Nuclear retention of receptor-oestrogen complex and nuclear acceptor sites

Transdermal estradiol for postpartum depression: results from a pilot randomized, double-blind, placebo-controlled study

Postpartum depression (PPD) is a common complication following delivery, though evidence-based treatment options are limited. This study explores the feasibility and efficacy of outpatient PPD treatment with transdermal estradiol (TE). In a pilot, double-blind, placebo-controlled trial, women with PPD were randomized to receive transdermal 17β-estradiol (100 mcg/day) or placebo patch. Over 6 weeks, women completed weekly ratings on the Beck Depression Inventory (BDI), Edinburgh Postnatal Depression Scale (EPDS), and Hamilton Depression Scale (HAM-D). Primary outcome measures were treatment response (> 50% decrease from baseline BDI) and remission (BDI < 10) at 6 weeks, and secondary outcome measures included severity on all scales at weeks 3 and 6. Of 12 recruited women, 6 received TE and 6 received placebo. By week 6, 5 women receiving TE responded to treatment and 4 showed symptom remission, compared to 2 responders and 1 remitter in the placebo group. This difference was not significant (p = 0.24). In a mixed-model of BDI ratings, TE was associated with a 9.2 point decrease at 3 weeks (95%CI - 19.5 to + 1.0, p = 0.074) and a 10.5 point decrease at 6 weeks (95%CI - 21.0-0.0, p = 0.049) compared to placebo, though these differences did not survive multiple comparisons correction. Analogous effects were found for HAM-D but not EPDS scores. Interestingly, no significant difference in plasma estradiol levels existed between groups. We were unable to demonstrate a significant therapeutic benefit of TE compared with placebo in PPD. Although limited by under-recruitment and loss to follow-up, our results suggest TE is a feasible option for outpatient PPD management, with preliminary evidence (based on secondary outcomes) for efficacy. Therapeutic effects may be seen as early as 3 weeks and may not directly depend on peripheral measures of estradiol.

The hormonal control of implantation

The hormonal control of implantation in mammalian species with and without embryonic diapause is described. In a majority of species displaying the obligate form of diapause the corpora lutea appear to exhibit a low level of steroidogenic activity throughout diapause, full luteal activity being resumed just before the initiation of implantation. Fluctuations in the plasma levels of oestrogen and progesterone during diapause may serve to prime the uterus for implantation. In species exhibiting the facultative form of diapause, such as the rat and mouse, both progesterone and nidatory oestrogen are required for the induction of implantation. In species not displaying embryonic diapause implantation will take place in the presence of progesterone alone. In the light of these considerations the selection of animal models for drug-screening purposes and possible new approaches to contraception are discussed.

Femara and the future: tailoring treatment and combination therapies with Femara

Long-term estrogen deprivation treatment for breast cancer can, in some patients, lead to the activation of alternate cellular pathways, resulting in the re-emergence of the disease. This is a distressing scenario for oncologists and patients, but recent intensive molecular and biochemical studies are beginning to unravel these pathways, revealing opportunities for new targeted treatments. Far from making present therapies redundant, these new discoveries open the door to novel combination therapies that promise to provide enhanced efficacy or overcome treatment resistance. Letrozole, one of the most potent aromatase inhibitors, is the ideal candidate for combination therapy; indeed, it is one of the most intensively studied aromatase inhibitors in the evolving combinatorial setting. Complementary to the use of combination therapy is the development of molecular tools to identify patients who will benefit the most from these new treatments. Microarray gene profiling studies, designed to detect letrozole-responsive targets, are currently under way to understand how the use of the drug can be tailored more efficiently to specific patient needs.

Fine structural alterations induced by cortisol administration in non-adrenalectomized/non-fasted rat hepatocytes

AIM

To investigate the impact of exogenously administered cortisol on non-adrenalectomized and non-fasted rat hepatocytes morphology, by means of electron microscopy. Emphasis has been given to alterations concerning particular organelles such as the nucleus, the endoplasmic reticulum, mitochondria and lysosomes.

MATERIAL AND METHOD

Accordingly to their treatment, 50 male Wistar rats were divided into two experimental groups: Group I (N=30): Hydrocortisol 8 mg/100 g of body weight intraperitoneally. Group II (N=20): Controls, given 2 ml of normal saline intraperitoneally. Animals were sacrificed 30 and 180 min after injection and liver specimens were taken for morphological study.

RESULTS

In cortisol-treated cells: At 30 min, a significant decondensation of chromatin fibers was noticed, whereas the nuclear envelope and the nucleoli remained almost intact. Endoplasmic reticulum increased in size and complexity, as well as the number of mitochondria. The number of lysosomes slightly decreased. At 180 min, chromatin remained fully decondensated. Large nucleoli were apparent within the nucleus and the external membrane of the nuclear envelope was devoid of ribosomes.

CONCLUSIONS

Corticosteroids seem to promptly induce changes in hepatocytes ultrastructucture. The alterations mainly concern the size of nucleoli, the number of mitochondria and the complexity of endoplasmic reticulum, thus being consistent with an increased etabolic activity and protein synthesis.

Pharmacological profile of 6,12-dihydro-3-methoxy-1-benzopyrano[3,4-b] [1,4]benzothiazin-6-one, a novel human estrogen receptor agonist

Pharmacological studies were carried out to characterize further the endocrinological profile and the binding mode to the estrogen receptor (ER) of 6,12-dihydro-3-methoxy-1-benzopyrano[3,4-b][1,4]benzothiazin-6-one (1). Binding experiments were conducted with highly purified recombinant human estrogen receptors hERa and beta. Potent estrogenic activity of compound 1 was assessed by testing its ability to down-regulate ERs and to enhance estrogen receptor element (ERE)-dependent transcription. The latest step of our work dealt with the synthesis of the 9-fluorinated derivative 15 for ionic microscopy experiments to determine the intracellular localization of compound 1. Although 1 failed to compete with [3H]E2 for binding to both ER isoforms, evidence was reported that it interacted with hERalpha in MCF-7 cells (ER down-regulation/ERE-dependent luciferase induction). Hence, an appropriate conformation of the hormone binding domain, most probably conferred by co-regulators of ER, is required for the onset of an activity of the compound 1. Estrogenic activity was weak but on the order of magnitude of that of coumestrol (slightly weaker). The synthesis of the 9-methoxylated derivative 16 and its pharmacological evaluation led us to propose a binding mode of 1 on hERalpha. Compound 1 appears to interact with ERa mainly through interactions of its 3-methoxy substituent with the residue His-524 of the hormone binding domain.

Estrogen receptor interaction with specific histones. Binding to genomic DNA and an estrogen response element

Chromosomal proteins that impart high affinity and specificity to the binding of the estrogen receptor (ER) to DNA are termed estrogen receptor binding factors (ERBFs). Certain partially purified chromosomal protein fractions obtained from rabbit uterine chromatin by extraction with various molarities of GdnHCl when reconstituted to double-stranded DNA demonstrated high affinity binding for the ER. We report the purification and characterization of ERBFs in the chromosomal protein fraction extracted with 4 M GdnHCl (CP4) after large scale purification. These protein fractions were further purified by CL-Sepharose 6B column chromatography which resolved fractions from CP4 that recognized the ER bound by estrogen only or antiestrogen only. Thus, these hydrophobic chromosomal proteins enhanced the binding of the ER to reconstituted chromatin. To further investigate the interaction of ERBFs with ER, gel mobility shift assays were performed. The highly purified CP4 fraction with ERBF activity in the binding assay with reconstituted chromatin caused an increase in the formation of the retarded ER-estrogen responsive element (ERE) band. Thus, chromatin contains specific ERBFs for ER bound by estrogen which enhance the binding of ER to genomic DNA and a target ERE sequence. Further purification of the CL-Sepharose fraction with ERBF activity was achieved by preparative SDS-PAGE. ERBF activity was attributed to proteins with approximate molecular weights of 16,000, 13,000, and 12,000 and a pl of > 9.0. Peptides were partially sequenced by Edman degradation and were found to have identity with histones H2B and H4. A 17 kDa protein without ERBF activity was identified as H3. Since these histones were not readily extracted from chromatin with 3 M NaCl or 1-3 M GdnHCl, we postulate that some ERBFs may be histone variants or modified histones that display a very high affinity for DNA and ER.

The appearance, distribution, and longevity of receptor-[125I]T3 complexes within the nuclei of isolated rat hepatocytes

The nuclei of isolated rat hepatocytes were separable into three receptor compartments based upon their differential salt extractabilities: nucleoplasmic receptors (NP) extractable with 0.15 M KCl, high-salt extractable receptors (HSE) extractable with 0.4 M KCl, and salt-resistant receptors (SR) extractable with 0.4 M KCl/5 mM dithiothreitol. The receptor distribution among the three compartments was approximately NP, 45%; HSE, 30%; SR, 25%. The mean percent occupancy with endogenous T3 of the SR receptors (86%) was higher than the occupancies of the NP receptors (68%) and the HSE receptors (63%). When hepatocytes were pulsed with 3 nM [125I]T3 at 37 degrees C for brief intervals, receptor-[125I]T3 complexes were detectable in all three nuclear compartments within 15 sec. With increasing pulse intervals up to 120 sec, the receptor content of each nuclear compartment increased progressively and without evidence of preferential accumulation in any of the three compartments. To determine the life span and intercompartmental "migration" pattern of nuclear receptors, hepatocytes were pulsed with 3 nM [125I]T3 at 37 degrees C for 2.5 min or 5 min, followed by a chase with a 500-fold excess of nonlabeled T3. The population of receptor-[125I]T3 complexes generated during the pulse was serially recovered at increasing intervals after the chase. The complexes of each compartment dissociated with a half-life of approximately 3 min and manifested no predilection to accumulate in any of the compartments. Exposure of isolated hepatocytes to 3 nM T3 for 5 min or 10 min at 37 degrees C induced no change in the gross intercompartmental distribution of receptors compared to control hepatocytes incubated without T3.(ABSTRACT TRUNCATED AT 250 WORDS)

The ontogeny and cellular distribution of estrogen receptors in normal mouse mammary gland

The appearance, epithelial and stromal cell distribution of estrogen receptors (ER) in normal mouse mammary gland were determined between 1 and 10 weeks of age using immunohistochemistry. The effect of ovariectomy and estrogen (E)-treatment on the distribution and concentration of ER-positive cells at various ages was also analyzed. These studies demonstrate that ER are present in both mammary epithelial and stromal cells before the mammary gland exhibits a proliferative response or increase in progesterone receptor concentration as a result of E-treatment. Furthermore, an analysis of E-treatment suggests that although ER are present at an early age, there may be additional factors that determine the nature and extent of E-responsiveness.

The effects of hormonal and other stimuli on cell-surface Ro/SSA antigen expression by human keratinocytes in vitro: their possible role in the induction of cutaneous lupus lesions

Ultraviolet B light (UVB) has previously been shown to induce the expression of the extractable nuclear antigens (e.g. Ro/SSA) on the surfaces of human keratinocytes in vitro. This study assessed whether injurious, metabolic, inflammatory, immunological or hormonal stimuli would also induce this expression or modulate that produced by UVB. No stimulus initiated expression alone, but 17-beta oestradiol doubled that found in response to UVB. These findings confirm the potential role of UVB in the initiation and potentiation of cutaneous lupus lesions and may help to explain the female preponderance of the disease.

Tamoxifen increases plasma estrogen-binding equivalents and has an estradiol agonistic effect on histologically normal premenopausal and postmenopausal endometrium

OBJECTIVE

To determine the effects of single dose tamoxifen on plasma estrogen (E)-binding equivalents and endometrial estradiol (E2) and progesterone (P) receptors.

DESIGN

Controlled clinical study.

SETTING

Normal human volunteers were studied in an academic research environment.

PATIENTS

Premenopausal and postmenopausal women with histologically normal endometrium undergoing curettage or hysterectomy were selected.

INTERVENTIONS

Tamoxifen was administered orally; blood and endometrial samples were collected 4 to 96 hours after tamoxifen administration.

MAIN OUTCOME MEASURES

Plasma E-binding equivalents, endometrial cytosolic and nuclear E2 and P receptors.

RESULTS

(1) Plasma E-binding equivalents increased eightfold at 4 to 24 hours of tamoxifen administration and declined exponentially thereafter, reaching control levels at 73 to 96 hours. Plasma E-binding equivalents were not affected by endogenous E2 levels. (2) Endometrial total E2 and P receptor levels increased in all women 2.9 to 19.2-fold after tamoxifen. (3) Tamoxifen resulted in an increase in the fraction of the E2 receptor measured in the nuclear extract 2.1 to 7.5-fold in midcycle, secretory, and menopausal endometria but not in proliferative endometrium.

CONCLUSIONS

(1) Tamoxifen has an E2 agonistic effect on histologically normal human endometrium. (2) Irrespective of the total level of the endometrial E2 receptor, the nuclear capacity of that receptor in vivo is limited (approximately 75% to 80% of the total level).

Effect of age on physico-chemical properties of the uterine nuclear estrogen receptors of albino rats

Estrogen receptors (ER) were extracted with high ionic strength buffer from the nuclei of uteri of young (21 weeks) and old (89 weeks) rats. Following the analysis of these receptors on a sucrose gradient and a Sephadex column, two peaks representing the two forms of receptors were obtained. The minor peak sedimented at 6.8 S with Stokes radius (RS) = 7.2 nm, molecular weight (Mr) = 204 K and frictional ratio (f/f0) = 1.71. On the other hand, the major peak sedimented at 4.1 S with RS = 3.3 nm, Mr = 57 K and f/f0 = 1.18. These properties of nuclear ER were similar in both ages. Also, the half life of ER complexes from both ages at 25 degrees C and 37 degrees C were 135 min and 30 min, respectively. However, these complexes were retained for longer periods in the nuclei of young than old rats. Furthermore, the dissociation constant of the binding of nuclear receptors to estrogen remained constant, but the number of binding sites decreased from 1.56 in young to 1.05 pmol/mg DNA in the old. In young rats, about 61% of nuclear receptors bound to DNA-cellulose. Out of this 2/5 was eluted with 0.15 M and the remaining 3/5 with 0.5 M KCl. On contrary, only 37% of total receptors bound to DNA-cellulose in the old. Out of this 3/5 was eluted with 0.15 M and the remaining 2/5 with 0.5 M KCl. These data suggested that despite the similarity in different physicochemical properties, the number of estrogen binding sites and the retention time of ER complexes in nuclei and the ability of these complexes to bind to DNA decrease in the uterus of old age.

Hormone receptor status in human endometrial adenocarcinoma

Steroid receptor levels were determined in 196 samples of endometrial adenocarcinoma: cytosol estradiol receptors (ERc) were measured in 171 samples, cytosol progesterone receptors (PRc) in all samples; nuclear estradiol receptors (ERn) and nuclear progesterone receptors (PRn) in 68 samples; total estradiol receptors (ERt = ERc plus ERn) and total progesterone receptors (PRt = PRc plus PRn) were measured in 68 samples. The ERc levels were 88.2 +/- 8.9 (mean +/- SEM) and ERn were 94.4 +/- 15.6 fmol/mg protein; PRc levels were 197.9 +/- 25.9 and PRn 178.3 +/- 55.9 fmol/mg protein. The ERt levels were 162.6 +/- 23.2 and PRt 249.8 +/- 75.7 fmol/mg protein. The presence of PRc was related to the ERc levels according to the cut-off used. Estradiol receptors (ER) and progesterone receptors (PR) were present in the cytoplasmic and nuclear fractions in 60.2% and 36.8% of cases, respectively. The simultaneous presence of both ERt and PRt was observed only in 27.9% of cases. In the normal endometrium ERc and PRc were negatively correlated (r = -0.525, P less than 0.005), whereas in endometrial adenocarcinoma the correlation was positive (r = 0.491, P less than 0.001). In contrast with the normal endometrium the correlation between ERc and ERn was positive (r = 0.582, P less than 0.001) in tumor tissue. In neoplastic tissue Scatchard analysis showed a single class of specific ERc sites with a dissociation constant (Kd) of 1.39 +/- 0.8 X 10(-9) mol/l, one tenth of that found in the normal premenopausal endometrium. Qualitative and quantitative analysis of the receptor status showed that in 30% to 40% of cases studied the behavior of the neoplastic cell was similar to that found in the normal endometrial cell. In a 4-year follow-up of patients affected by endometrial adenocarcinoma there is better survival in the groups of patients with a simultaneous presence of ERt and PRt than in the group with their absence.

Estradiol and chlordecone interactions with the estradiol receptor

The in vivo and in vitro effects of the chlorinated pesticide, chlordecone, on the estradiol receptor of adult ovariectomized CDF-344 rats were examined. Chlordecone's competition with [3H]estradiol for binding to the estradiol receptor in vitro was similar whether receptors were derived from neural or uterine tissue. In vivo, chlordecone led to nuclear retention of estradiol receptors in both tissues, but in comparison to estradiol, the latency for such retention was slower following chlordecone. Nevertheless, chlordecone- and estradiol-treated animals eventually achieved the same degree of nuclear retention in uterine tissue. In brain, estradiol-like levels of nuclear retention were never found in chlordecone-treated females. Estradiol receptor replenishment following chlordecone or estradiol was similar in uterine tissue but not in brain. Chlordecone's lesser ability to mimic estradiol's receptor dynamics in the brain may contribute to the apparent tissue differences in chlordecone's estrogenicity.

The effect of homogenization temperature upon the apparent cellular compartmentalization of unoccupied estrogen receptor

Homogenization of rat uterus at elevated temperatures results in an increased nuclear localization of unoccupied estrogen receptor. This is a nonlinear effect which is accounted for by an increased population of KCl-resistant nuclear binding sites at the elevated homogenization temperatures.

Transient administration of estradiol-17 beta establishes an autoregulatory loop permanently inducing estrogen receptor mRNA

A single transient dose of estradiol-17 beta is sufficient to elicit the permanent induction of hepatic estrogen receptor mRNA, which is induced 18-fold (from 0.13 to 2.4 molecules per cell) and then remains fully induced for at least 125 days. In primary liver cultures, extremely low concentrations of estradiol-17 beta, which are below the Kd of the Xenopus laevis estrogen receptor, maintain persistent induction of estrogen receptor mRNA but not of estrogen-inducible vitellogenin mRNA. These data and the ability of the antiestrogen, hydroxytamoxifen, to reverse persistent induction of estrogen receptor mRNA, support a model in which transient doses of estradiol-17 beta induce the estrogen receptor and thereby establish an autoregulatory loop. The low levels of estradiol-17 beta normally circulating in male X. laevis and the elevated level of receptor provide sufficient hormone-receptor complex to permanently maintain the induced level of expression of the estrogen receptor gene. The permanent induction of the estrogen receptor may be the regulatory switch that results in the persistent expression of a recently identified class of proteins that exhibit long-term responses to estrogen.

Binding of the androgen receptor to the nuclear matrix of human foreskin

The nuclear matrix (NM) is a salt and nuclease-resistant nuclear substructure. It is associated with active DNA transcription and has been shown to contain acceptor sites for steroid receptors in a number of specific target tissues. We have investigated the presence of acceptor sites for the androgen receptor (AR) in the NM of human newborn foreskin. The NM was prepared from the 800 g pellet by successive treatments with detergent, DNase and high salt extraction. It contained 13 +/- 7% of total proteins and 10 +/- 6% of total DNA. After extensive washing, the NM spheres were incubated in the presence of cytosol and [3H]methyltrienolone +/- 200-fold excess of unlabeled steroid. Maximal binding of the AR to NM was reached in 30 min and decreased slightly thereafter to reach an equilibrium which was maintained for 18 h. Binding was saturable. In the absence of AR, the steroid did not bind to NM. When Scatchard analysis was performed on cytosol previously incubated with NM, cytosolic binding capacity significantly decreased relative to preincubation values (3.6 +/- 1.9 to 1.3 +/- 1.2 fmol/mg protein, P less than 0.05, n = 6). In contrast, apparent binding affinity was not changed. 0.8 mg of NM protein could bind AR from 2.4 mg of cytosol protein. In conclusion, NM from human foreskin binds the AR with high affinity. This binding is rapid and is maintained for at least 18 h. This is consistent with a potential role of NM in the mechanism of action of androgens in their target tissues.

Estrogen and progesterone receptor determinations in breast cancer. Technology, biology and clinical significance

Our present state of knowledge regarding estrogen and progesterone receptors (ER and PgR) has led to changes in treatment strategies: patients without receptors in their tumor tissues cannot be expected to respond to endocrine therapy. Furthermore, groups of patients with specifically good or poor prognoses can be selected. Treatment of the disease now approaches being of a rational rather than of an empirical nature. However, it is imperative that we achieve a considerably higher level of understanding before we can predict, with high probabilities, which patients will benefit from endocrine therapy. Only through a coordinated effort by many centers can we hope to attain this goal. In such collaborations there are several factors that must be taken into consideration if reproducible conclusions are to be reached: a) sampling of the tumor biopsy for analysis, b) potential differences in assay procedures which may affect results, and c) the composition of the population studied. Since the traditionally used ligand binding assay (dextran-coated charcoal (DCC) method) is highly sensitive even to slight modifications in assay procedure, intra- and interlaboratory standardization of receptor analyses is challenging. Accordingly, correlations between receptor status and/or concentrations and the clinical course of the disease from different centers often demonstrate discrepant results. With the greater reproducibility and sensitivity of the newly developed immunoenzymometric assay (IEMA) methods, many of these problems might be solved in the future and inter-center clinical studies will thus be facilitated. In the national Danish Breast Cancer Cooperative Group (DBCG) project, approximately 90% of all patients with primary breast cancer are registered. Estrogen and progesterone receptor (ER and PgR) determinations have been performed on tumor tissue from approximately 30% of these patients in one single laboratory. The results of these analyses are presented here for approximately 4,000 patients in relation to age, menopausal status, tumor size, grade of anaplasia, and lymph node involvement. Biologically and clinically there appear to be three fundamental types of tumor tissues; hormone responsive (ER+PgR+ and ER-PgR+), hormone non-responsive (ER-PgR-), and tissues of a more dubious hormone responsive nature (ER+PgR-), which occur predominantly among postmenopausal patients. Several lines of evidence indicate that among the postmenopausal patients there may be an estrogen binding molecule similar to but distinct from the normal, physiologically functioning ER molecule.(ABSTRACT TRUNCATED AT 400 WORDS)

Nuclear estrogen receptor molecular heterogeneity in the mouse uterus

Holomeric estrogen receptor (ER) prepared from ovariectomized mouse uteri displays heterogeneous electrophoretic mobility when analyzed by NaDodSO4/PAGE. ER derived from nuclei (ERn) appears as a closely spaced doublet having apparent molecular masses of 66.4 and 65 kDa, while ER from the cytosolic compartment (ERc) has a single band of 65 kDa. Both partially purified ERc and the 8S form of unactivated ERc show only the 65-kDa band. The appearance of the ERn doublet is hormonally inducible, and the relative proportions of the two doublet bands are influenced by the type of hormone treatment, with weakly estrogenic compounds yielding the lower band as predominant while potent estrogens increase the proportion of the upper band. Steroid binding of the ERn doublet was determined by [3H]tamoxifen aziridine affinity labeling of both the 66.4- and the 65-kDa peptides; binding to the 65-kDa peptide was predominant. The ERn doublet displays a time dependency after estrogen administration with maximal amounts occurring in a bimodal fashion at 1 and 8 hr.

A study on the effect of a single dose of tamoxifen on uterine hyperaemia and growth in the rat

1 The effect of a single subcutaneous dose of tamoxifen on the rat uterotrophic response was investigated. 2 The parameters examined were uterine blood flow (measured by the microsphere technique), uterine wet and dry weights and the concentrations of cytosolic and nuclear oestrogen receptors. 3 Tamoxifen or its metabolites proved to be capable of eliciting a uterotrophic response of 35-42 days duration. The changes seen in uterine blood flow and weight are discussed in relation to oestrogen receptor distribution.

Hormone independent activation of rat uterine estrogen receptor by exposure of isolated uteri to anaerobic conditions

Incubation of isolated rat uteri under anaerobic conditions, which consisted of either an atmosphere of carbon monoxide or nitrogen, caused an increase in nuclear estrogen binding which was not dependent on added estrogen. The incubation of uteri in the absence of added estrogen under aerobic conditions (atmosphere of oxygen or oxygen-carbon dioxide [95-5%]) did not increase uterine nuclear estrogen binding levels. High salt (0.5-M KCl) extracts of the nuclear estrogen binding moiety induced by anaerobiosis were shown to possess a sedimentation coefficient on sucrose-glycerol gradients of 4.8S, a binding specificity restricted to estrogens and an apparent affinity constant of 1.35 nM. These data confirm that the nuclear binding moiety induced by anaerobiosis possesses the characteristics of an estrogen receptor. The enhanced nuclear estrogen receptor retention induced under anaerobic conditions could be accounted for by a significant increase in nuclear receptor extracted by high salt (0.5 M KCl) and by ethanol (salt resistant fraction). Furthermore, sequential extraction of nuclear estrogen receptor from uteri exposed to aerobic conditions in the presence of added estradiol paralleled the results obtained with anaerobiosis. Total receptor retained under anaerobiosis represented 25% of that observed under aerobic conditions in the presence of estrogen. These results indicate that anaerobic conditions can cause an activation of uterine estrogen receptor. This activation process represents a pathway for receptor activation which does not require steroid.

Non-stoichiometric nuclear-cytoplasmic redistribution of estrogen receptor in adult rat uterus, following estradiol injection

In immature and ovariectomized rats acutely injected with estradiol (E2), accumulation of estradiol receptor complexes (E2R) from the uterine cytosol to the nucleus has been shown to be quantitative by numerous investigators. In the present study, translocation of E2R from the cytosol to the nuclear fraction in adult and ovariectomized estrogen prestimulated rats was analyzed. Twenty micrograms of E2, dissolved in saline containing 10% ethanol and 1 g% bovine serum albumin (B.S.A.) were injected intraperitoneally to the animals and 2 h later E2R in the cytosol and crude nuclear fractions were assayed by exchange techniques. Unlike a 91% recovery of the depleted cytosol E2R in the nuclear fraction of ovariectomized rats, only 39.2 and 27.5% were recovered in the adult and ovariectomized estrogen prestimulated rat uterus respectively. Moreover, depending on the temperature and duration of nuclear suspension incubation, from 18 up to 80% of the recovered nuclear E2R were solubilized in the incubation medium and nuclear post-incubation washes and could be measured by hydroxylapatite treatment (HAP). Saturation assays showed a plateau from 12 nM E2 3H onwards up to 80 nM. The Kd values computed for the receptors in the nucleus and HAP in all the three groups were of the order of 2 X 10(-9) M. In conclusion, after E2 administration to adult or ovariectomized estrogen prestimulated rats, a stoichiometric recovery of the depleted cytosol E2R in the nuclear fraction was not observed, even when leakage of nuclear receptor into the medium in course of exchange was taken into account. Chronic estrogenization appeared to modify the dynamics of uterine receptor.

Applicability of nuclear androgen receptor quantification to human prostatic adenocarcinoma

It has been proposed that concentrations of nuclear androgen receptor may be predictive of tumor hormone dependence in cases of advanced human prostatic cancer. We have investigated the ability of this receptor population to reflect patient prognosis during endocrine therapy in 12 cases of stage D disease. KCl-extractable, nuclear matrix-bound and total nuclear androgen receptor concentrations showed a significant positive correlation with duration of patient survival (p less than 0.05) while cytosolic and total cellular androgen receptor concentrations were not significantly correlated with survival. However, use of selected threshold concentrations of receptors revealed that only cytosolic, nuclear KCl-extractable and total cellular receptors could significantly differentiate long-term and short-term survivors. Even given the small number of patients studied, the potential use of this androgen receptor assay as an index of both tumor hormone-dependence and patient prognosis was evident. Therefore, in order to make these androgen receptor assays more applicable, we attempted to simplify the methods for use on readily available tissues. Similar amounts of nuclear androgen binding were observed in crude and purified nuclear pellets, in nuclei treated with DNase and KCl in differing orders or in nuclei from tissue homogenized using glass or Polytron homogenization procedures. More importantly, nuclear androgen receptor concentrations in specimens of prostatic cancer or benign hyperplasia taken by needle biopsy or transurethral resection involving electrocautery did not differ from those of parallel specimens taken by Thompson cold punch. Simplified nuclear androgen receptor assays of needle biopsy or electrocautery specimens are accurate and should prove clinically applicable.

Activation-inactivation of hormone binding sites of the oestradiol-17 beta receptor is a multiregulated process

The calf uterus oestradiol-17 beta receptor exists in a hormone binding form, which is phosphorylated on tyrosine, and in a non-hormone binding form, which is dephosphorylated. Two enzymes regulate the number of hormone binding sites of the receptor: a kinase which has been purified from cytosol and a phosphatase purified from nuclei. Recent and new findings on the regulation of this activation-inactivation process are reported. In vitro only a fraction (30-60%) of the receptor binding sites are inactivated by the phosphatase. Evidence is given suggesting that this is due to the production during the inactivation process of a powerful inhibitor of the phosphatase. Ca2+-calmodulin stimulates the kinase activity with a parallel increase of phosphorylation on tyrosine and hormone binding sites of the receptor. Nanomolar concentrations of oestradiol-17 beta also stimulate the kinase to activate hormone binding sites. These results suggest that in intact cells inactivation-activation of the oestradiol receptor is a multiregulated process.

Specific binding of 3H-estradiol to rat prostate nuclear matrix

Specific estradiol binding activities can be demonstrated in nuclear matrix preparations obtained from intact rat prostate nuclei. Some of the characteristics of these in vitro binding activities to intranuclear components are presented and compared to those exhibited by purified nuclear fractions. Examination of the effects of exposure to castration and testosterone on the number of nuclear matrix binding sites revealed that the quantity and quality (Type) of receptors was modified. Furthermore, these changes are prevented when protein synthesis was inhibited.

Relationship between concentrations of extractable and matrix-bound nuclear androgen receptor and clinical response to endocrine therapy for prostatic adenocarcinoma

The relationship between androgen receptor concentrations and clinical response to endocrine therapy for prostatic adenocarcinoma was investigated for 13 stage D patients. Both cytoplasmic and nuclear-androgen receptors were quantified. For nuclear androgen receptor, nuclei were isolated and treated with high ionic strength buffer (0.6 M KCl) to yield a KCl-extractable fraction; the nuclei were then treated with DNase I to yield nuclear matrices. Electron microscopy confirmed the relative nuclear purity and revealed matrix morphology. An hydroxylapatite binding assay and methyltrienolone (R1881) were used to quantify androgen receptor in cytosol, the KCl-extract and matrix preparations. Following 6 months of hormonal therapy, the clinical status of patients was re-evaluated and the patients were grouped according to disease response. The androgen receptor data obtained prior to therapy were compared for the disease response groups. The mean concentrations of cytoplasmic androgen receptor, KCl-extractable nuclear androgen receptor and nuclear matrix-bound androgen receptor, respectively, in those patients with disease progression or death (no. = 6), were 671 +/- 232, 45 +/- 17 and 119 +/- 34 fmol. per gm. of tissue +/- S.E.M., and for those with disease regression or stabilization (no. = 7), 1427 +/- 435, 193 +/- 53 and 611 +/- 92 fmol. per gm. of tissue +/- S.E.M. While cytoplasmic androgen receptor concentrations were not related to clinical status, both extractable and matrix-bound nuclear androgen receptor concentrations were significantly higher in the group which responded to hormonal therapy. These results suggest that nuclear-extractable and nonextractable androgen receptor concentrations are useful indices for the prediction of hormone-dependence of prostatic cancer.

The binding of estrogen to liver nuclei from Japanese quail

Specific binding sites for estrogen were characterized in liver nuclei from adult Japanese quail. A single class of high-affinity binding sites (KD = 2 X 10(-10) M) was revealed by saturation analysis using an exchange assay. Estradiol (E2), estrone, and estriol competed effectively with [3H]E2 for the nuclear binding sites but progesterone and testosterone were ineffective. The concentration of sites was 0.15 +/- 0.05 pmol/mg DNA (mean +/- 1 SD) in sexually immature females and 0.47 +/- 0.11 pmol/mg DNA in layers. Nuclear estrogen binding sites were not detected in liver nuclei from male Japanese quail. However, after treatment of male birds with E2 there was a dose-dependent accumulation of binding sites. The maximum number of occupied sites was obtained with 50 ng E2/g body wt and equaled that found in laying females. The estrogen binding sites were retained in nuclei of estrogen-treated male quail with a T1/2 of 2.5 hr. Thus, an estrogen binding component was characterized in quail liver nuclei that had features consistent with an estrogen receptor, including high affinity, limited capacity, structural specificity, tissue specificity, nuclear translocation, and nuclear retention.

Nuclear androgen binding sites in the male rat. III. Late spermatids and spermatozoa in the testis, with an introduction to epididymal spermatozoa

Nuclear androgen binding sites were examined in late spermatids (stages 12-19) which resisted sonication of homogenized testes of mature male rats. The measurement of unoccupied binding sites in salt extract of purified spermatid heads by nuclear exchange at -10 degrees C was developed and validated. As in the prostate, unoccupied nuclear androgen binding sites in sonicated testes were in low concentration, were not artefactual, and could be occupied both in vivo and in vitro by exogenous androgens, and uniquely in hemicastrated rats by endogenously compensated androgens in the remaining testis. The properties of occupied binding sites in salt extract of purified spermatid heads (measured by nuclear exchange at 4 degrees C for 48 or more hours with 5 nM [3H]dihydrotestosterone) were almost identical to those of occupied binding sites in nuclei of the ventral prostate, except for their concentration. However, levels of specific binding activity approaching 50 fmol/mg DNA could be expected in salt extract of spermatid pellets, by use of a sulfhydryl reducing agent (dithiothreitol) prior to salt extraction, a protease inhibitor (phenylmethylsulfonyl fluoride) in all buffers, and optimization of the sonication protocol. Nuclear androgen binding sites of sonicated epididymal spermatozoa, collected by retrograde perfusion of the cauda epididymidis, were found to be completely salt-resistant. These binding proteins could be extracted by 0.4 M KCl if dithiothreitol and dihydrotestosterone were incorporated into the sonication buffer, if phenylmethylsulfonyl fluoride was added to all buffers, and if the purified epididymal sperm pellet was treated with sarkosyl, a non-ionic detergent, just before salt extraction. The salt extract of epididymal spermatozoa which were treated as described above contained two binding components: a soluble form which was eluted from hydroxylapatite by increasing concentrations of phosphate buffers, and a non-soluble form, free of DNA, which remained in the hydroxylapatite column, and which contained most of the androgen binding sites. Affinity (Kd) of dihydrotestosterone to the soluble and insoluble fractions of the steroid-binding protein complex was determined to be 0.7 and 0.1 nM, respectively. Salt-resistance of binding proteins in germ cells was shown to develop significantly in the last stages of spermiogenesis.

Cellular receptor levels and glucocorticoid responsiveness of lymphoma cells

A series of mouse lymphoma cell lines of independent origin was investigated with respect to glucocorticoid sensitivity, cellular receptor levels, and properties of receptors. The concentrations of the glucocorticoid dexamethasone required to produce comparable growth-inhibitory effects varied considerably amongst these cell lines. Also a wide range in the number of receptors per cell was found. When the receptor-steroid complexes were compared with respect to nuclear binding properties and affinities for DNA, no differences were seen. For 7 out of 10 cell lines studied we obtained a direct correlation between hormonal sensitivity and the number of cellular receptor sites divided by the dissociation constants KD for the receptor-dexamethasone complexes. This suggests that the receptor is a major quantitative determinant for steroid responsiveness. The limitations of receptor measurements for glucocorticoid therapy of lymphoid neoplastic disease are discussed.

A study of the androgenic function of the epididymis

Rats were subjected to bilateral orchidectomy or orchido - epididymidectomy and maintained on either 500 micrograms testosterone or testosterone propionate daily. The ventral lobes of the prostate were subsequently excised and examined for androgen receptors in terms of the total present in the cytosol and the nucleus, the proportion unoccupied by endogenous androgen and the relative populations that were nuclease excisable or nuclease resistant in the two groups of animals. A further group of animals was subjected to unilateral deferential venotomy and the same parameters examined in the ipsi- and contra-lateral lobes of the ventral prostate and the seminal vesicles. In the absence of the epididymides there was a reduction in the number of receptors per prostatic cell and an increase in the proportion that were unoccupied. The nuclei from these glands contained fewer receptors than did those from the animals in which the epididymides had not been excised. The effect of unilateral deferential venotomy was to bring about a relative increase in the number of cytoplasmic receptors in the ipsilateral lobes of the ventral prostate with a much greater proportion unoccupied compared with the lobes contra-lateral to the ligation. There was again an increase in the proportion of nuclease-sensitive receptors in the nuclei ipsilaterally. The conclusions are that the absence of the epididymides in androgen-maintained rats or deferential venotomy induces a relative androgen- deficiency of the prostate and seminal vesicles as reflected in the androgen receptor populations of these organs.

Relations between cytosolic and nuclear estrogen receptors in castrated rat uterus following low 17 beta-estradiol doses

The effects of low 17 beta-estradiol (E2) doses (500, 10 or 1 ng/kg b X wt) on the uterine cytosolic (Rc) and nuclear (Rn) estrogen receptor content have been studied in adult-ovariectomized rats. The uterine Rc content after 500 ng E2/kg showed a depletion-replenishment-overshoot cycle. No significant Rc depletion could be observed with 1 or 10 ng E2/kg, but their corresponding overshoots were more intense than those observed for 500 ng E2/kg. The uterine Rn levels after 500 ng E2/kg increased during the Rc depletion and also during the replenishment and overshoot of Rc. With the lower doses Rn increased during the overshoot of Rc. In each dose Rn and Rc attained maximal values simultaneously. The return from Rc and Rn maxima to control levels was simultaneous in all cases. The high Rc overshoots obtained with 1 or 10 ng E2/kg could be the expression of a process of receptor synthesis induced by E2, more intense than the Rc breakdown produced by the complex formation with E2. The similar Rc and Rn time courses obtained with the lower doses suggest that the unbound receptor could enter into the nucleus. The simultaneous Rc and Rn decrease suggests the induction of a receptor degradation process affecting both cytosolic and nuclear compartments.

Androgen binding sites on nuclear matrix of normal and hyperplastic human prostate

To further characterize human prostatic androgen receptor, nuclei were isolated from normal prostate (no. = 3) and benign prostatic hyperplasia specimens (no. = 10). High ionic strength (0.6 M KCl) treatment of nuclei released nuclear extractable androgen receptor and DNase I digestion then yielded nuclear matrices. Androgen receptor was quantified in the nuclear extract and nuclear matrix preparations by Scatchard analysis of specific R1881 binding. Only 1 of the 3 normal tissues had extractable androgen receptor (113 fmol. per gm. of tissue) while the mean concentration of extractable androgen receptor for BPH was 189 fmol. per gm. of tissue. The mean concentrations of matrix-bound androgen receptor were 325 fmol. per gm. of tissue and 548 fmol. per gm. of tissue for normal and hyperplastic prostate, respectively. The androgen binding sites on nuclear matrix may represent the functional intranuclear androgen receptor and a characterization of these sites may provide an understanding of the etiology of BPH.

Rat uterine polyamine biosynthetic decarboxylase activities following multiple injections of estradiol-17 beta and/or estriol

A single injection of 0.5 micrograms estradiol-17 beta (E2) plus 0.5 micrograms estriol (E3) stimulated a different pattern in 22-24 day-old rat uterine ornithine decarboxylase (ODC) and S-adenosyl methionine decarboxylase (SAMDC) activities than was induced by either a single injection of 0.5 micrograms E2 or multiple injections of 0.5 micrograms E3. Differences included alterations in enzyme activity peak timing as well as activity duration. Every 3 hour injections of 0.05 micrograms E2 induced maximum uterine ODC activity at 4, 24, 32, and 40 hours, intermediate activity at 48, 64, and 72 hours as well as a small peak by 56 hours. When 0.05 micrograms E2 plus 0.05 micrograms E3 were injected simultaneously every 3 hours, the ODC activity pattern was similar except that activity fell to intermediate levels by 40 hours. It is suggested that E3 alterations of E2 induced uterine enzyme activities (when monitored at frequent intervals) could be physiological alterations in uterine growth responses due to E2-E3 hormone interactions. However, there appeared to be no differences between E2 or E2 plus E3 induction of DNA synthesis and luminal epithelial cell height and cross-sectional area or ODC and SAMDC activities when measured at 24, 48, or 72 hours.

Hepatic nuclear estrogen receptor concentrations in the rat--influence of age, sex, gestation, lactation and estrous cycle

Nuclear estrogen receptor concentrations in rat liver were determined by exchange assay. The concentration of estrogen receptors in nuclei from vehicle-treated male and female rats show age-dependent, but not sex-dependent variations in the course of life. Levels are highest during the perinatal period (approximately 1500 binding sites/nucleus), whereafter they decrease towards the onset of puberty (approximately 300 binding sites/nucleus) before rising again to reach the postpuberal maximum (approximately 800 binding sites/nucleus). Pregnancy further raised receptor concentrations in the last week of gestation when they reach approximately 1200 binding sites/nucleus. Studies with ethynylestradiol-treated rats demonstrated that virtually no translocation can be detected before the onset of puberty; thereafter the number of translocated receptors increases dramatically reaching a maximum (9000 binding sites/nucleus) between day 80 and 87 of life. The extractability of the nuclear receptors with 0.4 M KCl varies during the course of life. Extractability is very high (approximately 90%) up to about day 12 of life, but then decreases markedly (to approximately 70% in vehicle-treated and to approximately 50% in ethynylestradiol-treated rats) before the onset of puberty.

Possible significance of new target tissues for 1,25-dihydroxyvitamin D3

A sensitive sucrose gradient procedure provided evidence for specific 3.6S 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] receptor-like binding components with low affinity for 25(OH)D3 in several reproductive target tissues in the rat, including testis, uterus and probably epididymis. Thus, the presence of 1,25(OH)2D3 receptors in non-vitamin D endocrine tissues is not restricted to the hormone secreting glands. Estrogen-stimulated uterine growth paralleled increased levels of the putative 1,25(OH)2D3 receptors, providing in vivo evidence for the concept of a relationship between these phenomena. However, a similar correlation was not observed in the growing testis (prepubertal vs mature rats). Whether this result stems from receptor localization in a cell type prevalent in the adult or a true dissociation between testis growth and receptor levels is unclear. Finally, significant levels (10.3 +/- 1.0% vs intestinal mucosa) of the putative 1,25(OH)2D3 receptors were found in the heart, an organ in which calcium mediates many specialized functions. Taken collectively, these observations on new target tissues of quite different overall function suggest that 1,25(OH)2D3 and its receptors may play a role in intracellular calcium homeostasis and possibly in regulating specialized intracellular functions of calcium.

CEA-like material in cytosols from human breast carcinomas. Correlation with biochemical and pathologic parameters

CEA-like material was found in 51 of 62 primary human breast carcinomas and in only 2 of 12 fibroadenomas. Levels of carcinoma CEA-like material correlated weakly with cytoplasmic estradiol receptor levels, total cytosol estrogens, and cytosol progesterone. Levels of CEA-like material showed no significant correlation with carcinoma stage, grade, cellularity, size or histologic type. Levels, however, correlated inversely with lymphocyte infiltration.

Androgenic regulation of estrogenic action on accessory sex organ smooth muscle

Our previous research has shown that 4 weeks of daily estrogen treatment, started on the day of castration, resulted in significant growth of the guinea pig seminal vesicle smooth muscle, yet little or no estrogenic effect on muscle tissue weight or DNA content was observed when the treatment was initiated after a 1-month period of castration induced regression. With the hypothesis that castration induced reductions in estrogenic sensitivity were due to alterations in the intracellular fate of estradiol in the muscle, we determined, following the intravenous injection of 3H-estradiol to normal, 24-hour castrates and 1-month castrates, the whole muscle tissue accumulation and subcellular distribution of 3H-estradiol. In the same 3 experimental groups, we also determined, using in vitro exchange assays with 3H-estradiol, the number of estrogen binding sites in both the cytosol and salt (1.2 M KCl) soluble fraction of the crude nuclear-myofibrillar pellet. It was found that the loss of estrogenic sensitivity in the 1-month castrate was not due to a reduction in either whole tissue accumulation, subcellular distribution, cytosol binding or salt-soluble nuclear binding of 3H-estradiol. Restoration of estrogenic responses in muscle DNA content and wet weight was achieved by priming 1-month castrates with 5 daily injections of dihydrotestosterone immediately prior to the onset of estrogen treatment. Shorter periods of androgen priming (e.g., 1, 2 or 3 days) slightly enhanced, but did not completely restore, estrogenic responses in muscle wet weight and DNA content. For estrogen sensitive parameters of muscle growth, such as collagen and RNA content, which were not altered in their response to the estrogen treatment by a 1-month period of castration-induced regression, androgen priming prior to estrogen treatment had no effect. Therefore, testicular androgens regulate selected facets of estrogenic sensitivity in guinea pig seminal vesicle smooth muscle; changes in the muscle cytosol or salt-soluble nuclear myofibrillar estrophiles do not appear to be responsible for the changes in estrogenic sensitivity.

Early increases in RNA polymerase I activity and 18S and 28S rRNA synthesis in the male rat pituitary after oestradiol treatment

This article reports the effect of a single injection of 17 beta-oestradiol on RNA synthesis, in the male rat pituitary. An increase in RNA polymerase I activity, with a maximum effect between 10 and 15 hours, is described. No modification in RNA polymerase II activity was detected. These results were extended and confirmed, using in vitro double labelling of RNA, following in vivo oestrogen treatment. Polyacrylamide gel electrophoresis of nuclear and cytoplasmic RNA showed an increased incorporation of adenine into 28S and 18S rRNA, in the pituitaries of oestrogen-treated animals. The 5S rRNA was not modified by the hormonal treatment. These effects on RNA polymerase I activity and on 28S and 18S rRNA synthesis were closely correlated with the long-term nuclear retention of receptor-oestradiol complexes, in vivo. Taken together, these observations argue in favor of the nucleolus as a preferential target for receptor-bound oestradiol, in the cell nucleus of the male rat pituitary.