GENETIC ANALYSIS OF THE MULTIPLE DRUG RESISTANCE PHENOTYPE IN TUMOR CELLS

在人类癌症的化疗过程中，变异是 对多种药物的耐药性频繁出现。我们一直在调查 霍乱多药耐药(MDR)的遗传和生化基础 人类肿瘤细胞对化疗药物的敏感性。模型系统使用 培养的KB细胞是一种人类癌细胞系，在该细胞系中 独立选择的突变细胞对高水平的 秋水仙素、阿霉素或长春花碱也被发现是 对秋水仙碱、阿霉素、长春新碱、长春花碱、 嘌呤霉素和放线菌素-D多药耐药基因的表达与卵巢癌 存在由mdrl基因编码的4.5kb的mrna，经鉴定和 从扩增它的高度耐多药的细胞系中克隆。一个完整的 获得了mdr1基因产物的cDNA编码序列。转账 将多药耐药人细胞的DNA转移到对药物敏感的小鼠细胞 表达完整的多药耐药表型，并与转移和 人mdrl基因的表达。人类mdrl基因定位于染色体 7.多药耐药细胞系耐药性增加 药物从耐药细胞中的能量依赖性外流及其与 细胞表面17万道尔顿糖蛋白表达增加。 多药耐药细胞膜上的囊泡结合更多的长春花碱 与药物敏感细胞相比，它含有17万道尔顿蛋白， 可以用长春花碱的光亲和类似物标记。这个标签 被维拉帕米阻断，维拉帕米被证明可以逆转MDR表型 在培养的细胞中。目前的工作假设是，17万人 道尔顿长春花碱结合蛋白是mdrl基因的产物，该基因 作为外排泵机制的一部分，赋予抗药性。

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.