Effects of genistein on experimental metastasis of B16-BL6 mouse melanoma cells

AIM: To investigate the effects of genistein, an isoflavone, on mouse experimental metastasis in order to explore the possibility of developing genistein as a novel anti-cancer drug. METHODS: B16-BL6 mouse melanoma cells were injected into C57BL/6 mouse via tail lateral vein, which subsequently colonized into the animal lungs to form a large amount of pulmonary metastases after 15 days. Genistein was suspended in 2% lecithin and administered at 100 or 200 mg•kg^-1 • d^-1 by intraperitoneal injection daily from the day before the cell injection. RESULTS: The mean number of metastases in the animal group that were given genistein 200 mg•kg^-1 was significantly reduced as compared with that of the control group(P<0.01), suggesting the anti-metastasis effect of genistein. n contrast, cyclophosphamide 100 mg • kg^-1 ip did not significantly decrease the number of pulmonary metastases, while it was found to dramatically reduce the size of metastases. When genistein was administrated with cyclophosphamide, the survival time of the metastatic mice was significantly prolonged. CONCLUSION: Genistein inhibited experimental metastasis through a mechanism different from that of cyclophosphamide. The stronger life-prolonging effect of co-administration of genistein with cyclophosphamide suggests that it may be valuable to combine genistein with another cytotoxic drug for cancer metastasis chemotherapy.