Characterization of catecholestrogen membrane binding sites in estrogen receptor positive and negative human breast cancer cell-lines.
A specific membrane-binding of an estradiol metabolite, the catecholestrogen (CE) 2 hydroxyestrone (2OH-E1), was demonstrated in two receptor-positive (MCF7 and VHB1) and one receptor-negative (MDA-MB-231) human mammary carcinoma cell lines. The three cell lines were found to be able to synthesise and inactivate CE. Solubilization of membrane bound CE results in a high molecular weight component whose specificity differs from that of the classical estrogen receptor. Apparent dissociation constants were 6-10. 10(-9) M and binding capacities were higher in the receptor-positive cell lines than in the receptor-negative one. Since CE are susceptible to rapid degradation, the presence of such a site may be relevant in the protection and concentration of 2OH-E1 which has been shown to have "in vitro" anti-estrogenic properties in MCF7 breast tumor cells.
Vandewalle
B
B
Laboratoire d'Endocrinologie Expérimentale, Centre Oscar Lambret, Lille, France.
Hornez
L
L
Lefebvre
J
J
D001665:Binding Sites; D001943:Breast Neoplasms / Q000032:analysis*; D002460:Cell Line; D002462:Cell Membrane / Q000032:analysis; D002499:Centrifugation, Density Gradient; D002851:Chromatography, High Pressure Liquid; D004970:Estrone / Q000031:analogs & derivatives*; D005260:Female; D006801:Humans; D006894:Hydroxyestrones / Q000378:metabolism*; D008861:Microsomes / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis*; D012995:Solubility; D013347:Subcellular Fractions / Q000032:analysis
D006894:Hydroxyestrones; D011960:Receptors, Estrogen; D004970:Estrone