Tumor cell-intrinsic STING signaling and IFN-Beta gene regulation in cancer

有自发抗肿瘤T细胞反应证据的患者预后较好，很可能 对目前临床上使用的检查点封锁免疫疗法做出反应。找出为什么有些患者 缺乏自发的抗肿瘤免疫反应并找到促进内源性反应的方法将很可能 将疗效扩大到这些患者。我们的实验室之前已经显示免疫原性肿瘤自发激活 先天免疫系统通过刺痛途径。刺痛通路感知胞浆DNA，它 激活信号转导通路，最终导致转录因子IRF3和IRF3的核转位 核因子-κB，进而诱导包括干扰素-β在内的几个基因的表达。STING信号与干扰素-β受体 肿瘤浸润性免疫细胞中的信号对CD8T细胞抗肿瘤的最佳启动都是必需的 抗原。同样，瘤内注射STING激动剂可增加干扰素-β的表达，抗肿瘤T细胞 启动，并在临床前模型中引起戏剧性的肿瘤排斥。作为我们对肿瘤内治疗工作的一部分 我们观察到肿瘤细胞本身是肿瘤中唯一存在的细胞类型 微环境不能表达干扰素-β对胞浆DNA或直接刺痛激动剂的反应。我们测试了一个 发现绝大多数肿瘤细胞株都不能在STING下游表达干扰素-β 信号传递，认为这一通路的失活可能是肿瘤发生的一个组成部分。 我们的总体假设是，确定肿瘤细胞缺乏干扰素-β表达的原因并逆转这一点 表型可能导致诱导内源性抗肿瘤免疫反应的新策略。我们的预赛 数据表明，在肿瘤细胞中，STING信号很大程度上是巧妙的，直到并包括核转位 IRF3.我们发现肿瘤细胞在干扰素-β位点存在IRF3DNA结合缺陷，并且缺乏干扰素-β STING激活后的表达是一种主要的表型。为了更好地了解肿瘤细胞的内在特性 STING信号，以及它在肿瘤细胞中的缺陷，我们建议：1)识别和逆转分子 用临床前模型防止干扰素-β在肿瘤细胞中的刺痛诱导机制 观察这如何影响体内的肿瘤/免疫界面2)了解STING信号在体内的潜在作用 通过分析细胞系和肿瘤活检组织，研究人类癌症。初步数据显示肿瘤细胞不同 来自对照细胞的干扰素基因座的表观遗传可及性和核因子-κB信号转导后的刺激性。 因此，我们将研究肿瘤细胞中的核因子-kB信号及其对干扰素基因座可及性的影响。我们会 也沉默少数能够表达干扰素-β的肿瘤细胞中的刺痛通路，以观察这一过程 使用主机免疫性调整接口。当我们分析人类肿瘤细胞系和活组织检查时，我们将开始 确定有多大比例的患者可能对旨在使肿瘤细胞表达的疗法有反应 干扰素-β。最终，我们的工作将成为越来越多的证据中的重要组成部分，这些证据表明 肿瘤发生和先天免疫之间的联系意味着后者是一种肿瘤抑制因子。 好了！

Patients with evidence of spontaneous anti-tumor T cell responses have a better prognosis and are likely to respond to checkpoint blockade immunotherapies currently used in the clinic. Identifying why some patients lack spontaneous anti-tumor immune responses and finding ways to promote endogenous responses will likely expand efficacy to these patients. Our lab has previously shown immunogenic tumors spontaneously activate the innate immune system through the STING pathway. The STING pathway senses cytosolic DNA, which activates a signal transduction pathway culminating in nuclear translocation of transcription factors IRF3 and NF-κB that, in turn, induce expression of several genes including IFN-β. STING signaling and IFN-β receptor signaling in tumor-infiltrating immune cells are both required for optimal priming of CD8+ T cells against tumor antigens. Likewise, intratumoral injection of STING agonists increases IFN-β expression, anti-tumor T cell priming, and causes dramatic tumor rejection in pre-clinical models. As part of our work with intratumoral STING agonists we observed that the tumor cells themselves were the only cell type present in the tumor microenvironment unable to express IFN-β in response to cytosolic DNA or direct STING agonists. We tested a range of tumor cell lines and found the vast majority was unable to express IFN-β downstream of STING signaling, arguing that loss of activation of this pathway might occur regularly as a component of oncogenesis. Our over-arching hypothesis is that determining why tumor cells lack IFN-β expression and reversing this phenotype could lead to a new strategy to induce endogenous anti-tumor immune responses. Our preliminary data indicates that STING signaling is largely in tact in tumor cells up to and including nuclear translocation of IRF3. We find tumor cells have a defect in IRF3 DNA binding at the IFN-β locus and that the lack of IFN-β expression following STING activation is a dominant phenotype. To better understand tumor cell-intrinsic STING signaling, and how it is defective in tumor cells, we propose to: 1) identify and reverse the molecular mechanism preventing STING induction of IFN-β in tumor cells using pre-clinical models where we can observe how this affects the tumor/immune interface in vivo 2) understand the potential for STING signaling in human cancer by analyzing both cell lines and tumor biopsies. Preliminary data suggests tumor cells differ from control cells in the epigenetic accessibility of the IFN locus and NF-κB signaling after STING activation. Therefore we will study NF-kB signaling in tumor cells and it's affect on accessibility of the IFN locus. We will also silence the STING pathway in the few tumor cells capable of expressing IFN-β to observe how this modulates the interface with host immunity. As we analyze human tumor cell lines and biopsies we will begin to determine what fraction of patients might respond to therapies designed to enable tumor cells to express IFN-β. Ultimately our work will be an important part of a growing body of evidence indicating a deeper connection between oncogenesis and innate immunity that implicates the latter as a tumor suppressor. !