Estrogen receptors in human breast cancer nuclei

Abstract

The specific interaction of estrogen with human breast cancer nuclei has been studied from incubation in vitro of tumor slices at 37°C with 3H-17β-estradiol. Analysis of nuclear extract on Sephadex gel filtration and sucrose density gradient revealed the presence of a macromolecule binding the steroid with a sedimentation coefficient of approximately 4 S that was completely destroyed by treatment with pronase. The quantity of nuclear estrogen receptor and the affinity of the complex was measured by the exchange assay. The values were: Kd = 0.2 x 10-9 M; nM = 3.1 x 10-13 moles/mg DNA. The binding process is inhibited by estrogenic compounds such as estrone, estradiol, and estriol but not by testosterone, progesterone, and corticosterone