DNA damage signaling to immune checkpoints

肺癌诊断较晚，5年生存率仅为15%，比结直肠癌死亡人数更多， 乳腺癌和前列腺癌不到30%的肺癌被切除， 患者用顺铂和电离辐射（IR）治疗。我们发现抑制DNA损伤信号 在用顺铂和IR治疗期间通过ATR激酶的抑制是耐受良好的，并且在小鼠中导致持久的反应。 异种移植物和肺癌遗传模型。出乎意料的是，我们发现，除了增强 DNA损伤，两种临床ATR激酶抑制剂（ATRi），具有不相关的结构，阻断了 免疫检查点蛋白PD-L1与肺癌细胞中MHC I类抗原提呈增加 红外光谱我们发现DNA损伤信号和免疫检查点之间存在串扰， 这是前面提到的，也是本书的重点。免疫抑制途径，称为免疫 检查点被肿瘤细胞吸收以逃避细胞毒性免疫细胞。PD-1在细胞毒性T细胞上表达 细胞及其配体PD-L1在肺癌中上调。PD-1与PD-L1的结合阻止了 细胞毒性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抑制DNA 修复和细胞周期检查点增强顺铂和IR诱导的DNA损伤，同时 抑制PD-L1表达和恢复抗肿瘤免疫应答。我们提出这项建议的目的是 定义连接DNA损伤信号和免疫检查点的机制。这一目标将是 实现以下具体目标。目的1：确定ATRi如何抑制肺中PD-L1的表达 本研究的目的是确定ATR、ATM、IRF-1、NF-κB和p53对PD-L1的作用 目的2：确定ATRi如何增加肺癌细胞上的MHC I类表达 这一目标将确定ATR，ATM和p53信号，抑制蛋白质合成和MHC I类 目的3：鉴定ATRI诱导的肺癌中的PDL-1/PD-1免疫检查点阻断。 该目的将鉴定IR后肺癌中ATRI诱导的免疫检查点阻断。 这些目标的结果将确定DNA损伤信号与免疫自我之间的联系机制， 宽容这将定义一个新的治疗机会，使用ATRi的，以加强DNA损伤 诱导顺铂和IR，同时诱导免疫检查点阻断。

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.