miR-133b Regulation of Connective Tissue Growth Factor: A Novel Mechanism in Liver Pathology

miRNAs are involved in liver regeneration, and their expression is dysregulated in hepatocellular carcinoma (HCC). Connective tissue growth factor (CTGF), a direct target of miR-133b, is crucial in the ductular reaction (DR)/oval cell (OC) response for generating new hepatocyte lineages during liver injury in the context of hepatotoxin-inhibited hepatocyte proliferation. Herein, we investigate whether miR-133b regulation of CTGF influences HCC cell proliferation and migration, and DR/OC response. We analyzed miR-133b expression and found it to be down-regulated in HCC patient samples and induced in the rat DR/OC activation model of 2-acetylaminofluorene with partial hepatectomy. Furthermore, overexpression of miR-133b via adenoviral system in vitro led to decreased CTGF expression and reduced proliferation and Transwell migration of both HepG2 HCC cells and WBF-344 rat OCs. In vivo, overexpression of miR-133b in DR/OC activation models of 2-acetylaminofluorene with partial hepatectomy in rats, and 3,5-diethoxycarbonyl-1,4-dihydrocollidine in mice, led to down-regulation of CTGF expression and OC proliferation. Collectively, these results show that miR-133b regulation of CTGF is a novel mechanism critical for the proliferation and migration of HCC cells and OC response.