR-30c-1^* as tumor-suppressive miRNAs, whereas miR-576-5p appears as potential tumor-promoting oncomiR. Thus, miR-193b and miR-30c-1^* mimics as well as antagomiRs directed against miR-576-5p might become useful tools in future therapy approaches against advanced melanoma.

BRN2, a POUerful driver of melanoma phenotype switching and metastasis

The POU domain family of transcription factors play a central role in embryogenesis and are highly expressed in neural crest cells and the developing brain. BRN2 is a class III POU domain protein that is a key mediator of neuroendocrine and melanocytic development and differentiation. While BRN2 is a central regulator in numerous developmental programs, it has also emerged as a major player in the biology of tumourigenesis. In melanoma, BRN2 has been implicated as one of the master regulators of the acquisition of invasive behaviour within the phenotype switching model of progression. As a mediator of melanoma cell phenotype switching, it coordinates the transition to a dedifferentiated, slow cycling and highly motile cell type. Its inverse expression relationship with MITF is believed to mediate tumour progression and metastasis within this model. Recent evidence has now outlined a potential epigenetic switching mechanism in melanoma cells driven by BRN2 expression that induces melanoma cell invasion. We summarize the role of BRN2 in tumour cell dissemination and metastasis in melanoma, while also examining it as a potential metastatic regulator in other tumour models.

Quantification of microRNA-21 and microRNA-125b in melanoma tissue

Although microRNAs (miRNAs) have emerged as potent mediators of melanoma development and progression, a precise understanding of their oncogenic role remains unclear. In this study, we analysed formalin-fixed and paraffin-embedded tissues from two separate melanoma cohorts and from a series of benign melanocytic nevi. Using three different quantification methods [array analysis, quantitative PCR (qPCR) and in-situ hybridization (ISH) quantified by digital image analysis], we found considerable miRNA dysregulation in tumours. Using array analysis, samples mainly clustered according to their biological group (benign vs. malignant) and 77 miRNAs differed significantly between nevi and melanoma samples. Increase of miR-21 and miR-142, and decrease of miR-125b, miR-211, miR-101 and miR-513c in the melanomas were verified in both cohorts using qPCR, whereas the decrease of miR-205 observed with array analysis could not be confirmed using qPCR. ISH with digital quantification showed expression of miR-21 and miR-125b in the melanocytic lesions. miR-21 ISH was increased in melanomas, whereas quantification of miR-125b showed uniform ISH expression across nevi and melanomas. Our results support the important involvement of different miRNAs in melanoma biology and may serve as solid basics for further miRNA investigations in melanoma formalin-fixed and paraffin-embedded tissue. In particular, there is increased expression of miR-21 in melanomas compared with benign nevi.

miR-101-3p induces autophagy in endometrial carcinoma cells by targeting EZH2

OBJECTIVE

This study aimed to investigate the effect of miR-101-3p on autophagy in endometrial carcinoma (EC) cells and the connection between miR-101-3p and EZH2.

METHODS

The expression levels of miRNAs were analyzed by microarray. The expression level of autophagy related proteins was measured by western blot. The mRNA expression level of beclin-1 was determined by qRT-PCR. Autophagy in EC cells was traced by GFP-LC3 fusion protein and observed by fluorescence microscopy. The number of autophagic vacuoles was determined by transmission electron microscopy (TEM). A luciferase reporter assay was utilized to assess the target relationship between miR-101-3p and EZH2.

RESULTS

The expression level of miR-101-3p in EC tissues was lower than in normal tissues. miR-101-3p upregulated the expression levels of the autophagy-related proteins LC3-II and beclin-1 in EC cells in a time- and dose-dependent manner. Overexpression of miR-101-3p and silencing of EZH2 both promoted autophagy in EC cells. Luciferase reporter assays verified that miR-101-3p inhibited EZH2 expression by binding to its 3'-UTR region.

CONCLUSION

miR-101-3p promoted autophagy in EC cells by downregulating the expression of EZH2, and it induced autophagy in EC cells by suppressing EZH2 expression. Inhibition of miR-101-3p could reduce its autophagy induction effect on EC cells.

In vitro transfection of anti-tumor miR-101 induces BIM, a pro-apoptotic protein, expression in acute myeloid leukemia (AML)

Acute myeloid leukemia (AML) frequently relapses after initial treatment, though it is possible that drug resistance occurs. Hence, it seems necessary to develop novel therapies such as gene therapy specifically via miRNA transfection. MicroRNA-101 has been considered as a tumor suppressor in different types of cancer. It is demonstrated that exogenous miR-101 transfection is associated with decreased viability in AML in this paper. Besides, the increase of pro-apoptotic protein BIM expression in both mRNA and protein level has been illustrated. The recent findings provide an insight into the novel function of miR-101 in AML by activating BIM as an important mediator in intrinsic apoptosis pathways. Generally, miR-101 has been considered as a therapeutic target in our data and might have a valuable role in AML.

miRNAs, Melanoma and Microenvironment: An Intricate Network

miRNAs are central players in cancer biology and they play a pivotal role in mediating the network communication between tumor cells and their microenvironment. In melanoma, miRNAs can impair or facilitate a wide array of processes, and here we will focus on: the epithelial to mesenchymal transition (EMT), the immune milieu, and metabolism. Multiple miRNAs can affect the EMT process, even at a distance, for example through exosome-mediated mechanisms. miRNAs also strongly act on some components of the immune system, regulating the activity of key elements such as antigen presenting cells, and can facilitate an immune evasive/suppressive phenotype. miRNAs are also involved in the regulation of metabolic processes, specifically in response to hypoxic stimuli where they can mediate the metabolic switch from an oxidative to a glycolytic metabolism. Overall, this review discusses and summarizes recent findings on miRNA regulation in the melanoma tumor microenvironment, analyzing their potential diagnostic and therapeutic applications.

Effects of microRNA-136 on melanoma cell proliferation, apoptosis, and epithelial-mesenchymal transition by targetting PMEL through the Wnt signaling pathway

The study aims to evaluate the effects of miR-136 on the proliferation, apoptosis, and epithelial–mesenchymal transition (EMT) of melanoma cells by targetting premelanosome protein (PMEL) through the Wnt signaling pathway. After establishment of melanoma mouse models, melanoma (model group) and normal tissues (normal group) were collected. Immunohistochemistry was performed to determine PMEL protein concentration. Mouse melanoma cells were assigned into control, blank, negative control (NC), miR-136 mimics, miR-136 inhibitors, siRNA-PMEL, and miR-136 inhibitors + siRNA-PMEL, LiC1 (Wnt signaling pathway activator), and siRNA-PMEL+ LiCl groups. MTT, Scratch test, Transwell assay, and flow cytometry were performed to measure cell proliferation, migration, invasion, and apoptosis. Quantitative real-time PCR (qRT-PCR) and Western blotting were performed to evaluate miR-136, PMEL, β-catenin, Wnt3a, Bcl-2, Bax, Caspase, E-cadherin, and N-cadherin expressions. PMEL is highly expressed in melanoma tissues. MiR-136, Bax, Caspase, and E-cadherin expressions decreased in the model group, whereas PMEL, β-catenin, Bcl-2, Wnt3a, and N-cadherin expressions increased. Bax, Caspase, and E-cadherin expressions increased in the miR-136 mimics and siRNA-PMEL groups, whereas the expressions decreased in the miR-136 inhibitors group and LiC1 group. PMEL, β-catenin, Bcl-2, Wnt3a, and N-cadherin expressions, cell proliferation, migration, and invasion decreased, and the apoptosis rate inceased in the miR-136 mimics and siRNA-PMEL groups; whereas the tendencies were opposite to those in the miR-136 inhibitors group and LiC1 group. In the siRNA-PMEL+ LiCl group, PMEL expression decreased. These findings indicated that overexpression of miR-136 inhibits melanoma cell EMT, proliferation, migration, invasion, and promotes apoptosis by targetting PMEL through down-regulation of the Wnt signaling pathway.

microRNA-33a-5p increases radiosensitivity by inhibiting glycolysis in melanoma

Glycolysis was reported to have a positive correlation with radioresistance. Our previous study found that the miR-33a functioned as a tumor suppressor in malignant melanoma by targeting hypoxia-inducible factor1-alpha (HIF-1α), a gene known to promote glycolysis. However, the role of miR-33a-5p in radiosensitivity remains to be elucidated. We found that miR-33a-5p was downregulated in melanoma tissues and cells. Cell proliferation was downregulated after overexpression of miR-33a-5p in WM451 cells, accompanied by a decreased level of glycolysis. In contrast, cell proliferation was upregulated after inhibition of miR-33a-5p in WM35 cells, accompanied by increased glycolysis. Overexpression of miR-33a-5p enhanced the sensitivity of melanoma cells to X-radiation by MTT assay, while downregulation of miR-33a-5p had the opposite effects. Finally, in vivo experiments with xenografts in nude mice confirmed that high expression of miR-33a-5p in tumor cells increased radiosensitivity via inhibiting glycolysis. In conclusions, miR-33a-5p promotes radiosensitivity by negatively regulating glycolysis in melanoma.

MicroRNA-605 functions as a tumor suppressor by targeting INPP4B in melanoma

MicroRNAs (miRNAs) play crucial roles in the initiation and progression of various cancers, including melanoma. Recently, the genetic variants and deregulation of miR-605 have been reported to participate in carcinogenesis. However, the expression status of the miR-605 in melanoma tissues and its role in melanoma progression remain unknown. In this study, we found that miR-605 was significantly downregulated in melanoma cell lines and clinical specimens. Further function studies demonstrated that miR-605 suppressed melanoma cell growth both in vitro and in vivo. Moreover, INPP4B gene was identified as a target of miR-605 through bioinformatics analysis and luciferase reporter assays. Further analysis demonstrated that the inhibition of INPP4B mediated SGK3 activation was required for the suppressive role of miR-605 on melanomas cell growth. Collectively, our data suggest that miR-605 functions as a tumor suppressor by negatively regulating INPP4B mediated SGK3 activation in melanoma and may present a potential target for therapeutic intervention.

MiR-101 and doxorubicin codelivered by liposomes suppressing malignant properties of hepatocellular carcinoma

MiR-101, an important tumor-suppressive microRNA (miRNA) in hepatocellular carcinoma (HCC), has been affirmed significantly downregulated in HCC and participated in promoting apoptosis, decreasing proliferation and invasiveness of HCC cells, as well as increasing sensitivity of chemotherapeutic drug. However, miR-101-based combination therapies with doxorubicin (DOX) are not reported yet. Recently, nanomaterials-based approaches, especially liposome formulations, have been approved for clinical use and seem to provide a great opportunity to codeliver therapeutic agents for cancer therapy. In this study, we have successfully prepared liposome (L) nanoparticles to efficiently deliver miR-101 and DOX to HCC cells simultaneously. The effects of codelivery system miR-101/doxorubicin liposome (miR-101/DOX-L) on tumor malignant phenotypes of HCC cells were evaluated through analyzing cell proliferation, colony formation, cell migration, cell invasion, cell apoptosis assay, and the expression of related genes. In subcutaneous xenografts developed by HCC cells, the inhibition of tumor growth was analyzed through gross morphology, growth curve, proliferation marker Ki-67, apoptosis signals, and the expression of related genes. These experiments demonstrated that miR-101/DOX-L inhibited tumor properties of liver cancer cells in vitro and in vivo through targeting correlative genes by combinatory role of miR-101 and DOX. In conclusion, our results indicated that liposome nanoparticle is a reliable delivery strategy to codeliver miR-101 and DOX simultaneously, and miR-101- and DOX-based combination therapy can result in significant synergetic antitumor effects in vivo and vitro.

NFIB Mediates BRN2 Driven Melanoma Cell Migration and Invasion Through Regulation of EZH2 and MITF

While invasion and metastasis of tumour cells are the principle factor responsible for cancer related deaths, the mechanisms governing the process remain poorly defined. Moreover, phenotypic divergence of sub-populations of tumour cells is known to underpin alternative behaviors linked to tumour progression such as proliferation, survival and invasion. In the context of melanoma, heterogeneity between two transcription factors, BRN2 and MITF, has been associated with phenotypic switching between predominantly invasive and proliferative behaviors respectively. Epigenetic changes, in response to external cues, have been proposed to underpin this process, however the mechanism by which the phenotypic switch occurs is unclear. Here we report the identification of the NFIB transcription factor as a novel downstream effector of BRN2 function in melanoma cells linked to the migratory and invasive characteristics of these cells. Furthermore, the function of NFIB appears to drive an invasive phenotype through an epigenetic mechanism achieved via the upregulation of the polycomb group protein EZH2. A notable target of NFIB mediated up-regulation of EZH2 is decreased MITF expression, which further promotes a less proliferative, more invasive phenotype. Together our data reveal that NFIB has the ability to promote dynamic changes in the chromatin state of melanoma cells to facilitate migration, invasion and metastasis.

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NFIB mediates a slow cycling, highly invasive/migratory melanoma cell phenotype downstream of BRN2.

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NFIB increases EZH2 expression downstream of BRN2, which further decreases MITF levels.

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NFIB expression is defined by an invasive gene signature and colocalises with BRN2 in primary and metastatic human melanoma tumours.

Melanoma is a heterogeneous cancer, made up of many cellular populations that differ in their ability to induce tumour growth or invasion throughout the body (metastasis). These populations have been found to switch back and forth to drive invasion and progression. This process appears to be controlled by an inverse axis between two genes, MITF and BRN2. BRN2 drives metastatic spread, but the process by which it acts is not well characterized and cannot be targeted clinically. This study has uncovered a role for the gene NFIB in driving invasion downstream of BRN2. Importantly, it appears to drive this process through EZH2, which can be targeted therapeutically to reduce metastasis.

MicroRNA expression in BRAF-mutated and wild-type metastatic melanoma and its correlation with response duration to BRAF inhibitors

Objective: Currently, the treatment of BRAF V600-mutated metastatic melanoma with BRAF inhibitors gives a response rate of ~ 50% with a progression-free survival of ~ 6 -- 7 months. In order to identify predictive biomarkers capable of stratifying BRAF-mutated patients at high risk of shorter response duration to anti-BRAF therapy, the authors analyzed the expression of 15 microRNAs (miRNAs) targeting crucial genes involved in melanoma biology and drug response.Research design and methods: A total of 15 miRNAs and target gene expression were investigated in 43 patients (30 BRAF-mutated, and 13 BRAF wild-type). Moreover, 20 BRAF-mutated patients treated with vemurafenib were analyzed for miRNA expression in respect to time-to-progression.Results: All miRNAs except miR-192 showed low expression in BRAF-mutated as compared with BRAF wild-type patients. In particular, miR-101, miR-221,miR-21, miR-338-3p and miR-191 resulted in significant downregulation inBRAF-mutated patients. Moreover, high expression of miR-192 and miR-193b* and low expression of miR-132 resulted in significant association with shorter progression.Conclusion: Three miRNAs were significantly associated with clinical outcome in metastatic melanoma patients. An increased understanding of the molecular assessment of BRAF-mutated melanomas could allow development of specific molecular tests able to predict response duration.

microRNAs regulate TAL1 expression in T-cell acute lymphoblastic leukemia

The transcription factor TAL1 is a proto-oncogene whose aberrant expression in committed T-cell precursors is associated with the development of T-cell acute lymphoblastic leukemia (T-ALL). The mechanisms leading to aberrant activation of TAL1 in T-ALL patients who lack chromosomal rearrangements involving the TAL1 locus remain largely unknown. We hypothesized that TAL1 levels decrease during normal T-cell development at least in part due to miRNA-dependent silencing, in which case TAL1 over-expression in some T-ALL cases could be the consequence of deregulated miRNA expression. By performing computational prediction of miRNAs that bind to the human TAL1 mRNA we compiled a list of miRNAs that are candidates to regulate TAL1. Using a luciferase reporter system and mutagenesis assays we confirmed the miRNA-TAL1 mRNA interactions and selected candidate miRNAs: miR-101, miR-520d-5p, miR-140-5p, miR-448 and miR-485-5p. Over-expression of these microRNAs in different T-ALL cell lines consistently resulted in the down-regulation of TAL1 protein. In accordance, inhibition of miR-101 and miR-520d-5p promoted TAL1 protein expression. Importantly, we found that miR-101, miR-140-5p, miR-448 and miR-485-5p were down-regulated in T-ALL patient specimens and T-ALL cell lines. Our results show for the first time the existence of epigenetic regulation of TAL1 by specific miRNAs which may contribute, at least in part, to the ectopic expression of TAL1 in some T-ALL cases.

Determinants of orofacial clefting II: Effects of 5-Aza-2'-deoxycytidine on gene methylation during development of the first branchial arch

Defects in development of the secondary palate, which arise from the embryonic first branchial arch (1-BA), can cause cleft palate (CP). Administration of 5-Aza-2'-deoxycytidine (AzaD), a demethylating agent, to pregnant mice on gestational day 9.5 resulted in complete penetrance of CP in fetuses. Several genes critical for normal palatogenesis were found to be upregulated in 1-BA, 12h after AzaD exposure. MethylCap-Seq (MCS) analysis identified several differentially methylated regions (DMRs) in DNA extracted from AzaD-exposed 1-BAs. Hypomethylated DMRs did not correlate with the upregulation of genes in AzaD-exposed 1-BAs. However, most DMRs were associated with endogenous retroviral elements. Expression analyses suggested that interferon signaling was activated in AzaD-exposed 1-BAs. Our data, thus, suggest that a 12-h in utero AzaD exposure demethylates and activates endogenous retroviral elements in the 1-BA, thereby triggering an interferon-mediated response. This may result in the dysregulation of key signaling pathways during palatogenesis, causing CP.

The Ezh2 polycomb group protein drives an aggressive phenotype in melanoma cancer stem cells and is a target of diet derived sulforaphane

Melanoma is a metastatic cancer associated with poor survival. Here, we study a subpopulation of melanoma cancer cells displaying melanoma cancer stem cell (MCS cells) properties including elevated expression of stem cell markers, increased ability to survive as spheroids, and enhanced cell migration and invasion. We show that the Ezh2 stem cell survival protein is enriched in MCS cells and that Ezh2 knockdown or treatment with small molecule Ezh2 inhibitors, GSK126 or EPZ-6438, reduces Ezh2 activity. This reduction is associated with a reduced MCS cell spheroid formation, migration, and invasion. Moreover, the diet-derived cancer prevention agent, sulforaphane (SFN), suppresses MCS cell survival and this is associated with loss of Ezh2. Forced expression of Ezh2 partially reverses SFN suppression of MCS cell spheroid formation, migration, and invasion. A375 melanoma cell-derived MCS cells form rapidly growing tumors in immune-compromised mice and SFN treatment of these tumors reduces tumor growth and this is associated with reduced Ezh2 level and H3K27me3 formation, reduced matrix metalloproteinase expression, increased TIMP3 expression and increased apoptosis. These studies identify Ezh2 as a MCS cell marker and cancer stem cell prevention target, and suggest that SFN acts to reduce melanoma tumor formation via a mechanism that includes suppression of Ezh2 function. © 2015 Wiley Periodicals, Inc.

Upregulation of miR-124 by physcion 8-O-β-glucopyranoside inhibits proliferation and invasion of malignant melanoma cells via repressing RLIP76

Melanoma is the most malignant type of skin cancer. In recent years, mounting studies have evidenced the involvement of miRNAs in melanoma. One of these miRNAs, miR-124 has been found aberrantly downregulated in a variety of human malignancies. In this study, our results showed that the expression of miR-124 was significantly lower in malignant melanoma tissues and cell lines and miR-124 functioned as a tumor suppressor in melanoma. Moreover, our findings showed that miR-124 exerted anti-tumor effect by directly targeting RLIP76, a stress-inducible non-ABC transporter that plays a crucial role in the development of melanoma. Furthermore, our study also showed that physcion 8-O-β-glucopyranoside, a natural compound from medicinal plant, could inhibit the proliferation and invasion of melanoma cells by targeting miR-124/RLIP76 signaling.

MicroRNA-101 regulates T-cell acute lymphoblastic leukemia progression and chemotherapeutic sensitivity by targeting Notch1

The present study aimed to investigate the role of microRNA (miR)-101 in acute lymphoblastic leukemia progression and chemoresistance. Furthermore, a novel target gene of miR-101 was identified. Here, we confirmed that miR-101 was significantly downregulated in the blood samples of patients with T-cell acute lymphoblastic leukemia (T-ALL) compared with the healthy controls, as determined by reverse transcription quantitative polymerase chain reaction (RTqPCR) analysis. The in vitro experiments demonstrated that miR-101 significantly repressed the proliferation and invasion, and induced potent apoptosis in Jurkat cells, as determined by CCK-8, flow cytometer and cell invasion assays. Luciferase assay confirmed that Notch1 was a target gene of miR-101, and western blotting showed that miR-101 suppressed the expression of Notch1 at the protein level. Moreover, functional restoration assays revealed that Notch1 mediates the effects of miR-101 on Jurkat cell proliferation, apoptosis and invasion. miR-101 enhanced the sensitivity of Jurkat cells to the chemotherapeutic agent adriamycin. Taken together, our results show for the first time that miR-101 acts as a tumor suppressor in T-cell acute lymphoblastic leukaemia and it could enhance chemotherapeutic sensitivity. Furthermore, Notch1 was identified to be a novel target of miR-101. This study indicates that miR-101 may represent a potential therapeutic target for T-cell acute lymphoblastic leukemia intervention.

Microphthalmia-associated transcription factor expression levels in melanoma cells contribute to cell invasion and proliferation

Microphthalmia-associated transcription factor (MITF) is a nodal point in melanoma transcriptional network that regulates dozens of genes with critical functions in cell differentiation, proliferation and survival. Highly variable MITF expression levels exist in tumor cell subpopulations conferring marked heterogeneity and plasticity in the tumor tissue. A model has been postulated whereby lower MITF levels favour cell invasion and suppress proliferation, whereas high levels stimulate differentiation and proliferation. Additionally, MITF is considered to be a prosurvival gene and a lineage addiction oncogene in melanoma. Herein, we review how MITF expression may affect the melanoma phenotype with consequences on the survival, invasion and metastasis of melanoma cells, and we discuss the research challenges.

miR-339-3p Is a Tumor Suppressor in Melanoma

Determinants of invasion and metastasis in cancer remain of great interest to define. Here, we report the definition of miR-339-3p as a novel tumor suppressive microRNA that blocks melanoma cell invasion without affecting cell survival. miR-339-3p was identified by a comprehensive functional screen of a human miRNA mimetic library in a cell-based assay for invasion by the melanoma cell line A375. miR-339-3p was determined as a strong inhibitor of invasion differentially expressed in melanoma cells and healthy melanocytes. MCL1 was defined as a target for downregulation by miR-339-3p, functioning through direct interaction with the 3' untranslated region of MCL1 mRNA. Blocking miR-339-3p by an antagomiR was sufficient to increase melanoma cell invasion, an effect that could be phenocopied by RNAi-mediated silencing of MCL1. In vivo studies established that miR-339-3p overexpression was sufficient to decrease lung colonization by A375 melanoma cells in NSG mice, relative to control cells. Overall, our results defined miR-339-3p as a melanoma tumor suppressor, the levels of which contributes to invasive aggressiveness. Cancer Res; 76(12); 3562-71. ©2016 AACR.

MicroRNA-101 inhibits cell proliferation and induces apoptosis by targeting EYA1 in breast cancer

MicroRNAs (miRNAs or miRs) regulate gene expression by negatively modulating the stability or translational efficiency of their target genes by targeting the 3'-untranslated region (3'-UTR). Aberrant miRNA expression has been reported in various types of cancer; miRNAs can function as either oncogenes or tumor suppressor genes in cancer. In this study, we examined the expression level of miR‑101 in breast cancer tissues and cell lines by RT-qPCR, and found that miR‑101 expression was downregulated in breast cancer tissues and cell lines; indeed, in 6 of the 28 tissue samples, miR‑101 could not be detected. Furthermore, miR‑101, when transfected into SKBR3 cells, inhibited cell proliferation and promoted apoptosis, while miR‑101 inhibitor had the opposite effect. A dual-luciferase reporter assay revealed that miR‑101 targeted the 3'-UTR of eyes absent homolog 1 (Drosophila) (EYA1). Western blot analysis demonstrated a significantly decreased protein level of EYA1 in the SKBR3 cells transfected with miR‑101 mimic, whereas transfection with miR‑101 inhibitor led to an increased level of EYA1. Moreover, an increased expression of EYA1 was also found in breast cancer tissues and cell lines. The silencing of EYA1 using siRNA targeting EYA1 (EYA1‑siRNA) significantly inhibited SKBR3 cell proliferation and promoted apoptosis, and also suppressed the increased proliferation induced by transfection with miR‑101 inhibitor. The protein expression levels of Notch signaling components (jagged1, Hes1 and Hey1) were significantly decreased by transfection with miR‑101 mimic and EYA1-siRNA, and were increased by transfection with miR‑101 inhibitor. Furthermore, the elevated protein expression levels of jagged1, Hes1 and Hey1 induced by transfection with miR‑101 inhibitor in the SKBR3 cells were significantly decreased by transfection with EYA1-siRNA. Taken together, these results suggest that miR‑101 is down-regulated in breast cancer, and can inhibit cell proliferation and promote apoptosis by targeting EYA1 through the Notch signaling pathway.

Epigenetic regulators: Polycomb-miRNA circuits in cancer

Polycomb group (PcG) proteins belong to a family of epigenetic modifiers and play a key role in dynamic control of their target genes. Several reports have found that aberrations in PcG-microRNA (miRNA) interplay in various cancer types often associated with poor clinical prognosis. This review discusses important PcG-miRNA molecular networks which act as critical interfaces between chromatin remodeling, and transcriptional and post-transcriptional regulation of their target genes in cancer. Moreover, here are discussed several compounds influencing the activity of PcG proteins entered in clinical arena for the treatment of solid tumors, multiple myeloma and B lymphomas, thus highlighting the therapeutic potential of targeting this protein family.

Epigenetic markers in melanoma

Melanoma, one of the most virulent forms of human malignancy, is the primary cause of mortality from cancers arising from the skin. The prognosis of metastatic melanoma remains dismal despite targeted therapeutic regimens that exploit our growing understanding of cancer immunology and genetic mutations that drive oncogenic cell signaling pathways in cancer. Epigenetic mechanisms, including DNA methylation/demethylation, histone modifications and noncoding RNAs recently have been shown to play critical roles in melanoma pathogenesis. Current evidence indicates that imbalance of DNA methylation and demethylation, dysregulation of histone modification and chromatin remodeling, and altered translational control by noncoding RNAs contribute to melanoma tumorigenesis. Here, we summarize the most recent insights relating to epigenetic markers, focusing on diagnostic potential as well as novel therapeutic approaches for more effective treatment of advanced melanoma.

Epigenetic regulation in human melanoma: past and future

The development and progression of melanoma have been attributed to independent or combined genetic and epigenetic events. There has been remarkable progress in understanding melanoma pathogenesis in terms of genetic alterations. However, recent studies have revealed a complex involvement of epigenetic mechanisms in the regulation of gene expression, including methylation, chromatin modification and remodeling, and the diverse activities of non-coding RNAs. The roles of gene methylation and miRNAs have been relatively well studied in melanoma, but other studies have shown that changes in chromatin status and in the differential expression of long non-coding RNAs can lead to altered regulation of key genes. Taken together, they affect the functioning of signaling pathways that influence each other, intersect, and form networks in which local perturbations disturb the activity of the whole system. Here, we focus on how epigenetic events intertwine with these pathways and contribute to the molecular pathogenesis of melanoma.

MicroRNA-101 is a potential prognostic indicator of laryngeal squamous cell carcinoma and modulates CDK8

BACKGROUND

Various microRNAs (miRNAs) negatively modulate genes that are involved in cellular proliferation, differentiation, invasion, and apoptosis. In many types of cancer, the expression profiles of these miRNAs are altered. Recently, miR-101 was identified as a tumour suppressor and was found to be expressed at low levels in various types of tumours, including prostate, breast, endometrium, and bladder cancers. However, the function(s) of miR-101 in laryngeal carcinoma remain unknown.

METHODS

The expression levels of miR-101 in laryngeal squamous cell carcinoma (LSCC) tissues and cells were detected by qPCR. Cell proliferation, migration, cell cycle, and apoptosis assay were applied to assess the function(s) of miR-101 in vitro. Nude mice subcutaneous tumour model was used to perform in vivo study. Moreover, we identified Cyclin-dependent kinase 8 (CDK8) as the target of miR-101 by a luciferase assay. The possible downstream effectors of CDK8 were investigated in Wnt/β-catenin signaling pathway. Changes of CDK8, β-catenin, and cyclin D1 protein levels were analyzed by western blotting and immunohistochemical staining. The prognostic effect of miR-101 was evaluated using the Kaplan-Meier method.

RESULTS

Expression of miR-101 was down-regulated in the LSCC tissues compared with the adjacent normal tissues. Furthermore, downregulation of miR-101 correlated with T3-4 tumour grade, lymph node metastasis, and an advanced clinical stage in the LSCC patients examined (P < 0.05). The low level of miR-101 expression was associated with poor prognosis (P < 0.05). CDK8 was identified as the target gene of miR-101 by luciferase reporter assay. Moreover, we showed that up-regulation of miR-101 expression suppressed humen LSCC Hep-2 cells proliferation and migration, and induced cell-cycle arrest. Increased expression of miR-101 induced cells apoptosis both in vitro and in vivo. Correspondingly, exogenous expression of miR-101 significantly reduced the growth of tumour in a LSCC xenograft model. Furthermore, the miR-101 level was inversely correlated with levels of CDK8, β-catenin, and cyclin D1 in western blotting assay and immunohistochemical staining assay.

CONCLUSIONS

These results indicate that miR-101 is a potent tumour repressor that directly represses CDK8 expression. Thus, detection and targeting of miR-101 may represent a novel diagnostic and therapeutic strategy for LSCC patients.

Polycomb Group (PcG) Proteins and Human Cancers: Multifaceted Functions and Therapeutic Implications

Polycomb group (PcG) proteins are transcriptional repressors that regulate several crucial developmental and physiological processes in the cell. More recently, they have been found to play important roles in human carcinogenesis and cancer development and progression. The deregulation and dysfunction of PcG proteins often lead to blocking or inappropriate activation of developmental pathways, enhancing cellular proliferation, inhibiting apoptosis, and increasing the cancer stem cell population. Genetic and molecular investigations of PcG proteins have long been focused on their PcG functions. However, PcG proteins have recently been shown to exert non-classical-Pc-functions, contributing to the regulation of diverse cellular functions. We and others have demonstrated that PcG proteins regulate the expression and function of several oncogenes and tumor suppressor genes in a PcG-independent manner, and PcG proteins are associated with the survival of patients with cancer. In this review, we summarize the recent advances in the research on PcG proteins, including both the Pc-repressive and non-classical-Pc-functions. We specifically focus on the mechanisms by which PcG proteins play roles in cancer initiation, development, and progression. Finally, we discuss the potential value of PcG proteins as molecular biomarkers for the diagnosis and prognosis of cancer, and as molecular targets for cancer therapy.

miR-101 suppresses vascular endothelial growth factor C that inhibits migration and invasion and enhances cisplatin chemosensitivity of bladder cancer cells

Background

The microRNA miR-101 is downregulated in several cancers, including bladder cancer. However, miR-101’s role in the invasion, metastasis, and chemosensitivity of bladder cancer cells remains unclear. This study was conducted to determine miR-101’s role on the lymphangiogenic molecule vascular endothelial growth factor C (VEGF-C) and their effects upon bladder cancer cell migration, invasion, and chemosensitivity to cisplatin.

Methods

Two bladder cancer cell lines (T24 and 5637) and the tool cell line 293T were employed here. Bladder cancer cells were transfected with either a miR-101 overexpression vector or a scrambled-sequence lentivirus, both of which exhibited a high transfection efficiency. Non-transfection was used as a mock negative control. Wound healing and Transwell assays were performed to measure cell migration and invasiveness. A luciferase reporter assay was performed to validate miR-101’s interaction with VEGF-C’s 3′ untranslated region followed by RT-PCR and Western blot confirmation. An MTS assay was used to evaluate the cisplatin sensitivity of the cell lines.

Results

miR-101 overexpression significantly inhibited the migration and invasiveness while significantly enhancing cisplatin sensitivity. miR-101 negatively regulated VEGF-C protein expression, and VEGF-C overexpression rescued the effects of miR-101 overexpression, indicating that miR-101 negatively regulates VEGF-C protein expression post-transcriptionally. miR-101 and VEGF-C interference independently enhanced cisplatin cytotoxicity in bladder cancer cells.

Conclusions

miR-101 suppresses VEGF-C expression, inhibits cell migration and invasion, and increases cisplatin sensitivity in bladder cancer cells. This study provides new insight into miR-101’s role in bladder cancer and shows miR-101’s promise as a potential molecular target for bladder cancer.

The epigenetic modifier EZH2 controls melanoma growth and metastasis through silencing of distinct tumour suppressors

Increased activity of the epigenetic modifier EZH2 has been associated with different cancers. However, evidence for a functional role of EZH2 in tumorigenesis in vivo remains poor, in particular in metastasizing solid cancers. Here we reveal central roles of EZH2 in promoting growth and metastasis of cutaneous melanoma. In a melanoma mouse model, conditional Ezh2 ablation as much as treatment with the preclinical EZH2 inhibitor GSK503 stabilizes the disease through inhibition of growth and virtually abolishes metastases formation without affecting normal melanocyte biology. Comparably, in human melanoma cells, EZH2 inactivation impairs proliferation and invasiveness, accompanied by re-expression of tumour suppressors connected to increased patient survival. These EZH2 target genes suppress either melanoma growth or metastasis in vivo, revealing the dual function of EZH2 in promoting tumour progression. Thus, EZH2-mediated epigenetic repression is highly relevant especially during advanced melanoma progression, which makes EZH2 a promising target for novel melanoma therapies.

MiR-101 sensitizes human nasopharyngeal carcinoma cells to radiation by targeting stathmin 1

Radioresistance remains a major problem in the treatment of patients suffering from nasopharyngeal carcinoma (NPC). A better understanding of the mechanisms involved in the induction of radioresistance may provide strategies to improve NPC patients' response to therapy. The present study aimed to investigate the effect of microRNA (miR)-101 on the radioresistance of NPC cells. Analysis of miR-101 expression levels indicated that miR-101 was downregulated in NPC cell lines. Furthermore, ectopic expression of miR-101 suppressed cell proliferation and enhanced radiosensitivity of NPC cells. Stathmin 1 (STMN1) was additionally verified as a direct functional target of miR-101, which was found to be involved in cell viability, radioresistance and radiation-induced autophagy of NPC cells. In conclusions, the results of the present study suggested that the identified miR-101/STMN1 pathway contributed to the elucidation of the mechanisms of radioresistance in human NPC and that it may represent a potential therapeutic target.

Polycomb group proteins--epigenetic repressors with emerging roles in melanocytes and melanoma

Melanocytes undergo rapid and significant changes in their gene expression programs at regular intervals during development and the hair follicle cycle. In melanoma, the gene expression pattern found in normal melanocytes is disrupted. These gene expression patterns are regulated in part by post-translational histone modifications catalyzed by Polycomb group (PcG) proteins, which play a major role in many developmental processes and are often altered in cancer. In this review, we discuss the role of the PcG proteins in stem cell and cancer biology, in general, as well as in melanocyte development and melanomagenesis. Highlights include the discussion of newly identified treatments that target the activity of PcG proteins as well as new developments in the understanding of the role that these proteins play in melanocyte biology.

MITF in melanoma: mechanisms behind its expression and activity

MITF (microphthalmia-associated transcription factor) represents a melanocytic lineage-specific transcription factor whose role is profoundly extended in malignant melanoma. Over the last few years, the function of MITF has been tightly connected to plasticity of melanoma cells. MITF participates in executing diverse melanoma phenotypes defined by distinct gene expression profiles. Mutation-dependent alterations in MITF expression and activity have been found in a relatively small subset of melanomas. MITF activity is rather modulated by its upstream activators and suppressors operating on transcriptional, post-transcriptional and post-translational levels. These regulatory mechanisms also include epigenetic and microenvironmental signals. Several transcription factors and signaling pathways involved in the regulation of MITF expression and/or activity such as the Wnt/β-catenin pathway are broadly utilized by various types of tumors, whereas others, e.g., BRAF^V600E/ERK1/2 are more specific for melanoma. Furthermore, the MITF activity can be affected by the availability of transcriptional co-partners that are often redirected by MITF from their own canonical signaling pathways. In this review, we discuss the complexity of a multilevel regulation of MITF expression and activity that underlies distinct context-related phenotypes of melanoma and might explain diverse responses of melanoma patients to currently used therapeutics.