MOLECULAR MECHANISM OF ACTION OF ANTITUMOR ALKYLATING AGENTS

这个项目现在主要集中在细胞周期调节上，作为主要的 烷化剂和其他DNA的细胞毒性反应的决定因素 破坏性的抗癌药物。我们正在利用最近开发的工具和 研究细胞周期调控之间关系的概念 以及细胞在DNA损伤中存活的能力。我们目前的研究 关注识别DNA损伤的信号传递机制 从G2到控制细胞周期进程的分子检查点 进入有丝分裂期，由G1期进入S期。我们的长远目标 正在将细胞周期控制的新知识应用于未来的抗癌药物 发展和治疗。在对G2检查站的研究中，我们发现 氮芥处理的人淋巴瘤细胞G2期停滞不是由于 缺乏cdc2或细胞周期蛋白B；关键的激酶复合体的成分 通过这个检查点控制细胞周期进程。相反，cdc2 由于持续的抑制作用，激酶活性仍然受到抑制 磷酸化。我们现在正在调查这一机制 确定抑制磷酸化，并希望追踪序列 事件回到了DNA损伤被识别的地步。在未来 研究，将特别注意细胞类型之间的差异 这可能解释了为什么有些癌细胞对DNA选择性敏感。 破坏性的毒品。我们还在研究CDK2-细胞周期蛋白A激酶复合体， 它在细胞周期中的确切作用仍不确定；我们发现， 与cdc2-细胞周期蛋白B激酶复合体相反，它的活性继续 G2期滞留细胞数量上升。此外，我们正在研究这种机制 像甲基黄嘌呤这样的药物能够绕过DNA 损伤导致G2停滞。影响细胞周期控制的化合物 可能被证明是DNA破坏性化疗的有用调节剂。

This project now focusses primarily on cell cycle regulation as a major determinant of cytotoxic responses to alkylating agents and other DNA damaging anticancer drugs. We are utilizing recently developed tools and concepts to investigate the relationships between cell cycle regulation and the ability of cells to survive DNA damage. Our current studies focus on the mechanisms by which recognition of DNA damage is signalled to the molecular checkpoints that govern cell cycle progression from G2 phase into mitosis, and from G1 into S phase. Our long-range objective is apply new knowledge on cell cycle control to future anticancer drug development and therapy. In studies of the G2 checkpoint, we found that G2 arrest in nitrogen mustard treated human lymphoma cells was not due to lack of cdc2 or cyclin B; components of the critical kinase complex that controls cell cycle progression through this checkpoint. Rather, cdc2 kinase activation remains suppressed due to persistence of inhibitory phosphorylations. We are now investigating the mechanism which determines inhibitory phosphorylations, and hope to trace the sequence of events back to the point where DNA damage is recognized. In future studies, special attention will be given to differences among cell types that may explain why some cancer cells are selectively sensitive to DNA damaging drugs. We are also studying the cdk2-cyclin A kinase complex, whose exact role in the cell cycle is still uncertain; we found that, contrary to the cdc2-cyclin B kinase complex, its activity continued to rise in G2-arrested cells. In addition, we are studying the mechanisms by which drugs such as methylxanthines are able to circumvent DNA damage-induced G2 arrest. Compounds that influence cell cycle control may prove useful modulators of DNA damaging chemotherapies.