On the role of 17 alpha-estradiol and 17 beta-estradiol in the proliferation of MCF7 and T47D-A11 human breast tumor cells.

A comparative study of the proliferative effect of 17 beta-estradiol and 17 alpha-estradiol on human estrogen-sensitive cell lines was performed. When using charcoal-dextran stripped human female sera-supplemented media the administration of the hormones, 17 alpha-estradiol at 3 X 10(-10)M, and 17 beta-estradiol at 3 X 10(-11)M, resulted in a ten-fold increase in cell yield when compared with non-estrogen supplemented controls after cells were grown for periods between 10 to 14 days. No significant metabolization of 17 alpha-estradiol into 17 beta-estradiol occurred as measured by the E2 levels in the supernatants of the cell culture flasks. Increased concentrations of 17 beta-estradiol and 17 alpha-estradiol added to the media bathing C7MCF7-173 cells resulted in a triggering of a partially successful shut-off effect; this phenomenon was not observed with T47D-All cells. These results are compatible with predictions stemming from the indirect and direct negative working hypothesis for the regulation of cell proliferation.