We evaluated the possibility of inducing a productive transfer of the IL-2 gene into human gastic cancer cells (GCC) and assessed the phenotypic and proliferative changes generated in the nude mice. The plasmid vector (BMGNeo-IL-2) carrying the human IL-2 gene was used to transduce the SGC-7901 GCC line by the lipofectin reagent. The IL-2 gene was analyzed by Southern blot and productive IL-2 release using IL-2-dependent CTLL. Cytotoxicity of LAK cells was tested by MTT colorimetry. The kinetics of in vitro growth and proliferation of parental and engineered cells were also measured. Parental and IL-2 gene transduced GCC were injected into nude mice. The tumorigenic potential of IL-2 gene-transfected GCC was evaluated by examining their in vivo growth in nude mice. The productive insertion of the IL-2 gene was achieved in SGC-7901. The amounts of IL-2 constitutively released by the engineered neoplastic cells ranged from 20 to 131 U/ml of IL-2 produced from 10(6) cells in 24 hours. Transduction of GCC with IL-2 gene did not modify the morphology and growth rate. IL-2 gene transfected cells demonstrated increased susceptibility to cell killing by LAK cells. IL-2 producing cells lost their tumorigenicity as evidenced by failure to grow in nude mice. The results demonstrate that IL-2 gene can be productively transduced into human gastric cancer cells without modifying their morphology and growth rate and this transduction leads to reduced or abrogated in vivo tumorigenic potential.