Compound Astragalus and Salvia miltiorrhiza extracts suppress hepatocarcinogenesis by modulating transforming growth factor-β/Smad signaling

Background and Aim Previous studies showed Compound Astragalus and Salvia miltiorrhiza extract (CASE), extract from Astragalus membranaceus and Salvia miltiorhiza, significantly suppresses hepatocellular carcinoma (HCC) in rats induced by diethylinitrosamine (DEN), and in vitro experiments further demonstrated that CASE's anti‐HepG2 cell invasion is associated with transforming growth factor‐β (TGF‐β). We hypothesized that CASE's suppression of HCC is modulated by TGF‐β/Smad signaling, and we conducted this in vivo study to test this hypothesis. Methods Rats were divided into the normal control, the DEN group, and three CASE (60, 120, and 240 mg/kg) treatment groups. The expression of phosphorylation(p) Smad both at C‐terminal and linker region, plasminogen activator inhibitor 1, and Smad4 and Smad7 of liver tissues were measured and compared across the five groups. Results The positive staining of pSmad2L and pSmad3L increased both in hepatoma nodule areas and adjacent relatively normal liver tissues in rats treated with DEN, while the positive staining of pSmad2C and pSmad3C increased only in relatively normal liver tissues adjacent to hepatoma tissues. The elevated expression of pSmad2C, pSmad2L, pSmad3L, Smad4, and plasminogen activator inhibitor 1 proteins were suppressed by CASE in a dose‐dependent manner. CASE treatment also significantly reduced the intranuclear amounts of pSmad2L and pSmad3L, and upregulated the elevation of pSmad3C positive cells and protein expression in a dose‐dependent manner. Conclusion The results suggest that CASE significantly suppresses HCC progression by mediating TGF‐β/Smad signaling, especially by modulating Smad3 phosphorylation both at the C‐terminal and linker region.