Structural Basis of Multidrug resistance in Cancer

描述（由申请人提供）：多药耐药是治疗癌症的主要障碍，因为癌细胞对多种不相关的治疗化合物产生耐药性。多药耐药的一个机制是ABC转运蛋白从癌细胞中主动挤出化疗药物。ABCG2是许多不相关化合物的混杂ABC转运体。突变形式的ABCG2在多种来源的多药耐药癌症中表达水平升高，包括成纤维细胞、乳腺癌、结肠癌、肺癌和卵巢癌。药物转运的机制尚不清楚，ABCG2的每个结构域的功能既没有测试也没有证实。此外，ABCG2没有三维结构。提出以下具体目标来纠正这种情况：1)表征全长ABCG2及其结构域。ABCG2的每个结构域的活性将通过测量细胞毒性、atp酶活性、药物结合和药物挤压的分析来测试。2)测定ABCG2胞质结构域的三维结构。x射线结构将揭示核苷酸与细胞质结构域的结合模式。3)确定全长ABCG2及其结构域的三维结构。对ABCG2的全长和活性结构域进行求解。结构和活性数据的相关性将阐明ABCG2及其同源转运体的药物转运机制，从而为开发针对多药耐药癌症的新型化疗方案提供新的策略。建议的具体目标1及2适用于第一阶段，而具体目标3适用于K01计划的第二阶段及以后。K01将为申请人提供受保护的时间，在她的导师的指导下，在Eppley研究所激励人心的教育环境中发展新技能并将现有技能应用于癌症研究。然后，她将准备好成功地竞争并获得一个独立的癌症研究终身职位。

DESCRIPTION (provided by applicant): Multidrug resistance is a major obstacle to curing cancer because cancer cells become resistant to diverse and unrelated therapeutic compounds. A mechanism for multidrug resistance is the active extrusion of chemotherapeutic drugs from cancer cells by ABC transporters. ABCG2 is a promiscuous ABC transporter of many unrelated compounds. Mutant forms of ABCG2 are expressed in elevated levels in multidrug resistant cancers of diverse origins including fibroblasts, breast, colon, lung, and ovaries. The mechanisms of drug transport remain unclear and the functions of each domain of ABCG2 are neither tested nor confirmed. Furthermore, there are no 3-dimensional structures of ABCG2. The following specific aims are proposed to rectify this situation: 1) To characterize full length ABCG2 and its domains. The activity of each domain of ABCG2 will be tested using assays that measure cytotoxicity, ATPase activity, drug binding and drug extrusion. 2) To determine 3-dimensional structures of ABCG2's cytosolic domain. X-ray structures will be solved that reveal the mode of binding of nucleotides to the cytosolic domain. 3) To determine 3-dimensional structures of full length ABCG2 and domains. Structures will be solved of full length and active domains of ABCG2. The correlation of structural and activity data will clarify the mechanism of drug transport by ABCG2 and homologous transporters, thus spearheading new strategies for the development of novel chemotherapies for multidrug resistant cancer. Specific aims 1 and 2 are proposed for Phase I, while specific aim 3 is proposed for Phase II of the K01 award and beyond. The K01 will afford the applicant protected time to develop new skills and to apply existing skills to cancer research, with the guidance of her mentors, at the stimulating educational environment of the Eppley Institute. She will then be ready to successfully compete for and obtain an independent tenure track position in cancer research.