WTAP介导的m6A修饰调控肿瘤相关巨噬细胞极化促进肝癌免疫逃逸的机制研究

肿瘤微环境中的肿瘤相关巨噬细胞（TAMs）是引起肝细胞癌免疫逃逸和免疫治疗抵抗的重要因素。我们前期研究发现肝癌微环境中的TAMs高表达肾母细胞瘤1相关蛋白（WTAP），当WTAP敲低后，溴结构域蛋白4（BRD4）和PD-L1表达量下降。由此我们提出科学假说：WTAP可以介导BRD4的m6A RNA甲基化修饰，进而增加PD-L1的表达，调控TAMs向M2型极化，促进肝癌免疫逃逸。本项目将研究WTAP介导的m6A修饰调控肝癌TAMs表型重塑的功能；阐明WTAP/BRD4/PD-L1通路在引起肝癌TAMs向M2型极化的分子机制；探索抑制m6A甲基化促进TAMs向抗肿瘤方向再极化的作用；在小鼠原位肝癌成瘤模型上评估PD-1抗体和m6A甲基化抑制剂联合应用克服肝癌免疫治疗抵抗的效果。本项目的深入开展，有助于阐明m6A修饰在肝癌TAMs表型重塑中的作用，为肝癌免疫治疗的联合用药提供新策略。

Tumor-associated macrophages (TAMs) in the tumor microenvironment is associated with immune escape and correlates with immunotherapy resistance in hepatocellular carcinoma(HCC). Our previous study found that Wilms tumor 1-associated protein (WTAP) was overexpressed in TAMs infiltrated in HCC and the knockdown of WTAP caused the decrease of mRNA expression of bromodomain protein 4 (BRD4) and PD-L1. Therefore, we propose a scientific hypothesis: WTAP can mediate the m6A methylation of BRD4 mRNA, thereby increasing the expression of PD-L1, regulating TAMs polarization to M2 type, and facilitating HCC to escape from the immune surveillance. Here, we attempt to investigate the effect of WTAP-mediated m6A methylation on TAMs reprogramming and to reveal the potential mechanism of WTAP / BRD4 / PD-L1 pathway in causing TAMs to M2 polarization in HCC. In addition, our study will explore whether WTAP inhibitor could promote TAMs reprogramming to restore antitumour properties, and evaluate the role of combined WTAP inhibitor and anti-PD-1 monoclonal antibody in overcoming immunotherapy resistance in mice model of in situ HCC formation. Together, this study will elucidate the role of RNA m6A methylation in TAMs reprogramming and provide a novel strategy for immunotherapy combined with target therapy in HCC.