Electroporation-mediated transfer of cytokine genes into human esophageal tumors produces anti-tumor effects in mice

Electroporation facilitates transfer of chemicals or plasmid DNA from extra cellular milieu into cells by increasing the permeability of the cell membr ane. Delivery of electric pulses to established tumors thereby can improve the susceptibility of tumors to an anti-cancer agent administered. We exami ned whether electroporation-mediated transfer of cytokine genes into solid tumors could produce anti-tumor effects in the tumor-bearing mice. Plasmid DNA containing cytokine genes were injected into human esophageal T.Tn tumo rs developed in nude mice and electric pulses were then delivered. Administ ration of murine GM-CSF or human IL-2 gene followed by electroporation sign ificantly suppressed the subsequent growth of T Tn tumors and prolonged the survival of the inoculated mice. In contrast, electroporation-mediated int roduction of a control gene, human GM-CSF gene, whose products do not bind to murine GM-CSF receptors, did not achieve any anti-tumor effects. In vivo transfection of cytokine genes with electroporation could be a possible th erapeutic strategy for established solid tumors.