整合素β1糖基化介导肿瘤相关巨噬细胞促进肝癌转移的作用及机制研究

The development and progression of hepatocellular carcinoma (HCC) is dependent on its local hypoxic microenvironment. Tumor cells can survive mild hypoxia, still undergo necrosis when severe hypoxia persists. However, the role of necrotic cell debris in HCC tumor environment remains poorly understood. Preliminary results showed that O-linked glycosylation of necrotic HCC cell debris could induce potent IL-1β release by tumor associated macrophages, causing a hypoxic-inflammatory microenvironment, which further facilitated tumor epithelial-mesenchymal transition and metastasis. More importantly, mass spectrometry results indicated a potential role of Integrin β1 in necrotic cell debris-mediated TAMs activation. Immunoblot analysis of VVL further confirmed O-Glycosylation of Integrin β1. In this project, we would explore the role of Integrin β1 O-Glycosylation in HCC progression and metastasis and discuss the potential mechanism of TAMs phenotype shift induced by O-Glycosylation of Integrin β1. Our results would contribute to further understanding of O-Glycosylation mediated crosstalk between TAMs and HCC cells and provide novel strategies for HCC treatment.

肝癌的发生发展与其低氧微环境密切相关。肿瘤细胞可耐受轻度低氧，但严重缺氧仍导致细胞坏死。坏死细胞成分对微环境中免疫细胞及存活肿瘤细胞的影响尚未明确。课题组前期研究发现肝癌坏死细胞碎片O-糖基化成分可被肿瘤相关巨噬细胞（TAMs）TLR4受体识别，促使IL-1β分泌并维持局部微环境炎性改变，进一步促进肝癌上皮间质转化（EMT）及转移。质谱结果提示整合素β1（Integrin β1）参与其中，体外实验也证实肝癌中Integrin β1存在O-GalNAc糖基化修饰。本课题拟在前期研究基础上，通过体内外实验研究肝癌Integrin β1 O-GalNAc糖基化修饰特征及在肝癌进展转移中的作用。探讨Integrin β1 O-GalNAc糖基化对诱导TAMs M2亚型的具体作用机制。研究结果有望明确O-GalNAc糖基化介导肝癌TAMs与肿瘤细胞相互作用的机制，为肝癌治疗提供潜在靶点。

肝癌的发生发展与其低氧微环境密切相关。肿瘤细胞可耐受轻度低氧，但严重缺氧仍导致细胞坏死。坏死细胞成分对微环境中免疫细胞及存活肿瘤细胞的影响尚未明确。课题组前期研究发现肝癌坏死细胞碎片O-糖基化成分可被肿瘤相关巨噬细胞（TAMs）TLR4受体识别，促使IL-1β分泌并维持局部微环境炎性改变，进一步促进肝癌上皮间质转化（EMT）及转移。但TAMs识别具体O-糖基化位点、细胞表型和功能特征及其在肝癌进展中的作用机制尚不清楚。本项目的研究成果明确了肝癌内O-GalNAc修饰谱改变特征。同时发现“蛋白O-GalNAc修饰结构单元”是TAMs识别的可能分子模式。进一步研究发现蛋白O-GalNAc修饰能诱导TAMs分化为CD61+ PDL1+IL-1β+ CXCL5+ TAMs亚型，且伴有代谢类型向糖酵解转变。体内研究证实CD61+TAMs可能通过分泌CXCL5招募微环境中性粒细胞浸润进而促进肝癌进展，诱导微环境免疫抑制。本课题的研究结果进一步丰富了O-GalNAc糖基化介导肝癌TAMs与肿瘤细胞相互作用的机制，为以CD61+TAMs为靶标的新型肝癌防止手段提供理论依据。