Abstract: Objective To investigate the effect of PLAB-induced apoptosis in human melanoma cells. Methods Apoptotic cells were detected using Hoechst Hoechst 33342/PI staining, and confirmed by DNA fragmentation assay. The expression of genes involved in apoptosis was analysized by RT-PCR. The level of the protein was determined by ELISA kit. Results PLAB clearly induced apoptosis in SK-28 cells; Treatment with PLAB for 12h, the protein expression of p53 was obviously increased; for 24h, caspase-3 activity was enhanced, the protein expression of Fas/APO-1 was increased, and the mRNA expression of Bax was also elevated, but the mRNA expression of Bcl-2 was reduced. Conclusions These results suggest PLAB induced apoptosis in human melanoma cells via a mechanism involving both Bcl-2-associated mitochondrial pathway and Fas-associated death receptor signaling pathway, which are two distinct downstream pathways of p53.

Key words: Pseudolaric acid B, p53, Fas/APO–1, Bcl–2, caspase–3