Use of a biotinyl-estradiol derivative to demonstrate estradiol-membrane binding sites on adherent human breast cancer MCF-7 cells.

A biotinyl-derivative of 17 beta-estradiol has been used to demonstrate a site of recognition and binding of estradiol located on the plasma membrane of human breast cancer MCF-7 cells by using the biotin/avidin-FITC system. The specificity of this binding has been shown by a displacement of the fluorescent label by 17 beta-estradiol. No displacement was observed when testosterone was added. Quantification of this phenomenon has been shown by laser scanning cytometry while preserving the cells adhesiveness to their growth support as well as their membrane integrity. An analysis by confocal laser scanning microscopy suggested that the fluorescence distribution on MCF-7 cells treated with estradiol-biotin was on the cell periphery. The results obtained are in favour of the recognition and binding site of 17 beta-estradiol located on the plasma membrane of MCF-7 cells and they would indicate that the biological activity of estradiol, among others, could be initiated by an interaction with the membrane.