Gene therapy by tumor cells transfected with genes of costimulatory molecular and cytokines

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In this study, we evaluated the antitumor immunity of tumor vaccine transfected IL-2, GM-CSF,or costimulatory molecule B7 gene using the adenovirus vector. Furthermore, tumor cells were cultured with IFN-gamma to increase the expression of MHC class I antigen.The expressions of IL-2 and GM-CSF protein in the cells infected with recombinant adenovirus were examined by Western blot and microscopic fluorecent analysis. The secretion of these cytokines from the cells was detected by ELISA assay. From the flow cytometry analysis, the cell surface expression of B7 protein was extremely high due to the infection of recombinant adenovirus transduced B7 gene, and the expression of MHC class I antigen of cell surface increased due to the preculture with IFN-gamma . For the animal study, mice were divided into 7 groups as follows : (1) IL2+B7+IFN-gamma (2) IL2+B7 (3) IL2 (4) B7 (5) IFN-gamma (6) non-transduced tumor cells (7) PBS.In the prevention model of tumor growth (day-7 tumor vaccine), IL2+B7+IFN-gamma, IL2+B7, and IL2 groups showed the significant decreases of tumor volume as compared to the nontransduced tumor cells and PBS groups (P<0.01), and the survival rates were 50%, 37.5%, and 25%, respectively. In the therapeutic model of the tumor (day 1 tumor vaccine), IL2+B7+IFN-gamma and IL2+B7 groups showed significant decreases of tumor volume (P<0.01), and the survival rates were 25% and 12.5%, respectively. Furthermore, IL2+B7+IFN-gamma, IL2+B7 and IL2 groups showed significant deacreases in the number of lung metastases (P<0.01).These results suggests that the vaccinations of irradiated tumor cells of transfected IL-2 and B7 gene, and pretreatment with IFN-r, showed the strongest antitumor effects in mice.