miR-192-5p Silencing by Genetic Aberrations Is a Key Event in Hepatocellular Carcinomas with Cancer Stem Cell Features

Abstract

Various cancer stem cell (CSC) biomarkers have been identified for hepatocellular carcinoma (HCC), but little is known about the implications of heterogeneity and shared molecular networks within the CSC population. Through miRNA profile analysis in an HCC cohort (n = 241) for five groups of CSC⁺ HCC tissues, i.e., EpCAM⁺, CD90⁺, CD133⁺, CD44⁺, and CD24⁺ HCC, we identified a 14-miRNA signature commonly altered among these five groups of CSC⁺ HCC. miR-192-5p, the top-ranked CSC miRNA, was liver-abundant and -specific and markedly downregulated in all five groups of CSC⁺ HCC from two independent cohorts (n = 613). Suppressing miR-192-5p in HCC cells significantly increased multiple CSC populations and CSC-related features through targeting PABPC4. Both TP53 mutation and hypermethylation of the mir-192 promoter impeded transcriptional activation of miR-192-5p in HCC cell lines and primary CSC⁺ HCC. This study reveals the circuit from hypermethylation of the mir-192 promoter through the increase in PABPC4 as a shared genetic regulatory pathway in various groups of primary CSC⁺ HCC. This circuit may be the driver that steers liver cells toward hepatic CSC cells, leading to hepatic carcinogenesis. SIGNIFICANCE: miR-192-5p and its regulatory pathway is significantly abolished in multiple groups of HCC expressing high levels of CSC markers, which may represent a key event for hepatic carcinogenesis.