Interferon gamma increases the antitumor activity of mitomycin C against human colon cancer cells in vitro and in vivo.

A combined antitumor activity of mitomycin C (MMC) and interferon gamma-1a (IFN-gamma) was evaluated to be synergistic by the 3-(4, 5-dimethylthiazol-2yl)-2,5-diphenyl-2H tetrazolium bromide assay and human tumor xenografts/severe combined immunodeficient (SCID) mouse system using colon cancer cell lines. The experimental metastasis of WiDr cells in SCID mouse was inhibited by MMC and IFN-gamma with their synergism. Intracellular uptake of MMC in WiDr cells in vitro was significantly increased by IFN-gamma, suggesting the mode of synergism of these agents. This model may also partly explain the antitumor activity of combined MMC, 5-fluorouracil and interleukin-2 treatment on hepatic metastasis of colon cancer.