Leveraging Vulnerabilities Induced by STING Activation in Pancreatic Cancer

项目摘要/摘要 干扰素基因刺激物(STING)是治疗实体瘤的新靶点。调查 STING激动剂的治疗相关性主要集中在免疫调节效应上。 肿瘤微环境中依赖刺激性诱生的I型干扰素的介导。 然而，STING激动剂诱导的干扰素信号如何影响肿瘤细胞的信号和代谢。 人们对此知之甚少，而且，这些效应是否可以在治疗上加以利用还没有得到调查。数据 研究表明，STING在胰腺导管腺癌(PDAC)中高度过度表达， 它在PDAC恶性细胞中的激活导致干扰素信号依赖的肿瘤生长受损 举止。因此，阐明刺痛驱动的干扰素信号转导的后果在PDAC中尤为重要 它是美国癌症相关死亡的第三大原因，总存活率不到1 年。初步的代谢组学和蛋白质组学分析指出了两种主要的相互关联的生化 干扰素信号对PDAC细胞过程的影响：(I)核苷酸代谢，这是由 脱氧核糖核酸三磷酸(DNTP)和烟酰胺腺嘌呤二核苷酸(NAD)池耗尽；以及 (Ii)毛细血管扩张性共济失调介导的DNA复制应激反应信号通路的激活 RAD3相关蛋白(ATR)。这一提议旨在检验这样一个假设，即叮咬驱动的dNTP和 恶性细胞中NAD耗竭是由于SAM结构域和HD结构域转录上调所致。 含有蛋白1(SAMHD1)，一种强大的dNTP磷酸水解酶，以及聚- ADP核糖聚合酶(PARP)家族(PARP9/10/14)分别增加NAD消耗。会的 进一步验证恶性细胞参与特定的适应性机制来抵消这些的假设 代谢改变，它们的抑制将与刺痛激动剂协同作用。目标1中的研究将 研究原位PDAC细胞株和患者来源的异种移植中STING激活的后果 模型，并将调查STING激活和 复制压力。AIM 2的研究将测试合理设计的联合疗法，以阻止两种主要的联合- PDAC细胞中STING激活引起的依赖性：(I)ATR调节的复制应激反应 和(Ii)烟酰胺磷酸核糖基转移酶(NAMPT)介导的烟酰胺循环。AIM 3中的研究 将使用免疫活性植入和固有的PDAC模型来测试靶向的概念 在正在进行的临床试验提供的背景下，目标1和目标2中确定的相互依赖关系 激动剂与免疫检查点封锁相结合。总体来说，本申请中建议的研究包括 旨在增加对STIN/干扰素信号、核苷酸/NAD之间相互作用的理解 PDAC中的新陈代谢和复制压力，最终目标是发现关键漏洞 被新的治疗方法利用来对抗这种极具侵袭性和难以治疗的恶性肿瘤。

PROJECT SUMMARY/ABSTRACT Stimulator of interferon genes (STING) is an emerging target for the treatment of solid tumors. Investigations of the therapeutic relevance of STING agonists have primarily focused on the immunomodulatory effects mediated by STING-activation dependent induction of type I interferons (IFN) in the tumor microenvironment. However, how IFN signaling induced by STING agonists impacts malignant cell signaling and metabolism is poorly understood and, whether these effects can be therapeutically exploited has not been investigated. Data are presented showing that STING is highly over-expressed in pancreatic ductal adenocarcinoma (PDAC) and that its activation in PDAC malignant cells results in impaired tumor growth in an IFN-signaling dependent manner. Thus, elucidating the consequences of STING-driven IFN signaling is particularly relevant in PDAC which is the third-leading cause of cancer-related mortality in the U.S. with an overall survival of less than one year. Preliminary metabolomic and proteomic analyses point to two major interconnected biochemical processes impacted by IFN signaling in PDAC cells: (i) nucleotide metabolism, which is evidenced by the depletion of deoxyribonucleotide triphosphate (dNTP) and nicotinamide adenine dinucleotide (NAD) pools; and (ii) activation of the DNA replication stress response signaling pathway mediated by Ataxia Telangiectasia and Rad3-related protein (ATR). This proposal is designed to test the hypothesis that STING-driven dNTP and NAD depletion in malignant cells result from the transcriptional upregulation of SAM domain and HD domain- containing protein 1 (SAMHD1), a powerful dNTP phosphohydrolase, and of specific members of the poly- ADP-ribose-polymerase (PARP) family (PARP9/10/14) which increase NAD consumption, respectively. It will further test the hypothesis that malignant cells engage specific adaptive mechanisms to counteract these metabolic alterations and that their inhibition will synergize with STING agonists. Studies in Aim 1 will investigate the consequences of STING activation in orthotopic PDAC cell line and patient-derived xenograft models from a pre-existing repository and will investigate mechanistic links between STING activation and replication stress. Studies in Aim 2 will test rationally designed combination therapies that block two major co- dependencies elicited by STING activation in PDAC cells: (i) the ATR-regulated replication stress response and (ii) nicotinamide phosphoribosyltransferase (NAMPT)-mediated nicotinamide recycling. Studies in Aim 3 will employ immunocompetent implantation and autochthonous PDAC models to test the concept of targeting co-dependencies identified in Aims 1 and 2 in the context provided by ongoing clinical trials in which STING agonists are combined with immune checkpoint blockade. Collectively, studies proposed in this application are designed to increase the understanding of the interplay between STING/IFN signaling, nucleotide/NAD metabolism and replication stress in PDAC with the ultimate goal of uncovering critical vulnerabilities to be exploited by new therapeutic approaches against this extremely aggressive and difficult to treat malignancy.