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-2 yl)-2,5-diphenyl 2H tetrazolium bromide assay and human tumor xenografts/ s evere combined immunodeficient (SCID) mouse system using colon cancer cell lines. The experimental metastasis of WiDr cells in SCID mouse was inhibite d by MMC and IFN-gamma with their synergism. Intracellular uptake of MMC in WiDr cells in vitro was significantly increased by IFN-gamma, suggesting t he mode of synergism of these agents. This model may also partly explain th e antitumor activity of combined MMC, 5-fluorouracil and interleukin-2 trea tment on hepatic metastasis of colon cancer.