Resveratrol suppresses 4-hydroxyestradiol-induced transformation of human breast epithelial cells by blocking IκB kinaseβ-NF-κB signalling.

Excess estrogen stimulates the proliferation of mammary epithelial cells and hence represents a major risk factor for breast cancer. Estrogen is subjected to cytochrome P450-catalysed oxidative metabolism to produce an oncogenic catechol estrogen, 4-hydroxyestradiol (4-OHE₂). 4-OHE₂ undergoes redox cycling during which reactive oxygen species (ROS) as well as the chemically reactive estrogen semiquinone and quinone intermediates are produced, thereby contributing to hormonal carcinogenesis. Resveratrol (3,4',5-trihydroxy stilbene), a phytoalexin present in grapes, has been reported to possess chemopreventive and chemotherapeutic activities. In the present study, we examined the inhibitory effects of resveratrol on 4-OHE₂-induced transformation of human breast epithelial MCF-10A cells. Resveratrol inhibited migration and anchorage-independent growth of MCF-10A cells treated with 4-OHE₂. Resveratrol treatment suppressed the 4-OHE₂-induced activation of IκB kinaseβ (IKKβ) and phosphorylation of IκBα, and consequently NF-κB DNA binding activity and cyclooxygenase-2 (COX-2) expression. Resveratrol suppressed ROS production and phosphorylation of Akt and ERK induced by 4-OHE₂ treatment. In conclusion, resveratrol blocks activation of IKKβ-NF-κB signalling and induction of COX-2 expression in 4-OHE₂-treated MCF-10A cells, thereby suppressing migration and transformation of these cells.