G[α.sub.12] gep oncogene deregulation of p53-responsive microRNAs promotes epithelial-mesenchymal transition of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has a poor prognosis owing to aggressive phenotype. G[α.sub.12] gep oncogene product couples to G-protein-coupled receptors, whose ligand levels are frequently increased in tumor microenvironments. Here, we report G[α.sub.12] overexpression in human HCC and the resultant induction of zinc-finger E-box-binding homeobox 1 (ZEB1) as mediated by microRNA deregulation. G[α.sub.12] expression was higher in HCC than surrounding non-tumorous tissue. Transfection of Huh7 cell with an activated mutant of G[α.sub.12] (G[α.sub.12]QL) deregulated microRNA (miRNA or miR)-200b/a/429, -194-2/192 and -194-1/215 clusters in the miRNome. cDNA microarray analyses disclosed the targets affected by G[α.sub.12] gene knockout. An integrative network of miRNAs and mRNA changes enabled us to predict ZEB1 as a key molecule governed by G[α.sub.12]. Decreases of miR-200a/b, -192 and -215 by G[α.sub.12] caused ZEB1 induction. The ability of G[α.sub.12] to decrease p53 levels, as a result of activating protein-1 (AP-1)/c-Jun-mediated mouse double minute 2 homolog induction, contributed to transcriptional deregulation of the miRNAs. G[α.sub.12]QL induced ZEB1 and other epithelial-mesenchymal transition markers with fibroblastoid phenotype change. Consistently, transfection with miR-200b, -192 or -215 mimic prevented the ability of G[α.sub.12]QL to increase tumor cell migration/invasion. In xenograft studies, sustained knockdown of G[α.sub.12] decreased the overall growth rate and average volume of tumors derived from SK-Hep1 cell (mesenchymal-typed). In HCC patients, miR-192, -215 and/or -200a were deregulated with microvascular invasion or growth advantage. In the HCC samples with higher G[α.sub.12] level, a correlation existed in the comparison of relative changes of G[α.sub.12] and ZEB1. In conclusion, G[α.sub.12] overexpressed in HCC causes ZEB1 induction by deregulating p53-responsive miRNAs, which may facilitate epithelial-mesenchymal transition and growth of liver tumor. These findings highlight the significance of G[α.sub.12] upregulation in liver tumor progression, implicating G[α.sub.12] as an attractive therapeutic target. Oncogene (2015) 34, 2910-2921; doi:10.1038/onc.2014.218; published online 28 July 2014