Liquiritigenin suppresses the activation of hepatic stellate cells via targeting miR-181b/PTEN axis

Liquiritigenin (LQ), an aglycone of liquiritin in licorice, has demonstrated antioxidant, anti-inflammatory and anti-tumor activities. Previously, LQ was found to inhibit liver fibrosis progression.Phosphatase and tensin homolog (PTEN) has been reported to act as a negative regulator of hepatic stellate cell (HSC) activation. However, the roles of PTEN in the effects of LQ on liver fibrosis have not been identified to date.The effects of LQ on liver fibrosis in carbon tetrachloride (CCl4) mice as well as primary HSCs were examined. Moreover, the roles of PTEN and microRNA-181b (miR-181b) in the effects of LQ on liver fibrosis were examined.LQ markedly ameliorated CCl4-induced liver fibrosis, with a reduction in collagen deposition as well as α-SMA level. Moreover, LQ induced an increase in PTEN and effectively inhibited HSC activation including cell proliferation, α-SMA and collagen expression, which was similar with curcumin (a positive control). Notably, loss of PTEN blocked down the effects of LQ on HSC activation. PTEN was confirmed as a target of miR-181b and miR-181b-mediated PTEN was involved in the effects of LQ on liver fibrosis. LQ led to a significant reduction in miR-181b expression. LQ-inhibited HSC activation could be restored by over-expression of miR-181b. Further studies demonstrated that LQ down-regulated miR-181b level via Sp1. Collectively, we demonstrate that LQ inhibits liver fibrosis, at least in part, via regulation of miR-181b and PTEN.LQ down-regulates miR-181b level, leading to the restoration of PTEN expression, which contributes to the suppression of HSC activation. LQ may be a potential candidate drug against liver fibrosis.