Serum and monohydroxytamoxifen inhibit progesterone receptor concentrations in primary rat uterine cells grown in serum-free medium.
Uterine cells dispersed from immature rat uteri were grown in culture in serum-free medium supplemented with insulin (5 micrograms/ml), transferrin (5 micrograms/ml), and selenous acid (5 ng/ml; ITS). Cells were grown to a confluent monolayer and had a fibroblastic appearance, similar to cells cultured in the presence of 10% serum [horse-fetal calf (6:1), stripped three times with dextran-coated charcoal]. However, estrogen receptor and progesterone receptor (PgR) concentrations were higher in cells grown in serum-free medium than in cells grown in serum. Uterine cells grown in ITS contain PgR levels that are near maximum (927 +/- 168 fmol/mg protein), and estradiol (0.1 nM; 24 h) causes a 10-50% increase in PgR. Addition of serum or monohydroxytamoxifen for 24 h decreases PgR levels by about 50%, and estrogen can completely overcome the inhibition caused by either serum or monohydroxytamoxifen. Our data suggest that PgR levels may be down-regulated by a component of serum.
Greco
T L
TL
Department of Biochemistry, University of Wisconsin, Madison 53706.
Gorski
J
J
D000818:Animals; D001769:Blood; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D007700:Kinetics; D051381:Rats; D011919:Rats, Inbred Strains; D011960:Receptors, Estrogen / Q000187:drug effects / Q000378:metabolism; D011980:Receptors, Progesterone / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D013629:Tamoxifen / Q000031:analogs & derivatives* / Q000494:pharmacology*; D014599:Uterus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D003470:Culture Media; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D013629:Tamoxifen; C016601:afimoxifene