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.
- Hepatocellular carcinoma
- epithelial-mesenchymal transition
- cancer genetics
- cell biology
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Funding This study was supported by grants made under the 973 project of China (Nos 2010CB529400 and 2010CB912802) and the 863 project of China (No 2007AA021901), and by a grant from the Guangzhou Science and Technology Bureau Foundation (No 2005Z1-E0131).
Competing interests None.
Ethics approval This study was conducted with the approval of the institute research ethics committee of the Cancer Center, Sun Yat-Sen University.
Provenance and peer review Not commissioned; externally peer reviewed.