Astragalus memebranaceus is used as immunomodulating agent in treating immunodeficiency diseases and to alleviate the adverse effects of chemotherapeutic drugs. In recent years, it has been proposed that Astragalus may possess anti-tumorigenic potential in certain
cancer cell types. In this study, the
anti-carcinogenic effects of Astragalus
saponin extract were investigated in HT-29 human
colon cancer cells and
tumor xenograft. Our findings have shown that Astragalus
saponins (AST) inhibit cell proliferation through accumulation in S phase and G2/M arrest, with concomitant suppression of p21 expression and inhibition of
cyclin-dependent kinase activity. Besides, AST promotes apoptosis in HT-29 cells through
caspase 3 activation and
poly(ADP-ribose) polymerase cleavage, which is indicated by DNA fragmentation and nuclear
chromatin condensation. Nevertheless, we also demonstrate the anti-tumorigenic effects of AST in vivo, of which the reduction of
tumor volume as well as pro-apoptotic and anti-proliferative effects in HT-29 nude mice xenograft are comparable with that produced by the conventional chemotherapeutic
drug 5-fluorouracil (5-FU). In addition, the side effects (
body weight drop and mortality) associated with the
drug combo
5-FU and
oxaliplatin are not induced by AST. These results indicate that AST could be an effective chemotherapeutic agent in
colon cancer treatment, which might also be used as an adjuvant in combination with other orthodox chemotherapeutic drugs to reduce the side effects of the latter compounds.