Reduction of the membrane fluidity of human breast cancer cells by tamoxifen and 17β-estradiol

Robert Clarke, Hendrik W. Van Den Berg, Richard F. Murphy

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114 Scopus citations


The intracellular steady-state levels of methotrexate were previously shown to be reduced in estrogen receptor (ER)-negative human breast cancer MDA-MB-436 cells and ER-positive human breast cancer MCF7 cells following treatment with pharmacologically relevant concentrations of 17B-estradiol (E2). We now report that both E2 and tamoxifen (TMX) significantly decreased the fluidity of MCF7 and MDA-MB-436 cellular membranes. With E2 or TMX at concentrations greater than 1 μM, perturbations in membrane fluidity were accompanied by apparently non-ER-mediated cytotoxicity. Alterations in membrane structure may have contributed to the cytotoxicity of high-dose endocrine therapy and to the ability of E2 to inhibit methotrexate transport and cytotoxicity in some human breast cancer cells. [J Natl Cancer Inst 82: 1702-1705, 1990].

Original languageEnglish (US)
Pages (from-to)1702-1705
Number of pages4
JournalJournal of the National Cancer Institute
Issue number21
StatePublished - Jul 7 1990
Externally publishedYes


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