Downregulation of miR-20b-5p Contributes to the Progression of Liver Fibrosis via the STAT3 Signaling Pathway In Vivo and In Vitro.

Background: Activated hepatic stellate cells (HSCs) are primarily involved in liver fibrosis and portal hypertension (PHT). We aimed to investigate the effect of miR-20b-5p on HSCs, liver fibrosis, and PHT.

Methods: MiR-20b-5p expression in HSCs and in mouse liver fibrosis was determined by qPCR. Further, the effects of miR-20b-5p mimic on HSCs migration, proliferation, and apoptosis were investigated in vitro. A dual-luciferase reporter assay was performed to confirm the direct interaction between miR-20b-5p and STAT3. In vivo, mouse liver fibrosis was established by common bile duct ligation and intervened by agomiR-20b-5p. Sirius red staining and hydroxyproline content were used to evaluate collagen deposition. The α-SMA expression in the liver was detected by IHC and Western blotting. The STAT3 signaling pathway and its downregulated cytokines as well as portal pressure and angiogenesis were explored.

Results: MiR-20b-5p was significantly downregulated during HSCs activation and in mouse liver fibrosis. The functional analyses demonstrated that miR-20b-5p inhibited cell proliferation, activation, and promoted apoptosis in HSCs in vitro. Moreover, miR-20b-5p regulated STAT3 expression by binding to the 3'UTR of its miRNA directly. Overexpression of miR-20b-5p facilitated HSC activation and proliferation by inhibiting the STAT3 signaling pathway. MiR-20b-5p overexpression suppressed the STAT3 and its downstream cytokines and ameliorated liver fibrosis in mice. The intra- and inter-hepatic angiogenesis were also effectively inhibited. The inhibition of liver fibrosis and neoangiogenesis contributed to the decrease of portal pressure.

Conclusions: MiR-20b-5p plays an important role in the fibrosis and angiogenesis of liver fibrosis by targeting the STAT3 signaling pathway.