TNF-α enhances estrogen-induced cell proliferation of estrogen-dependent breast tumor cells through a complex containing nuclear factor-kappa B

Breast tumors are usually classified according to their response to estrogens as hormone-dependent or -independent. In this work, we investigated the role of the proinflammatory cytokine TNF- α on the estrogen-receptor-positive T47D breast ductal tumor cells. We have found that TNF- α exerts a mitogenic effect, inducing cyclin D1 expression and activation of the transcription factor NF- κ B. Importantly, activation of NF- κ B was required for estrogen-induced proliferation and cyclin D1 expression. TNF- α enhanced the estrogen response by increasing the levels and availability of NF- κ B. Chromatin immunoprecipitation analysis suggested that the action of estrogens is mediated by a protein complex that contains the activated estrogen receptor, the nuclear receptor coactivator RAC3 and a member of the NF- κ B family. Finally, our results demonstrate that activation of this transcription factor could be one of the key signals for estrogen-mediated response.