MicroRNA deregulation in nonalcoholic steatohepatitis-associated liver carcinogenesis

Hepatocellular carcinoma (HCC) is the fastest-rising cause of cancer-related death in the United States. Recent epidemiological studies have identified nonalcoholic steatohepatitis (NASH), a progressive form of nonalcoholic fatty liver disease (NAFLD), as a major risk factor for HCC. Elucidating the underlying mechanisms associated with the development of NASH-derived HCC is critical for identifying early biomarkers for the progression of the disease and for treatment and prevention. In the present study, using liver samples from C57BL/6J mice submitted to the Stelic Animal Model (STAM) of NASH-associated liver carcinogenesis, we investigated the role of microRNA (miRNA) alterations in the pathogenesis of NASH-derived HCC. We found substantial alterations in the expression of miRNAs, with the greatest number occurring in full-fledged HCC. Mechanistically, altered miRNA expression was associated with activation of major hepatocarcinogenesis-related pathways, including the TGF-β, Wnt/β-catenin, ERK1/2, mTOR, and EGF signaling. In addition, the over-expression of the miR-221-3p and miR-222-3p and oncogenic miR-106b∼25 cluster was accompanied by the reduced protein levels of their targets, including E2F transcription factor 1 (E2F1), phosphatase and tensin homolog (PTEN), and cyclin-dependent kinase inhibitor 1 (CDKN1A). Importantly, miR-93-5p, miR-221-3p, and miR-222-3p were also significantly over-expressed in human HCC. These findings suggest that aberrant expression of miRNAs may have mechanistic significance in NASH-associated liver carcinogenesis and may serve as an indicator for the development of NASH-derived HCC.