Targeting posttranslational modifications of B7-H4 in carcinogenesis and therapy

靶向B7-H4翻译后修饰在肿瘤发生和治疗中的作用 本项目的目标是确定B7-H4的糖基化和泛素化之间的相互作用的影响 在乳腺癌发生和抗乳腺癌治疗中的应用。B7-H4，也称为含有V-set结构域的T细胞 激活抑制因子1（VTCN 1），作为免疫检查点蛋白，其局部异常积累是 与包括三阴性乳腺癌（TNBC）在内的各种类型癌症的不良预后相关。而 目前的一项TCGA研究表明，B7-H4在赋予肿瘤对化疗药物的敏感性方面起着关键作用， 和免疫检查点抑制剂，B7-H4是如何调节的，以及它的失调如何有助于乳腺癌的发生。 致癌作用和肿瘤药物反应仍然未知。我们最近对B7-H4的纯化结果 蛋白质复合物揭示了2个关键酶AMFR和STT 3复合物， B7-H7虽然E3泛素连接酶AMFR催化B7-H4的泛素化，然后降解，我们 观察到B7-H4蛋白被STT 3复合物（一种糖基转移酶）糖基化， 稳定B7-H4和抑制阿霉素诱导的免疫原性细胞死亡（ICD）。B7-H4标高 由于B7-H4糖基化增强而导致的水平抵消了B7-H4泛素化，这反过来又抑制了B7-H4泛素化。 内质网应激介导的对化疗药物应答的吞噬作用， 触发ICD的大规模肿瘤根除。我们进一步证明，阻断B7-H4糖基化， NGI-1是一种新的蛋白质糖基化抑制剂，它显著增强B7-H4泛素化和随后的 降解，导致由于树突细胞的吞噬作用增加而促进肿瘤杀伤功效， 它们引发产生CD 8+干扰素-γ的T细胞应答的能力。在这个项目中，我们计划测试 假设B7-H4通过糖基化和泛素化之间串扰而失调促进了 TNBC肿瘤逃避化疗和NGI-1阻断B7-H4糖基化可能是一种新的策略 用于抗TNBC治疗。我们提出以下具体目标来实现这一目标：（1）确定 糖基化和泛素化之间的相互作用调节B7-H4-协调 （2）确定STT 3介导的糖基化和AMFR促进的糖基化的生理相关性。 B7-H4介导的ICD对化疗药物的应答中的泛素化;以及（3）确定B7-H4介导的ICD对化疗药物的应答的临床意义。 在使用各种临床前小鼠的抗TNBC治疗中通过NGI-1阻断B7-H4糖基化的相关性 模型

Targeting post-translational modifications of B7-H4 in carcinogenesis and therapy The goal of this project is to determine the impact of interplay between glycosylation and ubiquitination of B7-H4 in breast carcinogenesis and anti-breast cancer therapy. B7-H4, also known as V-set domain containing T cell activation inhibitor 1 (VTCN1), acts as an immune checkpoint protein whose local abnormal accumulation is correlated with poor prognosis of various types of cancers including triple negative breast cancer (TNBC). While a current TCGA study suggests the critical role of B7-H4 in conferring tumor sensitivity to chemotherapy drugs and immune checkpoint inhibitors, how B7-H4 is regulated and how its deregulation contributes to breast carcinogenesis and tumor drug response remain unknown. Results from our recent purification of the B7-H4 protein complex revealed that 2 critical enzymes, AMFR and STT3 complex, tightly interact with and regulate B7-H7. While the E3 ubiquitin ligase AMFR catalyzes ubiquitination of B7-H4 followed by degradation, we observed that glycosylation of B7-H4 protein by the STT3 complex (a glycosyltransferase) results in the stabilization of B7-H4 and inhibition of doxorubicin-induced immunogenic cell death (ICD). Elevation of B7-H4 levels due to enhanced B7-H4 glycosylation counteracts B7-H4 ubiquitination, which in turn suppresses endoplasmic reticulum stress-mediated phagocytosis in response to chemotherapy drugs, a critical step in triggering mass tumor eradication by ICD. We further demonstrated that blockade of B7-H4 glycosylation by NGI-1, a novel protein glycosylation inhibitor, significantly enhances B7-H4 ubiquitination and subsequent degradation, resulting in promotion of tumor killing efficacy due to increased phagocytosis by dendritic cells and their capacity to elicit CD8+ interferon-γ-producing T cell responses. In this project, we plan to test the hypothesis that deregulation of B7-H4 by the crosstalk between glycosylation and ubiquitination promotes TNBC tumor evasion from chemotherapy and blockade of B7-H4 glycosylation by NGI-1 could be a new strategy for anti-TNBC treatment. We propose the following specific aims to pursue this goal: (1) to determine the mechanism by which interplay between glycosylation and ubiquitination regulates B7-H4-orchestrated phagocytosis; (2) to determine the physiological relevance of STT3-mediated glycosylation and AMFR-facilitated ubiquitination in B7-H4-mediated ICD in response to chemotherapy drugs; and (3) to determine the clinical relevance of blockade of B7-H4 glycosylation by NGI-1 in anti-TNBC treatment using various preclinical murine models.