目的：研究二烯丙基二硫（diallyl disulfide ，DADS ）诱导人白血病K562细胞凋亡的分子机制。方法 Real-time PCR检测Rac2基因mRNA水平；Western blot检测Rac2、JNK、p38等蛋白的表达；基因沉默Rac2蛋白的表达；流式细胞术检测凋亡细胞百分率以及细胞内的活性氧（reactive oxygen species ，ROS）水平；琼脂糖凝胶电泳检测晚期凋亡。结果随着DADS质量浓度的增加，Rac2基因mRNA水平明显上调（P＜0．05）。与未干扰组相比，siRac2 RNA组凋亡率明显降低（P＜0．05）。Rac2 siR-NA干扰的DADS诱导的 K562细胞并未出现梯状条带。与未干扰组相比，siRac2 RNA组在5．0，10．0和15．0 mg · L-1 DADS作用于K562细胞8 h后，荧光强度显著降低（P＜0．05）。Western blot分析结果显示：与对照组相比，10．0和15．0 mg · L-1 DADS作用于K562细胞24 h后，蛋白 Rac2的表达水平明显上调（P＜0．05）；用 siRNA抑制Rac2蛋白的表达后，JNK1的表达显著降低，p38和磷酸化的p38的表达在Rac2干扰前后没有明显变化。结论 Rac2与DADS诱导K562细胞凋亡、活性氧的产生密切相关。活化的Rac2选择性地激活JN K信号通路而不是p38信号通路导致细胞凋亡。%Objective To research the molecular mechanism of diallyl disulfide (DADS )-induced apoptosis in human leukemia K562 cells .Methods mRNA levels of Rac2 were detected by real-time PCR ;Rac2 ,JNK and p38 levels were measured by Western blot .Treatment of K562 cells with siRNAs resulted in inhibition of Rac2 expression .Flow cytometry method was used to deter-mine the percentage of apoptosis cells and DNA agarose electrophoresis was used to determine the late stage of apoptosis .Levels of ROS were measured by 2′,7′-dichlorofluorescein diacetate (DCFH-DA) fluorescence .Results There was a significant up regu-lation of the mRNA level of Rac2 in K562 cells after the treatment with different concentration of DADS (P<0 .05) .Compared with the control group ,there was a significant up regulation of Rac2 protein in K562 cells treated with 5 .0 and 10 .0 mg · L -1 DADS for 24 h (P<0 .05) .Treatment of cells with DADS for 24 h markedly reduced the percentage of apoptotic cells after inhibi-tion of Rac2 with siRNA .SiRNA-treated groups showed normal bands on agarose gel electrophoresis .After suppression of Rac2 , ROS production was markedly reduced after DADS treatment (P<0 .05) .The expression of JNK1 in K562 cells decreased when Rac2 expression was inhibited with siRNA ,while there was no change in p38 and p-p38 .Conclusion These results indicate Rac2 have a critical role in DADS-induced apoptosis and ROS production in DADS-induced K562 cells .Rac2 selectively activated the JNK pathway ,not the p38 pathway in DADS-induced apoptosis in K562 cells .
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