Anticancer potential of an ethanol extract of Asiasari radix against HCT-116 human colon cancer cells in vitro.

Radix of Asiasarum heterotropoides var. mandshuricum F. Maekawa (A. radix) has been prescribed for treating pain, allergies and inflammatory disorders in traditional oriental medicine. However, only limited information on the anticancer effects of A. radix is currently available. The aim of this study was to determine the anticancer effect of the ethanol extract of A. radix (EEAR) on HCT-116 human colon cancer cells and to investigate its underlying mechanisms of action. EEAR significantly induced G2/M cell cycle arrest and apoptosis in HCT-116 cells. EEAR-induced apoptosis was observed in parallel with activation of caspases and an increased ratio of Bax (pro-apoptotic)/Bcl2 (anti-apoptotic). Western blot analyses revealed that EEAR elevated the expression of p53 and p21(Waf/Cip1) and decreased the expression of the regulator proteins of G2/M phase progression, such as cdc2 and cyclin B. The upregulation of p53 by EEAR was due to the increased levels of p53 mRNA without a similar increase in proteasome-mediated p53 degradation. EEAR-induced apoptosis in HCT-116 cells was dependent on p53 expression, as determined by siRNA-mediated p53 knockdown. Taken together, these results suggest that EEAR inhibits the growth of the HCT-116 cells through induction of G2/M cell cycle arrest and apoptosis, which are mediated by p53 expression.