Capitalizing on NSAID enantiomer selectivity for cancer prevention and therapy(PQ

描述（由申请人提供）：挑衅性问题（PQ）5要求我们确定“常用于其他适应症的药物（如抗炎药（NSAID））可预防癌症发病率和死亡率”的机制。强有力的初步数据使我们提出，对于某些化学实体，化学预防和/或抗肿瘤活性可归因于所选NSAID的R-对映体与 新的癌症相关靶点。有许多药物活性的立体选择性差异的例子。非甾体抗炎药（NSAID）的R-型基本上对环加氧酶无活性，越来越多的证据表明R-对映体是具有独立药理学活性的不同化学实体。我们发现，R-对映异构体的napoleen和酮咯酸抑制小GTP酶Rac 1和Cdc 42。超过20种其他NSAID对这些蛋白质无活性，表明R-萘普生和R-酮咯酸具有新的靶点选择性。Rac 1和Cdc 42调节细胞骨架动力学以及其他功能，并且已被认为是有吸引力的癌症治疗靶点，尽管目前没有特异性抑制剂处于临床试验中。与Rac 1/Cdc 42在调节肌动蛋白功能中的已知功能一致，我们发现对映体选择性抑制卵巢肿瘤细胞的迁移和粘附。此外，在腹膜内异种移植模型中，R-萘普生（而不是S-萘普生或结构相关的6-甲氧基萘乙酸（6-MNA））将卵巢肿瘤的植入减少了约75%。本申请的目的是确定R-萘普生和R-酮咯酸观察到的生物活性的作用机制。这将为基于与新靶点的相互作用重新考虑其他NSAID R-对映体的潜在抗肿瘤活性提供基础。我们假设R-酮咯酸和R-萘普生通过一种基于药物与GDP结合（无活性）形式的酶结合的新机制抑制Rac 1和/或Cdc 42以及相关的细胞反应。我们将通过使用生物化学和细胞方法结合结构-活性分析来测试这一假设，我们将测试是否存在如化学信息学预测的与GTP酶的GDP结合形式的R-对映体选择性相互作用，从而导致GTP结合、酶活化和下游细胞应答的阻断。这项工作是重要的，因为NSAID R-对映体的新的药理学和肿瘤相关的功能活性以前没有被描述过，该项目的成功完成将为NSAID的抗癌益处提供新的机制见解。这些研究还将产生额外的 以及关于靶向Rac 1和Cdc 42在卵巢癌和其他癌症中的益处的关键信息。

DESCRIPTION (provided by applicant): Provocative question (PQ) 5 challenges us to determine the mechanism whereby 'drugs commonly used for other indications, such as anti-inflammatory drugs (NSAIDs), can protect against cancer incidence and mortality'. Strong preliminary data lead us to propose that for certain chemical entities the chemopreventive and/or anti-tumor activity is attributable to interaction of the R-enantiomer of select NSAIDs with novel cancer- relevant targets. There are many examples of stereoselective differences in drug activity. The R-forms of non- steroidal anti-inflammatory drugs (NSAIDs) are essentially inactive against cyclooxygenases and there is mounting evidence that R-enantiomers are distinct chemical entities with independent pharmacologic activities. We find that the R-enantiomers of naproxen and ketorolac inhibit the small GTPases Rac1 and Cdc42. More than 20 other NSAIDs were inactive against these proteins, suggesting novel target selectivity by R-naproxen and R-ketorolac. Rac1 and Cdc42 regulate cytoskeletal dynamics in addition to other functions, and have been recognized as attractive cancer therapeutic targets although no specific inhibitors are currently in clinical trials. In keeping with the known functions of Rac1/Cdc42 in regulating actin-based functions, we find enantiomer- selective inhibition of ovarian tumor cell migration and adhesion. Furthermore, R-naproxen, but not S-naproxen or the structurally-related 6-methoxy naphthalene acetic acid (6-MNA), reduced implantation of ovarian tumors by ~75% in an intraperitoneal xenograft model. The objective of this application is to define the mechanism of action for the observed biologic activities of R-naproxen and R-ketorolac. This will provide the foundations for re-consideration of potential anti-tumor activities of other NSAID R-enantiomers based on interaction with novel targets. We hypothesize that R-ketorolac and R-naproxen inhibit Rac1 and/or Cdc42 and associated cellular responses through a novel mechanism based on drug binding to the GDP-bound (inactive) form of the enzymes. We will test this hypothesis by using biochemical and cellular approaches coupled with structure- activity analyses, we will test whether there is R-enantiomer-selective interaction with the GDP-bound forms of the GTPases as predicted by cheminformatics, leading to blockade of GTP binding, enzyme activation and downstream cellular responses. The work is significant because the novel pharmacologic and tumor-relevant functional activities of NSAID R-enantiomers have not been previously described and successful completion of the project will offer new mechanistic insights into the anti-cancer benefit of NSAIDS. The studies will also yield additional and critical information on the benefits of targeting Rac1 and Cdc42 in ovarian and other cancers.