DRUG RESISTANCE MECHANISMS IN CANCER CELLS

化疗是成功的缓解，并在某些情况下，治愈一些 人类癌症的形式。 治疗失败的主要原因是 癌细胞亚群的过度生长， 间谍。 为了开发更有效的方法， 治疗人类癌症的分子机制 阻力必须加以界定。 烷化剂，如环磷酰胺和氮芥 是一些最常用的杀虫剂。 癌细胞 对这些药物治疗有抵抗力的患者通常表现出降低的 药物摄取水平，谷胱甘肽（GSH）水平升高， 谷胱甘肽-S-转移酶（GST）活性和DNA修复的增加 活动 谷氨酸被认为在细胞内 药物的失活，也与癌细胞 对放射治疗和热疗有抵抗力。 该提案概述了一系列旨在直接评估 GSH和GSH介导的过程对总体药物的贡献 抗性机制 结合核磁共振 光谱学、放射性示踪剂、HPLC和质谱技术将被 用于探测参与烷基化失活的机制， 在两个MCF-7人乳腺癌细胞系中的药物。 一行 对环磷酰胺和磷酰胺芥治疗敏感， 其中一个品系对这些药剂表现出五倍的抗性。 的 将测量稳定的GSH水平和GSH周转率 在这些细胞系中。 的结构和形成速率， 这些烷化剂的无活性代谢物将在细胞中测定， 裂解物和全细胞。 最初，将在缓冲液中进行研究。这将是 随后在细胞裂解物、单层全细胞中进行研究，最后， 完整的灌注细胞。 这种统一的方法，从缓冲区 通过细胞裂解物并最终到全细胞的溶液，将提供 更好地了解耐药机制。 这些实验将为主要机制提供直接证据 负责培养的人类癌细胞的耐药性。 与此 知识，新的治疗方案可以设计，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.