miR-224 functions as an onco-miRNA in hepatocellular carcinoma cells by activating AKT signaling.

ABSTRACT

microRNAs (miRNAs) are a class of small non-coding RNAs that post-transcriptionally regulate gene expression. Increasing evidence has shown that the deregulation of miRNAs is linked to cancer. The overexpression of miR-224 has been reported in several human cancers. The aim of the present study was to investigate the function of miR-224 in the pathogenetic process of hepatocellular carcinoma (HCC), and the precise mechanism underlying its function. Both gain-of-function and loss-of function assays were conducted through transfection with miR-224 mimics and miR-224 inhibitors in the HepG2 liver carcinoma cell line. The data revealed that miR-224 exerts a significant role in promoting cell proliferation, migration and invasion. Western blot analysis showed that the phosphorylation levels of AKT positively correlated with endogenous levels of miR-224. In addition, results from a dual luciferase reporter assay showed that the expression of the serine/threonine-protein phosphatase 2A 65 kDa regulatory subunit A ß isoform (PPP2R1B) is inhibited by miR-224; thus, it appears that PPP2R1B is a candidate target of miR-224 in HCC. These data suggest that miR-224 plays a significant role in HCC, possibly through the activation of the AKT signaling pathway by targeting PPP2R1B.