GENETIC ANALYSIS OF THE MULTIDRUG RESISTANCE PHENOTYPE IN TUMOR CELLS

我们一直有兴趣确定的主要机制， 癌细胞对多种化疗药物同时耐药 剂. 一个主要的机制是表达一种能量依赖性的 外排泵，称为P-糖蛋白（P-gp），或多药 转运蛋白，在人类中由MDR 1基因编码。 的序列 MDR 1 cDNA导致转运蛋白作为泵的模型，具有12 跨膜结构域和2个ATP位点; 负责底物结合和ATP酶活性偶联的P-gp 基板运输是我们工作的主要目标。 模型系统 基于突变的P-GPS的稳定表达或瞬时表达 已经开发了用于测定这些突变对 药物结合、药物依赖性ATP酶、耐药性和药物 运输 表达载体的创建能够赋予 多药耐药和MDR 1表达的证明， 小鼠骨髓中的一种基因导致对抗癌药物的抗性 药物使基因治疗载体的发展成为可能， 癌症和其他遗传性疾病，其中P-gp作为显性 选择性标记;对这些载体的改进导致了 动物模型和最终的患者是另一个重要的目标， 我们的研究 我们也开始探索 肝癌顺铂选择性多药耐药 细胞和酿酒酵母。 顺铂耐 肝癌细胞通过一种机制积累减少量的顺铂 至少有两种酵母基因与 已经分离出顺铂耐药性。

We have been interested in defining the major mechanisms of simultaneous resistance of cancer cells to multiple chemotherapeutic agents. One major mechanism is expression of an energy-dependent efflux pump, termed P-glycoprotein (P-gp), or the multidrug transporter, encoded in humans by the MDR1 gene. The sequence of the MDR1 cDNA led to a model of the transporter as a pump with 12 transmembrane domains and 2 ATP sites; determination of the domains of P-gp responsible for substrate binding and coupling of ATPase activity to substrate transport are the major goals of our work. Model systems based on stable expression or transient expression of mutated P-gps have been developed to assay functional effects of these mutations on drug binding, drug-dependent ATPase, drug resistance and drug transport. The creation of expression vectors able to confer multidrug resistance and the demonstration that expression of the MDR1 gene in the bone marrow of mice leads to resistance to anti-cancer drugs have enabled the development of vectors for gene therapy of cancer and other genetic diseases in which P-gp serves as a dominant selectable marker; improvements on these vectors leading to trials in animal models and eventually in patients are another important goal of our research. We have also begun to explore the mechanism of multidrug resistance resulting from selection in cisplatin of hepatoma cells and the yeast Saccharomyces cerevisiae. Cisplatin-resistant hepatoma cells accumulate reduced amounts of cisplatin by a mechanism as yet to be determined, and at least two yeast genes associated with cisplatin resistance have been isolated.