Diallyl disulfide induces reversible G2/M phase arrest on a p53-independent mechanism in human colon cancer HCT-116 cells.

Diallyl disulfide (DADS), a major organosulfur compound of garlic oil, is known to have an anticancer effect on human cancer cells. However, the exact mechanisms of this anticancer activity remain unclear. Here, we investigate the effects of DADS on cell cycle progression in human colon cancer HCT-116 cells by exploring the role played by regulatory molecules such as p53 and cyclin B1. Treatment of HCT-116 cells by DADS induced a marked growth inhibition with a slight reduction in viability and induced transient cell cycle arrest in the G2/M phase. Cyclin B1 is thought to play an important role in this process, as the DADS-induced G2/M phase arrest occurs with the increase of cyclin B1 expression. DADS also significantly induced the expression of p53, which contributes to cell cycle arrest in cancer cells, at a late time-point of 24 h. In addition, knockdown of p53 by siRNA did not affect cell cycle arrest, its reversibility, or the expression of cyclin B1 in the G2/M phase induced by DADS. Based on these results we conclude that, with the dynamic expression of cyclin B1, DADS induces reversible cell cycle arrest in the G2/M phase of HCT-116 cells through a p53-independent mechanism.