肿瘤基因疫苗临床效果不佳的主要原因，可能是肿瘤微环境中存在免疫抑制因素，或疫苗自身的免疫原性差。在肿瘤微环境中，表达成纤维细胞激活蛋白（FAP）的肿瘤相关成纤维细胞（TAF）具有免疫抑制和阻碍化疗药物吸收的功能。因此，本项目拟将FAP与前期研究的肿瘤抗原MUC1和survivin 联用，首次构建三基因融合表达的DNA和重组腺病毒载体疫苗，然后在模型小鼠上考查疫苗的抗肿瘤效果，同时使用佐剂和优化的免疫策略，进一步增强疫苗的T细胞免疫反应。为了充分发挥基因疫苗的优势，进一步构筑接枝甘露糖的壳聚糖寡聚物的自组装纳米载体疫苗，纳米载体可增强DNA的转染效率，解决腺病毒存在的预存免疫、肝毒性和迅速被免疫系统清除等问题，同时具有靶向抗原提呈细胞（APC）的能力。在小鼠模型上考察纳米载体疫苗的抗肿瘤效果；研究疫苗诱导高效T细胞免疫、消除肿瘤微环境中的免疫抑制因素、促进化疗药物吸收相结合的三重抗肿瘤机制。

Tumor genetic vaccines targeting tumor associated antigens (TAA) have been reported to be rarely effective in controlling tumor growth, which might be due to the presence of immune suppression within the tumor microenvironment or the incapacity of vaccine and immunization in inducing strong immune responses. In the tumor microenvironment, tumor-associated fibroblasts (TAF) which express fibroblast activation protein (FAP) are contribute to the local immunosuppressive microenvironment and render tumor cells more chemoresistant. Therefore, this study intends to construct the DNA and recombinant adenovirus vaccine expressing FAP, MUC1 VNTR and survivin and then investigate the anti-tumor effect of the vaccine in tumor-bearing mice. Meanwhile, in order to enhance the T cell immnune response, immunoadjuvant and optimized immune strategy will be applied in our stratey. To fully play to the advantages of genetic vaccine, self - assemblly nanocomplex with low molecular-weight mannose-bearing chitosan oligomers will be prepare by electrostatic interaction. Nnano-carrier is able to enhance the transfection efficiency of DNA, solve the problems of pre-existing immunity, liver toxicity and rapid clearance by immune system during systemic administration of adenovirus, meanwhile has the function of targeting the antigen presenting cells (APC). Furthermore, the anti-tumor effect will be tested in a mouse tumor model, and the triple anti-tumor mechanism of the vaccine, i.e., inducing high efficient T-cell immunity, eliminating of immune suppression in the tumor microenvironment and increasing intratumoral drug uptake，will also be studied in our project.