4-Hydroxytamoxifen-induced cytotoxicity and bisphenol A: Competition for estrogen receptors in human breast cancer cell lines

Jill B. Lewis, Carol A. Lapp, Tara E. Schafer, John C. Wataha, Tabitha M. Randol, George S. Schuster

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Increasing concerns over the effects of environmental estrogens on wildlife and humans have highlighted the need for screening systems to assess potentially estrogenic effects of test compounds. As a result, in vitro screening methods such as cell proliferation assays using the estrogen-responsive human breast cancer cell line, MCF-7, have been developed. The present study describes an alternative in vitro approach for the assessment of such xenoestrogens, based on estrogenic rescue of MCF-7 cells from antiestrogen-induced cytotoxicity. This method measures the ability of various estrogenic compounds to compete with a known estrogen-receptor-mediated antihormonal drug, 4-hydroxytamoxifen, using the 1-[4,5-dimethylthiazol-2-yl]- 3,5-diphenylformazan (MTT) assay to assess mitochondrial activity. Because 4-hydroxytamoxifen treatment of cells results in a dramatic decrease in mitochondrial dehydrogenase activity which is directly related to their estrogen-receptor content, inhibition of this effect with estrogenic compounds represents an estrogen-receptor interaction, or estrogenic rescue. The estrogenic compounds tested include a weak xenoestrogen, bisphenol A (BPA), and two biological estrogens, 17α- and 17β-estradiol. Competitive inhibition of 4-hydroxytamoxifen-induced cytotoxicity by BPA was compared to that of the biological estrogens. The results indicate that the biological estrogens can successfully compete with the antiestrogen in a dose-dependent manner. In addition, the assay is sensitive enough to detect estrogenic rescue by even the very weak xenoestrogen, BPA, albeit at high BPA concentrations. This simple in vitro method could be used as an alternative or second-line screen for potential xenoestrogens.

Original languageEnglish (US)
Pages (from-to)320-326
Number of pages7
JournalIn Vitro Cellular and Developmental Biology - Animal
Issue number5
StatePublished - May 2000


  • Biocompatibility
  • Dental sealants and composites
  • MCF-7
  • Xenoestrogen

ASJC Scopus subject areas

  • Developmental Biology
  • Cell Biology


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