406928

MIR137

Carboxyl-terminal binding protein 1 (CtBP1) is a transcriptional co-repressor that represses expression of various tumor suppressor genes. In the present study, we identified miR-137 as a potential regulator of CtBP1 expression in melanoma cells. expression of miR-137 in melanoma cell lines was found to inversely correlate with CtBP1 levels. Target Scan predicted a putative site for miR-137 within the CtBP1 3' untranslated region (3'UTR) at nt 710-716, which is highly conserved across species. To explore the mechanism of miR-137 targeting CtBP1, we performed an Argonaute 2 (Ago2)-pull down assay, and miR-137 was identified in complex with CtBP1 mRNA. miR-137 suppressed CtBP1 3' UTR luciferase-reporter activity, and this effect was lost with deletion of the putative 3' UTR target-site. Consistent with the results of the reporter assay, ectopic expression of miR-137 reduced expression levels of CtBP1. Furthermore, expression of miR-137 increased the immediate downstream effectors of CtBP1, such as E-cadherin and Bax. The human miR-137 gene is located at chromosome 1p22, which has previously been determined to be a susceptive region for melanoma. This study suggests miR-137 may act as a tumor suppressor by directly targeting CtBP1 to inhibit epithelial-mesenchymal transition (EMT) and inducing apoptosis of melanoma cells, thus illustrating a functional link between miR-137 and CtBP1 in melanoma development.

BACKGROUND: In ovarian cancer (OC) cells, Snail was reported to induce the epithelial-to-mesenchymal transition (EMT), which is a critical step in OC metastasis. At present little is known about controlling Snail expression in OC cells by using specific microRNAs (miRNAs). METHODS: We first used a computational target prediction analysis to identify 6 candidate miRNAs that bind to the 3'-untranslated region (3'-UTR) region of the Snail mRNA. Among these miRNAs, two miRNAs (miR-137 and miR-34a) with a potential to regulate Snail were validated by quantitative real-time PCR, Western blot analysis, and Snail 3'-UTR reporter assays. We assessed the effects of miR-137 and miR-34a on EMT, invasion and sphere formation in OC cells. We also evaluated the expression of miR-137 and miR-34a in OC tissues and adjacent normal tissues and analyzed the relationship between their expression and patient survival. RESULTS: We report that OC tissues possess significantly decreased levels of miR-137 and miR-34a and increased expression of Snail when compared to their adjacent normal tissues, and lower miR-137 and miR-34a expression correlates with worse patient survival. Using luciferase constructs containing the 3'-UTR region of Snail mRNA combined with miRNA overexpression and mutagenesis, we identified miR-137 and miR-34a as direct suppressors of Snail in OC cells. The introduction of miR-137 and miR-34a resulted in the suppression of Snail at both the transcript and protein levels, and effectively suppressed the EMT phenotype and sphere formation of OC cells. However, the inhibition of miR-137 and miR-34a with antisense oligonucleotides promoted EMT and OC cell invasion. Moreover, ectopic expression of Snail significantly reversed the inhibitory effects of miR-137 and miR-34a on OC cell invasion and sphere formation. CONCLUSIONS: These findings suggest that both miR-137 and miR-34a act as Snail suppressors to negatively regulate EMT, invasive and sphere-forming properties of OC cells.

BACKGROUND: Noncoding RNAs (ncRNAs), primarily microRNAs and long ncRNAs, play important roles in lung cancer. However, the role of long ncRNA (lncRNA)-X-inactive specific transcript (XIST) in non-small-cell lung cancer (NSCLC) is unclear. The purpose of this study was to explore the biologic function and potential mechanism of XIST in NSCLC progression. MATERIALS AND METHODS: XIST, miR-137, and Notch-1 expression were detected by quantitative real-time PCR (qRT-PCR). Levels of proliferation- and epithelial-mesenchymal transition (EMT)-related proteins were assessed by Western blot. The correlations between XIST and miR-137, as well as miR-137 and Notch-1, were evaluated by bioinformatic analysis and luciferase reporter assays. RESULTS: We confirmed that XIST is aberrantly upregulated in NSCLC tissues and cell lines. XIST depletion inhibited cell proliferation and TGF-beta1-induced EMT in A549 and H1299 cells. Spearman's correlation analysis showed an inverse correlation between miR-137 and XIST in NSCLC tissues, and miR-137 levels were found to be aberrantly reduced in A549 and H1299 cells. Furthermore, XIST could act as an endogenous sponge by directly binding to miR-137, negatively regulating its expression. miR-137 overexpression inhibited proliferation and TGF-beta1-induced EMT in A549 and H1299 cells, whereas XIST could reverse the inhibitory effect of miR-137 on proliferation and TGF-beta1-induced EMT. In addition, Notch-1 was identified as a direct target gene of miR-137, with the XIST-miR-137 axis regulating activation of the Notch-1 pathway. CONCLUSION: We identified a branch of the XIST/miR-137/Notch-1 pathway that regulates proliferation and TGF-beta1-induced EMT in NSCLC, which could be involved in NSCLC progression.

BACKGROUND Data on the expression of RCC tissues from the GEO database and patient survival data from TCGA were used to explore the prognostic significance of long noncoding RNA SNHG1. SNHG1 has been reported to participate in the development of several cancers, but, the underlying mechanism of SNHG1 in renal cell carcinoma (RCC) has not been reported. The purpose of our study was to investigate the potential function of SNHG1 in RCC. MATERIAL AND METHODS The expression of SNHG1 in 40 cases of RCC and adjacent normal tissues and 5 cell lines was detected by qRT-PCR. Cell proliferation, Transwell assay, and Western blotting assay were carried out to investigate the biological function of SNHG1. A rescue experiment was performed to verify that miR-137 can partly impede the effect of SNHG1 on renal cancer cells. RESULTS SNHG1 was identified to be overexpressed in RCC tissues and RCC cell lines. High levels of SNHG1 were correlated with poor prognosis of RCC patients. Knockdown of SNHG1 suppressed the proliferation, invasion, and EMT capacity in RCC. Moreover, miR-137 abrogated the effect of SNHG1 on RCC. CONCLUSIONS SNHG1 is significantly upregulated in RCC and renal cancer cell lines. Overexpression of SNHG1 participates in RCC tumorigenesis by regulating miR-137.