Doxorubicin generates a proapoptotic phenotype by phosphorylation of elongation factor 2
Doxorubicin generates a proapoptotic phenotype by phosphorylation of elongation factor 2
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DOI：
10.1016/j.freeradbiomed.2007.06.015
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发表时间：
2007-11-01
影响因子：
7.4
通讯作者：
Voelkel-Johnson, Christina
中科院分区：
文献类型：
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作者：
White, Shai J.;Kasman, Laura M.;Voelkel-Johnson, Christina
我们之前已经证明阿霉素可使前列腺癌细胞对肿瘤坏死因子相关凋亡诱导配体（TRAIL）敏感。致敏与抗凋亡细胞 FLICE 样抑制蛋白 (cFLIPs) 表达的降低相关。 cFLIP 的减少不能用转录调控或降解增加来解释，这使我们将注意力集中在翻译机制上。在这项研究中，我们发现阿霉素会引起延伸因子 2 (EF-2) 强烈且持续的磷酸化，从而干扰蛋白质延伸。 EF-2 的磷酸化似乎以不依赖于激酶的方式发生。用过氧化氢治疗概括了阿霉素治疗后观察到的事件。此外，用过氧化氢处理的细胞表达较少的X连锁凋亡抑制蛋白（XIAP）和生存素，它们与cFLIPs一样，都是具有抗凋亡功能的短半衰期蛋白，而DR5、caspases-8、-9、-3和Bax的表达水平得以维持。用铁螯合剂预处理可防止阿霉素介导的 cFLIPs 和 XIAP 减少以及 TRAIL 诱导的细胞凋亡，表明这些蛋白质的表达受到铁与阿霉素相互作用时自由基生成的影响。总之，我们的数据表明自由基可以影响 EF-2 的磷酸化，导致 eFLTP 和 XIAP 等短半衰期蛋白质的净损失，使细胞更容易受到凋亡刺激。由爱思唯尔公司出版
We have previously shown that doxorubicin sensitizes prostate cancer cells to tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL). Sensitization correlated with decreased expression of the antiapoptotic cellular FLICE-like inhibitor protein (cFLIPs). The decrease in cFLIPs could not be explained by transcriptional regulation or increased degradation, leading us to focus on translational mechanisms. In this study, we found that doxorubicin caused strong and sustained phosphorylation of elongation factor 2 (EF-2), which interferes with protein elongation. Phosphorylation of EF-2 appeared to occur in a kinase-independent manner. Treatment with hydrogen peroxide recapitulated the events observed after doxorubicin treatment. In addition, cells treated with hydrogen peroxide expressed less X-linked inhibitor of apoptosis protein (XIAP) and survivin which, like cFLIPs, are short-half-life proteins with an antiapoptotic function while expression levels of DR5, caspases-8, -9, -3, and Bax are maintained. The doxorubicin-mediated decrease in cFLIPs and XIAP and the TRAIL-induced apoptosis were prevented by pretreatment with an iron chelator, indicating that expression of these proteins was affected by free radical generation upon interaction of iron with doxorubicin. In conclusion, our data suggest that free radicals can affect the phosphorylation of EF-2 resulting in a net loss of short-half-life proteins such as eFLTPs and XIAP, leaving a cell more vulnerable to apoptotic stimuli. Published by Elsevier Inc.