The measurement of cytosolic estrogen receptors in human endometrial tissue and organ cultures

The Influence of 17-Oxo- and 17-Hydroxy-16,17-secoestratriene Derivatives on Estrogen Receptor

Since many of newly synthesised D-secoestratriene derivatives showed antiestrogenic effect, with almost a total loss of estrogenic activity, we studied the effects of some of these compounds on estrogen receptors (ER), the translocation of the estrogen-ER complexes formed in presence of competing substances into the nucleus, as well as the binding of these complexes to DNA. The results of uterotrophic effects of analysed derivatives are in agreement with the influence of these compounds on activity and binding parameters of estrogen receptors. Namely, compounds that show relatively high antiestrogenic activity predominantly increaseKdand inhibit translocation to nuclei of radioactive complexes formed in their presence. On the other hand, compounds that do not significantly change binding parameters of estrogen receptors do not show antiestrogenic effect inin vivoexperiments.

ECC-1 human endometrial cells as a model system to study dioxin disruption of steroid hormone function

ECC-1, an established epithelial cell line derived from an adenocarcinoma of human endometrial lining, was examined for growth optimization, steroid hormone receptor- and Ah receptor content, and dioxin modulation of estrogen receptor function. Proliferation of ECC-1 cells was accelerated by growth on a lethally irradiated feeder layer of murine 3T3 fibroblasts. Immunoblot analysis demonstrated the presence of Ah receptor an intracellular protein that binds and regulates the toxic action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The Ah receptor was functional in these cells as assessed by concentration and kinetic patterns of CYP1A1-mediated 7-ethoxycoumarin O-deethylase (ECOD) induction. The half-maximal effective concentration (EC50) for TCDD was 0.2 nM, and maximal activity appeared after 24-h exposure. A limited structure-activity examination of ECOD activity provided additional evidence for Ah receptor involvement. Competitive binding assays were performed to examine kinetic parameters for estrogen, progesterone, and glucocorticoid receptors. Binding parameters of dissociation constant (Kd) and number of binding sites (Bmax) derived from Scatchard analysis were: estrogen, Kd = 0.67 nM; Bmax = 321 fmol/mg cytosolic protein; progesterone, Kd = 1.31 nM; Bmax = 258 fmol/mg cytosolic protein; dexamethasone, Kd = 1.75 nM, Bmax = 128 fmol/mg cytosolic protein. Exposure of ECC-1 cells to TCDD reduced the estrogen receptor level by 40% without affecting the Kd value, and reduced estrogen receptor-mediated transcription by 50% assessed by transient transfection of an estrogen-responsive reporter plasmid. These data suggest that the ECC-1 cell line is a useful model system for examining the action of dioxin in human endometrial tissue. Both the estrogen receptor and Ah receptor have been implicated in diseases of the endometrium, and examining their interactions may elucidate mechanisms of uterine disease etiology, as well as potential targets for disease prevention.

Metabolism of adrenal androgens by human endometrium and adrenal cortex

The enzyme 17 beta-hydroxysteroid dehydrogenase (17OHSD) was studied in human endometrium and adrenal cortex with respect to the metabolism of 5-androstene-3 beta,17 beta-diol (androstenediol) and dehydroepiandrosterone (DHA). The aim was to provide further information concerning the origin and biological significance of these androgens in endometrium, particularly the increased concentrations of the secretory phase and to compare the characteristics of the enzyme in the two tissues. In both endometrium and adrenal cortex the metabolism of androstenediol to DHA was linear with time and increasing enzyme concentration. The preferred cofactor was NAD and the apparent Km values were 3.4 +/- 0.2 (SD) microM (n = 3) for endometrium and 30.5 +/- 6.1 microM (n = 3) for adrenal cortex. In endometrium DHA was not metabolised to androstenediol in the presence of either NADH or NADPH whereas in the adrenal cortex both cofactors were utilised. However, the concentration of NADH required to achieve maximum enzyme activity was 10-fold higher (1 mM) than for NADPH (0.1 mM) and maximum activity with NADH was only 30% of that using NADPH. The apparent Km was 125 microM DHA (n = 2). The study indicates that androstenediol in endometrium does not arise from DHA metabolism but that its presence could be due to a binding protein particularly during the secretory phase. Our findings also suggest that the enzyme of endometrium differs from that of the adrenal cortex and that the kinetic properties may be related to the physiological requirements of the two tissues.

Endometrial tissue and plasma concentrations of 5-androstene-3 beta, 17 beta-diol during the menstrual cycle in normal premenopausal and perimenopausal women

A radioimmunoassay for 5-androstene-3 beta, 17 beta-diol (ADIOL) in human endometrium and plasma is described. The recognised criteria of reliability have been fulfilled. Plasma and endometrial tissue concentrations of ADIOL were determined in samples obtained from normal premenopausal and perimenopausal women (average ages 37 and 48 years respectively) at different phases of the menstrual cycle. In perimenopausal women plasma concentrations of ADIOL did not vary throughout the cycle (proliferative phase: 411 +/- 95 (SEM) pg/ml; secretory phase: 462 +/- 28.5 (SEM) pg/ml). For the premenopausal group the pattern was similar (proliferative phase: 568.4 +/- 56.9 (SEM) pg/ml; secretory phase: 663.1 +/- 64.7 (SEM) pg/ml) although a significant difference (P less than 0.05) was noted between late proliferative and late secretory phase levels in these women. A different pattern was observed for endometrial tissue concentrations of ADIOL. In both groups of women a significant (3-4-fold) increase occurred during the secretory phase. There was no apparent relationship between plasma and tissue concentrations of ADIOL either during the proliferative or the secretory phase. There was, however, an age associated decrease for both tissue and plasma ADIOL. Theories are proposed to account for the increase in ADIOL concentration during the luteal phase.

Estrogen and progesterone receptors of human endometrial cells in vivo and in vitro: comparative results of radiochemical and histochemical assays

Oncopathologists have been developing histochemical methods of sex steroid receptor determination, essential in therapy selection in breast cancer, based on the binding of labeled hormone to receptor. We have applied the fluorescent hormones available commercially from Lee to endometrium. Our purpose was to compare biochemical and histochemical results, both in fresh tissue and in endometrial tissue cultures. We wished to examine the ability of the technique to determine subcellular localization of hormone binding and to trace the hormone-receptor pathway to the chromatin. Eleven fresh normal endometrial specimens, in culture for 3 months, were used for the determination of receptors. As a control we also used cells from 4 human carcinoma cell lines. In fresh tissue, histological patterns were similar to those described in breast cancer but there was little correlation with radiochemical values. In cultured cells also, there was no similarity between the two techniques. Morphologically the labeled hormone was unable to enter the living cell. After fixation it never got through the nuclear membranes. Moreover, the fluorescent cytoplasmic feature was fibrillar and reticular, which could evoke a non specific fixation on the cytoskeleton. We concluded that this molecule is not useful for subcellular localization of hormone-receptor complexes.