Abstract
The catechol estrogens (CE), 2-hydroxyestradiol (2-OH-E2) and 4-hydroxyestradiol (4-OH-E2) were analyzed for their binding affinity to the estrogen receptor of MCF-7 cells. Applying a competitive binding assay to cytosols prepared from MCF-7 breast cancer cells, we measured a relative binding affinity of 23% (2-OH-E2) and 26% (4-OH-E2) compared to E2. Nuclear binding assays with the same cell line demonstrated a high specific binding with Kd's of 0.31 nM (2-OH-E2) and 0.21 nM (4-OH-E2). The relative binding affinity measured was 25% and 42% for 2-OH-E2 and 4-OH-E2, respectively. Based on this nuclear binding it can be concluded that the estrogen receptor occupied by CE is bound within the nucleus and might therefore be transcriptionally active.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Binding, Competitive
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Breast Neoplasms / metabolism*
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Breast Neoplasms / pathology*
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Breast Neoplasms / ultrastructure
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Cell Nucleus / chemistry
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Cell Nucleus / metabolism
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Cell Nucleus / ultrastructure
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Cytosol / chemistry
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Cytosol / metabolism
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Cytosol / ultrastructure
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Estradiol / analogs & derivatives*
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Estradiol / analysis
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Estradiol / isolation & purification
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Estradiol / metabolism
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Estrogens, Catechol / analysis
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Estrogens, Catechol / isolation & purification
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Estrogens, Catechol / metabolism
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Humans
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Prolactin / metabolism
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Receptors, Estrogen / analysis
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Receptors, Estrogen / metabolism*
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Receptors, Progesterone / analysis
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Receptors, Progesterone / metabolism
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Tumor Cells, Cultured
Substances
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Estrogens, Catechol
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Receptors, Estrogen
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Receptors, Progesterone
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Estradiol
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Prolactin
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2-hydroxyestradiol
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4-hydroxyestradiol