CELL CYCLE CHECKPOINTS AND CHEMOSENSITIVITY OF HUMAN CANCER CELLS

人类癌细胞的细胞周期检查点和化学敏感性

• 批准号: 3752454
• 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/3752454
• 关键词: DNA damage; DNA repair; antineoplastics; apoptosis; cell cycle; cell cycle proteins; drug resistance; drug screening /evaluation; enzyme activity; flow cytometry; gene mutation; human tissue; neoplasm /cancer chemotherapy; neoplasm /cancer pharmacology; neoplastic cell; phosphorylation; protein kinase; tissue /cell culture; tumor suppressor genes

This research project focuses on cell cycle checkpoints as major determinants of chemosensitivity. We also aim to utilize emerging knowledge of these checkpoint control systems to design new chemotherapeutic stratagems for cancer treatment. We are elucidating the checkpoints that arrest human cells in G1 and G2 phases following DNA damage, and uncovering defects in these systems in cancer cells. We hope to trace these systems from the point where DNA damage or unreplicated DNA is sensed by the cell to the response elements that arrest the cell cycle, and in some cases induce apoptosis. We are searching for components of these systems that could be assayed to predict checkpoint integrity and chemosensitivity. Our results suggest that p53 gene mutations prevent cells from arresting in G1 following DNA damage and increase the likelihood of resistance to these agents. This resistance is due, at least in part, to an evasion of p53-mediated apoptosis, although other changes also occur in the mutant p53 cells. We are exploring the interaction of the p53 regulated gene product WAF1/CIP1 with the G1/S cyclin dependent kinases to better define the significance of this protein in G1 arrest, DNA repair and apoptosis. We are investigating both the mechanism of G2 arrest and integrity of the G2 checkpoint in cancer cells. This checkpoint appears to protect cells from DNA damage by extending the time available for DNA repair. We have found DNA damage suppresses activation of the cyclin A/Cdc2 and cyclin B/Cdc2 kinases by maintaining inhibitory phosphorylations on Cdc2. Consistent with this observation we have found that activation of the Cdc25C phosphatase is suppressed in cells treated with DNA damaging agents. We are investigating the mechanism of Cdc25C activation to better define the pathway by which unreplicated and damaged DNA arrest cells in G2 phase. We have applied flow cytometric assays to test the integrity of the G1 and G2 checkpoints in cell lines of the NCI- Anticancer Drug Screen and found that major differences exist. We are presently probing for relationships between the integrity of these- checkpoints and chemosensitivity.

本研究项目的重点是细胞周期检查点作为主要的 化学敏感性的决定因素。我们还希望利用新兴的 这些检查站控制系统的知识，以设计新的 用于癌症治疗的化学治疗策略。我们正在阐明 检查点，阻止人类细胞在G1和G2期DNA 损伤，并发现癌细胞中这些系统的缺陷。我们希望 从DNA损伤或未复制的DNA 被细胞感知到，并被反应元件所捕获， 并且在某些情况下诱导细胞凋亡。我们在寻找 这些系统可以被分析以预测检查点完整性， 化疗敏感性我们的结果表明p53基因突变可以预防 细胞停止在G1期后DNA损伤，并增加 对这些药物的抵抗力。这种抵抗至少是由于 部分原因是逃避p53介导的凋亡，尽管其他变化 也发生在突变型p53细胞中。我们正在探索 p53调控的基因产物WAF 1/CIP 1与G1/S细胞周期蛋白依赖性 激酶，以更好地确定该蛋白在G1期阻滞中的意义， DNA修复和凋亡。我们正在研究G2的机制 阻止和完整性的G2检查点的癌细胞。此检查点 似乎通过延长可用时间来保护细胞免受DNA损伤 for DNA修复.我们发现DNA损伤抑制了 细胞周期蛋白A/Cdc 2和细胞周期蛋白B/Cdc 2激酶 Cdc 2的磷酸化。与此相一致，我们发现 Cdc 25 C磷酸酶的激活在处理的细胞中被抑制， DNA破坏剂我们正在研究Cdc 25 C的作用机制 激活，以更好地定义未复制和受损的 DNA阻滞细胞于G2期。我们已经应用流式细胞术分析， 检测NCI细胞系中G1和G2检查点的完整性- 抗癌药物筛选发现存在较大差异。 我们 目前正在探索这些完整性之间的关系- 检查点和化学敏感性。