Antiestrogen(4-hydroxytamoxifen)-charged estrogen receptor binding to nuclei from normal and neoplastic rat mammary tissues is not affected by host hormonal status.
Interaction of [3H]4-hydroxytamoxifen-charged estrogen receptor [( 3H]AER) with nuclei was compared to that of [3H]17 beta-estradiol-charged estrogen receptor [( 3H]ER) in vitro. Specificity of [3H]AER binding was demonstrated since more than 90% of [3H]AER binding was displaced by ten-fold excess estradiol-charged ER. For R3230AC tumors, the number of [3H]AER binding sites was approximately 40% lower than the number of [3H]ER binding sites. There were no differences in affinity of binding of these receptors complexes (Kd range 0.7-1.6 nM). In contrast 0.7-1.6 nM). In contrast to a reduction of [3H]ER binding after ovariectomy, no difference in the number of [3H]AER binding sites was seen among tumors from intact, ovex, or estrogen-treated ovex rats. These results suggest that [3H]AER bind to 60% of the sites that bind [3H]ER, and that neither tissue type nor host ovarian status affects the number of nuclear [3H]AER binding sites.
Department of Biochemistry, University of Rochester School of Medicine and Dentistry, New York 14642.
C M
CM
Klinge
D T
DT
Knox
R A
RA
Bambara
S
S
Zain
R
R
Hilf
D000818:Animals; D001667:Binding, Competitive; D002467:Cell Nucleus / Q000378:metabolism; D004965:Estrogen Antagonists / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism*; D051381:Rats; D011960:Receptors, Estrogen / Q000187:drug effects* / Q000378:metabolism; D013629:Tamoxifen / Q000031:analogs & derivatives* / Q000494:pharmacology
D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D013629:Tamoxifen; C016601:afimoxifene