Estrogenic effects of extracts from cabbage, fermented cabbage, and acidified brussels sprouts on growth and gene expression of estrogen-dependent human breast cancer (MCF-7) cells

Cruciferous vegetable extracts from freeze-dried cabbage (FDC), freeze-drie d fermented cabbage (FDS), and acidified Brussels spl outs (ABS) were prepa red by exhaustive extraction with ethyl acetate. Estrogenic and antiestroge nic effects of these extracts were analyzed. To identify whether the extrac ts are potential estrogen receptor (ER) ligands that can act as agonists or antagonists, the binding affinity of extracts for the ER was measured usin g a competitive radiometric binding assay. The extracts bound with low affi nity to the ER, and the relative binding affinity is estradiol > FDS > FDC > ABS. These extracts were evaluated for their estrogenic and antiestrogeni c activities in estrogen-dependent human breast cancer (MCF-7) cells using as endpoints proliferation and induction of estrogen-responsive pS2 gene ex pression, which was analyzed using Northern blot assay. At low concentratio ns (5-25 ng/mL) all of the extracts reduced 1 nM estradiol-induced MCF-7 ce ll proliferation. Extracts at 25 ng/mL also inhibited estradiol-induced pS2 mRNA expression. At higher extract concentrations (50 ng/mL-25 mug/mL), ho wever, increased proliferation in MCF-7 cells was observed. Similarly, expr ession of the pS2 gene was induced by higher extract concentrations (0.25-2 5 mug/mL). The pure estrogen antagonist, ICI 182,780, suppressed the cell p roliferation induced by the extracts as well as by estradiol and also the i nduction of pS2 expression by the extracts. The ER subtype-selective activi ties of FDC and FDS were analyzed using a transfection assay in human endom etrial adenocarcinoma (HEC-1) cells. FDS acted as an ER alpha -selective ag onist while FDC fully activated both ER-alpha and ER-beta. Growth of the ER -negative MDA-231 cells was not affected by the extracts or by estradiol. T his study demonstrates that cruciferous vegetable extracts act bifunctional ly, like an antiestrogen at low concentrations and an estrogen agonist at h igh concentrations.