[Asiaticoside inducing apoptosis of tumor cells and enhancing anti-tumor activity of vincristine].

OBJECTIVE

Asiaticoside (ATS), a triterpene extracted from Centella asiatica (L.) Urban, a traditional Chinese herb, possesses good wound healing activities because of its stimulative effect on collagen synthesis. Recently, the anti-tumor effect of asiaticiside has been reported. This study was to examine the induction of apoptosis in cancer cells, and the enhancement of vincristine (VCR) cytotoxicity by asiaticoside.

METHODS

MTT assay was used to evaluate inhibitory effect of asiaticoside combined with vincristine on proliferation of several cancer cell lines, including KB, KBv200, MCF-7, and MCF-7/ADM. Cell cycle, and apoptosis of KB cells were analyzed by flow cytometry; apoptosis induction was also proved by electrophoresis,and morphologic assessment; the expression of apoptosis-, and cell cycle-related proteins were determined by Western blot.

RESULTS

The IC(50) values of asiaticoside for KB, KBv200, MCF-7, and MCF-7/ADM cells detected by MTT assay were (1.11+/-0.13) mg/ml, (1.82+/-0.08) mg/ml, (1.58+/-0.15) mg/ml, and (3.25+/-0.46) mg/ml, respectively. Multidrug resistant KBv200, and MCF-7/ADM cancer cells displayed similar sensitivity to asiaticoside as their parental counterparts (KB, and MCF-7 cells). Moreover, asiaticoside induced apoptosis in KB cells. At sub-cytotoxicity concentration, asiaticoside showed synergistic effect with vincristine in these 4 cell lines. The apoptosis rates were much higher in asiaticoside plus vincristine groups than in vincristine or asiaticoside groups. Bcl-2 phosphorylation levels were higher in the combination groups than in vincristine or asiaticoside alone groups. The activated caspase-3 protein was only presented in the combination groups. Asiaticoside plus vincristine enhanced S-G(2)/M arrest, up-regulated Cyclin B1 protein expression, and down-regulated P34(cdc2) protein expression in KB cells.

CONCLUSIONS

Asiaticoside, as a biochemical modulator, may induce apoptosis,and enhance anti-tumor activity of vincristine in cancer cells, might be useful in cancer chemotherapy.