Structural Basis of Multidrug resistance in Cancer

描述（由申请人提供）：多药耐药性是治愈癌症的主要障碍，因为癌细胞对多种和不相关的治疗化合物产生耐药性。多药耐药的一种机制是ABC转运蛋白主动将化疗药物从癌细胞中挤出。ABCG 2是许多不相关化合物的混杂ABC转运蛋白。ABCG 2的突变形式在多种来源的多药耐药癌症中以升高的水平表达，所述多种来源的多药耐药癌症包括成纤维细胞、乳腺癌、结肠癌、肺癌和卵巢癌。药物转运的机制尚不清楚，ABCG 2的每个结构域的功能既没有测试也没有证实。此外，没有ABCG 2的三维结构。提出了以下具体目标来纠正这种情况：1）表征全长ABCG 2及其结构域。将使用测量细胞毒性、ATP酶活性、药物结合和药物挤出的测定来测试ABCG 2的每个结构域的活性。2)确定ABCG 2胞质结构域的三维结构。X射线结构将被解决，揭示了结合的方式的核苷酸的胞质结构域。3)确定全长ABCG 2和结构域的三维结构。将解析ABCG 2的全长和活性结构域的结构。结构和活性数据的相关性将阐明ABCG 2和同源转运蛋白的药物转运机制，从而为开发多药耐药癌症的新型化疗药物提供新的策略。具体目标1和2是为第一阶段提出的，而具体目标3是为K01奖的第二阶段及以后提出的。K01将为申请人提供受保护的时间来发展新技能，并在她的导师的指导下将现有技能应用于癌症研究，在Eppley研究所的刺激教育环境中。然后，她将准备成功竞争并获得癌症研究的独立终身职位。

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.