GENETIC ANALYSIS OF THE MULTIDRUG RESISTANCE PHENOTYPE IN TUMOR CELLS

我们一直有兴趣定义以下主要机制： 肿瘤细胞对多种化疗药物的同时耐药 探员们。一个主要的机制是表达一种能量依赖的 外排泵，称为P-糖蛋白(P-gp)，或多药 转运蛋白，在人类中由mdr1基因编码。按顺序排列的 Mdr1基因的cdna导致了一个具有12个转运体的模型 跨膜结构域和2个三磷酸腺苷位点.结构域的测定 负责底物结合和偶联ATPase活性的P-gp 到衬底的运输是我们工作的主要目标。模型系统 基于突变P-GPS的稳定表达或瞬时表达 已经开发出用来测试这些突变对细胞功能的影响 药物结合、药物依赖性ATPase、耐药性与药物 运输。表达载体的创建能够赋予 多药耐药与多药耐药基因的表达 小鼠骨髓中的基因导致抗癌耐药性 药物使基因治疗载体的发展成为可能 癌症和其他以P-gp为主的遗传性疾病 可选择的标记；对这些载体的改进导致在 动物模型和最终用于患者的另一个重要目标是 我们的研究。我们也开始探索这一机制。 肝癌顺铂多药耐药研究进展 细胞和酿酒酵母。对顺铂耐药 肝癌细胞通过一种机制积累减少的顺铂 尚未确定，至少有两个酵母基因与 已分离出对顺铂耐药的菌株。

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.