Diallyl Disulfide Induces Apoptosis in Human Leukemia Hl-60 Cells Through Activation of Jnk Mediated by Reactive Oxygen

Diallyl disulfide (DADS) is a chemopreventive agent that can induce apoptosis in many tumor cells. Reactive oxygen species (ROS) are important mediators in apoptosis induced by various stimuli, including chemopreventive agents. The phosphotransferase c-JUN N-terminal kinase (JNK) has been shown to regulate apoptosis. In this study, we found that DADS-induced apoptosis in human leukemia HL-60 cells is mediated by ROS-activated JNK. The DADS-treated HL-60 cells showed a dose- and time-dependent decrease in cell viability and proliferation. Agarose gel electrophoresis of cells treated with 10.0 or 20.0 mg/L DADS for 24 h showed a characteristic ladder pattern in their DNA. Levels of DADS-induced ROS, as measured by 2',7'-dichlorofluorescein diacetate (DCFH-DA) fluorescence, also showed dose- and time-dependent increases in HL-60 cells. Activity of JNK was induced by DADS in a dose-dependent manner; HL-60 cells exposed to 10.0 mg/L DADS for 8 h showed maximum levels of phosphorylated JNK, which decreased when exposed for additional 4 h. In contrast, Sp600125, a specific inhibitor of JNK, blocked apoptosis of HL-60 cells exposed to DADS. N-Acetylcysteine (NAC), a known antioxidant, also decreased ROS generation, effectively blocked apoptosis, and decreased DADS-induced phosphorylated JNK levels. These results suggest that JNK is involved in DADS-induced ROS-mediated apoptosis in HL-60 cells.