MOLECULAR MECHANISM OF ACTION OF DNA DAMAGING AGENTS

DNA 损伤剂的分子作用机制

• 批准号: 3774549
• 负责人: P M O'CONNOR
• 金额: --
• 依托单位: DIVISION OF CANCER TREATMENT
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3774549
• 关键词: DNA damage; DNA repair; DNA replication; alkylating agents; antineoplastics; cell cycle; drug design /synthesis /production; drug metabolism; enzyme activity; neoplasm /cancer chemotherapy; neoplasm /cancer pharmacology; phosphorylation; protein kinase; tissue /cell culture

This research project focusses on cell cycle control as a major determinant of chemosensitivity. We aim to utilize cell cycle control as a basis for the development of new chemotherapeutic stratagems to selectively kill tumor cells. Research is oriented towards the molecular dissection of checkpoint control systems in human cells and to uncover defects in neoplasia. Our plan is to precisely map these control systems from the point where DNA damage or unreplicated DNA is sensed to the response elements that arrest cell cycle progression. We are also searching for molecular indicators to predict the fidelity of checkpoint control. Molecular dissection of the G2 checkpoint in human lymphoma cells revealed that the cdc2 kinase activity is suppressed by inhibitory phosphorylations. Failure to remove these phosphates correlated with suppression of the cdc25C phosphatase. Cdc25C activity is up-regulated by hyperphosphorylation and this did not occur in G2 arrested cells. We are now investigating the kinase/phosphatase couple that regulates cdc25C in response to DNA damage. We have found that G2 arrest does not inhibit the activation of cyclin A/cdk2 complexes while cyclin A/cdc2 and cyclin B1/cdc2 complex activation is suppressed. We suggest that activation of cyclin A/cdc2 complexes might act together with cyclin B1/cdc2 complexes to promote mitosis. We have also commenced a characterization of the G1 checkpoint in human cells with emphasis on the role of the tumor suppressor gene, p53 in G1 arrest induced by DNA damage. We are currently characterizing the interaction of p53 with the G1/S phase cyclin-dependent kinases. We are examining the actions of kinase/phosphatase inhibitors on cell cycle control to search for modulators that could enhance the antitumor activity of chemotherapeutic agents. For example, we are searching for non-toxic, non-DNA damaging agents that prolong the half- life of p53. Such agents will be used to arrest cells with normal p53 in G1. Tumors with defective p53 will then be selectively killed with cytotoxic agents specific for S and M phase.

该研究项目主要集中在细胞周期控制上， 化学敏感性的决定因素。我们的目标是利用细胞周期控制， 为开发新的化疗策略奠定了基础， 选择性地杀死肿瘤细胞。研究的方向是分子 剖析人体细胞中的检查点控制系统并揭示 肿瘤形成的缺陷。我们的计划是精确绘制这些控制系统 从DNA损伤或未复制的DNA被感知到的点到 抑制细胞周期进程的反应元件。我们也 寻找分子指标来预测检查点的保真度 控制 人类淋巴瘤G2检查点的分子解剖 细胞显示，CDC 2激酶活性被抑制剂抑制， 磷酸化未能清除这些磷酸盐与 抑制cdc 25 c磷酸酶。Cdc 25 C活性被上调， 在G2期阻滞的细胞中没有发生这种过度磷酸化。我们 目前正在研究调节cdc 25 C的激酶/磷酸酶对， DNA损伤的反应。我们发现G2期阻滞并不能抑制 细胞周期蛋白A/cdk 2复合物的激活，而细胞周期蛋白A/cdc 2和细胞周期蛋白 B1/cdc 2复合物的激活被抑制。我们认为， cyclin A/cdc 2复合物可能与cyclin B1/cdc 2复合物共同起作用 促进有丝分裂。我们还开始对G1进行表征 人类细胞中的检查点，重点是肿瘤的作用 抑制基因p53在DNA损伤诱导的G1期阻滞中的作用。我们目前正在 表征p53与G1/S期细胞周期蛋白依赖性 激酶。 我们正在研究激酶/磷酸酶抑制剂对 细胞周期控制，以寻找调节剂，可以提高 化疗剂的抗肿瘤活性。 比如我们 寻找无毒、无DNA损伤的物质， P53的生活 这些试剂将用于在细胞中抑制具有正常p53的细胞。 G1。 具有缺陷p53的肿瘤然后将被选择性地杀死， 对S期和M期具有特异性的细胞毒性剂。