Effect on colon cancer cells of human interferon‐β gene entrapped in cationic multilamellar liposomes

When cultured cells of human colon cancer cell line SW480 were transfected with human interferon‐β (hIFN‐β) gene by means of cationic multilamellar liposomes, the endogenously produced hIFN‐β exhibited a remarkable anti‐proliferative effect on the cells, which was more effective than that of exogenously added hIFN‐β. This effect lasted for several days, and was blocked completely by the addition of sufficient amounts of anti‐hIFN‐β antibody. From experiments using a transwell plate and an infusion pump, we found that endogenously produced hIFN‐β 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‐β expressed endogenously by transfer of its gene acted on these cancer cells mainly in a paracrine manner. Although the transfection with hIFN‐γ gene also revealed a definite growth‐inhibitory effect on the same tumor cells, the extent was less than that of hIFN‐β gene.