The effects of different lignans and isoflavones, tested as aglycones and glycosides, on hormone receptor-positive and -negative breast carcinoma cells in vitro.

PURPOSE: Phytooestrogens are known to cause anti-cancer effects on mamma carcinoma cells. In this study, the effects of the lignan secoisolariciresinol and the isoflavone glycosides and aglycones genistein, genistin, daidzein and daidzin were tested on MCF-7 and BT20 cells in vitro.
METHODS: First, the cellular expression of hormone receptors was examined by immunohistochemical procedures. The effects of the phytooestrogens on the cells were detected by using three different assays measuring cell letality, viability and proliferation. The phytooestrogens were tested in concentrations of 1, 5, 10 and 50 μg/mL, respectively. 17β-oestradiol and tamoxifen were used as controls, respectively, in the same concentrations as the phytooestrogens.
RESULTS: The immunohistochemistry showed evidence of oestrogen- and progesterone receptors at the MCF-7 cell line, whereas no expression could be seen at the BT20 cells. Among the phytooestrogens, genistein and secoisolariciresinol showed various anti-cancerogenic effects on both cell lines, respectively, but only in the highest concentration. Regarding the controls, tamoxifen showed a stronger antivital and anti-proliferative effect on BT20 than on MCF-7. Oestradiol caused sporadic anti-cancer effects on both cell lines, respectively, at its highest concentration.
CONCLUSIONS: Genistein and Secoisolariciresinol have anti-cancer properties on MCF-7 and BT20 in vitro. There are differences in the effects of isoflavones depending on the glycolysation status. The role of the oestrogen receptors in the mechanisms of action of both the phytooestrogens and controls is of less importance. Further investigations have to be carried out, especially concerning the mechanisms of action. Phytooestrogens may be potential substances in the therapy of mamma carcinomas.