Selenium disrupts estrogen signaling by altering estrogen receptor expression and ligand binding in human breast cancer cells

Ok Lee Soo, Nagalakshmi Nadiminty, Xian Wu Xiu, Wei Lou, Yan Dong, Clement Ip, Sergio A. Onate, Allen C Gao

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


Cancer prevention studies suggest that selenium is effective in reducing the incidence of cancers including prostate, colon, and lung cancers. Previous reports showed that selenium inhibits premalignant human breast MCF-10AT1 and MCF10AT3B cell growth in vitro and reduces mammary tumor incidence after exposure to carcinogens in tumor models. Because estrogen is critical to the development and differentiation of estrogen target tissues, including the breast, the present study was designed to examine the effect of selenium on estrogen receptor (ER) expression and activation using methylseleninic acid (MSA), an active form of selenium in vitro. Selenium decreased the levels of expression of ERα mRNA and protein and reduced the binding of labeled estradiol to estrogen receptor in MCF-7 cells. Selenium inhibited the trans-activating activity of estrogen receptor in MCF-7 cells expressing functional estrogen receptor using a luciferase reporter construct linked to estrogen responsive element. Selenium decreased the binding of estrogen receptor to the estrogen responsive element site using an electrophoretic mobility gel shift assay. Selenium suppressed estrogen induction of the endogenous target gene c-myc. In contrast to the effect on ERα in MCF-7 cells, selenium increased ERβ mRNA expression in MDA-MB231 human breast cancer cells. Thus, differential regulation of EKα and ERβ in breast cancer cells may represent a novel mechanism of selenium action and provide a rationale for selenium breast cancer prevention trial.

Original languageEnglish (US)
Pages (from-to)3487-3492
Number of pages6
JournalCancer Research
Issue number8
StatePublished - Apr 15 2005
Externally publishedYes

ASJC Scopus subject areas

  • Cancer Research
  • Oncology


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