| Objective To study the mechanism of Anti-hepatoma action of Compound Astragalus Extract(CAE). Methods The HepG2 cells were stimulated by TGF-Pi or serum and treated with CAE(5～80 mg·L-1), the proliferation of the cells were analyzed by MTT. The effect of CAE on expression level of pSmad2C and the effects of MAPK inhibitors on expression levels of pSmad2C, pSmad2L, pSmad3C, pSmad3L were investigated respectively by immunoprecipitation and/or Western blotting method in HepG2 cells induceded by TGF-β1. The effect of CAE on invasive capacity was determined by using transwells, stained by hematoxylin and counted the infiltrating cells in HepG2 cells induced by TGF-β1. Result 1. The proliferation of the cells was not remarkably stimulated by TGF-β1 (9 pM) or serum (12.5%) for 0.5 and 1h, but significantly for 2, 4, 8, 16, 24 h, and the elevated proliferation was inhibited by CAE(5～80 mg·L-1) treatment in a dose-dependent manner. 2. The invasive capacity was decreased by CAE(40 mg·L-1) treatment in HepG2 cells induced by TGF-β1 (200 pM·L-1,12 h). 3. The phosphorylations of Smad2C, Smad2L, Smad3C, and Smad3L were induced by 9 pM·L-1 TGF-β1 at 1 h in the HepG2 cells, and the phosphorylation of Smad2C was inhibited by CAE (20～80 mg·L-1) in a dose-dependent manner. 4. The phosphorylations of Smad2C and Smad3L in HepG2 cells induced by TGF-pi (9 pM·L-1, 1h) were inhibited by inhibitor for JNK (1, 3, 10μM·L-1) in a dose-dependent manner, the phosphorylation of Smad3C in HepG2 cells induced by TGF-β1 (9 pM·L-1, 1h) was slightly inhibited by inhibitor for JNK (1, 3, 10μM·L-1),but the phosphorylation of Smad2L in HepG2 cells induced by TGF-β1(9 pM·L-1, 1 h)was not affected by inhibitor for JNK (1,3, 10μM·L-1). The phosphorylations of Smad2C and Smad3L in HepG2 cells induced by TGF-pi (9 pM·L-1, 1 h) were inhibited by inhibitor for p38(l, 3, 10 μM·L-1) in a dose-dependent manner, the phosphorylation of Smad3C in HepG2 cells induced by TGF-β1 (9 pM·L-1, 1h) was slightly inhibited by inhibitor for p38(l, 3, 10μM·L-1), but the phosphorylationof Smad2L in HepG2 cells induced by TGF-β1 (9 pM·L-1, 1 h) was not affected by inhibitor for p38(l, 3,10μM·L-1). The phosphorylation of Smad2L in HepG2 cells induced by TGF-β1 (9 pM·L-1, 1h) was slightly inhibited by inhibitor for inhibitor for ERK (1, 3, 10 uM·L-1), but the phosphorylations of Smad2C, Smad3C, Smad3L were not affected by inhibitor for ERK (1, 3, 10μM·L-1). Conclusion 1. CAE could inhibit proliferation and invasive capacity of HepG2 cells; these suggest that CAE may inhibit growth and invasion of hepatoma cells. 2. CAE inhibit phosphorylation of Smad2C in HepG2 cells induced by TGF-β1 in a dose-dependent manner, these suggest that CAE may inhibit liver cancer pathogenesis through TGF-β/Smad signaling pathway. 3. Inhibitors for p38 and JNK could inhibit respectively phosphorylation of Smad2C and Smad3L in HepG2 cells induced by TGF-β1, these suggest that TGF-β1 might induce the phosphorylation of Smad2C/3L via activated JNK and p38 and then involve in liver cancer pathogenesis.
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