Liu Jia-Jun, Guo Yun-Wei, Fang Zhi-Gang, Si Xiao-Ning, Wu Xiang-Yuan, Liu Pei-Qing, Lin Dong-Jun, Xiao Ruo-Zhi, Xu Yan, Wang Chun-Zhi, Li Xu-Dong, He Yi, Huang Ren-Wei
Department of Hematology, The Third Hospital of Sun Yat-sen University, Guangzhou, 510630, PR China.
Int J Mol Med. 2009 Nov;24(5):623-32. doi: 10.3892/ijmm_00000273.
In the present study we investigated the in vitro apoptosis inducing effects of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligand ciglitazone (CGZ) on acute promyelocytic leukemia (APL) NB4 cells and its mechanisms of action. The results revealed that CGZ (10-50 micromol/l) inhibited the growth of leukemia NB4 cells and caused apoptosis in a time- and dose-dependent manner. Apoptosis was observed clearly by flow cytometry (FCM) and DNA fragmentation analysis. After treatment by CGZ for 48 h, the percentage of disruption of mitochondrial membrane potential (Deltapsim) was increased in a dose-dependent manner. Western blotting demonstrated the cleavage of caspase-3 zymogen protein and a time-dependent cleavage of poly (ADP-ribose) polymerase (PARP). The results also demonstrated that PPAR-gamma expression was increased concomitantly when apoptosis occurred, and that CGZ-induced apoptosis was inhibited by the PPAR-gamma antagonist GW9662, suggesting a PPAR-gamma dependent signaling pathway in CZG-induced cell death. Moreover, CGZ treatment remarkably downregulated the expression of the X-linked inhibitor of apoptosis protein (XIAP), which was inhibited by GW9662. Of note, a small-molecule XIAP antagonist (1396-12) mimicked the effect of CGZ-induced apoptosis via activation of caspase-3, 7 and 9. The apoptosis-inducing effects by CGZ on fresh APL cells were also found to be remarkable by using FCM and Wright's staining observation. Taken together, our results suggest that downregulation of XIAP and activation of capase-3 play an important role in mediating the PPAR-gamma-dependent cell death induced by CGZ in APL cells. These data provide a novel insight into potential therapeutic strategies for treatment of leukemia.
在本研究中，我们调查了过氧化物酶体增殖物激活受体γ（PPAR-γ）配体吡格列酮（CGZ）对急性早幼粒细胞白血病（APL）NB4细胞的体外凋亡诱导作用及其作用机制。结果显示，CGZ（10 - 50微摩尔/升）以时间和剂量依赖性方式抑制白血病NB4细胞的生长并诱导凋亡。通过流式细胞术（FCM）和DNA片段化分析可清楚观察到凋亡现象。用CGZ处理48小时后，线粒体膜电位（Δψm）的破坏百分比呈剂量依赖性增加。蛋白质免疫印迹法显示半胱天冬酶-3原蛋白的裂解以及聚（ADP-核糖）聚合酶（PARP）的时间依赖性裂解。结果还表明，凋亡发生时PPAR-γ表达随之增加，并且CGZ诱导的凋亡被PPAR-γ拮抗剂GW9662抑制，提示在CZG诱导的细胞死亡中存在PPAR-γ依赖性信号通路。此外，CGZ处理显著下调凋亡蛋白X连锁抑制剂（XIAP）的表达，而GW9662可抑制这种下调。值得注意的是，一种小分子XIAP拮抗剂（1396 - 12）通过激活半胱天冬酶-3、7和9模拟了CGZ诱导凋亡的作用。通过FCM和瑞氏染色观察还发现，CGZ对新鲜APL细胞的凋亡诱导作用也很显著。综上所述，我们的结果表明，XIAP的下调和半胱天冬酶-3的激活在介导CGZ诱导的APL细胞中PPAR-γ依赖性细胞死亡中起重要作用。这些数据为白血病的潜在治疗策略提供了新的见解。
