Oestrogen-binding components in human renal cell carcinoma.
Specific binding of [3H]oestradiol-17beta by the cytosol fraction of human renal cell carcinoma was studied. The binding reaction displayed marked ligand specificity and high affinity of binding. Unlabelled oestradiol, oestriol and oestrone inhibited the binding of [3H]oestradiol-17beta to the cytosol binding sites, wehereas all other steroids tested turned out to be only weak or insignificant competitors for the oestrogen binding sites. Scatchard analyses suggested the existence of a single class of binding sites. The dissociation constant of the oestradiol-binding complex was found to be 2.51 +/¿.75 x 10(-9) mol/l. The number of binding sites was limited (17.5 +/- 3.8 fmoles per mg of cytosol protein). Sucrose gradient centrifugation revealed these binding components to be macromolecules either displaying a complex sedimentation pattern (peaks at 3.5 S, 4S, 5.7S and, in addition, high molecular weight aggregates) or sedimenting in the 4S region alone. By agar gel electrophoresis it could be demonstrated that the oestradiol-inding components migrated into the receptor region of the gel. Binding of [3H]oestradiol-17beta to these entities was markedly reduced, when the cytosol was heated (60 min at 45 degrees C) prior to the reaction with the labelled hormone. Since the specific binding components exhibit properties of oestradiol receptors in target tissues, a direct effect of oestradiol on human renal cell carcinoma is suggested.
D000230:Adenocarcinoma / Q000378:metabolism*; D000368:Aged; D002499:Centrifugation, Density Gradient; D003600:Cytosol / Q000032:analysis; D004587:Electrophoresis, Agar Gel; D004958:Estradiol / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D007680:Kidney Neoplasms / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D011960:Receptors, Estrogen / Q000032:analysis*
D011960:Receptors, Estrogen; D004958:Estradiol