| OBJECTIVE: To obtain the IL-12 modified mammary sarcoma murine cell line EMT6/IL-12 which could highly express hIL-12 and investigate the anti-tumor effect of EMT6/IL-12 in mice model.METHODS: Recombinant eukaryotic plasmid encoding IL-12 gene (pcDNA6-p70) was transfected into EMT6. The positive clones were selected and identified. 30 mice were randomly divided into 3 groups: EMT6/IL-12, pcDNA6-p70 and EMT6. Mice in EMT6/IL-12 group were inoculated s.c in the right prothorax with EMT6/IL-12; then, on day 4, 7, 10, 14, 17 after the inoculation, saline were injected on the primary injected site. Mice in the pcDNA6-p70 and EMT6 groups were inoculated with EMT6 cells and then pcDNA6-p70, saline were injected respectively in the same way as that of EMT6/IL-12 group. All mice were sacrificed on day 21. Subcutaneous tumors, spleens, thymus glands were weighted and the capacities of anti-tumor immunity including cytotoxicity, proliferation of spleen lymphocytes, the serial IFN-γlevel and the frequencies of CD4~+/IFN-γand CD8~+/IFN-γdouble positive cells in spleen lymphocytes which stimulated by ConA were also investigated.RESULTS: EMT6/IL-12 could express hIL-12 in a high level. The inhibitory rate of tumor in EMT6/IL-12 (97.08%) is higher than that of pcDNA6-p70 (76.25%) and EMT6 (p<0.01). Moreover, the capacities of anti-tumor immunity such as cytotoxity and proliferation of spleen lymphocytes, level of serial IFN-γwere also enhanced in EMT6/IL-12 group (p<0.01). Frequencies of CD4+/IFN-γ,CD8+/IFN-γdouble positive cells in spleen lymphocytes were increased significantly in EMT6/IL-12 group (CD4/IFN-γ:7.49±0.05%; CD8/IFN-γ:6.35±0.06%) compared to that of groups pcDNA6-p70 (CD4/IFN-γ:4.3±0.03%;CD8/IFN-γ:3.7±0.05%) and EMT6 (CD4/IFN-γ:2.05±0.04%; CD8/IFN-γ:1.26±0.03%)(p<0.01).CONCLUSION: EMT6/IL-12 cell line which highly express hIL-12 were acquired and the recombinant IL-12 modified mammary sarcoma murine cell line reveals significantanti-tumor effect.
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