表达人FAPα的全肿瘤细胞疫苗抗肿瘤免疫效应及机制研究

Immunosuppressive factors in the tumor microenvironment reduce the efficacy of cancer treatments. Cancer-associated fibroblasts (CAFs) and their products fibroblast activation protein α（FAPα）are potential targets for cancer immunotherapy. Our previous study demonstrated a whole-tumor cell vaccine expressing FAPα inhibit tumor growth by targeting both tumor cells and CAFs in multiple tumor types. Gene sequence homology between human and murine FAPα is 90%. Heterogeneity of genes in the evolution of the formation of such nuances can be utilized to break immune tolerance, enhance immunogenicity, induce tumour cell autoimmune responses and thus inhibit tumor growth. Based on these important findings, in this proposal, muine tumor cells were transfected with vector encoding for human FAPα to further break immune tolerance, enhance immunogenicity and induce stronger therapeutic antitumor immunity. We will focus on two aims: (1) To evaluate the therapeutic efficacy and safety of whole tumor cell vaccine, expressing human FAPα, in three murine tumors (CT26 colon adenocarcinoma, Lewis lung carcinoma, and 4T1 breast cancer); (2) To study the molecular mechanism of by which antitumor activity was elicited by the tumor cell vaccine from three aspects: Innate immunity, humoral immunity, and cellular immunity. This study will lead to a better understanding of the immunosuppressive tumor microenvironment in the regulation of cancer initiation and development, and provides a new strategy for the clinical use of genetically modified tumor cells as cancer vaccines.

肿瘤相关成纤维细胞（CAFs）作为肿瘤微环境中最主要的细胞成分之一，对肿瘤发生、发展、转移、免疫抑制和治疗耐受起促进作用，清除CAFs对提高肿瘤治疗效果具有重要意义。既往研究表明，CAFs及其特异性表面抗原成纤维细胞激活蛋白α(FAPα)是抗肿瘤药物设计的理想靶点。本研究拟在前期发现表达FAPα肿瘤细胞疫苗诱导特异性CTL效应杀伤CAFs的基础上，利用小鼠FAPα与人FAPα基因的细微差别进一步增强疫苗免疫原性，制备表达人FAPα的全肿瘤细胞疫苗；并建立小鼠肺癌、结肠癌及乳腺癌肿瘤模型观察其抗肿瘤效应，同时检测固有免疫、体液免疫及细胞免疫对CAFs和肿瘤细胞的杀伤作用；在体外分析该疫苗对肿瘤组织中CAFs数量和生物功能的影响，以及肿瘤微环境中免疫细胞表型和相关细胞因子表达水平的变化。最终，阐明该疫苗抗肿瘤免疫效应机制，为提高肿瘤治疗效应提供新的方法和新的思路。

肿瘤相关成纤维细胞（CAFs）作为肿瘤微环境中最主要的细胞成分之一，对肿瘤发生、发展、转移、免疫抑制和治疗耐受起促进作用，清除CAFs对提高肿瘤治疗效果具有重要意义。既往研究表明，CAFs及其特异性表面抗原成纤维细胞激活蛋白α(FAPα)是抗肿瘤药物设计的理想靶点。本研究拟在前期发现表达FAPα肿瘤细胞疫苗诱导特异性CTL效应杀伤CAFs的基础上，利用小鼠FAPα与人FAPα基因的细微差别进一步增强疫苗免疫原性，制备表达人FAPα的全肿瘤细胞疫苗；并建立小鼠肺癌、结肠癌及乳腺癌肿瘤模型观察其抗肿瘤效应，同时检测固有免疫、体液免疫及细胞免疫对CAFs和肿瘤细胞的杀伤作用；在体外分析该疫苗对肿瘤组织中CAFs数量和生物功能的影响，以及肿瘤微环境中免疫细胞表型和相关细胞因子表达水平的变化，阐明该疫苗抗肿瘤免疫效应机制。结果表明，我们将hFAP重组质粒转染小鼠肿瘤细胞作为疫苗，提高了肿瘤细胞疫苗的免疫原性，进一步打破免疫耐受，诱导交叉免疫反应产生了特异性的 中和抗体和CTL效应，同时靶向肿瘤细胞和肿瘤间质中的CAFs，增强体液免疫和细胞免疫介导的抗肿瘤免疫反应，提高了肿瘤细胞疫苗的治疗效果。这一研究对提高治疗性肿瘤疫苗的临床疗效具有重要的参考价值，为肿瘤免疫研究提供了新思路。