[Combined effects of 5-fluorouracil and interferon on proliferation of human neoplastic cells in culture].

Potentiation of the cytotoxic effects of 5-fluorouracil (5-FU) by interferon on human tumor cells was examined. The human neoplastic cell lines used were HeLa (uterine cervical cancer), MCF-7 (mammary cancer), WI-38 CT-1 (embryonic lung fibroblasts transformed in culture by Co-60 gamma-ray irradiation), KMM-1 (myeloma), and Raji (Burkitt's lymphoma). As a normal human cell strain, WI-38 (embryonic lung fibroblasts) was used. The cytotoxic effects were determined by colony formation. Each cell line was different in sensitivity to interferon or 5-FU. Interferon potentiated synergistically the cytotoxic effects of 5-FU on HeLa, WI-38 CT-1, and KMM-1 cells. In the case of Raji cells, the cytotoxic effects of the combination of interferon and 5-FU were additive. Neither synergistic nor additive lethal effects of the combination of the two agents were observed in MCF-7 and WI-38 cells. The present results indicate a possibility that a combined treatment with interferon and 5-FU may be effective in certain types of human cancers.