GENE-THERAPY FOR LEWIS LUNG-CARCINOMA WITH TUMOR-NECROSIS-FACTOR AND INTERLEUKIN-2 CDNAS CO-TRANSFECTED SUBLINE

Gene therapy with cytokine cDNA will provide a new tool for cancer tre atment. We have already reported that immunization with interleukin-2 (IL2) cDNA transfected Lewis lung carcinoma (LLC) cells induced anti-t umor immunity, which, however, was not strong enough to eradicate an e stablished tumor. In an attempt to develop more effective gene therapy methods, we have used tumor cells co-transfected with IL-2 and tumor necrosis factor (TNF) cDNAs. These cDNAs were introduced into pBMG-Neo and poDV-X819 vectors, respectively, and then co-transfected into LLC cells. The co-transfectants were selected by incubating them in a med ium containing G418 followed by the limiting method twice to obtain IL 2 and TNF cDNA co-transfected LLC (LLC-TNF-IL2) cells. When 5 x 10(5)/ ml LLC-TNF-IL2 cells were incubated for 48 h, they secreted 7.56 U/ml TNF and 527.0 U/ml IL2 into the culture supernatant. When C57BL/6 mice were transplanted with 1 x 10(6) LLC-TNF-IL2 cells, all the tumors we re rejected. The growth of transplanted LLC, but not B16F10 melanoma c ells, was retarded in mice inoculated with LLC-TNF-IL2 on their contra lateral sides, which suggest specific immunity was induced. The immuni zation effect by the co-transfectant was superior to that of the IL2- and TNF-transfectants alone.