Immunochemical studies of estrogen receptors

Sex bias in multiple sclerosis and neuromyelitis optica spectrum disorders: How it influences clinical course, MRI parameters and prognosis

This review is a condensed summary of representative articles addressing the sex/gender bias in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). The strong effects of sex on the incidence and possibly also the activity and progression of these disorders should be implemented in the evaluation of any phase of clinical research and also in treatment choice consideration in clinical practice and evaluation of MRI parameters. Some relationships between clinical variables and gender still remain elusive but with further understanding of sex/gender-related differences, we should be able to provide appropriate patient-centered care and research.

Advances in the Prevention and Treatment of Obesity-Driven Effects in Breast Cancers

Obesity and associated chronic inflammation were shown to facilitate breast cancer (BC) growth and metastasis. Leptin, adiponectin, estrogen, and several pro-inflammatory cytokines are involved in the development of obesity-driven BC through the activation of multiple oncogenic and pro-inflammatory pathways. The aim of this study was to assess the reported mechanisms of obesity-induced breast carcinogenesis and effectiveness of conventional and complementary BC therapies. We screened published original articles, reviews, and meta-analyses that addressed the involvement of obesity-related signaling mechanisms in BC development, BC treatment/prevention approaches, and posttreatment complications. PubMed, Medline, eMedicine, National Library of Medicine (NLM), and ReleMed databases were used to retrieve relevant studies using a set of keywords, including "obesity," "oncogenic signaling pathways," "inflammation," "surgery," "radiotherapy," "conventional therapies," and "diet." Multiple studies indicated that effective BC treatment requires the involvement of diet- and exercise-based approaches in obese postmenopausal women. Furthermore, active lifestyle and diet-related interventions improved the patients' overall quality of life and minimized adverse side effects after traditional BC treatment, including postsurgical lymphedema, post-chemo nausea, vomiting, and fatigue. Further investigation of beneficial effects of diet and physical activity may help improve obesity-linked cancer therapies.

Identification of metastatic cell nucleus in human prostate cancer by electron microscopy

AIM

Metastatic prostate cancer is responsible for a large proportion of deaths worldwide. The aim of this study was to identify metastatic cells and determine if stromal invasion by cancer cells differs from those during metastasis.

METHODS & RESULTS

Tissue biopsy/prostatectomy samples, visualized by transmission electron microscopy, identified that metastatic cells are a lineage of stem cells, which have dedifferentiated into cancerous columnar/cuboidal cells. These cells demonstrate nuclear plasticity; the loss of nuclear membranes and boundary between nucleus and cytoplasm; and the presence of electron dense molecules, which can readily pass through basement membranes and enter the capillary, ready for dissemination to metastatic sites.

CONCLUSION

This is the first study to demonstrate differences between invasive and metastatic cell types.

Temperature-sensitive liposomes for co-delivery of tamoxifen and imatinib for synergistic breast cancer treatment

Co-delivery of chemotherapeutic agents using nanocarriers is a promising strategy for enhancing therapeutic efficacy of anticancer agents. The aim of this work was to develop tamoxifen and imatinib dual drug loaded temperature-sensitive liposomes to treat breast cancer. Liposomes were prepared using 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), monopalmitoyl-2-hydroxy-sn-glycero-3-phosphocholine (MPPC), and different surface active agents. The liposomes were characterized for the average particle size, zeta potential, transition temperature, and drug release below and above liposomal transition temperature. The temperature-sensitive liposomes co-encapsulated with tamoxifen and imatinib were investigated for their synergistic activity against MCF-7 and MDA-MB-231 breast cancer cells. The liposomal nanoparticles showed a transition temperature of 39.4 °C and >70% encapsulation efficiency for tamoxifen and imatinib. The temperature-responsive liposomes showed more than 80% drug released within 30 min above transition temperature. Dual drug loaded liposomes showed synergistic growth inhibition against MCF-7 and MDA-MB-231 breast cancer cells. Co-delivery of tamoxifen and imatinib using temperature-sensitive liposomes can be developed as a potential targeting strategy against breast cancer.

Determination of Estrogen Receptors in Human Breast Cancer: Comparison between Enzyme Immunoassay and Dextran-Coated Charcoal Method

Estrogen receptor determination was performed on 120 breast cancer cytosols, using the dextran-coated charcoal method (DCC) and an enzyme immunoassay (EIA) to compare the efficiency of the two techniques. A strong correlation was noted between ER concentrations determined by DCC and EIA (P < 0.001). The mean ER-EIA value was significantly higher than the mean ER-DCC value in premenopausal (P < 0.001) as well in postmenopausal (P < 0.001) patients.

Prognostic Factors for Carcinoma of the Male Breast

Male mammary carcinoma (MMC) affects approximately 1000 men in the United States each year. Aside from the impact of estrogen-receptor positivity on the clinical course of this tumor, relatively little information exists in published form on the ability of special pathologic studies to predict its biologic behavior. The authors analyzed 26 cases of invasive ductal MMC, comparing overall survival with tumor size, histologic grade (Page and Anderson), immunohistologic estrogen receptor protein status, DNA ploidy, expression of S 100 and gross cystic disease fluid proteins, and immunohisto chemically-detected amplification of the c-erbB-2 (HER-2/neu) oncoprotein. Tumor size and amplification of c-erbB-2 oncoprotein emerged as the statistically significant predictors in this group; MMCs of <2 cm had a more favorable prognosis than large tumors. Estrogen receptor protein was seen in 80% of cases; c-erbB-2 amplification was present in 35%; 80% were DNA-aneuploid; and S 100 and gross cystic disease fluid were observed in 38% and 62% of cases, respectively. The latter data are virtually identical to those on histologically similar tumors in women, but all except c-erbB-2 failed to achieve statistical prognostic value in this study. Substrata of histologic grades among MMCs were numerically too small to subject to statistical assessment. These findings suggest that no substantive differences exist between the pathologic features of male and female breast cancers. They also indicate that adjunctive laboratory studies are currently unhelpful in the prognostication of MMC. Int J Surg Pathol 2(3):199-206, 1995

Localization and regulation of reproductive steroid receptors in the raphe serotonin system of male macaques

We previously showed that tryptophan hydroxylase 2 (TPH2) and serotonin reuptake transporter (SERT) mRNAs are increased by the androgens, testosterone (T) and dihydrotestosterone (DHT) in serotonin neurons of male macaques. In addition, we observed that serotonin in axons of a terminal region were markedly decreased by aromatase inhibition and lack of estradiol (E) from metabolism of T. These observations implicated androgen receptors (AR) and estrogen receptors (ER) in the transduction of steroid hormone actions in serotonin neurons. Due to the longer treatment period employed, the expression of the cognate nuclear receptors was sought. We used single and double immunohistochemistry to quantitate and phenotypically localize AR, ERα and ERβ in the dorsal raphe of male macaques. Male Japanese macaques (Macaca fuscata) were castrated for 5-7 months and then treated for 3 months with [1] placebo, [2] T, [3] DHT (non-aromatizable androgen) plus ATD (steroidal aromatase inhibitor), or [4] Flutamide (FLUT; androgen antagonist) plus ATD (n = 5/group). After single labeling of each receptor, quantitative image analysis was applied and receptor positive neurons were counted. Double-label of raphe neurons for each receptor plus TPH2 determined whether the receptors were localized in serotonin neurons. There were significantly more AR-positive neurons in T- and DHT+ATD-treated groups (p = 0.0014) compared to placebo or FLUT+ATD-treated groups. There was no difference in the number of positive-neurons stained for ERα or ERβ⋅ Double-immunohistochemistry revealed that serotonin neurons did not contain AR. Rather, AR-positive nuclei were found in neighboring cells that are likely neurons. However, approximately 40% of dorsal raphe serotonin neurons contained ERα or ERβ⋅ In conclusion, the stimulatory effect of androgens on TPH2 and SERT mRNA expression is mediated indirectly by neighboring neurons contain AR. The stimulatory effect of E, derived from T metabolism, on serotonin transport is partially mediated directly via nuclear ERs.

Sex hormones and immune dimorphism

The functioning of the immune system of the body is regulated by many factors. The abnormal regulation of the immune system may result in some pathological conditions. Sex hormones of reproductive system are one of the major factors that regulate immune system due to the presence of hormone receptors on immune cells. The interaction of sex hormones and immune cells through the receptors on these cells effect the release of cytokines which determines the proliferation, differentiation, and maturation of different types of immunocytes and as a result the outcome of inflammatory or autoimmune diseases. The different regulations of sex hormones in both sexes result in immune dimorphism. In this review article the mechanism of regulation of immune system in different sexes and its impact are discussed.

Mouse monoclonal antibodies against estrogen receptor

The production of monoclonal antibodies, by cloning hybridoma derived from the fusion of myeloma cells and spleen lymphocytes, has allowed to obtain great advances in many fields of biological knowledge. The use of specific antibodies to the estrogen receptor, in fact, has been an invaluable method to bring out its mechanisms of action and its effects, both genomic and extra-genomic. Here we describe, step by step, the production of monoclonal antibodies, starting from protocol for antigen preparation to the selection of antibody-secreting hybridoma.

Steroid receptors, HER2/neu and Ki-67, in endometrioid type of endometrial carcinoma: Correlation with conventional histomorphological features of prognosis

Endometrial proliferation is regulated by steroid receptors such as estrogen receptor alpha (ERalpha), estrogen receptor beta (ERbeta) and progesterone receptor (PR). HER2/neu is an important growth factor receptor which affects cell proliferation and Ki67 is a marker of cellular proliferation. Their interaction in endometrioid type of endometrial carcinoma is still not fully understood. In this study, we analyzed the immunolocalisation of ERalpha and ERbeta with particular attention to the ERbetacx isoform, PR, HER2/neu and Ki67 in endometrioid carcinoma. Their correlations with each other and with the conventional morphological prognostic parameters of myoinvasion and tumor grade were analyzed with respect to overall survival. Out of a total 54 cases, 14 showed evidence of local recurrence or metastatic disease within 5 years with poor outcome, whereas the rest had no evidence of disease. ERalpha, ERbeta, ERbetacx, PR, HER2/neu and Ki67 were detected using immunohistochemistry. The histological grade of the tumor correlated inversely with the intensity of immunolabelling of ERalpha and PR, and this was highly significant. The depth of myoinvasion showed an inverse correlation only with the ERbeta2/betacx immunopositivity and was not significantly associated with any other receptor evaluated. Analysis of the inter-relationship between receptor immunopositivity revealed a significant association of ERalpha immunolocalisation with ERbeta and with PR. Immunodetection of HER2/neu receptor correlated positively with both ERalpha and PR immunolabelling. The Ki-67 proliferation index correlated only with ERalpha immunopositivity. Preliminary observations suggested that with the exception of ERalpha, there was no correlation of any of the receptors evaluated with survival.

Sex differences in the expression of sex steroid receptor mRNA in the quail brain

In Japanese quail, males will readily exhibit the full sequence of male-typical sexual behaviors but females never show this response, even after ovariectomy and treatment with male-typical concentrations of exogenous testosterone. Testosterone aromatisation plays a key-limiting role in the activation of this behavior but the higher aromatase activity in the brain of males compared to females is not sufficient to explain the behavioural sex difference. The cellular and molecular bases of this prominent sex difference in the functional consequences of testosterone have not been identified so far. We hypothesised that the differential expression of sex steroid receptors in specific brain areas could mediate this behavioural sex difference. Therefore, using radioactive in situ hybridisation histochemistry, we quantified the expression of the mRNA coding for the androgen receptor (AR) and the oestrogen receptors (ER) of the alpha and beta subtypes. All three receptors were expressed in an anatomically discrete manner in various nuclei of the hypothalamus and limbic system and, at usually lower densities, in a few other brain areas. In both sexes, the intensity of the hybridisation signal for all steroid receptors was highest in the medial preoptic nucleus (POM), a major site of testosterone action that is related to the activation of male sexual behaviour. Although no sex difference in the optical density of the AR hybridisation signal could be found in POM, the area covered by AR mRNA was significantly larger in males than in females, indicating a higher overall degree of AR expression in this region in males. By contrast, females tended to have significantly higher levels of AR expression than males in the lateral septum. ERalpha was more densely expressed in females than males throughout the medial preoptic and hypothalamic areas (including the POM and the medio-basal hypothalamus), an area implicated in the control of female receptivity) and in the mesencephalic nucleus intercollicularis. ERbeta was more densely expressed in the medio-basal hypothalamus of females but a difference in the reverse direction (males > females) was observed in the nucleus taeniae of the amygdala. These data suggest that a differential expression of steroid receptors in specific brain areas could mediate at least certain aspects of the sex differences in behavioural responses to testosterone, although they do not appear to be sufficient to explain the complete lack of activation by testosterone of male-typical copulatory behaviour in females.

Current molecular diagnostics of breast cancer and the potential incorporation of microRNA

Although comprehensive molecular diagnostics and personalized medicine have sparked excitement among researchers and clinicians, they have yet to be fully incorporated into today's standard of care. This is despite the discovery of disease-related oncogenes, tumor-suppressor genes and protein biomarkers, as well as other biological anomalies related to cancer. Each year, new tests are released that could potentially supplement or surpass standard methods of diagnosis, including serum, protein and gene expression analyses. All of these novel approaches have shown great promise, but initial enthusiasm has diminished as difficulties in reproducibility, expense, standardization and proof of significance beyond current protocols have emerged. This review will focus on current and novel molecular diagnostic tools applied to breast cancer with special attention to the exciting new field of microRNA analysis.

Estrogen action: a historic perspective on the implications of considering alternative approaches

In the 50 years since the initial reports of a cognate estrogen receptor (ER), much has been learned about the diverse effects and mechanisms of estrogens, such as 17beta-estradiol (E(2)). This expert narrative review briefly summarizes perspectives and/or recent work of the authors, who have been addressing different aspects of estrogen action, but take a common approach of using alternative considerations to gain insight into mechanisms with clinical relevance, and inform future studies, regarding estrogen action. Their "Top Ten" favorite alternatives that are discussed herein are as follows. 1 - E(2) has actions by binding to a receptor that do not require its enzymatic conversion. 2 - Using a different strategy for antibody binding could make the estrogen receptor (ER) more discernible. 3 - Blocking ERs, rather than E(2) production, may be a useful strategy for breast cancer therapy. 4 - Secretion of alpha-fetoprotein (AFP), rather than only levels of E(2) and/or progesterone, may influence breast cancer risk. 5 - A peptide derived from the active site of AFP can produce the same benefits of the entire endogenous protein in endocrine cancers. 6 - Differential distribution of ER subtypes in the body and brain may underlie specific effects of estrogens. 7 - ERbeta may be sufficient for the trophic effects of estrogen in the brain, and ERalpha may be the primary target of trophic effects in the body. 8 - ERbeta may play a role in the trophic effects of androgens, and may also be relevant in the periphery. 9 - Downstream of E(2)'s effects at ERbeta, there may be consequences for biosynthesis of progestogens and/or androgens. 10 - Changes in histones and/or other factors, which may be downstream of ERbeta, potentially underlie the divergent effects of E(2) in the brain and peripheral tissues.

Sex differences in the regulation of body weight

Obesity and its associated health disorders and costs are increasing. Males and females differ in terms of how and where body fat is stored, the hormones they secrete in proportion to their fat, and the way their brains respond to signals that regulate body fat. Fat accumulation in the intra-abdominal adipose depot is associated with the risk for developing cardiovascular problems, type-2 diabetes mellitus, certain cancers and other disorders. Men and postmenopausal women accumulate more fat in the intra-abdominal depot than do pre-menopausal women, and therefore have a greater risk of developing metabolic complications associated with obesity. The goal of this review is to explore what we know about sexual dimorphisms in adipose tissue accrual and deposition. Elucidating the mechanisms by which sex hormones may modulate the way in which fat is accumulated and stored is a critical area of research due to the prevalence of obesity and the metabolic syndrome, and the rapid increase in propensity for these diseases following menopause.

Control of glucocorticoid and progesterone receptor subcellular localization by the ligand-binding domain is mediated by distinct interactions with tetratricopeptide repeat proteins

The TPR proteins FKBP52, FKBP51, Cyp40, and PP5 are found in steroid receptor (SR) complexes, but their receptor-specific preferences and roles remain unresolved. We have undertaken a systematic approach to this problem by examining the contribution of all four TPRs to the localization properties of glucocorticoid (GR) and progesterone (PR) receptors. The GR of L929 cells was found in the cytoplasm in a complex containing PP5 and FKBP51, while the GR of WCL2 cells was nuclear and contained PP5 and FKBP52. Cyp40 did not interact with the GR in either cell line. To test whether FKBP interaction determined localization, we overexpressed Flag-tagged FKBP51 in WCL2 cells and Flag-FKBP52 in L929 cells. In WCL2 cells, the GR exhibited a shift to greater cytoplasmic localization that correlated with recruitment of Flag-FKBP51. In contrast, Flag-FKBP52 was not recruited to the GR of L929 cells, and no change in localization was observed, suggesting that both cell-type-specific mechanisms and TPR abundance contribute to the SR-TPR interaction. As a further test, GR-GFP and PR-GFP constructs were expressed in COS cells. The GR-GFP construct localized to the cytoplasm, while the PR-GFP construct was predominantly nuclear. Similar to L929 cells, the GR in COS interacted with PP5 and FKBP51, while PR interacted with FKBP52. Analysis of GR-PR chimeric constructs revealed that the ligand-binding domain of each receptor determines both TPR specificity and localization. Lastly, we analyzed GR and PR localization in cells completely lacking TPR. PR in FKBP52 KO cells showed a complete shift to the cytoplasm, while GR in FKBP51 KO and PP5 KO cells showed a moderate shift to the nucleus, indicating that both TPRs contribute to GR localization. Our results demonstrate that SRs have distinct preferences for TPR proteins, a property that resides in the LBD and which can now explain long-standing differences in receptor subcellular localization.

Expression of steroidogenic enzymes and sex-steroid receptors in human prostate

Identification of the cell types expressing the steroidogenic enzymes and sex steroid receptors in the human prostate has recently been performed using immunocytochemistry and in-situ hybridization. The enzymes 3beta-hydroxysteroid dehydrogenase (3beta-HSD), which converts dehydroepiandrosterone (DHEA) into androstenedione, and type 5 17beta-HSD, which catalyzes the reduction of androstenedione to testosterone, have been localized in basal cells of alveoli as well as in stromal cells and endothelial cells of blood vessels. On the other hand, type-2 5alpha-reductase, which converts testosterone into the most potent androgen dihydrotestosterone (DHT), has been mostly observed in the luminal cells in alveoli. Aromatase, which converts testosterone into estradiol, has also been found to be expressed in the luminal cells of the alveoli as well as in stromal cells. Androgen receptor (AR) has been localized in luminal cell nuclei of alveoli and a large number of stromal cells, while estrogen receptor beta has been detected in both basal and luminal cells in alveoli and also in stromal cells.

The nucleus para-retroambiguus: a new group of estrogen receptive cells in the caudal ventrolateral medulla of the female golden hamster

Receptive female hamsters display very rigid lordotic postures. Estradiol facilitates this behavior via activation of estrogen receptors. In the hamster brainstem estrogen receptor-alpha-immunoreactive neurons (ER-alpha-IR) are present in various brainstem regions including nucleus retroambiguus (NRA) in the caudal ventrolateral medulla (CVLM) and nucleus of the solitary tract. ER-alpha-IR neurons in the CVLM project to the thoracic and upper lumbar cord. However, A1 neurons in this region do not project to the spinal cord, in contrast to overlapping C1 neurons. The question now arises: are ER-alpha-IR cells in the CVLM part of the A1/C1 group, or do they belong to the NRA or do they compose a separate cluster. A study in ovariectomized female hamsters using a combination of double immunostaining and retrograde tracing techniques and measurement of soma diameters was carried out. The results showed that A1/C1 neurons in the CVLM are almost never ER-alpha-positive; neurons inside or bordering the NRA can be divided in two different types: large multipolar and small; the large NRA-neurons, projecting caudally, are neither tyrosine hydroxylase- (TH) nor ER-alpha-IR; the small neurons, bordering the NRA and projecting caudally, are ER-alpha-IR but not TH-IR. From the available evidence and the present findings it can be concluded that the group of small ER-alpha-IR neurons in the CVLM has to be considered as a distinct entity, probably involved in the autonomic physiological changes concurring with successive phases of the estrous cycle. Because the location is closely related to the NRA itself the nucleus is called nucleus para-retroambiguus, abbreviated (NPRA).

Discovery of NM23-H2 as an estrogen receptor beta-associated protein: role in estrogen-induced gene transcription and cell migration

The regulation of the estrogenic responses may be influenced by the proteins that associate with estrogen receptors (ERs) rather than solely with the receptors themselves. ERbeta is expressed in blood vessels and may play an important role in vascular disease. We hypothesized that specific proteins interact with ERbeta to modulate its response to estrogens. By means of a yeast two hybrid screen, we discovered that NM23-H2, a multi-faceted protein associates specifically with ERbeta. NM23-H2 and ERbeta consistently co-localize in a variety of human tissues (e.g. breast tissue), whereas ERalpha and NM23-H2 did not co-localize. Estrogen response element-mediated transcription increased by 97% when NM23-H2 and ERbeta were over-expressed in MCF-7 cells (p< or =0.001). Moreover, there was a synergistic effect of NM23-H2 over-expression with estrogen treatment on the reduction of MCF-7 cell migration (p< or =0.001). These results suggest that NM23-H2 associates with ERbeta and is capable of modulating estrogen-induced gene transcription, as well as cell migration. Hence, NM23-H2 may play an important role in modulating the response to endogenous and exogenous estrogens, perhaps even within the context of vascular disease.

PITX2 controls asymmetric gonadal development in both sexes of the chick and can rescue the degeneration of the right ovary

The gonads arise on the ventromedial surface of each mesonephros. In most birds, female gonadal development is unusual in that only the left ovary becomes functional, whereas that on the right degenerates during embryogenesis. Males develop a pair of equally functional testes. We show that the chick gonads already have distinct morphological and molecular left-right (L-R) characteristics in both sexes at indifferent (genital ridge) stages and that these persist, becoming more elaborate during sex determination and differentiation, but have no consequences for testis differentiation. We find that these L-R differences depend on the L-R asymmetry pathway that controls the situs of organs such as the heart and gut. Moreover, a key determinant of this, Pitx2, is expressed asymmetrically, such that it is found only in the left gonad in both sexes from the start of their development. Misexpression of Pitx2 on the right side before and during gonadogenesis is sufficient to transform the right gonad into a left-like gonad. In ZW embryos, this transformation rescues the degenerative fate of the right ovary, allowing for the differentiation of left-like cortex containing meiotic germ cells. There is therefore a mechanism in females that actively promotes the underlying L-R asymmetry initiated by Pitx2 and the degeneration of the right gonad, and a mechanism in males that allows it to be ignored or overridden.

Expression of estrogen and progesterone receptors and inhibin-alpha in hepatobiliary cystadenoma: an immunohistochemical study

To further characterize the immunohistochemical features of hepatobiliary cystadenoma with mesenchymal stroma, a battery of stains was performed on nine typical cases. All nine tumors had been resected from female patients who ranged in age from 30 to 59 years. Freshly cut sections were stained with antibodies to estrogen receptor (ER), progesterone receptor (PR), alpha-smooth muscle actin (SMA), inhibin-alpha, and cytokeratins (CK) 7, 8, 18, and 19. Nuclear staining of the mesenchymal stromal cells for ER and PR was present in all and seven out of nine cases, respectively. A strong cytoplasmic staining of the mesenchymal stromal cells for SMA was seen in all cases. A patchy pale cytoplasmic staining of the tumor epithelium for ER and PR was seen in five out of nine and four out of nine cases, respectively. Immunoreactivity of luteinized stromal cell for inhibin-alpha was documented in three out of nine cases. All tumors (nine out of nine) demonstrated strong cytoplasmic positivity of the epithelial lining of the cysts to CK7, CK8, CK18, and CK19, typical of biliary-type epithelium. The expression of ER, PR, and inhibin-alpha in the ovarian-like stroma supports the likely hormonal dependence of this tumor and probably explains its almost exclusive occurrence in women.

NM23-H2, an estrogen receptor β-associated protein, shows diminished expression with progression of atherosclerosis

While estrogen receptor (ER) profile plays an important role in response to estrogens, receptor coregulators act as critical determinants of signaling. Although the clinical effects of ovarian hormones on various normal and pathological processes are an active area of research, the exact signaling effects on, for example, the vessel wall, are incompletely understood. Hence, we sought to discover proteins that associate with ERβ, the isoform that shows upregulated mRNA expression after arterial injury. Using a yeast two-hybrid screen we identified NM23-H2, a multifaceted metastasis suppressor candidate protein, as an ERβ-associated protein. Although NM23-H2 was immunodetected in arteries from young subjects (27 ± 6 yr, 14 men and 6 women) with benign intimal hyperplasia, expression was diminished in fatty streaks/atheromas and altogether absent in advanced atherosclerotic lesions. Both nm23-H2 mRNA and protein were expressed by vascular cells in vitro. Treatment with 17β-estradiol and an ERβ-selective agonist, diarylpropionitrile, increased protein expression of NM23-H2; an effect that was not seen with an ERα-selective agonist, propylpyrazole-triol. Estrogen also prompted nuclear localization of NM23-H2 protein in human coronary smooth muscle cells (SMCs). An in vitro mimic of inflammation decreased the expression of NM23-H2 in SMCs, which was restored on addition of estrogen and dependent on the estrogen receptor. In summary, we report the novel association of NM23-H2 with ERβ and show for the first time its expression in vascular cells and demonstrate regulation of its expression and localization by estrogen. In that the abundance of NM23-H2 diminishes with both the advancement of atherosclerosis and inflammation, this ERβ-associated protein may play an important role in mediating the vasculoprotective effects of estrogens.

Implants of estradiol conjugated to bovine serum albumin in the male rat medial preoptic area promote copulatory behavior

The expression of mating behavior in male rats is dependent on estrogen-responsive neurons in the medial preoptic area (MPO). Previous reports showed that mating is attenuated if the aromatization of testosterone to estradiol (E2) is blocked in the MPO and that mating is maintained by MPO E2 implants. However, the mechanisms by which E2 exerts its action are not fully understood. It had been thought that E2 acted exclusively by binding to nuclear estrogen receptors to exert it effects; however, recent reports suggest that E2 also binds to membrane-associated receptors activating downstream intracellular cascade responses. In this study, we aimed to determine if an action of E2 at the cell surface is sufficient to support mating behavior. Therefore, either vehicle, E2, or E2 conjugated to bovine serum albumin (BSA-E2: a complex of E2 and a large protein that will not cross the plasma membrane, thereby restricting the action of E2 to cell surface signaling) was chronically administered bilaterally to the MPO of castrated, dihydrotestosterone-treated male rats. Mating behavior was supported by MPO BSA-E2 implants, suggesting that E2 operates in the MPO via a cell surface mechanism to facilitate male rat mating behavior.

Oestrogens inhibit interleukin 1beta-mediated nitric oxide synthase expression in articular chondrocytes through nuclear factor-kappa B impairment

OBJECTIVES

To investigate the presence and functionality of oestrogen receptor alpha (ERalpha) in interleukin (IL)1beta-treated rabbit articular chondrocytes in culture, and to determine the mechanisms of 17beta oestradiol (E2) effects on IL1beta-induced inducible nitric oxide synthase (iNOS) expression.

METHODS

The presence and functionality of ERalpha were investigated by immunocytochemistry and transient expression of an E2-responsive reporter construct. iNOS expression and production were determined by transient expression of a chimeric iNOS promoter-luciferase construct and protein immunoblotting. Nitric oxide (NO) production was determined by the Griess reaction. DNA-binding activities of nuclear factor-kappaB (NF-kappaB) and activated protein 1 were determined by electrophoretic mobility shift assay (EMSA)-ELISA assays. Nuclear translocation of p65 was studied by immunocytochemistry.

RESULTS

ERalpha was identified in the nucleus of chondrocytes. ERalpha efficiently transactivated a transiently expressed E2-responsive construct. On IL1beta treatment, ERalpha partially diffused from its nuclear localisation into the cytoplasm and its transactivation ability was impaired. Nevertheless, E2, tamoxifen and raloxifene efficiently inhibited IL1beta-induced NO production (-34%, -31% and -36%, respectively). E2 decreased IL1beta-induced iNOS protein expression (-40%). Transient expression of an iNOS promoter construct strongly suggested that iNOS expression was inhibited at the transcriptional level, and EMSA-ELISA assays showed that E2 reduced (-60%) the IL1beta-induced p65 DNA-binding capacity. Finally, the p65 nuclear translocation induced by IL1beta was also strongly decreased by E2.

CONCLUSIONS

Our data support a reciprocal antagonism between oestrogens and IL1beta, ultimately resulting in the decrease of cytokine-dependent NO production through transcriptional inhibition of iNOS expression. This effect was associated with selective inhibition of p65 DNA binding and nuclear translocation.

Diethylstilbestrol increases the density of prolactin cells in male mouse pituitary by inducing proliferation of prolactin cells and transdifferentiation of gonadotropic cells

Diethylstilbestrol (DES) has been implicated in mammalian abnormalities. We examined the effects of DES on follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) cells in the pituitaries of male mice treated with various doses of DES for 20 days. DES reduced the density of FSH and LH cells in a dose-dependent manner, but increased that of PRL cells. When the expression of estrogen receptor (ER) alpha and beta was assessed, an induction of ERbeta by DES was found predominantly in PRL cells. However, since these effects were abolished in ERalpha knockout mice, DES appears to act primarily through ERalpha. When the expression of Ki-67 and Pit-1 in PRL cells was examined at various time-points after DES treatment, some PRL cells became Ki-67 positive at 10-15 days, and Pit-1-positive cells were increased at 5-15 days. Furthermore, some FSH and LH cells became Pit-1 positive, and co-localized with PRL at 5-10 days. Our results indicate that DES increases PRL cells by inducing proliferation of PRL cells and transdifferentiation of FSH/LH cells to PRL cells.

Oestradiol rapidly inhibits Ca2+ signals in ciliary neurons through classical oestrogen receptors in cytoplasm

Oestrogen plays a key role in a great variety of actions in the nervous system, either through classical or alternative pathways. The classical pathways are initiated after oestrogen binding to the oestrogen receptors ERalpha or ERbeta, which translocate from the cytoplasm to the nucleus and act there as transcription factors. Alternative pathways are initiated at the plasma membrane and cytoplasm, via binding to classical or non-classical ERs. Using isolated ciliary ganglion neurons from the chick embryo and Ca2+ imaging, we demonstrated that a 10-min exposure to 17beta-oestradiol reduces Ca2+ influx through the plasma membrane. This effect was not reproduced by oestradiol conjugated to bovine serum albumin, which does not cross the plasma membrane, indicating that 17beta-oestradiol was acting intracellularly. ERalpha was detected in the cytoplasm by immunostaining and its involvement in the regulation of Ca2+ influx by ICI182,780 inhibition. The phosphatidylinositol-3 kinase (Pi3-kinase) inhibitor wortmannin and the nitric oxide synthase (NOS) inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME) both blocked the oestradiol effect. The oestradiol effect was reproduced by 8Br-cGMP and abolished in the presence of the cGMP-dependent protein kinase (PKG) inhibitor KT5823. Our study indicates that 17beta-oestradiol can regulate Ca2+ influx via PI3-kinase, NOS and PKG after activation of cytoplasmic ER.

Estrogen regulation of chicken riboflavin carrier protein gene is mediated by ERE half sites without direct binding of estrogen receptor

Estrogen is an important steroid hormone that mediates most of its effects on regulation of gene expression by binding to intracellular receptors. The consensus estrogen response element (ERE) is a 13bp palindromic inverted repeat with a three nucleotide spacer. However, several reports suggest that many estrogen target genes are regulated by diverse elements, such as imperfect EREs and ERE half sites (ERE 1/2), which are either the proximal or the distal half of the palindrome. To gain more insight into ERE half site-mediated gene regulation, we used a region from the estrogen-regulated chicken riboflavin carrier protein (RCP) gene promoter that contains ERE half sites. Using moxestrol, an analogue of estrogen and transient transfection of deletion and mutation containing RCP promoter/reporter constructs in chicken hepatoma (LMH2A) cells, we identified an estrogen response unit (ERU) composed of two consensus ERE 1/2 sites and one non-consensus ERE 1/2 site. Mutation of any of these sites within this ERU abolishes moxestrol response. Further, the ERU is able to confer moxestrol responsiveness to a heterologous promoter. Interestingly, RCP promoter is regulated by moxestrol in estrogen responsive human MCF-7 cells, but not in other cell lines such as NIH3T3 and HepG2 despite estrogen receptor-alpha (ER-alpha) co transfection. Electrophoretic mobility shift assays (EMSAs) with promoter regions encompassing the half sites and nuclear extracts from LMH2A cells show the presence of a moxestrol-induced complex that is abolished by a polyclonal anti-ERalpha antibody. Surprisingly, estrogen receptor cannot bind to these promoter elements in isolation. Thus, there appears to be a definite requirement for some other factor(s) in addition to estrogen receptor, for the generation of a suitable response of this promoter to estrogen. Our studies therefore suggest a novel mechanism of gene regulation by estrogen, involving ERE half sites without direct binding of ER to the cognate elements.

Angiotensin II and aldosterone regulate gene transcription via functional mineralocortocoid receptors in human coronary artery smooth muscle cells

Inhibition or blockade of the angiotensin-aldosterone system consistently decreases ischemic cardiovascular events in clinical trials. The steroid hormone aldosterone acts by binding to the mineralocorticoid receptor (MR), a ligand activated transcription factor that is a member of the nuclear hormone receptor superfamily. MR binds and is activated by aldosterone and cortisol with equal affinity, but MR activation by cortisol is diminished in tissues that express the cortisol-inactivating enzyme 11-beta-hydroxysteroid-dehydrogenase-2 (11betaHSD2). Although previous studies support that the vasculature is a target tissue of aldosterone, MR-mediated gene expression in vascular cells has not been demonstrated or systematically explored. We investigated whether functional MR and 11betaHSD2 are expressed in human blood vessels. Human coronary and aortic vascular smooth muscle cells (VSMCs) express mRNA and protein for both MR and 11betaHSD2. The endogenous VSMC MR mediates aldosterone-dependent gene expression, which is blocked by the competitive MR antagonist spironolactone. Inhibition of 11betaHSD2 in coronary artery VSMCs enhances gene transactivation by cortisol, supporting that the VSMC 11betaHSD2 is functional. Angiotensin II also activates MR-mediated gene transcription in coronary artery VSMCs. Angiotensin II activation of MR-mediated gene expression is inhibited by both the AT1 receptor blocker losartan and by spironolactone, but not by aldosterone synthase inhibition. Microarray and quantitative RT-PCR experiments show that aldosterone activates expression of endogenous human coronary VSMC genes, including several involved in vascular fibrosis, inflammation, and calcification. These data support a new MR-dependent mechanism by which aldosterone and angiotensin II influence ischemic cardiovascular events, and suggest that ACE inhibitors and MR antagonists may decrease clinical ischemic events by inhibiting MR-dependent gene expression in vascular cells.

Modulation of estrogen signaling by the novel interaction of heat shock protein 27, a biomarker for atherosclerosis, and estrogen receptor beta: mechanistic insight into the vascular effects of estrogens

OBJECTIVE

We sought to discover proteins that associate with estrogen receptor beta (ERbeta) and modulate estrogen signaling.

METHODS AND RESULT

Using a yeast 2-hybrid screen, we identified heat shock protein 27 (HSP27) as an ERbeta-associated protein. HSP27 is a recently identified biomarker of atherosclerosis that is secreted at reduced levels from atherosclerotic compared with normal arteries. In vitro protein-binding assays confirmed the specific interaction of HSP27 with ERbeta and not ERalpha. HSP27 expression was absent in coronary arteries with complex atherosclerotic lesions. Interestingly, HSP27 expression was also absent in 60% of coronary arteries from young males and females (27+/-6.5 years) with normal histology or nonobstructive fatty streaks/atheromas. Moreover, the absence of HSP27 in these normal or minimally diseased arteries coincided with the loss of ERbeta expression. Only 35% of arteries showed coexpression of HSP27 and ERbeta. Relative to controls, estradiol-mediated transcription was reduced 20% with overexpression of HSP27 and increased 44% when HSP27 protein levels were reduced with HSP27 siRNA.

CONCLUSIONS

HSP27, an ERbeta-associated protein, shows attenuated expression with coronary atherosclerosis and modulates estrogen signaling.

Estrogen receptor-alpha populations change with age in commercial laying hens

Older hens in production lay larger but fewer eggs than younger birds, and the incidence of soft and broken shells is greater in older hens than younger. These changes are attributable at least in part to changing hormone profiles and diminished ability of the hen to transport calcium at the duodenum. In further exploration of this relationship, a study was conducted with three ages of Hy-Line W-36 birds: prelay pullets (PL; 19 wk, 0% production), peak-production hens (PP; 29 wk, approximately 93% production), and late-stage hens (LS; 71 wk, approximately 80% production). Hens from the PP and LS groups were palpated for presence of an egg in the shell gland; hens were then euthanized and tissues (kidney, shell gland, hypothalamus) were removed for quantification of estrogen receptor-alpha (ERalpha) populations via immunocytochemical and Western blot analyses. Localization of ERalpha by immunostaining in the shell gland showed differences among age groups; however, no differences were noted in localization of ERalpha between age groups in the kidney and hypothalamus. In both the kidney and the shell gland there was a decrease in the amount of ERalpha, as detected by immunoblotting, in the LS hens compared to PL and PP birds (P < 0.05). The results suggest that failure of calcium regulating mechanisms with age may be mediated at least in part through the reduced populations of estrogen receptors in certain critical tissues.

Significance of immunohistochemical assessment of steroid hormone receptor status for breast cancer patients

The assessment of steroid hormone receptors in resected breast cancer tissues is essential to decide whether endocrine therapy is indicated and to select the best treatment for each patient on the basis of receptor status. Both enzyme immunoassay (EIA) and immunohistochemistry (IHC) have been generally used as methods for examination of estrogen receptor (ER) and progesterone receptor (PgR). In some patients, receptor status cannot be examined for various reasons. A questionnaire survey in Japan clarified that ER status is not examined in approximately 40% of patients receiving breast conserving surgery. To eliminate "receptor unknown" cases, IHC examination on paraffin-embedded tissue is useful to assess the in situ receptor status. The concordance rate of ER and PgR status between EIA and IHC is very high and a study of 88 cases revealed a 97.7% concordance for ER and 92.0% for PgR at a cutoff point of 10%. The cutoff point of IHC is controversial and some studies demonstrated that patients showing 1% ER positive cancer cells would benefit from endocrine therapy. On the other hand, immunohistochemical expression of receptors is heterogeneous and some patients with ER negative invasive tumors have ER positive intraductal components. A study of 65 breast cancers demonstrated that ER positive intraductal components were detected in 3.1% cases of ER negative invasive lesions. According to these results and the recommendation of the St. Gallen International Conference, IHC is thought to be more useful than EIA in the assessment of steroid hormone receptor status for breast cancer patients.

Loss of oestrogen receptor beta, high PCNA and p53 expression and aneuploidy as markers of worse prognosis in ovarian granulosa cell tumours

AIMS

Ovarian granulosa cell tumour (OGCT) is a sex-cord stromal tumour with a general trend toward late relapse and/or metastasis. However, mortality rate corrected for long-term follow-up shows that about 50% of patients die within 20 years of diagnosis. Classical clinicopathological parameters are unable to predict the biological behaviour of OGCT. The involvement of a recently characterized subtype of oestrogen receptor, ERbeta, in ovarian carcinogenesis has been hypothesized.

METHODS AND RESULTS

We examined by immunohistochemistry the expression of ERbeta, proliferating cell nuclear antigen (PCNA) and p53 in a selected series of 30 OGCT, to evaluate their role in the prognostic evaluation of this tumour. Immunohistochemistry was performed on formalin-fixed paraffin-embedded sections. Results were compared with the DNA-ploidy of the tumours (evaluated by image analysis) and with the follow-up data of the patients.

CONCLUSIONS

Loss of ERbeta expression, high PCNA expression and aneuploidy, characterized a subgroup of OGCT with a worse outcome. The identification of a high-risk subclass of OGCT may be of primary importance in addressing appropriate therapeutic strategies, offering the chance to prevent relapses and metastases by using adjunctive, specifically targetted, more aggressive therapies.

Estradiol in the male rat amygdala facilitates mounting but not ejaculation

Mating activates estrogen sensitive neurons in several regions of male rat brain, including the medial amygdala (MEA). Infusion of the aromatase inhibitor, Fadrozole, into the MEA reduced mating, presumably by inhibiting conversion of testosterone (T) to estradiol (E(2)). We investigated whether administering E(2) locally into the amygdala (AMG) would maintain sexual behavior in male rats given systemic Fadrozole to eliminate E(2) elsewhere in the brain. Gonadally intact male rats were divided into two matched groups, based on ejaculatory performance in weekly tests with receptive females. All males received 0.29 mg/kg/day sc Fadrozole and bilateral implants to AMG. E(2)-in-AMG males (N=6 experimentals) received implants tipped with a cured mixture of E(2) in Silastic Medical Adhesive, whereas Vehicle-in-AMG males (N=6 controls) received implants tipped with cured adhesive alone (without E(2)). In E(2)-in-AMG males, postoperative mount and intromission frequency did not differ significantly from pretreatment baseline levels, but ejaculation frequency declined significantly (P<.01). Conversely, in Vehicle-in-AMG males, postoperative mounts and intromissions (P<.01) and ejaculations (P<.01) declined significantly. Postoperative mount and intromission frequency of Vehicle-in-AMG males was significantly lower than that of E(2)-in-AMG males (P<.01), but ejaculation frequency did not differ significantly between groups. This suggests that E(2)-sensitive AMG neurons are important for sexual arousal but not ejaculatory performance.

Identification of estrogen receptor beta expression in Chinese hamster ovary (CHO) cells and comparison of estrogen-responsive gene transcription in cells adapted to serum-free media

Most cultured cell lines require addition of serum to the medium to maintain their proliferative capacity. For studies examining the cellular effects of estrogens serum is charcoal-stripped to remove steroids. Nonetheless, addition of the selective estrogen receptor modulator (SERM) 4-hydroxytamoxifen (4-OHT) inhibits the basal transcriptional activity of estrogen receptors alpha or beta (ERalpha or ERbeta) in transfected cells. We tested the hypothesis that elimination of serum from the culture medium will block 4-OHT's repression of basal activity. Chinese hamster ovary (CHO-K1) cells adapted to serum-free medium exhibited estrogen responsiveness that was identical with that of the cells grown in serum-containing media. 4-OHT-suppressed basal transcription of an estrogen response element (ERE)-reporter in ERalpha-transfected cells even in the absence of serum, indicating that the 4-OHT suppressive activity is not mediated by blocking ER interaction with serum estrogens. We speculate that 4-OHT-ER recruits co-repressors to suppress basal transcription. We discovered that CHO-K1 cells express ERalpha and ERbeta mRNA. However only ERbeta protein was expressed and use of ERbeta-selective 2,3-bis(4-hydroxy-phenyl)propionitrile (DPN) and ERalpha-selective 4-propyl-1,3,5-tris(4-hydroxy-phenyl)pyrazole) (PPT) revealed that only ERbeta was transcriptionally active. In conclusion, growing CHO-K1 in serum-free medium does not impact the estrogen responsiveness and this cell line expresses functional ERbeta.

Identification of a structural determinant necessary for the localization and function of estrogen receptor alpha at the plasma membrane

Estrogen receptors (ER) have been localized to the cell plasma membrane (PM), where signal transduction mediates some estradiol (E2) actions. However, the precise structural features of ER that result in membrane localization have not been determined. We obtained a partial tryptic peptide/mass spectrometry analysis of membrane mouse ERalpha protein. Based on this, we substituted alanine for the determined serine at amino acid 522 within the E domain of wild-type (wt) ERalpha. Upon transfection in CHO cells, the S522A mutant ERalpha resulted in a 62% decrease in membrane receptor number and reduced colocalization with caveolin 1 relative to those with expression of wt ERalpha. E2 was significantly less effective in stimulating multiple rapid signals from the membranes of CHO cells expressing ERalpha S522A than from those of CHO cells expressing wt ERalpha. In contrast, nuclear receptor expression and transcriptional function were very similar. The S522A mutant was also 60% less effective than wt ERalpha in binding caveolin 1, which facilitates ER transport to the PM. All functions of ERalpha mutants with other S-to-A substitutions were comparable to those of wt ER, and deletion of the A/B or C domain had little consequence for membrane localization or function. Transfection of ERalpha S522A into breast cancer cells that express native ER downregulated E2 binding at the membrane, signaling to ERK, and G1/S cell cycle events and progression. However, there was no effect on the E2 transactivation of an ERE-luciferase reporter. In summary, serine 522 is necessary for the efficient translocation and function of ERalpha at the PM. The S522A mutant also serves as a dominant-negative construct, identifying important functions of E2 that originate from activating PM ER.

Progesterone receptor, estrogen receptor alpha, and the type II glucocorticoid receptor are coexpressed in the same neurons of the ovine preoptic area and arcuate nucleus: a triple immunolabeling study

The neuroendocrine reproductive and stress axes are known to be closely linked, but the mechanisms underlying these links remain poorly understood. In the ovine brain, GnRH neurons do not contain type II glucocorticoid (GR), progesterone (PR), or alpha estrogen (ERalpha) receptors. We sought to determine whether PR, ERalpha, and GR coexist within the same hypothalamic neurons. A triple immunocytochemical study, involving antisera raised in three different species, was performed on cryostat sections from ovariectomized ewes treated either with estradiol and progesterone or with progesterone alone. All PR-immunoreactive neurons contained ERalpha, and about 95% of ERalpha were PR immunoreactive in the preoptic area and arcuate nucleus. Although the PR with ERalpha colocalization ratio was not affected by the steroid treatments, immunolabeling for PR was weaker in animals that did not receive estradiol. Numerous PR- and ERalpha-immunoreactive cells contain GR. PR+ERalpha+GR-immunoreactive cells represent 70% of PR, 65% of ERalpha, and 72% of GR in the preoptic area and 70% of PR, 66% of ERalpha, and 63% of GR in the arcuate nucleus. These results suggest that estrogen, progesterone, and glucocorticoids may influence the activity of the same neurons to modulate both reproductive and stress axes.

Localization of oestrogen receptors in the sensory and motor areas of the spinal cord in Japanese quail (Coturnix japonica)

In Japanese quail, the presence of aromatase (oestrogen synthase) in the dorsal horn of the spinal cord suggests that spinal sensory processes might be controlled by local actions of oestrogens. This is supported by the presence of oestrogen receptors and aromatase in the dorsal horn of the spinal cord in rats, and by the alteration of sensitivity by oestrogens in various mammalian species and also in canaries. We investigated whether oestrogens that are locally produced in the quail spinal cord can bind to specific receptors in the vicinity of their site of synthesis. We demonstrate the presence of numerous oestrogen receptor alpha-immunoreactive (ERalpha-ir) cell nuclei, predominantly in laminae II and, to a lesser extent, I and III of the dorsal horn of the spinal cord (i.e. in the area where aromatase was previously identified). ERalpha-ir cells were also seen in various parts of the intermediate zone (laminae V-VII). This presence of ERalpha-ir cells in the dorsal horn and intermediate zone fits in well with the distribution of ERalpha-ir cells in homologous areas in mammals, including rats. Only a few labelled cells were found in the ventral horn in the cervical, brachial, thoracic and first lumbar segments, but a conspicuous dense group of large ERalpha-ir cells was identified in lamina IX of the ventral horn in synsacral segments 8-10, which contain the motoneurones innervating the muscles of the cloacal gland. The presence of ERalpha-ir cells in lamina IX of these synsacral segments in quail contrasts with the finding that motoneurones innervating penile muscles in rats contain androgen, but not oestrogen receptors, and are influenced by androgens rather than by oestrogens. Together, these data suggest that spinal actions of oestrogens may modulate the sensory and motor systems that participate in reproduction, as well as other nonreproductive functions in quail.

Expression of ER-alpha and ER-beta in the hamster ovary: differential regulation by gonadotropins and ovarian steroid hormones

Spatiotemporal expression patterns of ER-alpha and ER-beta protein and mRNA in hamster ovarian cells during the estrous cycle and following hypophysectomy and selective hormone replacement were evaluated by immunofluorescence, immunoblotting and in situ hybridization analyses. Whereas ER-beta mRNA and protein expression predominated in granulosa cells and ER-alpha expression was in interstitial and thecal cells, overlap in receptor subtype expression across cell types was evident. Both ER subtypes were present from primordial follicle stage onward. ER-alpha mRNA levels and immunoreactivity started increasing from D3:0900 h in interstitial and granulosa cells and peaked on the proestrous (D4:0900 h). Regionalized higher expression of ER-alpha in granulosa cells in and around the forming antrum was evident. Surface epithelial cells were also positive. ER-beta mRNA and protein expression increased markedly in granulosa and interstitial cells on D2:0900 h, reached a peak on D3:0900 h, and then declined sharply on D4:0900 h. No change in ER expression occurred following the preovulatory gonadotropin surge. Whereas FSH or human CG stimulated ER-alpha mRNA and protein expression in hypophysectomized hamsters, only FSH could stimulate ER-beta mRNA and protein, and the effect was significantly attenuated by human CG. ER expression was stimulated by estrogen, but progesterone strongly inhibited estrogen action. These results indicate that ER expression is cell type specific to the larger extent and is critically regulated by reproductive hormones.

Effects of oral estrogen, raloxifene and arzoxifene on gene expression in serotonin neurons of macaques

The serotonin neural system contributes to cognition and affect, both of which exhibit pathologies with gender bias. We previously showed that estrogen (E) treatment of female macaques via Silastic implant alters gene expression for tryptophan hydroxylase (TPH), the serotonin reuptake transporter (SERT) and the 5HT1A autoreceptor. In addition, we have found that serotonin neurons of macaques express ER beta (ER beta). Together these studies suggest that the serotonin neural system could transduce the action of estrogen via ER beta on aspects of mood and cognition. However, estrogen replacement therapy can increase the risk for breast and uterine cancer. Therefore, we questioned whether the selective estrogen receptor modulators, raloxifene and arzoxifene, act in a manner similar to E on gene expression in serotonin neurons of a nonhuman primate model. Female rhesus macaques were ovariectomized and orally dosed with vehicle, estradiol 17beta, raloxifene or arzoxifene once per day by sipper bottles for 30 days. The animals were then euthanized and the midbrains were prepared for in situ hybridization for TPH, SERT and 5HT1A receptor mRNAs followed by densitometric analysis. There was a significant increase in TPH total signal (positive pixelsxOD) with E, raloxifene and arzoxifene, respectively. There was a significant decrease in SERT mRNA optical density with all treatments. 5HT1A autoreceptor mRNA did not change with any treatment. If these changes in gene expression are reflected by similar changes in the functional proteins, then raloxifene or arzoxifene could increase serotonin neurotransmission with little or no negative action in peripheral tissues. In conclusion, the selective estrogen receptor modulators, raloxifene and arzoxifene, act in a manner similar to natural E on TPH and SERT mRNA expression in serotonin neurons. This suggests that raloxifene and arzoxifene are agonists at ER beta in the context of the serotonin neuron. However, the responses to E were more variable and less robust with the oral dosing paradigm compared to a chronic implant paradigm.

[Temporary dependency of steroid-receptor prognostic value in breast cancer]

BACKGROUND

The influence of prognostic factors in breast cancer may change during follow-up. Our aim was therefore to look for time-related changes in hazard ratios for steroid receptor status and the risk of relapse.

PATIENTS AND METHOD

We studied 455 patients with operable primary breast cancer during a mean follow-up period of 72 months (range, 42-130 months). Clinical and histological characteristics were assessed and estrogen receptor (ER) and progesterone receptor (PgR) status were determined and compared to disease-free survival (DFS) and overall survival (OS). Analysis of DFS included fitting a multivariate Cox proportional hazards model, testing for non-proportionality, and examining diagnostic plots.

RESULTS

A total of 66.8% of the tumors were ER positive and 54.7% PgR positive. Receptor status is highly associated with menopausal status, histological grade, peritumoral lymphatic or blood vessel invasion and mitotic index. No correlation was found between steroid receptor status and tumor size, node status or tumor stage. In univariate analysis, ER/PR vs ER+/PR+ display a hazard ratio of 2.15 (IC del 95%, 1.59-2.99) for DFS (p = 0.001) and 1.95 (IC del 95%, 1.38-2.59) for OS (p = 0.0043). In multivariate analysis, steroid receptor status, node status and mitotic index were independent prognostic factors for DFS and OS. By using Cox regression time-dependent covariates model, we show that the steroid receptor status hazard ratio is 5.6 at diagnosis, decreases after 4 years, and loses its significance after 10 years of follow-up.

CONCLUSION

In patients with breast cancer the status steroid receptor have a relatively limited prognostic value and is lost within the first years.

Differential interaction of estrogen receptor and thyroid hormone receptor isoforms on the rat oxytocin receptor promoter leads to differences in transcriptional regulation

Both the estrogen receptor (ER) and thyroid hormone receptor (TR) are members of the nuclear receptor superfamily. Two isoforms of the ER, alpha and beta, exist. The TRalpha and beta isoforms are products of two distinct genes that are further differentially spliced to give TRalpha1 and alpha2, TRbeta1 and beta2. The TRs have been shown to interfere with ER-mediated transcription from both the consensus estrogen response element (ERE) and the rat preproenkephalin (PPE) promoter, possibly by competing with ER binding to the ERE or by squelching coactivators essential for ER-mediated transcription. The rat oxytocin receptor (OTR) gene is thought to be involved in several facets of reproductive and affiliative behaviors. 17beta-Estradiol-bound ERs upregulate the OTR gene in the ventromedial hypothalamus, a region critical for the induction of lordosis behavior in several species. We investigated the effects of the ligand-binding TR isoforms on the ER-mediated transcription from a physiological promoter of a behaviorally relevant gene such as the OTR. Only ERalpha could induce the OTR gene in two cell lines tested, the CV-1 and the SK-N-BE2C neuroblastoma cell lines. ERbeta was incapable of inducing the gene in either cell line. ERalpha is therefore not equivalent to ERbeta on this physiological promoter. Indeed, in the neural cell line, ERbeta can inhibit ERalpha-mediated induction from the OTR promoter. While the TRalpha1 isoform inhibited ERalpha-mediated induction in the neural cell line, the TRbeta1 isoform stimulated induction, thus demonstrating isoform specificity in the interaction. The use of a DNA-binding mutant, the TR P box mutant, showed that inhibition of ERalpha-mediated induction of the rat OTR gene promoter by the TRalpha1 isoform does not require DNA-binding ability. SRC-1 overexpression relieved TRalpha1-mediated inhibition in both cell lines, suggesting that squelching for coactivators is an important molecular mechanism in TRalpha-mediated inhibition. Such interactions between TR and ER isoforms on the rat OTR promoter provide a mechanism to achieve neuroendocrine integration.

Cell localization, physiology, and nongenomic actions of estrogen receptors

The existence of binding proteins for the female sex steroid, 17beta-estradiol, has been known for almost 50 years. Presently, two estrogen receptors (ERs), ER-alpha and ER-beta, have been cloned in mammals, and they are expressed in many cell types of metazoans. ERs act primarily as nuclear transcription factors, and this effect is enhanced by ligand binding. Emerging data have identified a separate pool of receptors for this steroid in the plasma membrane, but the mechanisms of action and cellular functions of these proteins are just beginning to be defined. In this review, the known details of the nuclear and plasma membrane ER functions will be discussed. A particular focus will be to define the signaling pathways from the membrane that lead to important cell physiology effects of estrogen. The potential interactions of membrane ER with other local proteins will also be discussed, and the unique but often complementary roles of the receptor pools will be highlighted. These details may be of additional relevance to other steroid receptors, since there is evidence of their existence in the cell membrane.

Distribution analysis of the two chicken estrogen receptor-alpha isoforms and their transcripts in the hypothalamus and anterior pituitary gland

Estrogen plays a key role in the control of reproductive behavior and in the regulation of the neuroendocrine system. To elucidate the mechanisms by which it controls these functions it is important to understand how estrogenic effects are mediated. We have investigated the distribution of the two isoforms of the chicken estrogen receptor alpha (cER-alpha) protein; the previously characterized cER-alpha 66 and a new N-terminal truncated isoform, cER-alpha 61. Immunolocalization demonstrated the presence of cER-alpha 66 protein in hypothalamic areas, principally the nucleus septalis lateralis, bed nucleus striae terminalis medialis, nucleus preopticus medialis, and nucleus infundibuli hypothalami, and in the anterior pituitary gland. When the distribution of ER-alpha immunoreactive cells was compared using the antibodies H 222 (directed against the hormone-binding domain) and ER 221 (directed against the 21-amino acid N-terminus), no apparent differences could be detected. Because this immunocytochemical approach was not able to distinguish whether full-length cER-alpha 66 is the only isoform observed in the ER-positive regions or whether both cER-alpha receptor isoforms are present, SI nuclease assays were performed to compare the relative abundance in these regions of the two distinct classes of cER-alpha mRNA variants (A1-D and A2), which encode the cER-alpha 66 and cER-alpha 61 protein isoforms, respectively. In cockerels and hens, both variants of cER-alpha mRNA are expressed in the anterior pituitary gland and basal hypothalamus with a dominance of the mRNA that encodes cER-alpha 66, whereas the mRNA that encodes cER-alpha 61 was not detectable in the anterior hypothalamus. Therefore, because both receptor isoforms differ in their ability to modulate estrogen target gene expression in a promoter and cell type-specific manner, these differences may mediate the pleiotropic actions of estrogen in reproductive behavior and neuroendocrine functions.

Crosstalk between oestrogen receptors and thyroid hormone receptor isoforms results in differential regulation of the preproenkephalin gene

Nuclear receptors are ligand-activated transcription factors, which have the potential to integrate internal metabolic events in an organism, with consequences for control of behaviour. Previous studies from this laboratory have shown that thyroid hormone receptor (TR) isoforms can inhibit oestrogen receptor (ER)alpha-mediated induction of preproenkephalin (PPE) gene expression in the hypothalamus. Also, thyroid hormone administration inhibits lordosis, a behaviour facilitated by PPE expression. We have examined the effect of multiple ligand-binding TR isoforms on the ER-mediated induction of the PPE gene in transient transfection assays in CV-1 cells. On a natural PPE gene promoter fragment containing two putative oestrogen response elements (EREs), both ER alpha and beta isoforms mediate a four to five-fold induction by oestrogen. Cotransfection of TR alpha 1 along with ER alpha inhibited the ER alpha transactivation of PPE by approximately 50%. However, cotransfection with either TR beta 1 or TR beta 2 expression plasmids produced no effect on the ER alpha or ER beta mediated induction of PPE. Therefore, under these experimental conditions, interactions with a single ER isoform are specific to an individual TR isoform. Transfection with a TR alpha 1 DNA-binding mutant could also inhibit ER alpha transactivation, suggesting that competition for binding on the ERE may not be the exclusive mechanism for inhibition. Data with the coactivator, SRC-1, suggested that coactivator squelching may participate in the inhibition. In dramatic contrast, when ER beta is cotransfected, TR alpha 1 stimulated ER beta-mediated transactivation of PPE by approximately eight-fold over control levels. This is the first study revealing specific interactions among nuclear receptor isoforms on a neuroendocrine promoter. These data also suggest that the combinatorics of ER and TR isoforms allow multiple forms of flexible gene regulations in the service of neuroendocrine integration.