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Cadmium induces mitogenic signaling in breast cancer cell by an ERα-dependent mechanism

Abstract

Breast cancer (BC) is linked to estrogen exposure. Estradiol (E2) stimulates BC cells proliferation by binding the estrogen receptor (ER). Hormone-related cancers have been linked to estrogenic environmental contaminants. Cadmium (Cd) a toxic pollutant, acts as estrogens in BC cells. Purpose of our study was to evaluate whether Cd regulates MCF-7 cell proliferation by activating ERK1/2, Akt and PDGFRα kinases. Cd increased cell proliferation and the ER-antagonist ICI 182,780 blunted it. To characterize an ER-dependent mechanism, ERα/β expression was evaluated. Cd decreased ERα expression, but not ERβ. Cd also increased ERK1/2, Akt and PDGFRα phosphorylation while ICI blocked it. Since stimulation of phosphorylation was slower than expected, c-fos and c-jun proto-oncogenes, and PDGFA were analyzed. Cd rapidly increased c-jun, c-fos and PDGFA expression. Cells were also co-incubated with the Cd and specific kinases inhibitors, which blocked the Cd-stimulated proliferation.

In conclusion, our results indicate that Cd increases BC cell proliferation in vitro by stimulating Akt, ERK1/2 and PDGFRα kinases activity likely by activating c-fos, c-jun and PDGFA by an ERα-dependent mechanism.