B7-H1/PD-1反向信号在调控胃癌干细胞功能中的机制

The tumor cells can express B7-H1 which can bind with PD-1 on T cells to inhibit tumor immunity.However,currently there is no research to clarify that B7-H1 can act as a receptor to enhance tumor growth.The applicant confirmed in early research that PD-1 can stimulate the B7-H1 on cancer stem cells.Therefore Wnt signal pathway is activated and the proliferation ability is enhanced.Thus this project will carry out following work. 1.To prove that PD-1 via the B7-H1/PD-1 pathway can promote the gastric cancer stem cell self-renewal, resistance to apoptosis, tolerance to chemotherapy, and the proliferation and differentiation of the tumor cells; 2. Screening to find proteins which can bind with B7-H1 intracellular domain to clear know which molecular can be activated by the activation of B7-H1 patheway; 3.we will test the reliability of key signal melacular or the function of down stream molecular and genes.

肿瘤细胞表达的B7-H1与T细胞表达的PD-1结合，正向抑制T细胞的抗肿瘤效应。但尚无研究阐明：B7-H1是否可接受PD-1的信号，反向影响肿瘤本身。申请者承接上一个基金的研究发现：HMGB1可上调胃癌细胞B7-H1表达，而B7-H1/PD-1反向信号能促进胃癌干细胞的成瘤能力，且此效应与Wnt通路相关。故本项目以“HMGB1—B7-H1/PD-1反向信号—胞内结合蛋白—Wnt通路—胃癌干细胞功能变化”为主轴，拟进行以下工作：1. 验证HMGB1可上调胃癌干细胞的B7-H1表达，而B7-H1/PD-1反向信号促进胃癌干细胞的功能；2. 筛选B7-H1胞内段的结合蛋白和介导B7-H1/PD-1反向信号的关键分子；3.明确关键信号分子与干细胞功能基因表达的相关性，阐明B7-H1/PD-1反向信号影响胃癌干细胞功能的机制，提出靶向干预B7-H1/PD-1通路治疗肿瘤的新的理论依据。

胃癌肿瘤细胞表达的B7-H1与T细胞表达的PD-1结合，正向抑制T细胞的抗肿瘤效应。然而PD-1/B7-H1逆向信号传导少有报道。本课题证实：（1）PD-1刺激可使高表达B7-H1的胃癌细胞抵抗5-Fu诱导的凋亡，从功能上提示PD-1/B7-H1反向信号通路的存在；（2）应用RT-qPCR对凋亡相关基因的差异表达筛选提示，PD-1/B7-H1反向信号使部分凋亡相关基因表达改变；（3）应用Co-IP结合质谱的方法对B7-H1可能的胞内结合蛋白进行筛选，提示Filamin A可与B7-H1结合而参与了PD-1/B7-H1反向信号通路的传导；（4）此外，以胃癌表达调控机制为切入点，运用ChIP、小鼠模型等方法证实HDAC是B7-H1表达中重要调控因子，是靶向B7-H1表达的治疗靶点之一。研究结果将B7-H1对胃癌肿瘤细胞的作用研究更推进一步，同时对B7-H1表达调控机制的阐明，有助于寻找新的治疗靶点。

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