The anti-hepatic fibrosis effects of dihydrotanshinone I are mediated by disrupting the yes-associated protein and transcriptional enhancer factor D2 complex and stimulating autophagy

Background and Purpose: Dihydrotanshinone I (DHI), a lipophilic component of traditional Chinese medicine Salvia miltiorrhiza Bunge, has various therapeutic effects. We investigated the anti-fibrotic effect of DHI and its underlying mechanisms in vitro and in vivo. Experimental Approach: Rats subjected to bile duct ligation (BDL) were treated with DHI (25 mg·kg⁻¹·day⁻¹, i.p.) for 14 days. Serum biochemical and liver tissue morphological analyses were performed. The human hepatic stellate cell line LX-2 served as a liver fibrosis model in vitro. Liver fibrogenic genes, yes-associated protein (YAP) downstream genes and autophagy markers were examined using western blot and real-time PCR analyses. Similar analyses were done in rat primary hepatic stellate cells (pHSCs). Autophagy flux was assessed by immunofluorescence. Key Results: In BDL rats, DHI administration attenuated liver necrosis, bile duct proliferation and collagen accumulation and reduced the expression of genes associated with fibrogenesis, including Tgfb1, Mmp-2, Acta2 and Col1a1. DHI (1, 5, 10 μmol·L⁻¹) time- and dose-dependently suppressed the protein level of COL1A1, TGFβ1 and α-SMA in LX-2 cells and rat pHSCs. Furthermore, DHI blocked the nuclear translocation of YAP, which inhibited the YAP/TEAD2 interaction and its downstream fibrogenic genes, connective tissue growth factor, SOX4 and survivin. This stimulated autophagic flux and accelerated the degradation of liver collagen. Conclusions and Implications: DHI exerts anti-fibrotic effects in BDL rats, LX-2 cells and rat pHSCs by inhibiting the YAP and TEAD2 complex and stimulating autophagy. These findings indicate that DHI may be a potential therapeutic for the treatment of liver fibrosis.