Inhibitors of the G protein GNAS which drives pancreatic tumorigenesis

促进胰腺肿瘤发生的G蛋白GαS的抑制物 项目摘要/摘要 GNAS基因编码异源三聚体G蛋白的GαS刺激亚单位，它介导G蛋白- 偶联受体(GPCR)信号，细胞感知和响应细胞外刺激的一种中央机制。 多种人类癌症类型在该途径中表现出反复出现的功能获得突变，最常见的是 目标是GNAS。GNAS经常突变的最致命的肿瘤类型是导管内乳头状瘤 粘液性肿瘤(IPMN)，侵袭性胰腺癌的先兆。Bardeesy最近推出的小鼠模型 和同事们已经证明，胰腺IPMN肿瘤包含三个重合的基因损伤，K-RAS (G12D)、GαS(R201C)和P53-/-，当GαS(R201C)沉默时，提供了强大的遗传 以此突变蛋白为靶点的验证。30多年来，流行的模型解释了- R201突变的功能活性是通过GTP酶活性的丧失而导致突变体不能 GαS关闭至国内生产总值状态。最近，我们实验室对这一型号进行了修改，并透露了R201C 突变可以绕过GTP结合的需要，通过稳定一个基因直接激活与Gdp结合的GαS 分子内氢键网络。这种理解导致了我们寻求的治疗机会 开发用于治疗胰腺肿瘤发生的药物。我们建议开发状态选择性G-αS结合分子 阻断腺苷环化酶(AC)的激活。灵感来自环肽天然产物YM-254890，这是一种 GDP态特异性环肽抑制剂GαQ，我们启动了一种药物发现的方法来鉴定两者的活性 G-α的状态和失活状态特异性抑制剂S。利用随机非标准肽的整合发现 (快速)系统由我们的合作者菅义伟博士开发，我们选择了活动状态和非活动状态 与GαS相比，我们更喜欢环肽。我们已经解决了我们函数的高分辨X射线共晶结构 封闭环肽，解释它们的核苷酸状态、特异性和抑制活性。我们建议 利用快速技术聚焦化学多样性以提高先导环肽的效力，并测试我们的 根据Bardeesy博士的模型产生的细胞中的铅分子。这项提议充分利用了最近的三个 突破，Bardeesy博士的小鼠建模，Suga博士的非自然环肽文库生成，以及 新型非正规型G蛋白信号转导原癌蛋白GαS由我室靶向致死 一种胰腺癌。

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.