Presence Of Estrogen Receptor Alpha Research Articles

Histopathological and Immunohistochemical Characteristics of Thyroid Carcinoma in the Dog

Thyroid carcinomas are a common form of endocrine neoplasia in dogs. In the present study, we combined histopathology with immunohistochemistry (IHC) to search for the presence of oestrogen receptor alpha (ORα), Cox-2 and Ki67 in canine thyroid carcinomas. Forty-eight thyroid carcinomas were diagnosed throughout the study period. Thyroglobulin and calcitonin IHC distinguished between thyroid tumours with a follicular and medullary (C-cell) origin, respectively. IHC-based diagnosis showed that 42 (87.50%) of the cases were follicular cell carcinoma. In these cases, the follicular-compact pattern was the most frequent (n=20/42; 47.62%) and six cases (12.5%) were medullary cell (C-cell) carcinomas. Both medullary (C-cell) and follicular carcinomas expressed Ki67 and Cox-2. No differences were observed between medullary and follicular carcinomas with respect to expression of Ki67 (P=0.34) and Cox-2 (P=0.9523) markers. A total of 4.17% (n=2/48) of thyroid carcinomas showed positive nuclear labelling for ORα, suggesting that oestrogen does not directly participate in the pathogenesis of canine thyroid neoplasia.

Good prognosis for follicular lymphoma with estrogen receptor α-positive follicular dendritic cells.

Follicular lymphoma (FL) has a meshwork of follicular dendritic cells (FDCs). We previously demonstrated the presence of estrogen receptor alpha (ERα)+CD23+ FDCs in grades 1‐2 FL. The significance of FDCs as a prognostic factor in FL remains unknown. The current study aimed to compare clinicopathological features, including prognosis, between FL with and without ERα+ FDCs. This study evaluated the clinicopathological significance of ERα expression in 70 FL patients by immunostaining. The presence of ERα mRNA on FDCs from 5 FL patients was confirmed by CD21/ERα double staining (immunohistochemistry and in situ hybridization). We defined patients with frequent ERα expression as the ERαhigh group and those with infrequent ERα expression as the ERαlow group. Thirty‐two patients were assigned to the ERαhigh group (45.7%), and 38 patients were assigned to the ERαlow group (54.3%). Both overall survival (OS) and progression‐free survival (PFS) were significantly better in the ERαhigh group than in the ERαlow group (OS, log‐rank, P = .0465; PFS, log‐rank, P = .0336). Moreover, high ERα expression on FDCs was an independent prognostic factor for OS in both the univariate ([hazard ratio] HR, 0.163; P = .0260) and multivariate (HR, 0.050; P = .0188) analyses and for PFS in both the univariate (HR, 0.232; P = .0213) and multivariate (HR, 0.084; P = .0243) analyses. ERα mRNA expression was detected in CD21+ FDCs within the neoplastic follicles of FL patients. In conclusion, a neoplastic follicular microenvironment with ERα‐positive FDCs might affect the grade and presence of the follicular pattern of FL and improve patient prognosis.

Abstract 2625: Identification of CTX-30916 as a novel antagonist of progesterone receptor signaling pathways

Abstract Breast cancer is the most commonly diagnosed cancer in women and the second leading cause of cancer related death in women. Progesterone is a major mitogen in the adult human mammary epithelium that, in addition to estrogen, is a key driver of breast cancer cell proliferation. Activated PR signaling through MAPK-driven phosphorylation of the progesterone receptor (PR) is also an important driver of breast cancer stem cells. PR expression is associated with the presence of estrogen receptor-alpha (ESR1) mutations that are constitutively active and linked to resistance in the clinic in response to aromatase inhibitors, antiestrogens and CDK4/6 inhibitors. Thus, PR may play a role in tumor relapse and resistance in the clinic and blocking both estrogen and progesterone receptors would likely be an effective approach in 2L treatment for patients with advanced breast cancer. There is great interest in evaluating antiprogestins in the clinic in combination with antiestrogens or CDK4/6 inhibitors. Apristor®, an extended release formulation of onapristone, a full antagonist of PR, that has efficacy in multiple in vivo and in vitro models in combination with antiestrogestins and CDK4/6 inhibitors, is currently being evaluated in several human clinical trials. In this study we have examined the in vitro properties of CTX-30916, a novel mono-N-desmethyl analog of onapristone. CTX-30916 binds potently to PR and acts as an antagonist in cell-based transfection assays. CTX-30916 displays selectivity against other steroid receptors in binding assays and is also a potent inhibitor of T47D breast cancer cell proliferation. Interestingly, CTX-30916 leads to a unique co-regulator binding pattern in the Microarray Assay for Real-time Co-regulator-Nuclear receptor interaction (MARCoNI) assay compared with onapristone and mifepristone indicating that the co-regulator peptide-PR interaction landscape is different between the various antiprogestins. These data suggest that CTX-30916 binding to PR leads to a distinct receptor conformation and antagonizes PR signaling pathways in cancer through a unique mechanism of action compared to other antiprogestins. Citation Format: Deepak Lala, Tasir Haque. Identification of CTX-30916 as a novel antagonist of progesterone receptor signaling pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2625.

In silico Molecular Modelling of Selected Natural Ligands and their Binding Features with Estrogen Receptor Alpha.

Breast cancer is one of the most common cancers diagnosed among women. It is now recognized that two receptors mediate estrogen action and the presence of estrogen receptor alpha (ERα) correlates with better prognosis and the likelihood of response to hormonal therapy. ERα is an attractive target for the treatment of breast cancer. Most of the drugs currently used for the breast cancer treatment have numerous side effects and they are often unsuccessful in removing the tumour completely. Hence, we focused on natural compounds like flavonoids, polyphenols, etc. which do not exhibit any high toxic effects against normal cells. To identify the potential natural inhibitors for BCa through an optimised in silico approach. Structural modification and molecular docking-based screening approaches were imposed to identify the novel natural compounds by using Schrödinger (Maestro 9.5). The Qikprop v3.5 was used for the evaluation of important ADME parameters and its permissible ranges. Cytotoxicity of the compounds was evaluated by MTT assay against MCF-7 Cell lines. From the docking studies, we found that the compounds, Myricetin, Quercetin, Apigenin, Luteolin and Baicalein showed the highest Glide Scores -10.78, -9.48, -8.92, -8.87 and -8.82 kcal mol-1 respectively. Of these, Luteolin and Baicalein showed the significant IC50 values (25 ± 4.0 and 58.3 ± 4.4 µM, respectively) against MCF-7 cell line. The ADME profiling of the test compounds was evaluated to find the drug-likeness and pharmacokinetic parameters. We mainly focused on in silico study to dock the compounds into the human estrogen receptor ligand binding domain (hERLBD) and compare their predicted binding affinity with known antiestrogens. Myricetin, Quercetin, Apigenin, Luteolin and Baicalein were identified as the most promising among all. Of these, Luteolin and Baicalein showed significant anticancer activities against MCF-7 cell line. These findings may provide basic information for the development of anti-breast cancer agents.

Paternal behavior in the Mongolian gerbil, and its regulation by social factors, T, ERα, and AR

The present study evaluates the role of social factors in the transition from infanticidal to paternal male behavior and its association with T concentration, presence of estrogen receptor alpha (ERα) and androgen receptor (AR) in the olfactory bulb (OB), medial preoptic area (mPOA) and medial amygdala (MeA) of Mongolian gerbils (Meriones unguiculatus). This study included thirty-six sexually inexperienced males displaying aggressive behavior toward foreign pups. The selected animals were mated and organized into four groups. The paternal behavior tests were performed on the day of copulation (DCOPUL), during cohabitation with a pregnant female (CPREG), on the day of birth (DBIRTH), and on day 6 postpartum (DPP6). Eight sexually inexperienced males (CTL (male-male cohabitation) were used as control. After paternal behavior tests, blood samples were obtained to quantify T by radioimmunoassay; the brains were removed and analyzed for immunoreactivity (ir) of ERα and AR. All males of the DCOPUL, DBIRTH, and DPP6 groups exhibited paternal behavior, whereas the males of CPREG and CTL groups were aggressive with the pups. Paternal behavior was associated with high T concentrations, and the presence of ERα-ir and AR-ir in the OB, MeA, and mPOA. These results suggest that the transition from aggressive to paternal response to pups is facilitated by copulation, and that in this transition is involved an increase in T concentration. Moreover, the presence of ERα-ir and AR-ir in the OB, mPOA, and MeA could indicate that estrogenic and androgenic pathways participate in the regulation of paternal behavior of the Mongolian gerbils.

Social environment affects central distribution of estrogen receptor-α in Peromyscus californicus

Social environment has well-established effects on an animal’s social behavior and associated neuroendocrine responses. The presence of estrogen receptor alpha (ERα) in limbic system brain regions is related to the expression of a variety of social, reproductive and aggressive behaviors. We hypothesized that alterations to the social environment, specifically social isolation, would cause changes in ERα throughout the limbic system. The number of ERα immunoreactive (ERα-ir) cells within specific limbic system brain regions was quantified in male and female California mice (Peromyscus californicus), isolated or same sex pair-housed for 4 or 24 days. Peromyscus californicus is a highly social rodent species (monogamous and bi-parental) and therefore, may be particularly sensitive to manipulations of its social environment. Isolated males had a significantly greater number of ERα-ir cells in the ventromedial nucleus of the hypothalamus (VMH) and similar patterns within the bed nucleus of the stria terminalis (BST) and medial preoptic area (MPOA). Males housed for 24 days had a significantly greater number of ERα-ir cells in the BST, VMH, MPOA when compared with males housed for 4 days. Females housed for 24 days had significantly greater ERα-ir in the dentate gyrus of the hippocampus (DG) when compared with females housed for 4 days. No differences were found in the medial amygdala (MeA). These data demonstrate that social environment has region and sex specific effects on ERα-ir cells in this species. These results add to the comparative evidence regarding ERα, demonstrating a consistent role for ERα in species specific responsiveness to changes in the social environment.

Oestrogen and progesterone receptors in melanoma and nevi: an immunohistochemical study.

The effect of hormonal stimulation and fertility treatments, on the development of malignant melanoma (MM) remains to be determined. The aim of this study was to investigate the presence of oestrogen receptor alpha (ERα) and progesterone receptor (PR) in MM and nevi after hormonal stimulation. Immunohistochemical analyses were performed utilizing antibodies specifically directed against ERα and PR in MM and atypical nevi specimens from patients: (1) diagnosed during pregnancy, (2) diagnosed in the six months following delivery, or (3) who had undergone repetitive cycles of hormonal stimulation for in vitro fertilization (IVF) in the year that preceded MM diagnosis. Controls were atypical nevi and MM specimens of female patients of the same age group who had received no hormonal therapies and reported no pregnancies in the five years before diagnosis. Twenty-eight female patients at childbearing age were selected for this study. Strong cytoplasmic positivity of ERα and PR was detected in atypical melanocytes of two MM specimens of patients who had undergone repetitive cycles of hormonal stimulation during IVF procedures. All other specimens showed no expression of ERα or PR. Since our results represent preliminary findings, conclusions regarding a possible correlation between IVF therapy and melanoma occurrence cannot be ascertained. Larger laboratory studies should be performed to investigate reproductive hormone receptor expression in MM in women following IVF, pregnancy, prolonged contraceptive use, or hormone replacement therapy.

Accumulation of the advanced glycation end product carboxymethyl lysine in breast cancer is positively associated with estrogen receptor expression and unfavorable prognosis in estrogen receptor-negative cases

Advanced glycation end products (AGEs) accumulate as a result of high concentrations of reactive aldehydes, oxidative stress, and insufficient degradation of glycated proteins. AGEs are therefore accepted biomarkers for aging, diabetes, and several degenerative diseases. Due to the Warburg effect and increased oxidative stress, cancer cells frequently accumulate significant amounts of AGEs. As the accumulation of AGEs may reflect the metabolic state and receptor signaling, we evaluated the potential prognostic and predictive value of this biomarker. We used immunohistochemistry to determine the AGE Nε-carboxymethyl lysine (CML) in 213 mammary carcinoma samples and Western blotting to detect AGEs in cell cultures. Whereas no significant correlation between hormone receptor status and CML was observed in cell lines, CML accumulation in tumors was positively correlated with the presence of estrogen receptor alpha, the postmenopausal state, and age. A negative correlation was found for grade III carcinomas and triple-negative cases. In a retrospective Kaplan-Meier survival analysis, there was a statistical trend that high CML accumulation correlated with a more favorable prognosis (relapse-free survival, RFS) under tamoxifen treatment (p=0.1). In estrogen receptor-negative cases, the high CML content was significantly correlated with an unfavorable outcome (RFS) of chemotherapy(p=0.046). CML is a therefore a potentially predictive marker for the treatment of breast cancer patients with tamoxifen or chemotherapy.

Evaluation of estrogen receptor expression and its relationship with clinicopathologic findings in gastric cancer.

Background:The presence of estrogen receptor alpha has been reported in the cell and tissue levels in gastric cancer; however, its impact on patients’ survival remains unclear. The aim of this study was to investigate the expression of estrogen receptor in gastric carcinoma as well as its relationship with the clinicopathologic findings of the patients.Materials and Methods:The study was performed on 100 endoscopic biopsies of gastric adenocarcinoma for estrogen receptor expression using an immunohistochemical method, and their relationship with the clinicopathologic findings of the patients, such as age, gender, tumor site, size, grade, depth of tumor invasion (T), and lymphatic status (N), were analyzed using independent sample t-test and Pearson Chi-square test. A P < 0.05 was considered significant in all analyses.Results:Using an immunohistochemical method on endoscopic biopsies of 74 males and 26 females with the mean age of 63 years, estrogen receptor was found to be positive in 41% of patients. No significant difference was found between estrogen receptor expression and other clinicopathologic findings (P = 0.75). There was a significant difference between estrogen receptor (+) and estrogen receptor (−) groups in nodal involvement (P = 0.001). The estrogen receptor (+) patients had more number of lymph nodes involved.Conclusion:This study showed that lymph node involvement has a significant relationship with estrogen receptor expression. However, no significant relationship was found between estrogen receptor expression and other clinicopathologic findings such as age, gender, tumor site in stomach, tumor size, tumor grade, and T-stage.

Changes in the cellular localization of estrogen receptor alpha in the growing and regressing ovaries of Gallus domesticus during development

In this work, the presence of estrogen receptor alpha (ER-α) was determined in different cell subpopulations in the left growing and right regressing ovaries of Gallus domesticus from 13-day-old chicken embryos to one-month-old chickens by immunohistochemistry. Results revealed positive ER-α immunostaining in both ovaries during development, but the percentage, staining intensity, and cellular distribution of ER-α immunostaining changes according to whether it is the left or right ovary and with the animal’s age. In the left ovary, the ER-α was localized in the nuclei of the germinal epithelium and in germ cells of the ovarian cortex, as well as in the interstitial cells, undifferentiated cells, and epithelial cells of the lacunar channels of the ovarian medulla in all ages. In contrast, in the right ovary from 13-day-old chicken embryos to one-week-old chickens, only the epithelial cells of lacunar channels were ER-α immunoreactive, but in the right ovary of one-month-old chickens both the epithelial cells of lacunar channels and the interstitial cells presented ER-α. These results demonstrate differential expression of ER-α in both chicken ovaries during development in a cell type-specific distribution, suggesting that these differences may be regarded as an important cause in the process of asymmetric ovarian development in the chicken.

Differences in the survival rate between premenopausal and post menopausal women with gastric cancer: U.S. SEER database.

e15092 Background: Gastric cancer is the fourth most common malignancy in the world, The presence of estrogen receptor alpha (ER a) and estrogen receptor beta (ER b) have been reported in cell and tissue level in gastric cancer, but its impact on patients' survival remains unclear. The male predominance of gastric cancer suggests that female sex hormones may have a protective effect against gastric cancer. To understand the clinical impact of the estrogen pathway, we analyzed the national SEER database to compare the outcomes for gastric cancer in premenopausal vs.postmenopausal women. Methods: Data from the national SEER registry between the years of 1985-2009 was analyzed. Women between the ages 31-50 were chosen as representative of the pre-menopausal group (n=1291) and 51-70 year-old women represented the post-menopausal group (n=3089) as defined by the American College of Obstetricians and Gynecologists. To control the effect of age alone as a determinant of outcome, we compared the survival between men were similarly divided into two categories: younger men (n = 2114) aged 31- 50 years and older men (n = 5102) aged 51 - 70 years. Survival rates were analyzed by Kaplan-Meier method and compared by Z-test through SEER*Stat software version 7.0.9. Results: The cardiac gastric cancer site type and diffuse histological subtype had statistical significance difference between premenopausal and postmenopausal groups (49% vs.72%), (44% vs. 692%) respectively. The Kaplan-Meier curve shows the survival rate in premenopausal superior to postmenopausal women in diffuse gastric cancer P=0.01, while no statistically significant difference regarding mixed sub-types P&gt;0.05 and control groups. Conclusions: The results suggest varying estrogen effects between localization and histological subtype of gastric cancer, the presence of estrogen in gastric cancer could have a protective effect against gastric cancer and support clinical strategies need to stimulate the ER pathway or use estrogen for the treatment of gastric cancer, and additional studies are warranted as well as experimental studies that can shed light on the mechanism underlying this potentially protective action.

An Immunohistochemical Study on the Expression of Sex Steroid Receptors in Canine Mammary Tumors

Steroid hormones are found to play a major role in the genesis and progression of mammary tumors. The aim of this study was to immunohistochemically detect the presence of estrogen receptor alpha (ERα), estrogen receptor beta (ERβ), and progesterone receptor (PR) and also to study the association between these markers in 29 cases of benign (11) and malignant (18) canine mammary tumors. ERα immunostaining was noticed in only one case of carcinosarcoma specifically in the nuclei of epithelial and a few myoepithelial cells. ERβ immunostaining was noticed in the nuclei and cytoplasm of epithelial cells and smooth muscles lining the blood vessels. Immunoexpression of ERβ was 82% in benign tumors and 78% in malignant tumors. PR immunostaining was expressed in the nuclei of epithelial cells in both benign and malignant tumors. Among the 15 PR+ cases, 6 (55%) were of benign type, and 9 (50%) were of malignant type. The most common group of hormone receptor was the ERα−/PR+/ERβ+ (46%) in benign tumors and ERα−/PR−/ERβ+ (38%) in malignant tumors. Although there was no significant association between ERα and PR with ERβ, the findings indicated that ERβ was consistently expressed in both benign and malignant tumors, irrespective of ERα and PR status.

Prognostic Role of Estrogen Receptor α and Estrogen Receptor β in Gastric Cancer

The presence of estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta) have been reported in cell and tissue level in gastric cancer, but its impact on patients' survival remains unclear. This study was designed to investigate the expression level of ERalpha and ERbeta and to assess clinical significance of ERalpha and ERbeta expression in gastric cancer. The expression level of ERalpha and ERbeta were assessed by reverse-transcriptase polymerase chain reaction (RT-PCR) in 35 surgically resected gastric cancer and corresponding normal tissues and by immunohistochemical staining in 211 surgically resected gastric cancer and match normal tissues. The expression level between ERalpha mRNA expression in gastric cancer tissues and match normal tissues had no statistically significant difference. The ERbeta mRNA level in normal tissues was significantly higher than that observed in gastric cancer tissues (P = 0.001). Neither ERalpha nor ERbeta mRNA expression levels had significant correlation with clinicopathologic parameters. Forty-eight of 211 (22.7%) gastric cancer tissues showed positive expression of ERalpha and ERbeta detected in gastric cancer. ERalpha-positive expression correlated with poorer overall survival (P = 0.014), as did the absence of ERbeta expression in patients with gastric cancer (P = 0.001). In multivariate analysis, the positive expression of ERalpha and the absence of ERbeta were significant independent prognostic factors for overall survival (hazard ratio 2.159, P = 0.013, and hazard ratio 2.016, P = 0.025 respectively). Our results indicated that ERalpha and ERbeta were expressed in both gastric cancer and corresponding normal tissues. ERalpha expression and the absence of ERbeta expression are associated with poor survival.

Steroid hormone receptors ERα and PR characterised by immunohistochemistry in the mare adrenal gland

BackgroundSex steroid hormone receptors have been identified in the adrenal gland of rat, sheep and rhesus monkey, indicating a direct effect of sex steroids on adrenal gland function.MethodsIn the present study, immunohistochemistry using two different mouse monoclonal antibodies was employed to determine the presence of oestrogen receptor alpha (ERalpha) and progesterone receptor (PR) in the mare adrenal gland. Adrenal glands from intact (n = 5) and ovariectomised (OVX) (n = 5) mares, as well as uterine tissue (n = 9), were collected after euthanasia. Three of the OVX mares were treated with a single intramuscular injection of oestradiol benzoate (2.5 mg) 18 – 22 hours prior to euthanasia and tissue collection (OVX+Oe). Uterine tissue was used as a positive control and showed positive staining for both ERalpha and PR.ResultsERalpha staining was detected in the adrenal zona glomerulosa, fasciculata and reticularis of all mare groups. Ovariectomy increased cortical ERalpha staining intensity. In OVX mares and one intact mare, positive ERalpha staining was also detected in adrenal medullary cells. PR staining of weak intensity was present in a low proportion of cells in the zona fasciculata and reticularis of all mare groups. Weak PR staining was also found in a high proportion of adrenal medullary cells. In contrast to staining in the adrenal cortex, which was always located within the cell nuclei, medullary staining for both ERalpha and PR was observed only in the cell cytoplasm.ConclusionThe present results show the presence of ERalpha in the adrenal cortex, indicating oestradiol may have a direct effect on mare adrenal function. However, further studies are needed to confirm the presence of PR as staining in the present study was only weak and/or minor. Also, any possible effect of oestradiol treatment on the levels of steroid receptors cannot be determined by the present study, as treatment time was of a too short duration.

Role of the Oestrogen Receptors GPR30 and ERα in Peripheral Sensitization: Relevance to Trigeminal Pain Disorders in Women

Oestrogen increases facial allodynia through its actions on activation of the MAPK extracellular-signal regulated kinase (ERK) in trigeminal ganglion neurons. This goal of study was to determine which oestrogen receptor is required for behavioural sensitization. Immunohistochemical studies demonstrated the presence of oestrogen receptor alpha (ERalpha) in nuclei of larger neurons and cytoplasm of smaller neurons, and the novel oestrogen receptor G-protein coupled receptor 30 (GPR30) in small diameter neurons that also contained peripherin, a marker of unmyelinated C-fibres. Specific agonists for ERalpha (PPT) and GPR30 (G-1), but not ERbeta (DPN), activated ERK in trigeminal ganglion neurons in vitro. Both G-1 and PPT treatment increased allodynia after CFA injections into the masseter of ovariectomized Sprague-Dawley rats. Treatment with oestrogen increased expression of ERalpha but not GPR30, while masseter inflammation increased GRP30 but not ERalpha. Differential modulation of these ERK-coupled receptors by oestrogen and inflammation may play a role in painful episodes of temporomandibular disorder and migraine.

Effects of Estrogen, Raloxifene and Levormeloxifene on α1A-Adrenergic Receptor Expression

We investigated the effect of estrogen, raloxifene and levormeloxifene on alpha1A-adrenergic receptor expression. Postpartum rats underwent intravaginal balloon injury and ovariectomy, and were then treated with estrogen or placebo for 8 weeks. The urethras were examined for alpha1A-adrenergic receptor expression by Western blot analysis and immunohistochemistry. Urethral smooth muscle cells were isolated from untreated female rats and examined for the expression of estrogen receptors alpha and beta by immunofluorescence microscopy. Urethral smooth muscle cells were treated with estrogen, raloxifene or levormeloxifene for 24 hours and examined for alpha1A-adrenergic receptor expression by real-time polymerase chain reaction. The effects of these drugs on alpha1A-adrenergic receptor expression were further examined by promoter assays. Estrogen treatment resulted in decreased alpha1A-adrenergic receptor expression in the urethras. Urethral smooth muscle cells expressed estrogen receptors alpha and beta, the former predominantly in the cytoplasm and the latter in the nucleus. Estrogen significantly down-regulated alpha1A-adrenergic receptor mRNA expression, while raloxifene and levormeloxifene had no significant effect. Estrogen also significantly down-regulated alpha1A-adrenergic receptor promoter in the presence of estrogen receptor alpha or beta. Raloxifene and levormeloxifene up-regulated alpha1A-adrenergic receptor promoter in the presence of estrogen receptor alpha but not beta. Estrogen down-regulated alpha1A-adrenergic receptor expression in the urethral smooth muscle of female rats, while raloxifene and levormeloxifene had no significant effect. These findings represent a possible molecular mechanism through which estrogen, raloxifene and levormeloxifene differentially affect urinary continence.

Oestrogen receptor α and β in female rat pituitary cells: An immunochemical study

Estradiol is a critical factor in the anterior pituitary secretory activity of mammalian females. Previous reports have demonstrated the presence of oestrogen receptor alpha (ERα) and beta (ERβ) in specific anterior pituitary cells from ovariectomized rats, as well as in the whole anterior pituitary at particular stages of the rat oestrous cycle. However, the ERα and ERβ distribution patterns in specific hormone producing cells of the anterior pituitary during the oestrous cycle remain to be clarified. The purpose of this study was to determine the cellular and subcellular distribution of both ER-subtypes during the rat oestrous cycle, using immunochemistry at light- and electron-microscope levels. ERα-immunoreactive (ir) cells mainly corresponded to PRL-ir cells and, to a lesser extent, to TSH-, FSH- and GH-ir cells. ERβ-ir cells corresponded to a few GH-, PRL- and FSH-ir cells, whichever the phase of the cycle. ERα-ir was found either in the cytoplasm and/or the nucleus, depending on the phase of the oestrous cycle, while ERβ-ir was always detected in the cytoplasm. Both ER-subtypes were immunoreactives inside the rough endoplasmic reticulum (RER), secretory vesicles (SV) and free in the cytosol. The highest number of ERα-ir cells was consistently found at pro-oestrus midday and the lowest at metaoestrous, while the number of ERβ-ir cells was low in all stages of the cycle. These results indicate that the genomic actions of oestrogen in the anterior pituitary cells during the oestrous cycle are mediated by ERα. However, the localization of ERα and ERβ in the RER and SV suggest a different translational and/or post-translational pathway, which could be involved in non-genomic mechanisms.

Unliganded estrogen receptor α inhibits breast cancer cell growth through interaction with a cyclin‐dependent kinase inhibitor (p21WAF1)

Estrogens are mitogenic in human breast cancer cells, but the presence of estrogen receptor alpha (ER alpha) is associated with a favorable prognosis in primary tumors and the molecular basis for this paradoxical relationship remains unknown. Here we show that ER alpha and ER alpha mutants devoid of ligand and DNA-binding domains inhibit cell growth in three-dimensional matrix as well as tumor formation in nude mice. Using in vitro and intracellular approaches, we have found that ER alpha, via its amino acids 184-283, interacts with cyclin-dependent kinase inhibitor p21(WAF1). Both proteins exhibit mutual interactions in the absence of estrogens or in the presence of pure antiestrogen ICI(182,780), whereas estradiol treatment disrupts their interactions. Cross-linking experiments reveal that these proteins are present in a larger complex of approximately 200 kDa that also contains cdk2 and cyclin E. We further demonstrate that the unliganded full-length ER alpha or the variant having the p21(WAF1) interaction region significantly increases p21(WAF1) expression, whereas ER alpha silencing reduces p21(WAF1) levels and silencing of p21(WAF1) is sufficient to prevent ER alpha-induced growth inhibition. Taken together, our results point to an antiproliferative function of the unliganded ER alpha through its physical interactions with p21(WAF1) that may also explain the favorable prognosis of ER alpha-positive breast cancers.

Estrogen Receptor-β Is the Predominant Estrogen Receptor Subtype in Normal Human Synovia

Joint pain increases after menopause with more than 50% of woman suffering from arthralgies. Since pain and inflammation of joints originate from synovial tissue, we aimed to discover whether estrogen receptors are present in the human synovia. This in vitro study was performed on samples of human synovial tissue, obtained from pre- (n = 8) and postmenopausal woman (n = 11) and men (n = 5) following surgery due to traumatic lesions. Fresh synovial tissue specimens were assessed for the localization as well as the presence of estrogen receptor-alpha (ER alpha) and estrogen receptor-beta (ER beta) by means of immunohistochemistry, as well as Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. ER beta protein and mRNA were found to be equally and highly expressed in synovial stroma and lining cells of all explants independent of sex or menopausal status. In contrast, weak ER alpha staining was localized in the synovial lining cells in only three of 24 explants. ER alpha protein was found to be weakly expressed in three of ten explants. ER alpha mRNA was found with highly variable amounts in seven of ten explants. In view of our observation that ER beta but not ER alpha is expressed regularly in normal human synovia in high amounts, we propose that estrogen could play a significant role in synovial membrane function in women and men, operating preferably via the ER beta isoform.

Immunohistochemical detection of estrogen receptor alpha in the growing and regressing ovaries of newly hatched chicks

The aim of this study was to detect the presence of estrogen receptor alpha in different cell subpopulations of the growing left and regressing right ovaries from newly hatched chicks, by immunohistochemical methods, using an indirect immunoperoxidase technique. Newly hatched chicks were killed by decapitation and the growing left and regressing right ovaries were removed and processed for histological and immunohistochemical studies. The percentage of estrogen receptor alpha (ERalpha) immunostained cells and the staining intensity were determined. Histological results demonstrated that the right ovary lacks cortex and is constituted by the medullary region, whereas the left ovary is composed by cortical and medullary compartments. The medullary region is similar in both ovaries and presents the same elements. Immunohistochemical analysis revealed ERalpha-positive cells in the left ovary, located in the nucleus of all cell subpopulations; in contrast, in the right ovary, only epithelial cells of the lacunar channels depicted estrogen receptors. The present findings indicate a cell-specific localization of ERalpha in left and right ovaries of newly hatched chick.