DNA damage signaling to immune checkpoints

肺癌确诊较晚，5年存活率只有15%，而且比结直肠癌导致更多的人死亡， 乳腺癌和前列腺癌加在一起。只有不到30%的肺癌被切除，而大多数 患者接受顺铂和电离辐射(IR)治疗。我们发现，DNA损伤信号的抑制 在顺铂和IR治疗期间使用ATR激酶具有良好的耐受性，并在小鼠中导致持久反应 肺癌的异种移植和遗传模型。非常出人意料的是，我们展示了除了增强 DNA损伤，两种临床ATR激酶抑制剂(ATRI)，具有无关的结构，阻断 免疫检查点蛋白PD-L1和MHC-I类抗原在肺癌细胞中的表达 IR.我们发现DNA损伤信号和免疫检查点之间存在串扰 这是前面描述的，也是本提案的重点。免疫抑制途径，称为免疫 检查点，是肿瘤细胞为了躲避细胞毒免疫细胞而选择的。PD-1在细胞毒性T细胞上的表达 细胞及其配体PD-L1在肺癌中表达上调。PD-1与PD-L1结合可阻止 细胞毒T细胞。使用抗PD-L1和抗PD-1抗体的免疫检查点阻断恢复抗肿瘤 免疫反应，并正在成为一种令人兴奋的肺癌治疗方法。我们认为ATRI‘s抑制DNA 修复和细胞周期检查点同时增强顺铂和IR诱导的DNA损伤 抑制PD-L1表达，恢复抗肿瘤免疫反应。我们在这项建议中的目标是 定义连接DNA损伤信号和免疫检查点的机制。这一目标将是 通过以下具体目标实现。目的1：研究ATRI对肺组织PD-L1表达的抑制作用 IR后的癌细胞。这一目标将确定ATR、ATM、IRF-1、NF-κB和P53对PD-L1的贡献 IR后的表达。目的2：研究ATRI对肺癌细胞MHC-I类分子表达的影响 在IR之后。这一目标将识别ATR、ATM和P53信号，这些信号抑制蛋白质合成和MHC I类 IR之后的演示。目的3：确定ATRI诱导的PDL-1/PD-1免疫检查点阻断对肺癌的作用 在IR之后。这一目的将确定ATRI诱导的免疫检查点阻断在肺癌IR后。这个 这些目标的结果将确定将DNA损伤信号与免疫自我联系起来的机制 宽容。这将定义一个新的治疗机会，使用ATRI来加强DNA损伤 顺铂和IR诱导，同时诱导免疫关卡阻断。

Lung cancer is diagnosed late, has a 5 year survival of only 15%, and kills more people than colorectal, breast and prostate cancer combined. Less than 30% of lung cancers are resected and the majority of patients are treated with cisplatin and ionizing radiation (IR). We show that inhibition of DNA damage signaling by ATR kinase during treatment with cisplatin and IR is well-tolerated and leads to durable responses in mouse xenograft and genetic models of lung cancer. Quite unexpectedly, we show that in addition to potentiating DNA damage, two clinical ATR kinase inhibitors (ATRi’s), with unrelated structures, block expression of the immune checkpoint protein PD-L1 and increase presentation of MHC class I antigens in lung cancer cells after IR. Our finding that crosstalk exists between DNA damage signaling and immune checkpoints has not been described previously and is the focus of this proposal. Immune-inhibitory pathways, termed immune checkpoints, are coopted by tumor cells to evade cytotoxic immune cells. PD-1 is expressed on cytotoxic T cells and its ligand PD-L1 is upregulated in lung cancers. PD-L1 binding by PD-1 prevents the activation of cytotoxic T cells. Immune checkpoint blockade using anti-PD-L1 and anti-PD-1 antibodies restores anti-tumor immune responses and is emerging as an exciting lung cancer therapy. We propose that ATRi’s inhibit DNA repair and cell cycle checkpoints potentiating the DNA damage induced by cisplatin and IR while concurrently inhibiting PD-L1 expression and restoring anti-tumor immune responses. Our objective in this proposal is to define the mechanisms that connect DNA damage signaling and immune checkpoints. This objective will be accomplished by the following Specific Aims. Aim 1: To determine how ATRi’s inhibit PD-L1 expression in lung cancer cells after IR. This aim will define the contribution of ATR, ATM, IRF-1, NF-κB and p53 to PD-L1 expression after IR. Aim 2: To determine how ATRi’s increase MHC class I expression on lung cancer cells after IR. This aim will identify ATR, ATM, and p53 signaling that inhibits protein synthesis and MHC class I presentation after IR. Aim 3: To identify ATRi-induced PDL-1/PD-1 immune checkpoint blockade in lung cancer after IR. This aim will identify ATRi-induced immune checkpoint blockade in lung cancer after IR. The outcomes of these Aims will identify mechanisms that connect DNA damage signaling to immune self- tolerance. This will define a novel therapeutic opportunity to use ATRi’s to potentiate the DNA damage induced by cisplatin and IR while concurrently inducing immune checkpoint blockade.