MicroRNA-92a contributes to tumor growth of human hepatocellular carcinoma by targeting FBXW7

Deregulation of microRNA-92a (miR-92a) has been reported in several human cancers and is associated with prognosis of patients. However, the clinical significance of miR-92a and the underlying mechanisms involved in hepatocarcinogenesis remain to be determined. The aim of the present study was to determine the role of miR-92a in hepatocellular carcinoma (HCC). The results showed that the expression of miR-92a was upregulated in HCC tissues as compared with matched tumor-adjacent tissues. A high expression of miR-92a was observed in HCC cell lines as compared with a non-transformed hepatic cell line. The gain- and loss-of-function studies revealed that miR-92a significantly promoted proliferation and cell cycle transition from G1 to S phase, and inhibited apoptosis of HCC cell in vitro. In tumor-bearing nude mice, the down-regulation of miR-92a suppressed tumor growth of HCC in vivo. miR-92a was inversely correlated with F-box and WD repeat domain-containing 7 (FBXW7) expression in HCC tissues. Furthermore, miR-92a negatively regulated FBXW7 abundance in HCC cells. In the present study, FBXW7 was identified as a direct target of miR-92a. Notably, alterations of FBXW7 expression abrogated the effects of miR-92a on HCC cell proliferation, cell cycle and apoptosis. Clinical association analysis revealed that a high expression of miR-92a was correlated with poor prognostic characteristics of HCC. Notably, the high expression of miR-92a conferred a reduced 5-year overall survival (OS) and recurrence-free survival (RFS) of HCC patients. The multivariate Cox regression analysis demonstrated that miR-92a expression was an independent prognostic marker for predicting survival of HCC patients. In conclusion, the results of the present study suggested that miR-92a promotes the tumor growth of HCC by targeting FBXW7 and may serve as a novel prognostic biomarker and therapeutic target for HCC.