Estrogenic Activity of Some Phytoestrogens on Bovine Oxytocin and Thymidine Kinase-ERE Promoter through Estrogen Receptor-α in MDA-MB 231 Cells

Phytoestrogens, a group of plant-derived polyphenolic compounds have recently come into considerable attention due to the increasing information on their potential adverse effects in human health. Some of phytoestrogens show estrogenic activity that may be carcinogenic for human. In the present study here, we investigated the transcriptional effects of variety of phytoestrogens on the bovine oxytocin and the thymidine kinase-ERE promoter by estrogen receptor α in MDA-MB 231 breast cancer cell line. Cells were seeded for transfections into 12- well plates at a density of 100000 cells per well and were transfected with a total of 3 μg of plasmid DNA using calcium phosphate coprecipitation. Estrogen and some phytoestrogens (naringenin, 8-prenyl-naringenin and 6-(1, 1-dimethylallyl) naringenin were used for stimulation of transfected cells. Findings of our study clearly demonstrated the subtype-selective activation of estrogen receptor (ER)α and (ER)β by the phytoestrogen naringenin (activating estrogen receptor β) and its substituted forms 8-prenyl-naringenin and 6-(1, 1-dimethylallyl) naringenin (activating estrogen receptor α), on the ERE-controlled promoter as well as on the oxytocin gene promoter. The study revealed that some phytoestrogens show estrogenic activity by classical or non-classical mechanisms as well as exhibit estrogenic activity by undetermined mechanisms in transfected MDA-MB 231 cell line.