Estrogen binding component in the pilosebaceous tumor developed in Suncus murinus.
We transplanted a pilosebaceous tumor developed on the sidegland of Suncus murinus to male nude athymic (BALB/c-nu/nu) mice. This tumor can be transplanted to female hosts as well, with a lower rate of graft-taking and slower growth rate. In this study we demonstrated the presence of macromolecules which specifically bind to estrogen. Measurement of 17 beta-estradiol (E2) binding by a dextran-coated charcoal assay revealed that the number of binding sites and the dissociation constant were 22.3 +/- 4.6 fmol/mg protein and 1.4 +/- 0.24 X 10(-9) M, respectively. This binding was specific for E2 and diethylstilbestrol (DES). Sucrose gradient centrifugation of the [3H]E2-labeled cytosol yielded a sharp peak of radioactivity at 3.5S-4S under high salt conditions and a 9S peak with a shoulder at 3.5S under low salt conditions. This 3.5S shoulder was due to dissociation of [3H]E2 from the 9S peak during the centrifugation, since only the 9S peak was obtained by postlabeled density gradient analysis. An assay of the in vivo binding of [3H]E2 showed significant radioactivity in the nuclear extract from the tumor. This nuclear uptake was markedly decreased by simultaneous administration of 100-fold excess of E2. In tumor-bearing castrated nude mice, 1-100 micrograms/day of E2 did not affect tumor growth, whereas it counteracted the stimulative effect of testosterone propionate.
Takayasu
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Department of Dermatology, Medical College of Oita, Japan.
Itami
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Komada
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Kurata
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S
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis*; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000032:analysis / Q000378:metabolism; D013196:Dihydrotestosterone / Q000032:analysis; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000378:metabolism; D005260:Female; D011960:Receptors, Estrogen; D012626:Sebaceous Gland Neoplasms / Q000032:analysis* / Q000503:physiopathology; D012788:Shrews; D013739:Testosterone / Q000494:pharmacology
D002352:Carrier Proteins; D004967:Estrogens; D011960:Receptors, Estrogen; C010140:estrophilin; D013196:Dihydrotestosterone; D013739:Testosterone; D004958:Estradiol