Understanding PD-L1/L2 protein regulation, detection and signaling to predict melanoma therapeutic sensitivity

项目总结/摘要 癌症中抗PD-1反应性的调节剂和效应物包括T细胞浸润、免疫调节剂和免疫调节剂。 抑制性微环境、肿瘤突变负荷和肿瘤细胞内在途径（例如，- 连环蛋白）改变。细胞表面PD-L1水平被认为是一种基线预测标志物， 抗PD-1反应性和细胞表面PD-L2水平可能具有独立于PD-1的预测价值。 L1。在黑色素瘤中，MAPK抑制剂治疗强烈诱导肿瘤中的PD-L1/L2表达水平， 基质和免疫细胞，这表明适应性抗性的贡献。细胞表面诱导 PD-L1是获得性免疫抵抗的核心，并涉及获得性抗PD-1的机制 阻力此外，表面PD-L1蛋白稳定性的调节与肿瘤的发生有关。 免疫监视，其中增加的降解增强肿瘤特异性T细胞活性。 我们假设，更好地了解控制细胞表面PD的调节机制， L1/L2稳定性、临床检测和肿瘤细胞内在的促生存信号传导可以揭示 黑色素瘤免疫逃避和治疗反应性。我们将使用蛋白质组学方法， 剖析这些过程，并探索黑色素瘤表面糖蛋白组，PD-L1/L2 相互作用体和细胞质信号体，以命名的机制和/或标志物， 治疗反应我们将反复询问临床肿瘤样品和同基因小鼠 Braf、Nras和Nf1突变型黑色素瘤模型。这些免疫活性的黑色素瘤模型是 考虑到其UV诱导的高突变负荷， 治疗反应和广泛转移的能力，包括脑转移。 我们将使用细胞表面标记含唾液酸的聚糖来分析活细胞表面 糖蛋白组，PD-L1/L2的共免疫沉淀以富集相互作用组，以及基于APEX的 蛋白质组学策略，以确定原位动态细胞内PD-L1/L2邻近相互作用组， 对PD-1连接或IFN γ治疗的应答。我们将讨论是什么调节PD-L1/L2泛素化， 回收和降解，糖基化如何影响膜PD-L1免疫组化 检测，去糖基化是否改善了基线和治疗期间抗PD-1应答的预测。 治疗，以及PD-L1/L2的新型胞质基序如何介导PD-1依赖性肿瘤细胞前体， 生存信号我们将对临床黑色素瘤使用邻近连接试验来测试PD-L1/L2是否 肿瘤细胞内在信号传导降低治疗功效。这些蛋白质组学方法应该会有所进展 我们对转移性黑色素瘤治疗反应模式的理解和提名的预测 生物标志物和组合靶标。

PROJECT SUMMARY/ABSTRACT Modulators and effectors of anti-PD-1 responsiveness in cancer include T cell infiltration, an immune- suppressive microenvironment, tumor mutational burden, and tumor cell-intrinsic pathway (e.g., - catenin) alterations. Cell-surface PD-L1 level has been implicated as a baseline predictive marker of anti-PD-1 responsiveness, and cell-surface PD-L2 level may have predictive value independent of PD- L1. In melanoma, MAPK inhibitor therapy strongly induces PD-L1/L2 expression levels in tumor, stromal and immune cells, suggesting contributions to adaptive resistance. Induction of cell-surface PD-L1 is central to adaptive immune resistance and implicated as a mechanism of acquired anti-PD-1 resistance. Moreover, the regulation of surface PD-L1 protein stability has been implicated in tumor immune surveillance, where increased degradation augments tumor-specific T cell activity. We hypothesize that a better understanding of regulatory mechanisms controlling cell-surface PD- L1/L2 stability, clinical detection, and tumor cell-intrinsic pro-survival signaling could shed insights into melanoma immune evasion and therapeutic responsiveness. We will use proteomic approaches to dissect these processes and to explore the melanoma surface glycoproteome, the PD-L1/L2 interactome and the cytoplasmic signalosome in order to nominate mechanisms and/or markers of therapeutic responsiveness. We will interrogate iteratively clinical tumor samples and syngeneic mouse models of Braf, Nras and Nf1 mutant melanoma. These immune-competent models of melanoma are clinically relevant given their UV-induced high mutational burdens, dependence on CD8 T cells for therapeutic responses and capability for widespread metastases, including metastases to the brain. We will use cell-surface labeling of sialic acid-containing glycans to analyze the live cell surface glycoproteome, co-immunoprecipitation of PD-L1/L2 to enrich for interactomes, and APEX-based proteomic strategy to define in situ dynamic intracellular PD-L1/L2 neighborhood interactomes in response to PD-1 ligation or IFN treatment. We will address what regulate PD-L1/L2 ubiquitination, recycling and degradation, how glycosylation affects membrane PD-L1 immunohistochemical detection, whether deglycosylation improves prediction of anti-PD-1 responses at baseline and on- treatment, and how novel cytoplasmic motifs of PD-L1/L2 mediate PD-1-dependent tumor cell pro- survival signaling. Using proximity ligation assays on clinical melanoma, we will test whether PD-L1/L2 tumor cell-intrinsic signaling reduces therapy efficacy. These proteomic approaches should advance our understanding of therapy response patterns in metastatic melanoma and nominate predictive biomarkers and combinatorial targets.