Preliminary Study On Antituomr DNA Vaccine With Multitarget Complex Antigen To Inhibit Tumor Growth

The function of antitumor DNA vaccine involves gene therapy and immunological regulation for tumor. Because of generating strong and lasting immune responses, antitumor DNA vaccines have been used in a wide range of cancer immunotherapy.First of all, the eukaryotic bi-cistronic expression vector pVAX1-IRES-GM/B7 which could express human GM-CSF and B7.1 fusion gene (GM/B7) was constructed by inserting fusion gene GM/B7 that encoding human GM-CSF and B7.1 gene into eukaryotic expression vector pVAX1-IRES. Secondly, human inhibition apoptosis protein survivin and chorionic gonadotropinβchain- CTP37 gene were used as antigens. Multitarget complex antigen 2PAG fusion gene encoding both the most Cytotoxic T Lymphocyte Epitopes of human survivin and CTP37 of human and monky was constructed by PCR. Thirdly, the fusion gene sig-2PAG-Fc-GPI (2PAG-Fc-GPI) encoding the targeting signal peptide of human Igκ(sig), human IgG-Fc and GPI. was constructed. Then the antituomr DNA vaccine pVAXl-2PFcGB was constructed by inserting fusion gene 2PAG-Fc-GPI into the eukaryotic bi-cistronic expression vector pVAXl-IRES-GM/B7. The following experiment showed that the fusion gene 2PAG-Fc-GPI and GM/B7 could co-express in eucaryotic cell.Finally, the anti tumor effect of pVAX1-2PFcGB was tested in murine EMT6 breast cancer model. Humoral immunoresponse and specific cellullar immunologic response induced by pVAXl-2PFcGB were tested by ELISA and Cytotoxicity Assay. The results demonstrated that pVAX1-2PFcGB could induce favourable humoral immunoresponse and the maximum of titer antibody is 1:6400. Meanwhile, specific cellullar immunologic response was induced. Cytotoxic T lymphocytes (CTLs)-mediated cytotoxicity was 68.74%, 44.39% and 30.99% when effector-target ratio was 60:1 % 30:1 and 15:1. In tumor therapy assay, femal Balb/c mice were injected with EMT6 cells and then immunized with DNA vaccine. The time of tumor forming in vaccine group was longer than the control groups (6days), to about 12.29 days; and tumor grew slowly and therapeutic vaccination did significantly reduce tumour growth as compared with the controls; and the tumor control rate was 77.27%.It is concluded that DNA vaccine pVAX1-2PFcGB has great therapeutic effect on tumor, and it would be a novel antitumor DNA vaccine.