GENETIC ANALYSIS OF THE MULTIPLE DRUG RESISTANCE PHENOTYPE IN TUMOR CELLS

在人类癌症的化疗过程中， 对多种药物的耐药性经常出现。 我们一直在研究 这种多药耐药（MDR）的遗传和生化基础 人肿瘤细胞与化疗剂的反应。 一个模型系统使用 已经开发了培养的KB细胞，一种人癌细胞系，其中 独立选择的突变细胞对高水平 还发现秋水仙碱、阿霉素或长春碱 对秋水仙碱，阿霉素，长春新碱，长春碱， 嘌呤霉素和放线菌素D。 MDR的表达与肿瘤的发生、发展有关。 存在由mdr1基因编码的4.5kb mRNA， 从其被扩增的高度MDR细胞系中克隆。 一个完整 获得了mdr1基因产物的cDNA编码序列。 转移 从MDR人类细胞到药物敏感小鼠细胞的DNA的转移导致 完整MDR表型的表达，并与转移和 人mdr1基因的表达。 人类mdrl基因定位于染色体 7. MDR细胞系中的耐药性是由增加的 药物从耐药细胞的能量依赖性流出，并与 增加细胞表面上170，000道尔顿糖蛋白的表达。 MDR细胞的膜囊泡与长春碱的结合量增加 它含有一种170，000道尔顿的蛋白质， 可以用长春碱的光亲和类似物标记。 该标签 被维拉帕米阻断，维拉帕米已被证明可以逆转MDR表型 在培养的细胞中。 目前的工作假设是，17万人 道尔顿长春碱结合蛋白是MDR1基因的产物， 作为外排泵机制的一部分赋予耐药性。

During the course of chemotherapy of human cancers, variants which are resistant to multiple drugs frequently arise. We have been investigating the genetic and biochemical basis for this multidrug resistance (MDR) of human tumor cells to chemotherapeutic agents. A model system using the cultured KB cell, a human carcinoma cell line, has been developed in which mutant cells selected independently for resistance to high levels of either colchicine, adriamycin or vinblastine have also been found to be cross-resistant to colchicine, adriamycin, vincristine, vinblastine, puromycin and actinomycin-D. Expression of MDR correlates with the presence of a 4.5 kb mRNA encoded by the mdrl gene which was identified and cloned from highly MDR cell lines in which it is amplified. A complete cDNA coding sequence for the mdrl gene product has been obtained. Transfer of DNA from MDR human cells to drug-sensitive mouse cells results in expression of the complete MDR phenotype and is linked to transfer and expression of the human mdrl gene. The human mdrl gene maps to chromosome 7. Drug-resistance in MDR cell lines results from increased energy-dependent efflux of drugs from resistant cells and correlates with increased expression of a 170,000 dalton glycoprotein on the cell surface. Membrane vesicles from MDR cells bind increased amounts of vinblastine compared to drug-sensitive cells and contain a 170,000 dalton protein which can be labeled with a photoaffinity analog of vinblastine. This labeling is blocked by verapamil, which has been shown to reverse the MDR phenotype in cultured cells. The current working hypothesis is that the 170,000 dalton vinblastine binding protein is the product of the mdrl gene which confers drug-resistance as part of an efflux pump mechanism.