Effect of isoflavones genistein and daidzein in the inhibition of lung metastasis in mice induced by B16F-10 melanoma cells.

Two dietary soybean isoflavones, genistein and daidzein, were studied for the inhibition of lung metastasis induced by B16F-10 melanoma cells in C57BL/6 mice. The isoflavone genistein at 200 mumol/kg body wt significantly inhibited (53.6%, p < 0.001) lung tumor nodule formation. The lung collagen hydroxyproline content and the serum sialic acid level, a marker of metastasis, were also significantly lower in these animals than in untreated tumor-bearing animals. Genistein treatment also increased the life span of the tumor-bearing animals (47.7%, p < 0.001). The isoflavone daidzein had no significant effect on the reduction of lung metastasis induced by B16F-10 melanoma cells.