HBV增强Tim-3表达维持肝癌起始细胞干性促进肿瘤发生的机制研究

免疫检查点分子Tim-3调控多种免疫细胞功能，是肿瘤免疫治疗的重要候选分子。课题组已报道Tim-3通过调控CD8+T、NK细胞功能和巨噬细胞分化，参与慢乙肝和肝癌发生。前期研究还发现，Tim-3可高表达于肝癌细胞，与HBsAg、病理分级正相关，与生存期负相关，促进肝癌细胞体内外生长，且Tim-3+肝癌细胞表达更高CD133，具有更强的成球能力。据此，提出本课题假说：HBV上调肝细胞中Tim-3表达，维持肿瘤起始细胞干性特征，促进肝癌进程。本课题拟在前期工作基础上，利用突变体分析、质谱技术结合功能阻断实验，通过体内外实验和临床检测，进一步研究HBV上调肝细胞中Tim-3表达的机制，明确肝癌细胞Tim-3维持干性特征参与肿瘤发生的作用，探讨Tim-3维持肿瘤起始细胞干性特征的分子机制。课题的实施将阐释为Tim-3参与肿瘤发生的新机制，为以其为靶点的药物设计和生物学治疗提供更为确凿的实验依据。

Tim-3, an immune checkpoint molecule, regulates the function of immune cells and participates in tumorigenesis, which makes it being an candidate target in tumor immunotherapy. We reported previously Tim-3 was involved in the pathogenesis of chronic hepatitis B and liver cancer by regulating the function of T cell and NK cell and the differentiation of macrophage. We also found that Tim-3 is highly expressed on malignant hepatocytes, which is positively correlated with HBsAg and pathologic grade and negatively correlated with patient survival. Tim-3 promotes the growth of liver cancer cells both in vitro and in vivo. Moreover, Tim-3+ hepatocytes have higher level of CD133 and stronger sphere formation ability. Thus, we hypothesized that HBV-enhanced Tim-3 maintains the stemness of tumor initiating cells and promotes the development of liver cancer. Here, we would utilize mutants analysis, mass spectrometry and functional blocking assay to study the mechanism of HBV enhancement on Tim-3 expression on hepatocytes, to demonstrate the function of Tim-3 in maintaining the stemness and promoting carcinogenesis, and to probe into the mechanisms by using in vitro and in vivo model and clinical HCC samples. This study would be helpful for clarifying the novel mechanisms for Tim-3 involvement in tumorigenesis and for the drug design and biological treatment based on Tim-3.