Binding of 2-hydroxyestradiol and 4-hydroxyestradiol to the estrogen receptor of MCF-7 cells in cytosolic extracts and in nuclei of intact cells.
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.
Schütze
N
N
Institut für Biochemische Endokrinologie, Medizinische Universität zu Lübeck, Germany.
Vollmer
G
G
Wünsche
W
W
Grote
A
A
Feit
B
B
Knuppen
R
R
D001667:Binding, Competitive; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology* / Q000648:ultrastructure; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D004958:Estradiol / Q000031:analogs & derivatives* / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D002393:Estrogens, Catechol / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D011388:Prolactin / Q000378:metabolism; D011960:Receptors, Estrogen / Q000032:analysis / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000032:analysis / Q000378:metabolism; D014407:Tumor Cells, Cultured
D002393:Estrogens, Catechol; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D004958:Estradiol; D011388:Prolactin; C001390:2-hydroxyestradiol; C014036:4-hydroxyestradiol