Functional Interactions of Cu-ATPase ATP7B with Cisplatin and the Role of ATP7B in the Resistance of Cells to the Drug
Functional Interactions of Cu-ATPase ATP7B with Cisplatin and the Role of ATP7B in the Resistance of Cells to the Drug
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DOI：
10.1074/jbc.m805145200
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发表时间：
2009-03-20
影响因子：
4.8
通讯作者：
Huster, Dominik
中科院分区：
文献类型：
--
作者：
Leonhardt, Karoline;Gebhardt, Rolf;Huster, Dominik
顺铂是一种广泛用于治疗卵巢癌、睾丸癌、肺癌和胃癌的化疗药物。对该药物的初始反应强烈；然而，肿瘤细胞通常会对顺铂产生耐药性，这使治疗变得复杂。最近，卵巢细胞中铜 - ATP酶ATP7B的过度表达与细胞对顺铂的耐药性增加有关；并且有人提出铜 - ATP酶在顺铂从细胞排出过程中的作用。我们的研究结果支持顺铂和ATP7B之间存在功能性相互作用，但不认为通过铜转运途径的主动运输是耐药的机制。在肝细胞中，我们观察到内源性ATP7B的水平与细胞对顺铂的耐药性之间没有相关性。与铜不同，顺铂不会诱导肝癌细胞中ATP7B的转运，在运输试验中它也不会与铜竞争。然而，顺铂与ATP7B结合并刺激催化磷酸化，其半数有效浓度（EC50）与铜相似。ATP7B的前五个N末端铜结合位点的突变不会抑制顺铂诱导的ATP7B磷酸化。相反，前四个铜结合位点的缺失消除了顺铂对ATP7B活性的影响。因此，顺铂与ATP7B的结合和/或细胞内铜稳态的总体变化可能是对该药物耐药性增加的原因。通过用铜螯合剂处理Huh7细胞并增加其对顺铂的耐药性，证实了铜稳态变化与顺铂耐药性之间的联系。
Cisplatin is a widely used chemotherapeutic agent for treatment of ovarian, testicular, lung, and stomach cancers. The initial response to the drug is robust; however, tumor cells commonly develop resistance to cisplatin, which complicates treatment. Recently, overexpression of the Cu-ATPase ATP7B in ovary cells was linked to the increased cellular resistance to cisplatin; and the role for Cu-ATPases in the export of cisplatin from cells was proposed. Our results support functional interactions between cisplatin and ATP7B but argue against the active transport through the copper translocation pathway as a mechanism of drug resistance. In hepatocytes, we observed no correlation between the levels of endogenous ATP7B and the resistance of cells to cisplatin. Unlike copper, cisplatin does not induce trafficking of ATP7B in hepatoma cells, neither does it compete with copper in a transport assay. However, cisplatin binds to ATP7B and stimulates catalytic phosphorylation with EC50 similar to that of copper. Mutations of the first five N-terminal copper-binding sites of ATP7B do not inhibit the cisplatin-induced phosphorylation of ATP7B. In contrast, the deletion of the first four copper-binding sites abolishes the effect of cisplatin on the ATP7B activity. Thus, cisplatin binding to ATP7B and/or general changes in cellular copper homeostasis are likely contributors to the increased resistance to the drug. The link between changes in copper homeostasis and cisplatin resistance was confirmed by treating the Huh7 cells with copper chelator and increasing their resistance to cisplatin.