Rac GTPases as targets in lymphomagenesis

描述(由申请人提供)：摘要NOT-OD-09-058：NIH宣布恢复法案资金可用于竞争性修订申请。本项目的目标是将RAC GTP酶与其调节的鸟核苷酸交换因子(GEF)之间相互作用的机制洞察应用于设计针对人类淋巴瘤中RAC活性解除调节的新型小分子抑制剂。全球环境基金-RAC信号轴位于许多信号事件的十字路口，这些信号事件由生长因子、细胞因子、压力和黏附分子启动。它们的功能相互作用导致RAC的激活和RAC介导的一系列生理反应，包括肌动蛋白和微管细胞骨架的重组、黏附、迁移和增殖。在父母的资助中，我们试图确定Rac GTPase信号在p53缺失的小鼠和人类淋巴瘤模型中的作用，并暗示Rac信号是一个有用的抗癌靶点。我们的跟踪记录和初步数据为研究rac1与GEF的相互作用的结构-功能关系，获得与rac1相关的几种功能相互作用的结构和动力学信息，以及在小鼠中通过条件基因打靶方法研究rac1的作用提供了强有力的证据。特别是，我们发现了一种第一代小分子抑制剂NSC23766，它在体外和体内都能有效地靶向RAC，并利用它研究了RAC GTP酶的一系列生理和病理功能，从造血干细胞动员、血小板调节、神经鞘瘤表型逆转到淋巴瘤抑制。在这项补充建议中，我们将(1)通过基于新拆分的rac1-NSC23766晶体结构的虚拟筛选，寻求基于结构-功能的合理设计和改进RAC靶向小分子抑制剂；(2)通过药物化学寻求改善RAC抑制剂的构效关系；(3)在体外系统和细胞内验证新的RAC靶向抑制剂，并将RAC靶向小分子抑制剂应用于RAC活性异常高的p53缺陷性淋巴瘤。这些在新的病理学背景下基于机制的小分子抑制剂设计和临床前验证的研究将加快研究项目的节奏，以与父母的赠款资金协同作用，使创新的、基于机制的基础科学假设更接近翻译应用，并将在美国保留和创造就业机会。这些研究的终点将提供改进的一代RAC GTPase抑制剂，用于癌症研究的广泛使用，特别是用于有效根除淋巴瘤。 公共卫生相关性：项目描述拟议的工作将通过转化从长达十年的RAC GTP酶的生化、结构、细胞生物学和动物研究中获得的机制信息，进行基于结构的RAC GTP酶新的化学抑制剂的设计，以用于抗癌治疗。此外，拟议的工作将有助于建立一种新的治疗概念，即在p53缺失的淋巴瘤细胞中靶向RAC可能有利于传统的、耐药的癌症。这些研究将加快研究项目的节奏，与父母的拨款资金协同作用，使创新的、基于机制的基础科学假设更接近翻译应用，并将在美国保留和创造就业机会。

DESCRIPTION (provided by applicant): Abstract NOT-OD-09-058: NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications. The goal of this project is to apply the mechanistic insights of the interaction between Rac GTPases and their regulatory guanine nucleotide exchange factors (GEFs), to the design of novel small molecule inhibitors targeting deregulated Rac activities in human lymphoma. The GEF-Rac signaling axis lies in the crossroads of many signaling events initiated by growth factors, cytokines, stress, and adhesion molecules. Their functional interaction leads to the activation of Rac and a variety of Rac-mediated physiological responses including actin and microtubule cytoskeletal reorganization, adhesion, migration, and proliferation. In the parental grant, we seek to define the role of Rac GTPase signaling in p53 deficient mouse and human lymphoma models and to implicate Rac signaling as a useful anti-cancer target. Our track record and preliminary data provide strong credential in studying the structure-function relationship of Rac1 in regard of its interaction with GEFs, in deriving structural and kinetic information of several functional interactions involving Rac1, and in studying the role of Rac1 by conditional gene targeting approach in mice. In particular, we have discovered a first generation small molecule inhibitor, NSC23766, that is effective in targeting Rac in vitro and in vivo, and have utilized it to study a number of physiological and pathological functions of Rac GTPases ranging from hematopoietic stem cell mobilization, platelet regulation, schwannoma phenotype reversion, to lymphoma suppression. In this supplemental proposal, we will (1) pursue structure-function based rational design and improvement of Rac-targeting small molecule inhibitors by virtual screening based on a newly resolved Rac1-NSC23766 crystal structure, (2) seek to improve the structure-activity relations of the Rac inhibitors by medicinal chemistry, and (3) validate the new Rac inhibitors in purified in vitro systems and in cells, and apply the Rac-targeting small molecule inhibitors to p53 deficient lymphoma where Rac activity is abnormally high. These mechanism-based studies of small molecule inhibitor design and pre- clinical validation in a novel pathologic context will accelerate the tempo of the research project to synergize with the parental grant funding to move an innovative and mechanism based, basic science hypothesis closer to translational applications, and will retain and create jobs in US. The end point of these studies will provide an improved generation of Rac GTPase inhibitors for a wide range of usage in cancer research, particularly for effective eradication of lymphoma. PUBLIC HEALTH RELEVANCE: Project Narrative The proposed work will pursue structure-based design of new chemical inhibitors of Rac GTPases by translating the mechanistic information obtained from the decade-long biochemical, structural, cell biological, and animal studies of Rac GTPases for anti-cancer therapy. Further, the proposed work will help establish a novel therapeutic concept that targeting Rac in p53 deficient lymphoma cells could be beneficial to conventional, chemoresistant cancer. The studies will accelerate the tempo of the research project to synergize with the parental grant funding to move an innovative and mechanism based, basic science hypothesis closer to translational applications, and will retain and create jobs in US.