Background and aims: Compound Astragalus and Salvia miltiorrhiza extract (CASE) is made up of astragalosides, astragalus polysaccharide and salvianolic acids extracted from Astragalus membranaceus Bunge (Leguminosae) and Salvia miltiorhiza Bunge (Lamiaceae) with a standard ratio. Previous reports showed that CASE inhibited hepatic fibrosis by mediating transforming growth factor (TGF)-beta/Smad signaling. This study further investigated the effect of CASE on hepatoma HepG2 cells stimulated by TGF-beta(1) and its potential action mechanisms by TGF-beta/Smad signaling.
Methods: Cell proliferation was studied by MTT assay and cell invasion was evaluated by measuring cell migration through Matrigel. Protein expression in hepatoma HepG2 cells stimulated by TGF-beta(1) was analyzed by western blotting and plasminogen activator inhibitor type 1 (PAI-1) transcriptional activity in HepG2 cells was evaluated.
Results: CASE (40 microg/mL) markedly suppressed cell invasion triggered by TGF-beta(1). Smad3 phosphorylation at the linker region (pSmad3L) and Samd2 phosphorylation at the C-terminal region (pSmad2C) were significantly reduced by CASE. Mild elevated Smad3 phosphorylation at C-terminal (pSmade3C) region was enhanced by CASE at 20 microg/mL. In addition, treatment of CASE decreased the level of Smad2/3/4 complex at 80 microg/mL, but upregulated the expression of Smad7 in a dose-dependent manner. CASE also showed inhibitory effect on PAI-1 transcriptional activity.
Conclusion: All these results suggest that CASE exerts anti-HepG2 cell invasion effect by modulating TGF-beta/Smad signaling.