Induction of caspase-3-dependent apoptosis in human leukemia HL-60 cells by δ-elemene.

d-Elemene, an antitumor component, is a chemical compound isolated from Curcuma wenyujin ,aC hinese tradi- tional herb. We examined whether d-elemene could inhibit cell growth and cell cycle progression and induce apoptosis in human leukemia HL-60 cells. The results demonstrated that d-elemene induces signicant apoptosis of HL-60 cells, as shown by MTT assay, annexin V (AnV) binding of externalized phosphatidylserine (PS), and the mitochondrial probe JC-1 using ‰ow cytometry. HL-60 cells treated with d-elemene showed high percentages in the early apoptotic and late apoptoctic/necrotic stages, as well as caspase-3 activation of HL-60 cells. By monitoring the changes in cell cycle pro- ˆles, we conrmed that d-elemene could interfere with the cell cycle in the G2/M phase and induce apoptosis in HL-60 cells in a time-dependent manner. Caspase-3 plays a direct role in proteolytic cleavage of the cellular proteins responsible for progression to apoptosis. Therefore we examined apoptosis in HL-60 cells after exposure to d-elemene and measured caspase-3 activities with or without Z-Val-Ala-Asp-‰uoromethylketone (z-VAD-fmk, a broad-spectrum caspase inhibi- tor) pretreatment using ‰ow cytometric analysis. The results showed that d-elemene could induce caspase-3 activation as detected by the decrease in d-elemene-induced caspase-3 activities after treatment with z-VAD-fmk. In the present study, d-elemene activated typical caspase-dependent apoptosis in HL-60 cells, as demonstrated by an inhibitory eSect of z- VAD-fmk on this cell death. Duringd-elemene-induced apoptosis, cytochrome c and apoptosis-inducing factor were released into the cytosol and BAX was translocated from the cytosol to mitochondria. However, these were not prevent- ed by z-VAD-fmk. In conclusion, our study demonstrated that d-elemene could induce G2/M cell cycle transition and trigger apoptosis through a caspase-3-dependent pathway. Key words―apoptosis; HL-60 cell; cell cycle; caspase-3; cyt c; Curcuma wenyujin