EFFECT ON COLON-CANCER CELLS OF HUMAN INTERFERON-BETA GENE ENTRAPPED IN CATIONIC MULTILAMELLAR LIPOSOMES

When cultured cells of human colon cancer cell line SW480 were transfe cted with human interferon-beta (hIFN-beta) gene by means of cationic multilamellar liposomes, the endogenously produced hIFN-beta exhibited a remarkable anti-proliferative effect on the cells, which was more e ffective than that of exogenously added hIFN-beta. This effect lasted for several days, and was blocked completely by the addition of suffic ient amounts of anti-hIFN-beta antibody. From experiments using a tran swell plate and an infusion pump, we found that endogenously produced hIFN-beta acted effectively on the cells around the transfectants and that the growth-inhibitory effect was totally retained upon continuous dilution of the medium. These data indicate that hIFN-beta expressed endogenously by transfer of its gene acted on these cancer cells mainl y in a paracrine manner. Although the transfection with hIFN-gamma gen e also revealed a definite growth-inhibitory effect on the same tumor cells, the extent was less than that of hIFN-beta gene.