The putative tumour suppressor microRNA-124 modulates hepatocellular carcinoma cell aggressiveness by repressing ROCK2 and EZH2

作者：Zheng F; Liao Y J; Cai M Y; Liu Y H; Liu T H; Chen S P; Bian X W; Guan X Y; Lin M C; Zeng Y X; Kung H F; Xie D^*

来源：Gut, 2012, 61(2): 278-289.

DOI：10.1136/gut.2011.239145

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 epithelialemesenchymal 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 epithelialemesenchymal 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.