Proliferative effect of whey from cows’ milk varying in phyto-oestrogens in human breast and prostate cancer cells

Summary

Intake of dietary phytoestrogens has received a great deal of attention due to their potential influence on hormone-sensitive cancers such as breast and prostate cancer. Cow´s milk contains phytoestrogens and the content varies according to the composition of the feed and the type and amount of legumes used. In this study we evaluated the proliferative effect of milk with different phytoestrogen content in human breast (MCF-7) and prostate cancer cells (PC-3). Milk was obtained from cows fed either a birdsfoot trefoil-timothy silage based ration (B1) or two different red clover silage based diets (R1 and R2) resulting in total phytoestrogen contents of 403 ng/ml, 1659 ng/ml and 1434 ng/ml for the B1, R1 and R2 diets, respectively. Whey was produced from the milk and added to cell culture medium in concentrations up to 5% for PC-3 cells and 10% for MCF-7 cells. Cell viability (proliferation) was measured fluorometrically after 5 to 7 days of treatment. There was no significant difference in the proliferative effect of whey from the different dietary treatments at any of the whey concentrations tested. An anti-estrogenic effect (P<0.01) of 5 and 10 % whey was seen when tested in the presence of 10 pM estradiol in the medium. This effect was independent of dietary treatment of cows. Whey induced a significant (P<0.01) proliferative response in PC-3 cells independent of dietary treatment. Purified equol in concentrations similar equol concentrations in milk decreased PC-3 cell proliferation and therefore the stimulatory effect of whey in PC-3 cells is believed to be mediated by other bioactives than equol. In conclusion, our results suggest that using these assay set-ups, it was not possible to discriminate between milk with high or low levels of phytoestrogens.