Gα12 gep oncogene deregulation of p53-responsive microRNAs promotes epithelial–mesenchymal transition of hepatocellular carcinoma

Abstract

Hepatocellular carcinoma (HCC) has a poor prognosis owing to aggressive phenotype. Gα12 gep oncogene product couples to G-protein-coupled receptors, whose ligand levels are frequently increased in tumor microenvironments. Here, we report Gα12 overexpression in human HCC and the resultant induction of zinc-finger E-box-binding homeobox 1 (ZEB1) as mediated by microRNA deregulation. Gα12 expression was higher in HCC than surrounding non-tumorous tissue. Transfection of Huh7 cell with an activated mutant of Gα12 (Gα12QL) 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 Gα12 gene knockout. An integrative network of miRNAs and mRNA changes enabled us to predict ZEB1 as a key molecule governed by Gα12. Decreases of miR-200a/b, -192 and -215 by Gα12 caused ZEB1 induction. The ability of Gα12 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. Gα12QL 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 Gα12QL to increase tumor cell migration/invasion. In xenograft studies, sustained knockdown of Gα12 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 Gα12 level, a correlation existed in the comparison of relative changes of Gα12 and ZEB1. In conclusion, Gα12 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 Gα12 upregulation in liver tumor progression, implicating Gα12 as an attractive therapeutic target.

Serum microRNA profiles as prognostic biomarkers for HBV-positive hepatocellular carcinoma

“…Decrease of both miR-192-5p and miR-29a-3p has been shown in HCC cells in several studies [8, 38–40], but two other studies have identified these same miRNAs as HCC diagnostic markers increased in the circulation of HCC patients [19, 41]. Our studies are in agreement with the literature on diagnostic circulating miRNA panels which indicate that miR-192-5p and miR-29a-3p have considerable clinical credibility for HCC diagnosis.…”

Gα12 ablation exacerbates liver steatosis and obesity by suppressing USP22/SIRT1-regulated mitochondrial respiration

“…Moreover, Gna12 KO lowered basal or fasting-inducible SIRT1 expression in skeletal muscle and brown adipose tissue; although the fasting effect on SIRT1 in white adipose tissue seemed to be relatively mild, the inhibitory effect of Gna12 KO on SIRT1 was also observed in this tissue (Supplemental Figure 2). To further evaluate the regulatory role of Gα 12 in lipid metabolism, WT mice were hydrodynamically injected with a plasmid (50 μg) encoding shRNA-Gα 12 (sh-Gα 12 ) or shRNA-nontargeting control luciferase (sh-Luci) via the tail vein for knockdown of Gα 12 in the liver (10). As expected, mice injected with sh-Gα 12 plasmid exhibited diminished SIRT1 and CPT1 expression pared with individuals without steatosis.…”

“…Tae Hyun Kim, 1 Yoon Mee Yang, 1,2 Chang Yeob Han, 1,3 Ja Hyun Koo, 1 Hyunhee Oh, 4 Su Sung Kim,4 Byoung Hoon You, 5 Young Hee Choi, 5 Tae-Sik Park, 6 Chang Ho Lee, 7 Hitoshi Kurose, 8 Mazen Noureddin, 9 Ekihiro Seki, 2 Yu-Jui Yvonne Wan, 10 Cheol Soo Choi, 4,11 and Sang Geon Kim 1 Sirtuin 1 (SIRT1), a NAD + -dependent protein deacetylase, plays a role in the regulation of the transcriptional network in various metabolic processes, especially FA oxidation (14,15). However, the upstream regulator linking cell-surface signaling and SIRT1 is incompletely understood.…”

“…In particular, Gα 12 has drawn considerable interest in the field of cancer biology due to its triggering effect on cell growth and oncogenic transformation (7,8). Moreover, Gα 12 was overexpressed in highly proliferating cancer cells (8)(9)(10)(11). Interestingly, a considerable portion of endogenous Gα 12 , but not other Gα subunits, is physically associated with mitochondria (12), raising the possibility that Gα 12 is associated with mitochondrial function (e.g., mitochondrial energy metabolism) more directly than other Gα proteins.…”

TP53/MicroRNA Interplay in Hepatocellular Carcinoma

“…Indeed, high E-cadherin and low vimentin expression levels are indicative markers of an epithelial phenotype. A further article by Yang and coworkers contributed to shed light on p53-activated miRNAs contributing to the aggressive mesenchymal phenotype of HCC [30]. Briefly, an overexpression of the oncogenic G protein Gα12 was detected in HCC patients with the resultant induction of ZEB1.…”