Cleavage of Bcl-2 in oxidant- and cisplatin-induced apoptosis of human melanoma cells
Cleavage of Bcl-2 in oxidant- and cisplatin-induced apoptosis of human melanoma cells
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DOI：
10.1038/sj.onc.1204618
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发表时间：
2001-07-27
期刊：
影响因子：
8
通讯作者：
Maellaro, E
中科院分区：
文献类型：
--
作者：
Del Bello, B;Valentini, MA;Maellaro, E
尽管Bcl-2的抗凋亡作用已得到充分证实，但Bcl-2在肿瘤对治疗的反应和耐药性中的作用仍不清楚。Bcl-2的翻译后修饰可能参与细胞凋亡途径的控制。在本研究中，我们已经调查了Bcl-2的作用，在细胞反应氧化应激（过氧化氢）和顺铂使用克隆的人转移性黑色素瘤，尽管Bcl-2（过）表达，表现出中度化疗敏感性。两种处理均导致黑色素瘤细胞通过凋亡过程死亡，与细胞从单层脱落相关。在由过氧化氢或顺铂产生的漂浮凋亡细胞中，沿着凋亡的形态学和生物化学特征，我们检测到显著的Bcl-2切割，产生23 kDa的Bcl-2样片段。用半胱天冬酶-3/-7抑制剂DEVD-CHO预孵育细胞完全抑制Bcl-2裂解，从而证实这种特异性蛋白水解需要激活半胱天冬酶-3/-7。在本研究中记录的氧化剂和顺铂诱导的Bcl-2的加工可能代表了一种调节机制，以规避Bcl-2的生存功能后，细胞凋亡触发和增强细胞凋亡反应。由于Bcl-2裂解应被视为促凋亡事件，因此预期Bcl-2表达增加对凋亡的敏感性。因此，这种途径可用于提高表达Bcl-2的黑色素瘤的细胞毒性疗法的功效。
Although the anti-apoptotic effect of Bcl-2 is well established, the role of Bcl-2 in tumour response to therapy and drug resistance is still unclear. The posttranslational modifications of Bcl-2 are likely involved in the control of the apoptotic pathway. In the present study we have investigated the role of Bcl-2 in cellular response to oxidative stress (hydrogen peroxide) and cisplatin using a clone of human metastatic melanoma, which, in spite of Bcl-2 (over)expression, exhibited a moderate chemosensitivity. With both treatments melanoma cells died through an apoptotic process, associated with detachment of cells from the monolayer. In the floating apoptotic cells generated by either hydrogen peroxide or cisplatin, along with morphological and biochemical features of apoptosis, we detected a significant Bcl-2 cleavage, yielding the Bax-like fragment of 23 kDa. Preincubation of cells with the caspase-3/-7 inhibitor DEVD-CHO completely suppressed Bcl-2 cleavage, thus confirming that such a specific proteolysis requires activation of caspase-3/-7. The oxidant- and cisplatin-induced processing of Bcl-2 documented in the present study may represent a regulatory mechanism to circumvent the survival function of Bcl-2 upon apoptosis triggering and to enhance apoptotic response. Since the Bcl-2 cleavage should be regarded as a pro-apoptotic event, Bcl-2 expression is expected to increase susceptibility to apoptosis. Thus, such a pathway could be exploited to improve the efficacy of cytotoxic therapy of melanomas expressing Bcl-2.