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Human breast cancer: biologically active estrogen receptor in the absence of estrogen?

D T Zava, G C Chamness, K B Horwitz

    Science (New York, N.Y.)
    |May 6, 1977
    PubMed

    Insights

    MCF-7 breast cancer cells grow without estrogen but are inhibited by antiestrogens. Researchers found their estrogen receptors are nuclear, suggesting this receptor drives growth and antiestrogens block it.

    Area of Science:

    • Endocrinology
    • Cancer Biology
    • Molecular Cell Biology

    Background:

    • The MCF-7 human breast cancer cell line exhibits estrogen-independent growth.
    • Paradoxically, antiestrogens inhibit MCF-7 cell proliferation, contrary to their typical function.

    Purpose of the Study:

    • To investigate the unusual behavior of MCF-7 cells regarding estrogen and antiestrogen response.
    • To determine the subcellular localization of estrogen receptors in MCF-7 cells.

    Main Methods:

    • Cellular fractionation and subcellular localization studies.
    • Immunocytochemistry to visualize receptor distribution.

    Main Results:

    • MCF-7 cells possess estrogen receptors predominantly in the nucleus, even without estrogen binding.
    • Androgen and progesterone receptors are found in the cytoplasm, as expected.
    • This nuclear localization suggests constitutive activity of the estrogen receptor.

    Conclusions:

    • The constitutive nuclear localization of estrogen receptors in MCF-7 cells may drive proliferation.
    • Antiestrogen binding could antagonize this inherent growth stimulation, explaining their inhibitory effect.

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