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Soybean
isoflavones reduce experimental metastasis in mice
Li D,
Yee JA, McGuire MH, Murphy PA, Yan L
Department
of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE
68178, USA
We
investigated the effect of dietary supplementation with isoflavones on pulmonary
metastasis of B16BL6 murine melanoma cells in C57BL/6 mice.
Mice were fed a basal AIN-93G diet or the basal diet supplemented with the
isoflavones genistein and daidzein at 113 micromol/kg, 225 micromol/kg, 450
micromol/kg, or 900 micromol/kg for 2 wk before and after the intravenous
injection of 0.5 x 10(5) melanoma cells.
At necropsy, the number and size of tumors that formed in the lungs were
determined.
The number of mice that had >15 lung tumors was 17 in the control group, and
16, 15, 13, and 10 in the groups fed isoflavones at 113 micromol/kg, 225
micromol/kg, 450 micromol/kg and 900 micromol/kg, respectively.
The latter two were significantly different from the control (P </=
0.05).
The median number of tumors in the control group was 67, and those in the
isoflavone-supplemented groups were 57, 33, 32, and 17, respectively.
The last was significantly different from the control (P </= 0.05).
Dietary supplementation with isoflavones at 225 micromol/kg, 450 micromol/kg,
and 900 micromol/kg also significantly decreased tumor size (median
cross-sectional area and volume) compared to the control values.
We conclude that dietary supplementation with isoflavones reduces experimental
metastasis of melanoma cells in mice.
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