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向我们提出挑战，要求我们确定“通常用于其他适应症的药物，如抗炎药(NSAID)，可以预防癌症发生和死亡的机制”。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/或抗肿瘤活性归因于特定非类固醇抗炎药的R-对映体与 与癌症相关的新靶点。有许多药物活性的立体选择性差异的例子。非甾体抗炎药(NSAIDs)的R-构型基本上对环氧合酶没有活性，越来越多的证据表明R-对映体是具有独立药理活性的不同化学实体。我们发现，萘普生和酮咯酸的R-对映体抑制了小的GTP酶rac1和cdc42。其他20多种非甾体抗炎药对这些蛋白没有活性，这表明R-萘普生和R-酮咯酸具有新的靶点选择性。除了其他功能外，rac1和cdc42还调节细胞骨架动力学，已被认为是有吸引力的癌症治疗靶点，尽管目前还没有特定的抑制剂处于临床试验中。与已知的rac1/CDc42调节肌动蛋白功能的功能一致，我们发现对映体选择性地抑制卵巢肿瘤细胞的迁移和黏附。此外，在异种腹膜移植模型中，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)，可使卵巢肿瘤的种植减少约75%。本应用的目的是确定R-萘普生和R-酮咯酸对观察到的生物活性的作用机制。这将为基于与新靶点相互作用的其他NSAID R对映体潜在的抗肿瘤活性的重新考虑提供基础。我们假设R-酮咯酸和R-萘普生通过一种新的机制抑制rac1和/或cdc42及其相关的细胞反应，该机制基于药物与GDP结合(非活性)的酶的形式。我们将使用生化和细胞方法结合结构-活性分析来验证这一假设，我们将测试是否像化学信息学预测的那样，与GTP酶的GDP结合形式存在R-对映体选择性相互作用，导致阻断GTP结合、酶激活和下游细胞反应。这项工作意义重大，因为NSAID R对映体的新药理和肿瘤相关功能活性以前从未被描述过，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rac1和cdc42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.