406907

MIR124-1

BACKGROUND: Recent profile studies of microRNA (miRNA) expression have documented a deregulation of miRNA (miR-124) in hepatocellular carcinoma (HCC). OBJECTIVE: To determine the status of miR-124 expression and its underlying mechanisms in the pathogenesis of HCC. METHODS: The expression levels of miR-124 were first examined in HCC cell lines and tumour tissues by real-time PCR. The in vitro and in vivo functional effect of miR-124 was examined further. A luciferase reporter assay was conducted to confirm target associations. RESULTS: The expression levels of miR-124 were frequently reduced in HCC cells and tissues, and low-level expression of miR-124 was significantly associated with a more aggressive and/or poor prognostic phenotype of patients with HCC (p<0.05). In HCC cell lines, stable overexpression of miR-124 was sufficient to inhibit cell motility and invasion in vitro, and suppress intrahepatic and pulmonary metastasis in vivo. In addition, ectopic overexpression of miR-124 in HCC cells inhibited epithelial-mesenchymal cell transition, formation of stress fibres, filopodia and lamellipodia. Further studies showed that miR-124 could directly target the 3'-untranslated region (3'-UTR) of both ROCK2 and EZH2 mRNAs, and suppress their mRNA and protein expressions. These findings suggest that miR-124 plays a critical role in regulating cytoskeletal events and epithelial-mesenchymal cell transition and, ultimately, inhibits the invasive and/or metastatic potential of HCC, probably by its direct target on ROCK2 and EZH2 genes. These results provide functional and mechanistic links between the tumour suppressor miRNA-124 and the two oncogenes ROCK2 and EZH2 on the aggressive nature of HCC. CONCLUSION: These data highlight an important role for miR-124 in the regulation of invasion and metastasis in the molecular aetiology of HCC, and suggest a potential application of miR-124 in prognosis prediction and cancer treatment.

Transforming growth factor-alpha (TGF-alpha) is upregulated in advanced stages of prostate cancer and strongly correlated with metastasis. However, the effect of TGF-alpha on epithelial-mesenchymal transition (EMT) in prostate cancer and the underlying mechanisms remain unclear. Recently, microRNAs have emerged as new regulators of EMT. This study found that treatment of DU145 cells with TGF-alpha suppressed the expression of epithelial marker E-cadherin and increased the expression of mesenchymal marker Vimentin as well as changed the cell morphology from cobblestone shape to spindle shape. The level of miR-124 was downregulated by TGF-alpha in several different cancer cell lines. Enforced expression of miR-124 abolished TGF-alpha-induced EMT. Slug was proven to be a target of miR-124 and mediated the inhibitory effect of miR-124 on TGF-alpha-induced EMT. Furthermore, overexpression of miR-124 reduced the migratory and invasive capacity of TGF-alpha-treated DU145 cells. In conclusion, our findings suggest that miR-124 inhibits TGF-alpha-induced EMT in DU145 cells by targeting Slug. Thus, miR-124 may be a potential target for prostate cancer therapeutic intervention.

PURPOSE: MicroRNA-124 (miR-124) is thought to be involved in the epithelial-mesenchymal transition (EMT) of RPE. We investigated the regulation of TGF-beta1-induced EMT by miR-124 in human RPE cells (ARPE-19). METHODS: expression of miR-124 was evaluated after TGF-beta1 treatment by quantitative RT-PCR. Phenotypic alterations were analyzed by Western blot analysis and immunocytochemical staining. Target validation was performed by a luciferase reporter assay to identify the putative target of miR-124. RESULTS: The expression level of miR-124 was downregulated during the progression of EMT. Overexpression of miR-124 upregulated the levels of zonular occludens 1 and occludin, and downregulated those of fibronectin, alpha-smooth muscle actin, and vimentin. Furthermore, inhibition of endogenous miR-124 increased and decreased the levels of mesenchymal and epithelial factors, respectively. TargetScan predicted two well-conserved and two vertebrate-only conserved miR-124 target sequences in the 3' untranslated region (UTR) of the Ras homology Growth-related (RHOG) mRNA. Direct targeting of this 3' UTR by miR-124 was demonstrated using a luciferase assay. Silencing of RHOG using a specific siRNA had identical effects on EMT regulation. Overexpression of miR-124 repressed TGF-beta1-induced RPE cell-collagen gel lattice contraction by altering cell spreading/cell-to-cell adhesion. CONCLUSIONS: This study describes the regulation of EMT in RPE cells by TGF-beta1/miR-124/RHOG signaling and suggests that the supplement of miR-124 exogenously would be a valuable therapeutic approach for the prevention or treatment of proliferative vitreoretinopathy.

OBJECTIVES: Lung cancer remains the leading cause of cancer-related mortality worldwide. Recently, accumulating studies have evidenced that microRNAs (miRNAs) contribute to the carcinogenesis of lung cancer through acting as either oncogenes or tumor suppressors. The purpose of our study was to investigate the functional role of miR-124 in lung cancer. METHODS: The expression of miR-124 was assessed by real-time RT-PCR in non-small cell lung cancer (NSCLC) tissues in comparison to its adjacent normal tissues. After transfection with miR-124 Mimics or negative controls into A549 cells, migration and invasion assays, apoptosis, and cell viability were evaluated. Luciferase reporter assay and RT-PCR were performed to explore whether zinc finger e-box binding homeobox 1 (ZEB1) was a target of miR-124. Further, the effects of miR-124 Mimic on migration and invasion were assessed after overexpression of ZEB1. RESULTS: MiR-124 expression was significantly down-regulated in NSCLC tissues compared to the normal tissue. In in-vitro study, overexpression of miR-124 in A549 cells suppressed cell migration and invasion activity, decreased expression of vimentin, but increased expression of E-cadherin and induced apoptosis. Luciferase reporter assay ensured that ZEB1 was a direct target of miR-124 and was negatively regulated by miR-124. Overexpression of ZEB1 could reverse the effect of miR-124 Mimic on the migration and invasion of the cells. CONCLUSION: The results suggests that miR-124 inhibits lung cancer cell migration and invasion through suppressing epithelial-mesenchymal transition (EMT) and inducing apoptosis of the lung cancer cells.

MicroRNA-124 (miR-124) was reported to be attenuated in human cervical cancer (CC) specimens. However, its role in CC remains elusive. In the present study, quantitative real-time PCR (qRT-PCR) analysis demonstrated that miR-124 expression is significantly downregulated in human CC tissues and several CC cell lines. Transfection of miR-124 mimics in CC cell lines HeLa and SiHa markedly inhibits cell proliferative, migratory and invasive capacities, as well as the epithelial-mesenchymal transition (EMT) process in vitro. Further studies have identified astrocyte-elevated gene-1 (AEG-1) as a direct target gene of miR-124. miR-124 downregulated AEG-1 expression through interaction with its 3'-untranslated regions (3'-UTRs), and miR-124 expression was inversely correlated with AEG-1 levels in CC specimens. Moreover, exogenous overexpression of AEG-1 significantly rescued the miR-124-induced inhibition of cell proliferation, migration and invasion, as well as the EMT process in HeLa cells. In conclusion, these findings suggested that miR-124 was able to suppress cell proliferation, invasion and migration, as well as the EMT process in cervical carcinomas through directly targeting AEG-1. miR-124 and AEG-1 may be potential therapeutic targets for the treatment of cervical carcinoma.