Inhibitors of the G protein GNAS which drives pancreatic tumorigenesis

驱动胰腺肿瘤发生的G蛋白Gαs的抑制剂 项目总结/摘要 GNAS基因编码异源三聚体G蛋白的Gαs刺激亚基，其介导G蛋白- 偶联受体（GPCR）信号传导，细胞感知和响应细胞外刺激的中枢机制。 多种人类癌症类型在该途径中表现出复发性功能获得性突变，最常见的是 针对GNAS。GNAS经常发生突变的最致命的肿瘤类型是导管内乳头状癌。 粘液性肿瘤（IPMN），侵袭性胰腺癌的前兆。Bardeesy最近的小鼠建模 和同事已经表明，胰腺IPMN肿瘤含有三个同时发生的遗传病变，K-Ras， 当Gαs（R201 C）沉默时，G αs（G12 D）、Gαs（R201 C）和p53 -/-被抑制，从而提供了强的遗传学效应。 验证针对该突变蛋白的有效性。30多年来，解释收益的流行模型- R201突变的功能活性是通过GT3活性的丧失和导致的突变体不能表达GT3活性来实现的。 Gαs切换到GDP状态。最近，我们的实验室修改了这个模型，并揭示了R201 C 突变可以绕过GTP结合的需要，直接激活GDP结合的Gαs，通过稳定一个 分子内氢键网络这种理解带来了一个治疗的机会，我们寻求 用于治疗胰腺肿瘤。我们建议开发状态选择性Gαs结合分子， 阻断腺苷酸环化酶（AC）的激活。受环肽天然产物YM-254890的启发， GDP状态的特异性环肽抑制剂Gαq，我们发起了一个药物发现的方法，以确定两个活性 状态和非活性状态的Gαs特异性抑制剂。使用随机非标准肽集成发现 （RaPID）系统由我们的合作者Hiroaki Suga博士开发，我们选择了活动状态和非活动状态 喜欢环肽而不喜欢Gα。我们已经解决了我们的函数的高分辨率X射线共晶结构 阻断环肽，解释其核苷酸状态特异性和抑制活性。我们建议 使用RaPID技术集中化学多样性，以提高先导环肽的效力，并测试我们的 Bardeesy博士的模型中产生的细胞中的铅分子。该提案利用了最近三个 突破，Bardeesy博士的小鼠建模，Suga博士的非天然环肽文库生成，以及 一种新的非典型类型的G蛋白信号由驱动癌蛋白Gαs由我们的实验室靶向一个致命的 胰腺癌的症状

Inhibitors of the G protein Gαs which drives pancreatic tumorigenesis Project Summary / Abstract The GNAS gene encodes the Gαs stimulatory subunit of heterotrimeric G proteins, which mediate G-protein- coupled receptor (GPCR) signaling, a central mechanism by which cells sense and respond to extracellular stimuli. Multiple human cancer types exhibit recurrent gain-of-function mutations in the pathway, most frequently targeting GNAS. The most lethal tumor type where GNAS is frequently mutated is the intraductal papillary mucinous neoplasms (IPMN), a precursor of invasive pancreatic cancer. Recent mouse modelling from Bardeesy and coworkers has shown that pancreatic IPMN tumors which contain three coincident genetic lesions, K-Ras (G12D), Gαs (R201C), and p53 -/-, are suppressed when Gαs (R201C) is silenced, providing strong genetic validation for targeting this mutant protein. For over 30 years, the prevailing model explaining the gain-of- function activity of the R201 mutations was through the loss of GTPase activity and resulting inability of mutant Gαs to switch off to the GDP state. Recently, our laboratory revised this model and revealed that the R201C mutation can bypass the need for GTP binding by directly activating GDP-bound Gαs through stabilization of an intramolecular hydrogen bond network. This understanding has led to a therapeutic opportunity that we seek to exploit to treat pancreatic tumorigenesis. We propose to develop state-selective Gαs binding molecules which block adenylyl cyclase (AC) activation. Inspired by the cyclic peptide natural product YM-254890 which is a GDP-state specific cyclic peptide inhibitor of Gαq, we initiated a drug discovery approach to identify both active state and inactive state specific inhibitors of Gαs. Using the Random non-standard Peptide Integrated Discovery (RaPID) system developed by our collaborator Dr. Hiroaki Suga we have selected active state and inactive state preferring cyclic peptides against Gαs. We have solved high resolution X-ray co-crystal structures of our function blocking cyclic peptides which explain their nucleotide state specificity and inhibitory activity. We propose to use the RaPID technology to focus chemical diversity to improve potency of the lead cyclic peptides and test our lead molecules in cells generated from Dr. Bardeesy's model. This proposal capitalizes on three recent breakthroughs, mouse modeling by Dr. Bardeesy, unnatural cyclic peptide library generation by Dr. Suga, and a new non-canonical type of G protein signaling by the driver oncoprotein Gαs by our laboratory to target a deadly form of pancreatic cancer.