DRUG RESISTANCE MECHANISMS IN CANCER CELLS

化疗在缓解症状方面是成功的，在某些情况下，还能治愈一些 各种形式的人类癌症。治疗失败的主要原因是 对这些药物耐药的癌细胞亚群过度生长 抗肿瘤药物。为了开发出更有效的方法 治疗人类癌症，这种药物的分子机制 必须勾勒出阻力。 烷化剂，如环磷酰胺和氮芥末 是一些最常用的抗肿瘤药物。癌细胞 对这些药物的治疗有抵抗力的人通常表现出减少 药物摄取水平、谷胱甘肽(GSH)水平和 谷胱甘肽-S-转移酶(GST)活性和DNA修复增加 活动。谷胱甘肽被认为在细胞内起作用 这些药物的失活也与癌细胞有关 对放射治疗和热疗的抵抗。 这项提案概述了一系列旨在直接评估 GSH和GSH介导的过程对整体药物的贡献 抗性机制。核磁共振的组合 光谱学、放射性示踪剂、高效液相色谱和质谱学技术将 用于探讨烷基化失活的机理 两株人乳腺癌细胞株MCF-7的药理作用。一行 对环磷酰胺和磷酰胺芥末治疗敏感， 有一条线对这些药物表现出五倍的耐药性。这个 将测量稳定的GSH水平和GSH周转率 在这些细胞系中。它的结构和形成速度 这些烷基化试剂的非活性代谢物将在细胞中被测定。 裂解物和整个细胞.. 最初，研究将在缓冲溶液中进行。这将是 接下来是对细胞裂解物、单层完整细胞的研究，最后， 完整的灌流细胞。这种统一的方法，从缓冲区开始 通过细胞裂解液并最终到达整个细胞，将提供一种 更好地了解耐药机制。 这些实验将主要为这些机制提供直接证据 对培养的人类癌细胞产生抗药性负责。有了这个 知识，可以设计新的治疗方案，这将增加 化疗的有效性。

Chemotherapy is successful in alleviating and, in some cases, curing some forms of human cancer. The major reason for treatment failure is the overgrowth of a subpopulation of cancer cells resistant to these antineoplastic agents. In order to develop more effective methods for treating human cancers, the molecular mechanisms responsible for this drug resistance must be delineated. The alkylating agents, such as cyclophosphamide and the nitrogen mustards are some of the most commonly used antineoplastic agents. Cancer cells which are resistant to treatment with these agents often show a decreased level of drug uptake, increased levels of glutathione (GSH) adn glutathione-S-transferase (GST) activity, and an increase in DNA repair activity. Glutathione is thought to play a role in the intracellular inactivation of the drugs and also has been implicated in cancer cell resistance to radiotherapy and hyperthermic therapy. This proposal outlines a series of studies designed to directly assess the contribution of GSH and GSH-mediated processes to the overall drug resistance mechanism. A combination of nuclear magnetic resonance spectroscopy, radiotracer, HPLC, and mass spectrometric techniques will be used to probe the mechanisms involved in the inactivation of alkylating agents in two lines of MCF-7 human mammary adenocarcinoma cells. One line is sensitive to treatment with cyclophosphamide and phosphoramide mustard, and one line displays a five-fold resistance to these agents. The steady-stater levels of GSH and the rate of GSH turnover will be measured in these cell lines. The structure and the rate of formation of the inactive metabolites of these alkylating agents will be determined in cell lysates and whole cells.. Initially, studies will be performed in buffer solution. This will be followed by studies in cell lysates, whole cells in monolayer, and finally, intact perfused cells. This unified approach, progressing from buffer solution through cell lysates and finally to whole cells, will provide a better understanding of the drug resistance mechanism. These experiments will provide direct evidence for the mechanisms primarily responsible for drug resistance in cultured human cancer cells. With this knowledge, new treatment protocols may be designed which will increase the effectiveness of chemotherapy.