Anti-cancer effects of 20(S)-protopanoxadiol on human acute lymphoblastic leukemia cell lines Reh and RS4;11

Although the treatment outcome of acute lymphoblastic leukemia (ALL) has been improved in the past decades by combination chemotherapy, toxic side-effects of chemotherapeutics remain a major problem. Therefore, new alternative agents with low toxicity are urgently needed. Natural products provide a rich source of screening potential anti-cancer drugs. 20(S)-protopanoxadiol (PPD), a major gastrointestinal metabolic product of ginsenosides, exhibits promising anti-cancer activity with low toxicity. However, the anti-cancer activity of PPD against ALL has not been evaluated. In this study, we examined the anti-cancer effect of PPD on ALL cell lines Reh and RS4;11. The growth of leukemia cells and normal cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The cell cycle, apoptosis and differentiation was determined by flow cytometry. The results showed that PPD inhibited the growth of Reh and RS4;11 cells, but had little toxicity to peripheral blood mononuclear cells (PBMC). PPD also blocked cell cycle progression from G0/G1 phase and induced cell differentiation. However, cell apoptosis was not affected. These data indicate that PPD exerts anti-cancer effects by stimulating differentiation and inhibiting growth and cell cycle progression of ALL cells.