Inhibition of glutathione synthesis overcomes Bcl-2-mediated topoisomerase inhibitor resistance and induces nonapoptotic cell death via mitochondrial-independent pathway.
Inhibition of glutathione synthesis overcomes Bcl-2-mediated topoisomerase inhibitor resistance and induces nonapoptotic cell death via mitochondrial-independent pathway.
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DOI：
10.1158/0008-5472.can-05-3916
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发表时间：
2006-06
期刊：
影响因子：
11.2
通讯作者：
A. Yoshida;H. Takemura;H. Inoue;T. Miyashita;T. Ueda
中科院分区：
文献类型：
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作者：
A. Yoshida;H. Takemura;H. Inoue;T. Miyashita;T. Ueda
Bcl-2蛋白在抑制抗癌药物诱导的细胞凋亡中起关键作用。我们发现，Bcl-2的过度表达与细胞谷胱甘肽水平增加近3倍，并与依托泊苷或SN-38，喜树碱的衍生物，在白血病697细胞与野生型p53治疗后，细胞死亡的抵抗力增加。用谷胱甘肽合成的抑制剂丁硫丙磺酰亚胺（BSO）处理Bcl-2过表达的697细胞（697-Bcl-2），降低细胞谷胱甘肽水平并完全消除Bcl-2介导的耐药性。形态学研究表明，非凋亡性细胞死亡诱导697-Bcl-2细胞与BSO加足叶乙甙或SN-38处理后。这些药物处理后，在697-Bcl-2细胞中未检测到caspase-3/7的激活和细胞色素c的释放。值得注意的是，我们发现蛋白酶体介导的Puma和Noxa蛋白的下调发生在697-Bcl-2细胞用BSO加拓扑异构酶抑制剂处理后，尽管在这些697-Bcl-2细胞中p53蛋白水平增加。相比之下，在存在或不存在BSO的情况下，用拓扑异构酶抑制剂处理后，亲代697细胞经历典型的细胞凋亡，Puma和Noxa蛋白上调，随后细胞色素c释放和caspase-3/7激活。我们的数据表明，BSO可能具有独特的活性，以克服Bcl-2介导的耐药性，通过刺激信号，可以绕过Bcl-2过表达细胞中的线粒体过程。
Bcl-2 protein plays a critical role in inhibiting anticancer drug-induced apoptosis. We found that Bcl-2 overexpression is associated with a nearly 3-fold increase in cellular glutathione levels and with increased resistance to cell death after treatment with etoposide or SN-38, a derivative of camptothecin, in leukemia 697 cells with wild-type p53. Treatment of Bcl-2-overexpressing 697 cells (697-Bcl-2) with buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, reduced cellular glutathione levels and completely abolished Bcl-2-mediated drug resistance. Morphologic studies revealed that nonapoptotic cell death was induced in 697-Bcl-2 cells after treatment with BSO plus etoposide or SN-38. Activation of caspase-3/7 and cytochrome c release could not be detected in 697-Bcl-2 cells after these drug treatments. Notably, we showed that proteasome-mediated down-regulation of Puma and Noxa proteins occurs in 697-Bcl-2 cells after treatment with BSO plus topoisomerase inhibitor, although there is an increase in the protein levels of p53 in these 697-Bcl-2 cells. In contrast, parental 697 cells underwent typical apoptosis with up-regulation of Puma and Noxa proteins, followed by cytochrome c release and caspase-3/7 activation after treatment with topoisomerase inhibitor in the presence or absence of BSO. Our data suggest that BSO may possess a unique activity to overcome Bcl-2-mediated drug resistance by stimulating the signals that can bypass mitochondrial process in Bcl-2-overexpressing cells.