GLUTATHIONE/GLUTATHIONE S TRANSFERASE MEDIATED MECHANISMS OF DRUG RESISTANCE

尽管对化疗的初步反应令人印象深刻，但大多数 病人最终对他们的疾病有所缓和，主要是因为 获得对化疗药物的耐药性， 治疗失败。在过去的十年里，越来越多的注意力已经被 着重于确定谷胱甘肽（GSH）和GSH依赖性 解毒系统，特别是GSH-S-转移酶（GST）的作用， 谷胱甘肽过氧化物酶（GSH-PX）、γ-谷氨酰半胱氨酸合成酶（γ-GTP） 以及GSH连接-GSH缀合物外排泵在抗肿瘤药物耐药性中的作用 烷基化剂GSH与DNA竞争药物的能力 约束力GST介导的GSH与各种烷化剂的缀合 确立了习我们对顺铂耐药的 在耐药骨髓瘤细胞系中GSH含量的低水平表明 在抗性细胞中GSH含量明显较高。虽然 GST活性在野生型和抗性细胞中相同， 细胞系在K/m值和对 GST的抑制剂。这些研究表明， 在获得抗性的过程中，抗性细胞的GST可能发生改变 或者GST的多态性变体在我的耐药细胞中过度表达。 因此，我们建议研究的一级结构GST 野生型和抗性细胞通过经典化学表征 和基因测序方法，并比较它们的微结构， 异质性由于抗性细胞被认为相对维持 高水平的谷胱甘肽，我们还建议调查谷胱甘肽水平， GSH代谢酶活性及其mRNA水平。在 此外，GSH结合转运蛋白在输出中的作用 潜在的细胞毒性缀合物及其在耐药性中的意义 将被评估。预计拟议的研究将大大 有助于了解烷基化剂的作用机理 阻力，并为长期目标提供宝贵的信息， 开发策略以防止针对烷基化的耐药性 化疗期间的药物。

Despite impressive initial response to chemotherapy, the majority of the patients eventually relent to their disease primarily because of acquisition of resistance against the chemotherapeutic drugs which cause treatment failure. In the last decade, increasing attention has been focused on establishing the role of glutathione (GSH) and GSH-dependent detoxification system, particularly the role of GSH-S-transferase (GST), GSH-peroxidase (GSH-PX), gamma-glutamyl cysteine synthetase (gamma-GTP) and GSH-linked-GSH conjugate efflux pump in drug resistance against alkylating agents. An ability of GSH to compete with the DNA for drug binding. GST mediated conjugation of GSH with various alkylating agents has been established. Our preliminary studies with cisplatin resistant small levels of GSH content in the resistant myeloma cell line indicated distinctly higher levels of GSH content in the resistant cells. Although the GST activity is same in the wild type and resistant cells, the two cell lines show apparent differences in K/m values and sensitivities to inhibitors of the GST. These studies suggest that primary structures of GST of the resistant cells may be altered during acquisition of resistance or a polymorphic variant of a GST is over expressed in my resistant cells. We are, therefore proposing to investigate the primary structure GST of the wild type and resistant cells by classical chemical characterization and gene sequencing methods, and compare their structures of micro- heterogeneity. Since resistant cells are believed to maintain relatively high levels of GSH, we also proposes to investigate the GSH levels and activities of enzymes of GSH metabolism and their mRNA levels. In addition, the role of the GSH-conjugate transporter protein in the export of potentially cytotoxic conjugates and it significance in drug resistance will be evaluated. The proposed studies are expected to significantly contribute towards understanding the mechanism of alkylating agent resistance and provide invaluable information for the long term goals of developing strategies to prevent drug resistance against the alkylating agents during chemotherapy.