MicroRNA-101 suppresses liver fibrosis by downregulating PI3K/Akt/mTOR signaling pathway.

BACKGROUND:MicroRNA-101 (miR-101) is markedly downregulated in both hepatitis B virus-related liver cirrhosis and hepatocellular carcinoma (HCC). In this study, we aimed to investigate the effect and mechanism of miR-101 on hepatic stellate cell (HSC) activation and liver fibrosis. MATERIALS AND METHODS:HSC LX-2 was treated with TGF-β1 and with or without miR-101 mimics. LX-2 vitality and proliferation, the expression of F-actin and mRNAs for α-SMA, collagen 1α1 (Col 1α1), and connective tissue growth factor 2 (CCN2) were measured. A 6-week intraperitoneal injection of carbon tetrachloride (CCl4) was used to induce experimental liver fibrosis in mice, which were treated using a miR-101 negative control or miR-101 agomir from the fourth week until the end of the experiment. Liver function, hepatic hydroxyproline, liver histopathology, collagen deposition, α-SMA, type I collagen (Col I) and the protein-expressions of p-PI3K, p-Akt and p-mTOR were measured. RESULTS:MiR-101 significantly suppressed the increased LX-2 vitality and high accumulation of extracellular matrix (ECM) induced by TGF-β1. Exposure to CCl4 led to the impairment of liver function and disruption of normal hepatic parenchyma in mice, as well as obvious liver fibrosis indicated by elevated levels of hydroxyproline, α-SMA, and Col 1α1 in liver tissues. MiR-101 administration significantly improved liver function, relieved hepatic parenchyma damage, and reversed liver fibrosis by decreasing the accumulation of ECM components. Furthermore, miR-101 substantially downregulated the CCl4-increased p-PI3K, p-Akt, and p-mTOR in mouse liver. CONCLUSIONS:MiR-101 has antifibrotic effects in experimental liver fibrosis, and downregulating the PI3K/Akt/mTOR signaling pathway may be one of its antifibrotic mechanisms.