Cisplatin resistance mediated by cooper export pathways

描述(由申请人提供)：铜(铜)出口商ATP7A和ATP7B通过改变细胞内的隔离和外排来调节肿瘤细胞对含铂药物的敏感性的能力现已在多个实验系统中得到证实。该项目的总体目标是确定ATP7A和ATP7B介导顺铂、卡铂和奥沙利铂从卵巢癌细胞外流的机制。我们的假设是，在临床上相关的浓度，铂药物进入细胞，分配到不同的亚细胞间隔，并通过已进化到控制铜稳态的转运体和伴侣蛋白从细胞输出。这一假说的推论是，对于铜，这些PI-型ATPase的功能是通过将铂类药物隔离到最终从细胞输出的分泌途径的小泡中来解毒。其具体目的是：1)确定ATP7A和ATP7B是否与顺铂、卡铂和奥沙利铂结合并运输到分泌囊泡中；2)研究铂药物与ATP7A、ATP7B和ATOX1蛋白金属结合序列中的铜结合基序的结合能力；以及3)确定铜伴侣ATOX1是否对ATP7A和ATP7B介导活细胞中铂耐药、隔离和输出的能力是必需的。仔细剖析铜外排转运体调节铂类药物出口的机制，有望深入了解为什么顺铂、卡铂和奥沙利铂的疗效和毒性不同，并确定提高这些药物的治疗指数的策略。这些研究还将进一步阐明介导对这类重要化疗药物的耐药性的机制，并提出临床上相关的逆转耐药性的策略。

DESCRIPTION (provided by applicant): The ability of the copper (Cu) exporters ATP7A and ATP7B to regulate tumor cell sensitivity to the platinum-containing drugs by altering their intracellular sequestration and efflux has now been demonstrated in multiple experimental systems. The overall goal of this project is to determine the mechanism by which ATP7A and ATP7B mediate the efflux of cisplatin, carboplatin and oxaliplatin from ovarian carcinoma cells. Our hypothesis is that at clinically relevant concentrations, the platinum drugs enter the cell, are distributed to various subcellular compartments and are exported from the cell using transporters and chaperones that have evolved to control Cu homeostasis. A corollary to this hypothesis is that, as for Cu, these PI-type ATPases function to detoxify the Pt drugs by sequestering them into or onto vesicles of the secretory pathway that are eventually exported from the cell. The specific aims are to: 1) determine whether ATP7A and ATP7B bind and transport cisplatin, carboplatin and oxaliplatin into secretory vesicles; 2) investigate the ability of the Pt drugs to bind to the Cu-binding motif in the metal binding sequences of ATP7A, ATP7B and ATOX1 proteins; and, 3) determine whether the Cu chaperone ATOX1 is essential to the ability of ATP7A and ATP7B to mediate Pt drug resistance, sequestration, and export in living cells. Careful dissection of the mechanism by which the Cu efflux transporters modulate the export of the Pt drugs is expected to offer insight into why cisplatin, carboplatin and oxaliplatin differ in their efficacy and toxicity, and to identify strategies for improving the therapeutic index of these agents. These studies will also further elucidate the mechanisms that mediate resistance to this important class of chemotherapeutic agents and suggest clinically relevant strategies for reversing resistance.