GENETIC ANALYSIS OF MULTIDRUG RESISTANCE GENES

对化疗药物产生抗药性是一个主要限制因素 癌症治疗的成功。特别有问题的是 建立多药耐药(MDR)；由于过度表达 P糖蛋白/多药耐药基因。MDR基因编码一种蛋白质，该蛋白质是 膜结合运输分子超家族的成员。这一类人 蛋白质含有一对三磷酸腺苷(ATP)结合域 和一对疏水结构域。依赖三磷酸腺苷的泵超家族 包括许多原核透膜，酵母交配因子转运体， 囊性纤维化基因和人类白细胞抗原多肽转运体。MDR基因是 能够将多种疏水药物从细胞中排出，包括 秋水仙碱、长春花碱和长春新碱。我们设计了一套 将寡核苷酸简并到MDR基因的ATP结合区。 这些引物已用于聚合酶链式反应以扩增 果蝇、酿酒酵母和大肠杆菌的序列。 对这些产物进行了克隆和测序。每个唯一的克隆都包含一个 与MDR基因有同源性的开放阅读框，没有显示克隆 与任何以前表征的基因的同一性。每个克隆一个 物种已被用来分离基因组克隆。果蝇序列 定位于2号染色体50号带；与HSC-5基因相邻。酵母菌 序列映射到7号染色体。整个序列已经确定，并 它含有一个疏水结构域，与人MDR1有25%的氨基酸同源性 和一个与人MDR1 45%相同的ATP结合域。大肠埃希菌 该序列包含一对与人类38%-45%相同的ATP结合区 MDR1。基因实验正在进行中，试图确定这种功能 这些新的多药耐药相关基因。如果这些基因能够运输 药物，它们可能被证明是有用的模型，以更好地理解 MDR基因的功能，用于设计有效的化疗药物，以及 识别多药耐药蛋白的抑制剂。

The development of resistance to chemotherapy drugs is a major limitation in the success of cancer treatment. Particularly problematic is the establishment of multidrug resistance (MDR); due to overexpression of the P-glycoprotein/MDR genes. The MDR genes encode a protein that is a member of a superfamily of membrane-bound transport molecules. This class of proteins contains a pair of adenosine triphosphate (ATP)-binding domains and a pair of hydrophobic domains. The ATP-dependent pump superfamily includes many prokaryotic permeases, the yeast mating factor transporter, the cystic fibrosis gene, and the HLA peptide transporter. MDR genes are capable of pumping a variety of hydrophobic drugs out of cells, including colchicine, vinblastine, and vincristine. We have designed a set of degenerate oligonucleotides to the ATP-binding domain of the MDR genes. These primers have been used in polymerase chain reactions to amplify sequences from Drosophila, Saccharomyces cerevisiae, and Escherichia coli. These products were cloned and sequenced. Each unique clone contained an open reading frame that had homology to the MDR genes, and no clone showed identity to any previously characterized genes. One clone from each species has been used to isolate genomic clones. The Drosophila sequence was mapped to chromosome 2, band 50; adjacent to the Hsc-5 gene. The yeast sequence maps to chromosome 7. The entire sequence has been determined and it contains a hydrophobic domain with 25% amino acid identity to human MDR1 and an ATP-binding domain 45% identical to human MDR1. The E. coli sequence contains a pair of ATP-binding domains 38-45% identical to human MDR1. Genetic experiments are in progress to try to determine the function of these new MDR-related genes. If these genes are capable of transporting drugs, they could prove to be useful models for better understanding the function of MDR genes, for designing effective chemotherapy agents, and for identifying inhibitors of MDR proteins.