Investigating the molecular mechanisms of growth in GNAS mutant pancreatic cancer.

项目总结 胰腺导管腺癌(PDA)是美国第四大癌症死亡原因， 检测后的五年存活率不到10%。动脉导管未闭起源于导管内乳头状黏液 肿瘤(IPMN)前体病变通过GNAS中反复出现的激活突变来区分，GNAS编码 G蛋白GαS，并诱导环磷酸腺苷(CAMP)信号转导。GNAS被突变激活和扩增 胰腺和许多其他人类肿瘤，但其致癌功能尚不清楚。因此，理解 突变的GNAS的功能将提供疾病机制，并提供治疗PDA的机会，即使在他们的 早期阶段。为了了解致癌GNAS的功能，我们建立了多西环素可调节的小鼠模型 并表明突变的GNAS与致癌的KRAS合作启动IPMN，从而进展为侵袭性的 P53丢失后的PDA。GNAS仍然是维持已建立的肿瘤的关键，通过蛋白激酶A (PKA)依赖的网络和由此产生的盐诱导激酶的抑制(SIK1-3)。我们证明了这一点 网络显著地重新编程代谢途径，这些途径是TCA循环的潜在替代来源 可支持GNAS生长的代谢物、呼吸底物和脂肪酸中间体 突变的肿瘤。重要的是，GNAS突变的癌细胞对这些基因的抑制特别敏感 与GNAS-wt肿瘤相比的途径。这些结果确立了突变的GNAS是一种新的肿瘤维持机制 驱动程序，发现潜在的PKA依赖程序，建立SIK作为主要的肿瘤抑制因子，以及 证明未预料到的代谢异质性助长了胰腺癌的亚群。基于我们的 关于已发布和未发布的支持数据，本提案的首要目标是了解 调控细胞增殖和代谢表达的GNAS-PKA信号关键下游靶点 基因。我们的研究还将阐明突变的GNAS是如何调节酮脱氢酶的表达的 产生生物合成和生物能量中间体以支持肿瘤生长。最后，我们的研究将询问 GNAS突变型胰腺癌呼吸活动的调节及其需求。这项研究将 利用先进的方法和独特的工具，包括全球转录分析和基于同位素的分析 临床前胰腺癌基因界定的小鼠和人类器官系统的代谢特征 动物模型、相关患者来源的异种移植系统和原始样本。我们的研究将提供 了解突变GNAS的独特生物学，并指出基因亚群中有针对性的脆弱性 胰腺肿瘤。

PROJECT SUMMARY Pancreatic ductal adenocarcinoma (PDA) is the fourth leading cause of cancer death in the United States with five-year survival after detection is less than 10%. The subset of PDA arises from Intraductal papillary mucinous neoplasm (IPMNs) precursor lesions are distinguished by recurrent activating mutations in GNAS, that encodes G-protein Gαs, and induces cyclic-AMP (cAMP) signaling. GNAS is mutationally activated and amplified pancreatic and many other human tumors, yet its oncogenic functions remain unclear. Therefore, understanding the function of mutant GNAS will provide disease mechanisms and give opportunities to treat PDA even in their early stages. To understand the function of oncogenic GNAS we established a doxycycline-tunable mouse model and showed that mutant GNAS cooperates with oncogenic KRAS to initiate IPMNs that progress to invasive PDA upon p53 loss. GNAS remains critical for the maintenance of established tumors, via a protein kinase A (PKA)-dependent network and resulting inhibition of salt-inducible kinases (SIK1-3). We demonstrated that this network prominently reprograms metabolic pathways which are potential alternative sources of TCA cycle metabolites, respiratory substrates (NADH) and fatty acid intermediates that can support the growth of GNAS mutant tumors. Importantly, GNAS-mutant cancer cells are specifically sensitive to the inhibition of these pathways compared to GNAS-wt tumors. These results establish mutant GNAS as a novel tumor maintenance driver, uncover the underlying PKA-dependent program, establish SIKs as major tumor suppressors, and demonstrate unanticipated metabolic heterogeneity fueling subsets of pancreatic cancer. Based on our published and unpublished supporting data, the overarching goal of this proposal is to understand the roles of critical downstream targets of GNAS-PKA signaling that control the expression of proliferation and metabolic genes. Our research will also illuminate how mutant GNAS regulated expression of a keto dehydrogenase generate biosynthetic and bioenergetic intermediates to support tumor growth. Finally, our study will interrogate the regulation of respiratory activity and its requirement in GNAS mutant pancreatic cancer. This study will leverage advanced methods and unique tools, including global transcriptomic analysis and isotopomer-based metabolic profiling in genetically defined mouse and human organoid systems, preclinical pancreatic cancer animal models, relevant patient-derived xenograft systems and primary samples. Our research will provide understanding of the unique biology of mutant GNAS and points out targetable vulnerabilities in genetic subsets of pancreatic tumors.