Diallyl trisulphide-induced apoptosis in human melanoma cells involves downregulation of Bcl-2 and Bcl-xL expression and activation of caspases.

BACKGROUND: Although diallyl trisulphide (DATS) has been found to induce apoptosis in various tumour cells, its cytotoxicity in melanoma cells has not yet been defined and the molecular pathway by which DATS induces apoptosis is not well understood.
OBJECTIVES: To determine growth inhibition of DATS in human melanoma cells (A375 and M14) by inducing apoptosis, and to investigate the mechanism underlying such effects.
METHODS: Growth inhibition by DATS was estimated by the tetrazolium assay. Apoptosis induction in DATS-treated cells was assessed by staining with 4',6-diamidino-2-phenylindole (DAPI) and double staining with annexin V and propidium iodide. Expression of Bcl-2, Bax, Bcl-xL/Bcl-xS, cytochrome c release, activation of caspase-9 and poly(ADP-ribose) polymerase (PARP) were determined by western blotting. The activity of caspase-3 was measured using a colorimetric assay.
RESULTS: DATS exerted its cytotoxic effect in a time-dependent and dose-dependent manner by inducing apoptosis in A375 and M14 cells. Expression of Bcl-2 and Bcl-xL was downregulated. Release of cytochrome c and activation of the downstream effectors caspase-3, caspase-9 and PARP were detected after DATS sensitization.
CONCLUSIONS: DATS inhibits growth of melanoma cells by inducing apoptosis in association with downregulation of Bcl-2 and Bcl-xL and activation of caspases.