Identification Of Estrogen Receptor Research Articles

Estrogen Receptor Expression in Pancreatic Adenocarcinoma: Time to Reconsider Evidence.

Pancreatic adenocarcinoma remains a chemotherapy-resistant and refractory malignancy with high mortality, unaffected by recent progress in anticancer treatment. Expression of estrogen receptors was detected almost 50 years ago, in both benign and malignant pancreatic cells. However, early preclinical studies in pancreatic cancer led to contradictory findings, and most clinical studies failed to demonstrate an effect with tamoxifen treatment. The identification of a second form of estrogen receptor seems to provide some explanation for these discrepancies. Predominantly expressed in malignant cells and structurally different from what was considered the only estrogen receptor, estrogen receptor β was recognized as a negative prognostic factor and a possible therapeutic target in pancreatic ductal adenocarcinoma. Therefore, findings of research before the identification of estrogen receptor β should be reconsidered, and further studies should be designed to reassess the expression and effect of this specific estrogen receptor type in pancreatic cancer.

Estrogen in the male: a historical perspective.

Estrogens have traditionally been considered female hormones. Nevertheless, the presence of estrogen in males has been known for over 90 years. Initial studies suggested that estrogen was deleterious to male reproduction because exogenous treatments induced developmental abnormalities. However, demonstrations of estrogen synthesis in the testis and high concentrations of 17β-estradiol in rete testis fluid suggested that the female hormone might have a function in normal male reproduction. Identification of estrogen receptors and development of biological radioisotope methods to assess estradiol binding revealed that the male reproductive tract expresses estrogen receptor extensively from the neonatal period to adulthood. This indicated a role for estrogens in normal development, especially in efferent ductules, whose epithelium is the first in the male reproductive tract to express estrogen receptor during development and a site of exceedingly high expression. In the 1990s, a paradigm shift occurred in our understanding of estrogen function in the male, ushered in by knockout mouse models where estrogen production or expression of its receptors was not present. These knockout animals revealed that estrogen's main receptor (estrogen receptor 1 [ESR1]) is essential for male fertility and development of efferent ductules, epididymis, and prostate, and that loss of only the membrane fraction of ESR1 was sufficient to induce extensive male reproductive abnormalities and infertility. This review provides perspectives on the major discoveries and developments that led to our current knowledge of estrogen's importance in the male reproductive tract and shaped our evolving concept of estrogen's physiological role in the male.

Sex Hormones and Healthy Psychological Aging in Women.

Besides their key role in reproduction, estrogens have effects in several organs in the body, as confirmed by the identification of estrogen receptors (ER) in multiple tissues. Experimental evidence has shown that estrogens have significant impacts on the central nervous system (CNS), and a key question is to what extent the fall in estrogen levels in the blood that occurs with increasing age, particularly around and following the menopause, has an impact on the cognitive function and psychological health of women, specifically regarding mood. This review will consider direct effects of menopausal changes in estrogens on the brain, including cognitive function and mood. Secondary pathways whereby health factors affected by changes in estrogens may interact with CNS functions, such as cardiovascular factors, will be reviewed as well insofar as they also have an impact on cognitive function. Finally, because decline in estrogens may induce changes in the CNS, there is interest in clarifying whether hormone therapy may offer a beneficial balance and the impact of hormone therapy on cognition will also be considered.

Identification of estrogen receptor α ligands with virtual screening techniques

Utilization of computer-aided molecular discovery methods in virtual screening (VS) is a cost-effective approach to identify novel bioactive small molecules. Unfortunately, no universal VS strategy can guarantee high hit rates for all biological targets, but each target requires distinct, fine-tuned solutions. Here, we have studied in retrospective manner the effectiveness and usefulness of common pharmacophore hypothesis, molecular docking and negative image-based screening as potential VS tools for a widely applied drug discovery target, estrogen receptor α (ERα). The comparison of the methods helps to demonstrate the differences in their ability to identify active molecules. For example, structure-based methods identified an already known active ligand from the widely-used bechmarking decoy molecule set. Although prospective VS against one commercially available database with around 100,000 drug-like molecules did not retrieve many testworthy hits, one novel hit molecule with pIC50 value of 6.6, was identified. Furthermore, our small in-house compound collection of easy-to-synthesize molecules was virtually screened against ERα, yielding to five hit candidates, which were found to be active in vitro having pIC50 values from 5.5 to 6.5.

Receptor-based virtual screening evaluation for the identification of estrogen receptor β ligands

In this paper, a receptor-based virtual screening study for the identification of estrogen receptor β (ERβ) ligands was developed. Starting from a commercial database of 400 000 molecules, only six compounds resulted to be potential active ligands of ERβ. Interestingly, all the six molecules possess scaffolds that had already been reported in known ERβ ligands. Therefore, the results obtained herein confirm the reliability of our virtual screening procedure, thus encouraging the application of this protocol to larger commercial databases in order to identify new ERβ ligands.

Abstract 2889: Identification of estrogen receptor modulated gene methylation network in breast cancer.

Abstract While cancer as a complex disease is known to arise from a series of aberrant genetic and epigenetic profiles, its growth and disease-specific outcome can often be characterized by status of one oncogene, such as Estrogen Receptor (ER) of breast cancer. Positive ER appears in around 70% of human breast cancer cases and recent studies dissected the Estrogen-mediated gene regulation through specific DNA methylation patterns by comparison between ER+ and ER- tumor samples. However, this simple approach did not take into consideration the influence of other confounding regulation factors due to the heterogeneity of breast cancer and may be limited in uncovering complex underlying mechanism. To address this problem, we first hypothesize that DNA methylation status and its inter-gene similarity are modulated by multiple factors including ER. The disruption of ER will disrupt association of methylation patterns between two genes which are correlated otherwise. The epigenetic signaling cascade maintained by specific ER status can be further interpreted from the “co-methylation” relationship among genes. Here we proposed a novel algorithm to identify the modulated gene methylation based on the “modulator of regulation” concept. Setting ER as the modulator, an ER modulated gene pair (ER-GP) was defined as pair of genes with differential correlation between ER+ and ER- samples. Fisher transformation on Pearson correlation coefficients was adopted for statistical power adjustment on sample sizes and the differences of absolute correlation coefficients were tested for statistical significance in the Fisher transform domain. By applying the algorithm to the MBDCap-Seq data of 76 breast tumors (47 ER+ and 29 ER-), we identified 5,673 putative ER-GPs of co-methylation (co-methyl. ER-GPs) involving 1,657 unique genes. In order to delineate a comprehensive and systematic view of interaction between identified ER-GPs, the co-methyl. ER-GPs were combined to construct the ER modulated gene methylation network. With an overall connectivity (average number of first-order neighbors of each gene in a network) of 6.85, genes in the methylation network were highly linked to each other and formed a branched signaling cascade. The nucleosome assembly protein 1-like 5 NAP1L5, previously reported as regulated by both estradiol and tamoxifen treatment, was identified as the top hub gene, indicating that it may serve as an important regulator in the ER modulation. Further Gene Ontology analysis revealed that NAP1L5 and its co-methylated genes were involved in nucleotide biosynthetic process, chromosome organization, and cell proliferation. In the present study, we proposed a novel algorithm to identify the ER modulated methylation regulatory network. The findings provided biological insights into the underlying mechanism of epigenetic signaling governed by ER and may contribute to improvement of breast cancer treatment. Citation Format: Yu-Chiao Chiu, Tzu-Hung Hsiao, Fei Gu, Yidong Chen, Tim H-M Huang, Eric Y. Chuang. Identification of estrogen receptor modulated gene methylation network in breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2889. doi:10.1158/1538-7445.AM2013-2889 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Identification of Estrogen Receptor β as a SUMO-1 Target Reveals a Novel Phosphorylated Sumoylation Motif and Regulation by Glycogen Synthase Kinase 3β

SUMO conjugation has emerged as a dynamic process in regulating protein function. Here we identify estrogen receptor β (ERβ) to be a new target of SUMO-1. ERβ SUMO-1 modification occurs on a unique nonconsensus sumoylation motif which becomes fully competent upon phosphorylation of its contained serine residue, which provides the essential negative charge for sumoylation. This process is further regulated by phosphorylation of additional adjacent serine residues by glycogen synthase kinase 3β (GSK3β), which maximizes ERβ sumoylation in response to hormone. SUMO-1 attachment prevents ERβ degradation by competing with ubiquitin at the same acceptor site and dictates ERβ transcriptional inhibition by altering estrogen-responsive target promoter occupancy and gene expression in breast cancer cells. These findings uncovered a novel phosphorylated sumoylation motif (pSuM), which consists of the sequence ψKXS (where ψ represents a large hydrophobic residue) and which is connected to a GSK3-activated extension that functions as a SUMO enhancer. This extended pSuM offers a valuable signature to predict SUMO substrates under protein kinase regulation.

Abstract 5535: Availability of a newly designed technique, triple-combination array analysis: Identification of estrogen receptor 1 gene in hepatocellular carcinoma using this method

Abstract Background: Hepatocellular carcinoma (HCC) is one of the top five causes of cancer-related deaths worldwide. Recent developments in the treatment of HCC have failed to treat completely or prevent HCC. Genome-wide gene-expression profile analyses can now detect many candidate genes that are modified by HCC. We have developed a new technique to identify suppressor genes of HCC: triple-combination array analysis. Methods: Triple-combination array analysis, which combines gene expression profiles, single nucleotide polymorphism arrays and methylation arrays, was performed on each HCC tissue sample. Subsequently, samples from 48 HCC patients were subjected to quantitative real-time reverse-transcriptase polymerase chain reaction (PCR) and methylation-specific PCR. Results: Using this method, estrogen receptor 1 (ESR1) was detected as a candidate suppressor gene. Of the 48 clinical samples, 40 (83.3%) showed ESR1 promoter hypermethylation. In 24 (50%) HCC samples, the expression level of ESR1 gene was decreased by >90%, which was significantly related to hepatitis B virus, high liver damage score, and pathological invasion of the intrahepatic portal vein. Conclusions: The present study indicates that triple-combination array is an available and convenient technique for detecting the genes with altered expression in disease, and we suggest that the ESR1 gene acts as a suppressor gene in HCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5535. doi:1538-7445.AM2012-5535

Debate: tailored targeted therapy for all - a realistic and worthwhile objective? Introduction to Session 2

A pre-debate vote showed the audience to be overwhelmingly in favour of the motion. Dr Per Lonning spoke in favour. He made the point that tailormade therapy should not be confused with implementing simple prognostic or predictive factors that in general do not define direct biological targets but rather should implement biological parameters revealing a variable statistical correlation to outcome. He discussed that breast cancers have recently been separated into five distinct classes based on gene expression profiles: luminal A, luminal B, HER2, basal class, and, finally, so-called normal breast-like tumours. Dr Lonning argued that the identification of oestrogen receptor as a predictive marker has made endocrine therapy in breast cancer the ultimate targeted or tailored cancer therapy. Over the past decade, tailored therapy with the use of anti-HER2 strategies has revolutionised treatment for around 20% of cancer patients. The introduction of poly(ADP-ribose) polymerase inhibitors has improved the process of tailoring treatment for patients carrying BRCA1 and BRCA2 defect tumours, and probably also for many additional patients carrying triple-negative tumours. His argument was that the results achieved up to now suggest that tailored therapy for most if not all breast cancer patients in need of systemic treatments is a realistic approach in the near future. Dr Kathy Pritchard then spoke against the motion. She likewise acknowledged the role of oestrogen receptor and HER2 in targeted therapy, and further discussed gene expression arrays such as OncotypeDX for targeting treatment. She went on to caution against so-called predictive factors for specific chemotherapies including HER2 and topoisomerase IIα, demonstrating that their role so far is uncertain given the inconsistency of individual studies addressing the issue. She concluded that neither of these markers were ready for use and that methodologic issues remained, including lack of reproducibility of measurements, publication bias and lack of power of individual studies. She agreed that the motion was laudable in principle but argued that more research was needed. At the conclusion of the debate, the majority of the audience still supported the motion but a significant minority switched their vote against. Both Dr Lonning and Dr Pritchard could therefore be said to have won.

Identification of estrogen receptors in rainbow trout immune cells

Identification of estrogen receptors in rainbow trout immune cells

Identification of estrogen receptor α gene polymorphisms by SSCP and its effect on reproductive traits in Japanese flounder ( Paralichthys olivaceus)

Estrogen receptor ( ERα) modifies the expression of genes involved in cell growth, proliferation and differentiation through binding to estrogen response elements (EREs) located in a number of gene promoters, so the ERα gene is considered as an important factor affecting reproductive endocrinology in Japanese flounder ( Paralichthys olivaceus). In this study, twelve single nucleotide polymorphisms (SNPs) within eight CDS exons and 1 kb of 3′-UTR of the ERα gene were tested to association with four reproductive traits in a population of 119 Japanese flounder individuals with polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP). The association analysis of SNPs within Japanese flounder ERα gene with the reproductive traits was carried out using General Linear Model (GLM) estimation. Results indicated that two SNPs in the exon4 of ERα gene, P1 (A803G and C864T), were significantly associated with hepatosomatic index (HSI) ( P < 0.05) in female Japanese flounder. Other ten SNPs in 3′-UTR associated to serum 17β-estradiol (E 2) and HSI showed that P2 (A1982T) was significantly associated with E 2 ( P < 0.01) and P3 (A2149G, 2181TTACAAG2182 insertion or deletion, T2324G, A2359G and G2391A) was significantly associated with HSI ( P < 0.05) in female Japanese flounder. However, P2 (A1982T) and P4 (G2256T, T2294C, T2309G and A2333T) had significant effects on E 2 ( P < 0.05 and P < 0.01, respectively) in male Japanese flounder. In addition, there were significant associations between diplotype D1 based on fourteen SNPs and reproductive traits. The genetic effects for HSI (female) or E 2 (male) of diplotype D1 were significantly higher than those of other eight diplotypes ( P < 0.05), respectively. Our findings implied that P1 of ERα gene affecting the reproductive traits could be a potential QTN (quantitative trait nucleotide) which would be useful genetic marker in the selection of some reproductive traits for its in Japanese flounder.

Definition of Clinically Distinct Molecular Subtypes in Estrogen Receptor–Positive Breast Carcinomas Through Genomic Grade

A number of microarray studies have reported distinct molecular profiles of breast cancers (BC), such as basal-like, ErbB2-like, and two to three luminal-like subtypes. These were associated with different clinical outcomes. However, although the basal and the ErbB2 subtypes are repeatedly recognized, identification of estrogen receptor (ER) -positive subtypes has been inconsistent. Therefore, refinement of their molecular definition is needed. We have previously reported a gene expression grade index (GGI), which defines histologic grade based on gene expression profiles. Using this algorithm, we assigned ER-positive BC to either high-or low-genomic grade subgroups and compared these with previously reported ER-positive molecular classifications. As further validation, we classified 666 ER-positive samples into subtypes and assessed their clinical outcome. Two ER-positive molecular subgroups (high and low genomic grade) could be defined using the GGI. Despite tracking a single biologic pathway, these were highly comparable to the previously described luminal A and B classification and significantly correlated to the risk groups produced using the 21-gene recurrence score. The two subtypes were associated with statistically distinct clinical outcome in both systemically untreated and tamoxifen-treated populations. The use of genomic grade can identify two clinically distinct ER-positive molecular subtypes in a simple and highly reproducible manner across multiple data sets. This study emphasizes the important role of proliferation-related genes in predicting prognosis in ER-positive BC.

Functional Genomics Identifies a Mechanism for Estrogen Activation of the Retinoic Acid Receptor α1 Gene in Breast Cancer Cells

The identification of estrogen receptor (ERalpha) target genes is crucial to our understanding of its predominant role in breast cancer. In this study, we used a chromatin immunoprecipitation (ChIP)-cloning strategy to identify ERalpha-regulatory modules and associated target genes in the human breast cancer cell line MCF-7. We isolated 12 transcriptionally active genomic modules that recruit ERalpha and the coactivator steroid receptor coactivator (SRC)-3 to different intensities in vivo. One of the ERalpha-regulatory modules identified is located 3.7 kb downstream of the first transcriptional start site of the RARA locus, which encodes retinoic acid receptor alpha1 (RARalpha1). This module, which includes an estrogen response element (ERE), is conserved between the human and mouse genomes. Direct binding of ERalpha to the ERE was shown using EMSAs, and transient transfections in MCF-7 cells demonstrated that endogenous ERalpha can induce estrogen-dependent transcriptional activation from the module or the ERE linked to a heterologous promoter. Furthermore, ChIP assays showed that the coregulators SRC-1, SRC-3, and receptor-interacting protein 140 are recruited to this intronic module in an estrogen-dependent manner. As expected from previous studies, the transcription factor Sp1 can be detected at the RARA alpha1 promoter by ChIP. However, treatment with estradiol did not influence Sp1 recruitment nor help recruit ERalpha to the promoter. Finally, ablation of the intronic ERE was sufficient to abrogate the up-regulation of RARA alpha1 promoter activity by estradiol. Thus, this study uncovered a mechanism by which ERalpha significantly activates RARalpha1 expression in breast cancer cells and exemplifies the utility of functional genomics strategies in identifying long-distance regulatory modules for nuclear receptors.

Identification of Estrogen Receptor β RNA in Human Breast and Abdominal Subcutaneous Adipose Tissue

This study reports the initial observation of the novel estrogen receptor, ERβ, in human subcutaneous adipose tissue. Human adipose tissue was obtained from various anatomic sites including the subcutaneous depots of lipectomy patients (healthy controls), and from subcutaneous abdominal and breast depots of lean and obese women with breast cancer. ERβ mRNA expression, determined by reverse transcription and polymerase chain reaction (RT-PCR), was present in each adipose tissue sample examined. Cloning and sequencing of the PCR product confirmed its identity as ERβ. Separation of adipose tissue into component fractions indicated that ERβ was expressed in both adipocytes and the stroma-vasculature. Primary culture of human preadipocytes indicated that ERβ mRNA was present only after differentiation to the adipocyte phenotype. This novel observation of ERβ mRNA indicates that this receptor subtype may have a role in ER-mediated responses in human adipose tissue.

Identification of Estrogen Receptor 2, A Functional Variant of Estrogen Receptor Expressed in Normal Rat Tissues

Identification of Estrogen Receptor 2, A Functional Variant of Estrogen Receptor Expressed in Normal Rat Tissues

Identification of oestrogen receptors and oestrogen receptor mRNA in human adipose tissue.

The distribution of adipose tissue has a major impact on the morbidity and mortality associated with obesity. Furthermore, the distribution of adipose tissue seems to be regulated by sex hormones. Controversy exists over whether the effects of sex hormones (oestrogen and testosterone) on human adipose tissue are an indirect or a direct effect as contradictory results have been obtained when investigating the existence of these receptors in human adipose tissue. In the present study the authors reinvestigated the possible existence of oestrogen receptors (ERs) in human adipose tissue. Human adipocytes from both genders were found to contain specific oestrogen binding sites determined by ligand-binding techniques. The binding protein had a molecular weight of 65 kD (which is similar to that of the ER found elsewhere) and it was found that adipocytes contained mRNA encoding the ER. Moreover, human preadipocytes had no oestrogen-binding capacity and did not possess mRNA encoding the ER. Finally, the authors detected regional differences in receptor density. Women had an equal oestrogen-binding capacity in adipose tissue from the subcutaneous abdominal and the visceral depot, whereas men had twice as high oestrogen-binding capacity in subcutaneous adipose tissue compared with adipose tissue in the visceral fat depot. These findings indicate that mature human adipocytes possess ERs and thus, might be an oestrogen-responsive tissue and that oestrogen may be acting directly in mature adipocytes via its specific receptor. Human preadipocytes, however, seemed not to be an oestrogen-responsive tissue. Finally, preliminary data suggest that there might be differences in ER densities in different fat depots.

Identification of estrogen receptor in human adipose tissue and adipocytes

Identification of estrogen receptor in human adipose tissue and adipocytes

Identification of estrogen receptor in human adipose tissue and adipocytes.

Estrogen has various effects on adipose tissue. Although the presence of estrogen receptor (ER) has been demonstrated in rat adipose tissue and adipocytes, ER has not been identified in human adipose tissue. In this study, we demonstrated the existence of ER protein and ER messenger RNA (mRNA) in human sc adipose tissue and adipocytes. The cytosol fraction of human adipose tissue was partially purified by ammonium sulfate precipitation, and the presence of ER protein was analyzed by [3H]estradiol (E2) binding assay and Western blot analysis. [3H]E2 binding assay showed a low specific binding due to high nonspecific binding, and the dissociation constant (Kd) and maximal binding sites could not be obtained by Scatchard analysis. Western blots, however, showed the presence of ER protein in both the partially purified cytosol and nuclear fractions of human adipose tissue. The mol wt of ER in both fractions was approximately 66,000. Furthermore, Northern blot analysis of total RNA samples isolated from human adipose tissue showed the expression of ER mRNA at 6.2 kilobase in size. ER mRNA was also identified in isolated human adipocytes by the reverse transcription and polymerase chain reaction. These results indicated that both ER protein and ER mRNA are expressed in human adipocytes, suggesting that the effect of estrogen on human adipose tissues might involve a direct action.

Effect of estrogens on the liver

Although the liver is not generally regarded as a target organ for estrogens, several clinical observations and a number of physiological studies suggest that it is. The identification of estrogen receptors in liver cytosol and nuclei support this conclusion.1, 2 We shall discuss several of the more important physiological and clinical effects of estrogens upon the liver (table 1) and shall illustrate them by brief case reports.