Characterizing the Mechanism of DPP8/9 Inhibitor-Induced Pyroptosis

项目摘要 癌症免疫疗法--免疫系统被释放出来摧毁癌细胞--是一场革命 对抗癌症的新方法。然而，尽管免疫疗法取得了前所未有的成就， 尽管免疫疗法在临床上没有疗效，但许多癌症还不适合免疫疗法，即使对于那些适合免疫疗法的癌症， 大多数患者没有反应。具有改进的或互补的作用机制的新药剂是 因此需要。一个有趣的，但知之甚少的潜在癌症免疫治疗剂是小的 分子Val-boroPro。Val-boroPro在多种小鼠模型中诱导免疫介导的肿瘤消退 通过诱导单核细胞和巨噬细胞中的细胞凋亡（一种程序性细胞死亡的裂解形式）来治疗癌症。 值得注意的是，Val-boroPro是发现的第一个诱导细胞凋亡的小分子。现已成立 VbP对胞质丝氨酸肽酶DPP8和DPP9（DPP8/9）的抑制激活了前蛋白 caspase-1的形式来介导细胞死亡，但DPP8/9抑制如何导致caspase-1的激活 仍然完全未知。该项目的长期目标是成功地利用这一途径， 癌症免疫疗法本提案的目的是确定DPP 8/9的抑制如何诱导 单核细胞和巨噬细胞中的焦亡。核心假设是DPP 8/9切割和双氢吡喃酮 或多种肽，其如果不被切割，则激活先天免疫传感器蛋白Nlrp1。激活的Nlrp1 然后激活半胱天冬酶原1引发细胞凋亡这一假设是根据以下事实提出的： 申请人实验室提供的初步数据，并在申请中予以描述。这一假设将 通过追求三个具体目标进行测试：1）确定菌株、物种和细胞类型对DPP 8/9的敏感性 抑制剂，因为Nlrp1是高度多态性的，并且在菌株和物种之间变化很大; 2）确定 通过DPP8/9抑制剂激活Nlrp1的分子机制;和3）确定特定的共- DPP8/9介导的焦亡所需的分子伴侣，我们假设这是导致 稳定性、折叠或运输关键的焦亡因子（例如，Nlrp1或DPP 8/9底物）。成功 完成这项提案将揭示新的原则和机制，调节先天免疫 系统，提供病原体识别，自身免疫性疾病和炎症的见解。此外，委员会认为， 这项工作具有非凡的潜力，以确定新的目标和战略，可以形成新的基础， 癌症免疫疗法

PROJECT SUMMARY Cancer immunotherapy – where the immune system is unleashed to destroy cancer cells – is a revolutionary new approach for combating cancer. However, even though immunotherapy has achieved unprecedented efficacies in the clinic, many cancers are not yet amenable to immune therapy, and even for those that are, a majority of patients fail to respond. New agents with improved or complementary mechanisms of action are therefore needed. One intriguing, yet poorly understood potential cancer immunotherapy agent is the small molecule Val-boroPro. Val-boroPro induces immune-mediated tumor regressions in multiple mouse models of cancer by inducing pyroptosis, a lytic form of programmed cell death, in monocytes and macrophages. Notably, Val-boroPro was the first small molecule discovered that induces pyroptosis. It is now established that inhibition of the cytosolic serine peptidases DPP8 and DPP9 (DPP8/9) by VbP activates the pro-protein form of caspase-1 to mediate cell death, but how DPP8/9 inhibition leads to the activation of caspase-1 remains entirely unknown. The long-term goal of this project is to successfully harness this pathway for cancer immunotherapy. The objective of this proposal is to determine how the inhibition of DPP8/9 induces pyroptosis in monocytes and macrophages. The central hypothesis is that DPP8/9 cleave and inactivate one or more peptides, which, if not cleaved, activates the innate immune sensor protein Nlrp1. Activated Nlrp1 then activates pro-caspase-1, triggering pyroptosis. This hypothesis has been formulated on the basis of preliminary data produced in the applicant's laboratory and described in the application. This hypothesis will be tested by pursuing three specific aims: 1) Determine strain, species, and cell type sensitivity to DPP8/9 inhibitors, as Nlrp1 is highly polymorphic and varies considerably across strains and species; 2) determine the molecular mechanism of Nlrp1 activation by DPP8/9 inhibitors; and 3) determine the function of a specific co- chaperone required for DPP8/9 inhibitor-induced pyroptosis, which we hypothesize is responsible for the stability, folding, or trafficking of a key pyroptosis factor (e.g., Nlrp1 or the DPP8/9 substrate). Successful completion of this proposal will uncover new principles and mechanisms regulating the innate immune system, providing insights into pathogen recognition, autoimmune disorders, and inflammation. Moreover, this work has extraordinary potential to identify new targets and strategies that could form the bases of novel cancer immunotherapies.