Institute of Biomedical Sciences, National Sun Yat-Sen University-Kaohsiung Medical University Joint Research Center, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
Toxicon. 2010 Jun 15;55(7):1306-16. doi: 10.1016/j.toxicon.2010.01.024. Epub 2010 Feb 6.
CMS-9, a phospholipase A(2) (PLA(2)) isolated from Naja nigricollis venom, induced apoptosis of human leukemia K562 cells, characterized by mitochondrial depolarization, modulation of Bcl-2 family members, cytochrome c release and activation of caspases 9 and 3. Moreover, an increase in intracellular Ca2+ concentration and the production of reactive oxygen species (ROS) was noted. Pretreatment with BAPTA-AM (Ca2+ chelator) and N-acetylcysteine (NAC, ROS scavenger) proved that Ca2+ was an upstream event in inducing ROS generation. Upon exposure to CMS-9, activation of p38 MAPK and JNK was observed in K562 cells. BAPTA-AM or NAC abrogated CMS-9-elicited p38 MAPK and JNK activation, and rescued viability of CMS-9-treated K562 cells. SB202190 (p38 MAPK inhibitor) and SP600125 (JNK inhibitor) suppressed CMS-9-induced dissipation of mitochondrial membrane potential, Bcl-2 down-regulation, Bax up-regulation and increased mitochondrial translocation of Bax. Inactivation of PLA(2) activity reduced drastically the cytotoxicity of CMS-9, and a combination of lysophosphatidylcholine and stearic acid mimicked the cytotoxic effects of CMS-9. Taken together, our data suggest that CMS-9-induced apoptosis of K562 cells is catalytic activity-dependent and is mediated through mitochondria-mediated death pathway triggered by Ca2+/ROS-evoked p38 MAPK and JNK activation.
CMS-9 是从竹叶青蛇蛇毒中分离得到的一种磷脂酶 A(2)（PLA(2)），可诱导人白血病 K562 细胞凋亡，其特征为线粒体去极化、Bcl-2 家族成员的调节、细胞色素 c 释放和半胱天冬酶 9 和 3 的激活。此外，还观察到细胞内 Ca2+浓度的增加和活性氧物质（ROS）的产生。用 BAPTA-AM（Ca2+螯合剂）和 N-乙酰半胱氨酸（NAC，ROS 清除剂）预处理证明 Ca2+是诱导 ROS 产生的上游事件。在 K562 细胞中，暴露于 CMS-9 后观察到 p38 MAPK 和 JNK 的激活。BAPTA-AM 或 NAC 消除了 CMS-9 诱导的 p38 MAPK 和 JNK 激活，并挽救了 CMS-9 处理的 K562 细胞的活力。SB202190（p38 MAPK 抑制剂）和 SP600125（JNK 抑制剂）抑制了 CMS-9 诱导的线粒体膜电位耗散、Bcl-2 下调、Bax 上调以及 Bax 的线粒体易位增加。PLA(2)活性的失活大大降低了 CMS-9 的细胞毒性，而溶血磷脂酰胆碱和硬脂酸的组合模拟了 CMS-9 的细胞毒性作用。总之，我们的数据表明，CMS-9 诱导的 K562 细胞凋亡是依赖于催化活性的，并且是通过 Ca2+/ROS 触发的 p38 MAPK 和 JNK 激活引发的线粒体介导的死亡途径介导的。
