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: 2468446
• 负责人: P M O'CONNOR
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 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/2468446
• 关键词: DNA damage; DNA repair; antineoplastics; apoptosis; cell cycle; cell cycle proteins; drug screening /evaluation; enzyme activity; gene mutation; molecular cloning; neoplasm /cancer genetics; neoplasm /cancer pharmacology; neoplastic cell; protein kinase; protein structure function; tumor suppressor genes

The major focus of this research group is to study the role of cell cycle checkpoints in the chemosensitivity of human cancer cells. Such studies are aimed at addressing 4 fundamental questions: (1) Do cell cycle checkpoint differences exist in human cancer cells; (2) Do checkpoint differences, when observed, impart altered sensitivity to currently available anticancer agents; (3) Can we dissect out the molecular components of these checkpoints and determine how these components mediate cell cycle arrest, DNA repair and apoptosis, and (4) Can we discover new chemotherapeutic agents and/or stratagems that exploit checkpoint differences as a basis for the preferential destruction of cancer cells. We are focusing on the checkpoints that respond to DNA damage to arrest cell cycle progression in G1 and/or G2 phase. The G1 DNA damage checkpoint is commonly disrupted in cancer cells and this results from defects in the p53 pathway. We have found that a number of cancer cell lines also exhibit an attenuated G2 checkpoint response to DNA damage. Although this attenuation cannot be fully explained on the basis of p53 status, we have found that checkpoint modulators such as pentoxifylline and UCN-01, preferentially abrogate the G2 checkpoint in p53 defective cells. We have exploited this vulnerability in drug combinations to preferential kill p53 defective cancer cell lines in vitro. We aim to disclose the molecular basis of this vulnerability and will focus on UCN-01, which has just entered clinical trials. We have found that p53 disruption imparts altered sensitivity to a number of commonly used anticancer agents and these effects are dependent upon both the cell type and class of agents used to treat the cells. Most recently we have found that disruption of the p53-regulated gene CIP1/WAF1 preferentially sensitizes cells to DNA crosslinking agents. In collaboration with Dr. Fornace's laboratory, we have found this sensitization correlates with reduced DNA repair activity in the CIP1/WAF1 disrupted cells, implicating Cip1/Waf1 in DNA repair. We and others have now characterized the integrity of the p53 pathway in the NCI cell screen. This analysis has allowed the discovery of agents with potentially greater activity in cells with mutant p53. We are preparing several isogenic cell systems for further investigation of these agents. We are continuing to investigate the mechanisms of G1 and G2 arrest. For G2 arrest, we are focusing on the Wee1 and PLK kinases and for G1 arrest we are investigating the role of a novel p53-regulated phosphatase (Wip1), that was recently cloned as part of a collaboration with Dr. Appella's group at the NCI.

这个研究小组的主要重点是研究细胞的作用 人类癌细胞化疗敏感性中的周期检查点。是这样的 研究旨在解决四个基本问题：(1)DO细胞 人类癌细胞中存在周期检查点差异；(2)确实 当观察到检查点差异时，会使敏感度发生变化 目前可用的抗癌药物；(3)我们能否解剖出 这些检查点的分子组成，并确定这些 调节细胞周期停滞、DNA修复和细胞凋亡的成分，以及 (4)我们能否发现新的化疗药物和/或策略 利用检查点差异作为优先选项的基础 破坏癌细胞。我们正在关注的检查站 对DNA损伤作出反应以阻止G1和/或G2中的细胞周期进展 相位。G1DNA损伤检查点在癌症中通常被破坏 细胞，这是由于P53途径的缺陷造成的。我们发现了 一些癌细胞株也表现出减弱的G2 检查点对DNA损伤的反应。尽管该衰减不能 在充分解释P53状况的基础上，我们发现 检查点调制器，例如己酮可可碱和UCN-01， 优先取消P53缺陷细胞中的G2检查点。我们 已经利用了药物组合中的这个漏洞来优先 体外杀伤p53基因缺陷的癌细胞株。我们的目标是披露 该漏洞的分子基础，并将重点关注UCN-01，它 刚刚进入临床试验阶段。我们发现P53基因的中断 使一些常用的抗癌药物具有改变的敏感性 药物和这些影响取决于细胞类型和 用于处理细胞的试剂的类别。最近我们发现 优先阻断P53调控基因CIP1/WAF1 使细胞对DNA交联剂敏感。与Dr. Fornace的实验室，我们发现这种敏化与 CIP1/WAF1中断细胞中DNA修复活性降低， Cip1/Waf1参与DNA修复。我们和其他人现在 在NCI细胞筛选中表征了P53通路的完整性。 这一分析使人们能够发现潜在的 具有突变型p53的细胞具有更大的活性。我们正在准备几个 为进一步研究这些制剂提供了同基因细胞系统。我们 正在继续研究G1和G2停滞的机制。为 G2停滞，我们专注于Wee1和PLK激酶以及G1 我们正在调查一种新的由P53调控的基因的作用 磷酸酶(Wip1)，最近被克隆为 与阿佩拉博士在国家情报局的团队合作。