Unraveling the Dynamics of Estrogen and Progesterone Signaling in the Endometrium: An Overview

The endometrium is crucial for the perpetuation of human species. It is a complex and dynamic tissue lining the inner wall of the uterus, regulated throughout a woman's life based on estrogen and progesterone fluctuations. During each menstrual cycle, this multicellular tissue undergoes cyclical changes, including regeneration, differentiation in order to allow egg implantation and embryo development, or shedding of the functional layer in the absence of pregnancy. The biology of the endometrium relies on paracrine interactions between epithelial and stromal cells involving complex signaling pathways that are modulated by the variations of estrogen and progesterone levels across the menstrual cycle. Understanding the complexity of estrogen and progesterone receptor signaling will help elucidate the mechanisms underlying normal reproductive physiology and provide fundamental knowledge contributing to a better understanding of the consequences of hormonal imbalances on gynecological conditions and tumorigenesis. In this narrative review, we delve into the physiology of the endometrium, encompassing the complex signaling pathways of estrogen and progesterone.

17β-Estradiol mediates TGFBR3/Smad2/3 signaling to attenuate the fibrosis of TGF-β1-induced bovine endometrial epithelial cells via GPER

Abnormal function and fibrosis of endometrium caused by cows' endometritis pose difficult implantation of embryos and uterine cavity adhesions. 17β-Estradiol (E2) serves as the most effective aromatized estrogen, and its synthetase and receptors have been detected in the endometrium. Studies have demonstrated the positive role of estrogen in combating pathological fibrosis in diverse diseases. However, it is still unknown whether E2 regulates endometrium fibrosis in bovine endometritis. Herein, we evaluated the expression patterns of transforming growth factor-β1 (TGF-β1), epithelial-mesenchymal transformation (EMT)-related proteins (α-SMA, vimentin N-cadherin and E-cadherin), cytochrome P450 19A1 (CYP19A1), and G protein-coupled estrogen receptor (GPER) in bovine healthy endometrium and Inflammatory endometrium. Our data showed that the inflamed endometrium presented low CYP19A1 and GPER expression, and significantly higher EMT process versus the normal tissue. Moreover, we established a TGF-β1-induced fibrosis model in BEND cells, and found that E2 inhibited the EMT process of BEND cells in a dose-dependent manner. The anti-fibrotic effect of E2 was blocked by the GPER inhibitor G15, but not the estrogen nuclear receptors (ERs) inhibitor ICI182780. Moreover, the GPER agonist G1 inhibited fibrosis and Smad2/3 phosphorylation but increased the expression of TGFBR3 in BEND cells. Transfection with TGFBR3 small interfering RNA blocked the effect of G1 on fibrosis of BEND cells and upregulated the expression of P-Smad2/3. Our in vivo data also showed that E2 and G1 affected uterus fibrosis in mice endometritis model caused by LPS, which was associated with the inhibition of TGFBR3/Smad2/3 signaling. In conclusion, our data implied that E2 alleviates the fibrosis of TGF-β1-induced BEND cells, which is associated with the GPER mediation of TGFBR3/Smad2/3 signaling.

Identification of Ferroptosis-Related Genes in Heart Failure Induced by Transverse Aortic Constriction

Background

Heart failure (HF) is a common clinical syndrome due to ventricular dysfunction and is a major cause of mortality worldwide. Ferroptosis, marked by excessive iron-dependent lipid peroxidation, is closely related to HF. Therefore, the purpose of this study is to explore and validate ferroptosis-related markers in HF by bioinformatics analysis and animal experiments validation.

Materials and Methods

The gene expression profiles (GSE36074) of murine transverse aortic constriction (TAC) were obtained from the Gene Expression Omnibus (GEO); From the FerrDb database, ferroptosis-related genes (FRGs) were identified. Using GEO2R, differential expressed genes (DEGs) were screened. An overlapping analysis was conducted among DEGs and FRGs to identify ferroptosis-related DEGs (FRDEGs). We then performed clustering, functional enrichment analysis, and protein-protein interaction (PPI) analyses. In addition, the key FRDEGs were extracted by cytoHubba plugin and the networks of transcription factors (TFs)-key FRDEGs and microRNA-key FRDEGs were constructed. Lastly, the key FRDEGs were carried by quantitative reverse transcription PCR (RT-qPCR) and immunohistochemistry (IHC).

Results

Fifty-nine FRGs showing significantly different expression were identified from a total of 1918 DEGs in mice heart by transverse aortic constriction. GO and KEGG functional enrichment analysis revealed that these 59 ferroptosis-related DEGs mostly associated with positive regulation of apoptotic process, FoxO signaling pathway, VEGF signaling pathway, Apoptosis, Ferroptosis. Five key FRDEGs (Mapk14, Hif1a, Ddit3, Tlr4 and Ptgs2) were identified using PPI networks; Based on TFs-key FRDEGs networks, we found that Mapk14, Hif1a, Tlr4 and Ptgs2 were regulated by 3, 4, 5, and 29 TFs, respectively; however, Ddit3 was not regulated by any TF; By analyzing the miRNA-key FRDEGs networks, we found that 39, 74, 11, 28, and 18 miRNAs targets regulate the expression of Mapk14, Hif1a, Ddit3, Tlr4 and Ptgs2, respectively. Lastly, five key FRDEGs were validated at the mRNA and protein levels by RT-qPCR and IHC, which were in line with our bioinformatics analysis.

Conclusion

Our findings reveal that Mapk14, Hif1a, Ddit3, Tlr4 and Ptgs2 may be involved in the development of HF through regulating ferroptosis and as potential targets for HF.

The Role of G Protein-Coupled Estrogen Receptor (GPER) in Vascular Pathology and Physiology

OBJECTIVE

Estrogen is indispensable in health and disease and mainly functions through its receptors. The protection of the cardiovascular system by estrogen and its receptors has been recognized for decades. Numerous studies with a focus on estrogen and its receptor system have been conducted to elucidate the underlying mechanism. Although nuclear estrogen receptors, including estrogen receptor-α and estrogen receptor-β, have been shown to be classical receptors that mediate genomic effects, studies now show that GPER mainly mediates rapid signaling events as well as transcriptional regulation via binding to estrogen as a membrane receptor. With the discovery of selective synthetic ligands for GPER and the utilization of GPER knockout mice, significant progress has been made in understanding the function of GPER. In this review, the tissue and cellular localizations, endogenous and exogenous ligands, and signaling pathways of GPER are systematically summarized in diverse physiological and diseased conditions. This article further emphasizes the role of GPER in vascular pathology and physiology, focusing on the latest research progress and evidence of GPER as a promising therapeutic target in hypertension, pulmonary hypertension, and atherosclerosis. Thus, selective regulation of GPER by its agonists and antagonists have the potential to be used in clinical practice for treating such diseases.

Identification of hub genes associated with oxidative stress in heart failure and their correlation with immune infiltration using bioinformatics analysis

Both oxidative stress and the immune response are associated with heart failure (HF). In this study, our aim was to identify the hub genes associated with oxidative stress andimmune infiltration of HF by bioinformatics analysis and experimental verification. The expression profile of GSE36074 was obtained from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were screened by GEO2R. The genes related to oxidative stress were extracted from GeneCards websites. Then, the functional enrichment analysis of oxidative stress-related DEGs (OSRDEGs) was performed using DAVID. In addition, we constructed a protein-protein interaction (PPI) network using the STRING database and screened for hub genes with Cytoscape software. We also used CIBERSORTx to analyze immune infiltration in mice heart tissues between the TAC and Sham groups and explored the correlation between immune cells and hub genes. Finally, the hub genes were carried out using reverse transcription quantitative PCR (RT-qPCR), immunohistochemistry (IHC) and western blot. A total of 136 OSRDEGs were found in GSE36074. Enrichment analysis revealed that these OSRDEGs were enriched in the mitochondrion, HIF-1, FoxO, MAPK and TNF signaling pathway. The five hub genes (Mapk14, Hif1a, Myc, Hsp90ab1, and Hsp90aa1) were screened by the cytoHubba plugin. The correlation analysis between immune cells and hub genes showed that Mapk14 was positively correlated with Th2 Cells, while Hif1a and Hsp90ab1exhibited a negative correlation with Th2 Cells; Myc exhibited a negative correlation with Monocytes; whereas, Hsp90aa1 was negatively correlated with NK Resting. Finally, five hub genes were validated by RT-qPCR, IHC and western blot. Mapk14, Hif1a, Myc, Hsp90ab1, and Hsp90aa1 are hub genes of HF and may play a critical role in the oxidative stress of HF. This study may provide new targets for the treatment of HF, and the potential immunotherapies are worthy of further study.

Role of Estrogen Receptor β, G-Protein Coupled Estrogen Receptor and Estrogen-Related Receptors in Endometrial and Ovarian Cancer

Ovarian and endometrial cancers are affected by estrogens and their receptors. It has been long known that in different types of cancers, estrogens activate tumor cell proliferation via estrogen receptor α (ERα). In contrast, the role of ERs discovered later, including ERβ and G-protein-coupled ER (GPER1), in cancer is less well understood, but the current state of knowledge indicates them to have a considerable impact on both cancer development and progression. Moreover, estrogen related receptors (ERRs) have been reported to affect pathobiology of many tumor types. This article provides a summary and update of the current findings on the role of ERβ, GPER1, and ERRs in ovarian and endometrial cancer. For this purpose, original research articles on the role of ERβ, GPER1, and ERRs in ovarian and endometrial cancers listed in the PubMed database have been reviewed.

Estradiol and Estrogen-like Alternative Therapies in Use: The Importance of the Selective and Non-Classical Actions

Estrogen is one of the most important female sex hormones, and is indispensable for reproduction. However, its role is much wider. Among others, due to its neuroprotective effects, estrogen protects the brain against dementia and complications of traumatic injury. Previously, it was used mainly as a therapeutic option for influencing the menstrual cycle and treating menopausal symptoms. Unfortunately, hormone replacement therapy might be associated with detrimental side effects, such as increased risk of stroke and breast cancer, raising concerns about its safety. Thus, tissue-selective and non-classical estrogen analogues have become the focus of interest. Here, we review the current knowledge about estrogen effects in a broader sense, and the possibility of using selective estrogen-receptor modulators (SERMs), selective estrogen-receptor downregulators (SERDs), phytoestrogens, and activators of non-genomic estrogen-like signaling (ANGELS) molecules as treatment.

Estrogen Receptor Function: Impact on the Human Endometrium

The physiological role of estrogen in the female endometrium is well established. On the basis of responses to steroid hormones (progesterone, androgen, and estrogen), the endometrium is considered to have proliferative and secretory phases. Estrogen can act in the endometrium by interacting with estrogen receptors (ERs) to induce mucosal proliferation during the proliferative phase and progesterone receptor (PR) synthesis, which prepare the endometrium for the secretory phase. Mouse knockout studies have shown that ER expression, including ERα, ERβ, and G-protein-coupled estrogen receptor (GPER) in the endometrium is critical for normal menstrual cycles and subsequent pregnancy. Incorrect expression of ERs can produce many diseases that can cause endometriosis, endometrial hyperplasia (EH), and endometrial cancer (EC), which affect numerous women of reproductive age. ERα promotes uterine cell proliferation and is strongly associated with an increased risk of EC, while ERβ has the opposite effects on ERα function. GPER is highly expressed in abnormal EH, but its expression in EC patients is paradoxical. Effective treatments for endometrium-related diseases depend on understanding the physiological function of ERs; however, much less is known about the signaling pathways through which ERs functions in the normal endometrium or in endometrial diseases. Given the important roles of ERs in the endometrium, we reviewed the published literature to elaborate the regulatory role of estrogen and its nuclear and membrane-associated receptors in maintaining the function of endometrium and to provide references for protecting female reproduction. Additionally, the role of drugs such as tamoxifen, raloxifene, fulvestrant and G-15 in the endometrium are also described. Future studies should focus on evaluating new therapeutic strategies that precisely target specific ERs and their related growth factor signaling pathways.

Female Reproductive Systems: Hormone Dependence and Receptor Expression

The female reproductive system which consists of the ovaries, uterus (myometrium, endometrium), Fallopian tubes, cervix and vagina is exquisitely sensitive to the actions of steroid hormones. The ovaries play a key role in the synthesis of bioactive steroids (oestrogens, androgens, progestins) that act both within the tissue (intracrine/paracrine) as well as on other reproductive organs following release into the blood stream (endocrine action). Sex steroid receptors encoded by the oestrogen (ESR1, ESR2), progesterone (PR) and androgen (AR) receptor genes, which are members of the superfamily of ligand activated transcription factors are widely expressed within these tissues. These receptors play critical role(s) in regulation of cell proliferation, ovulation, endometrial receptivity, myometrial cell function and inflammatory cell infiltration. Our understanding of their importance has been informed by studies on human tissues and cells, which have employed immunohistochemistry as well as a wide range of molecular and genetic methods to identify which processes are dependent steroid ligand activation. The development of mice with targeted deletions of each of these receptors has provided complementary data that has extended our appreciation of cell-cell interactions in the fine tuning of reproductive tissue function. This large body of work has formed the basis of new and improved therapeutics to treat conditions such as infertility.

The change pattern in serum G protein-coupled estrogen receptor-1 (GPER1) levels during pregnancy with and without gestational diabetes mellitus

OBJECTIVES

The purpose of this study was to evaluate serum G protein-coupled estrogen receptor-1 (GPER1) levels in non-pregnant and pregnant with and without gestational diabetes mellitus (GDM).

METHODS

The study comprised 40 pregnant women with (n=20) and without GDM (n=20) and 20 healthy non-pregnant women. Data as maternal age, gestational age, and body mass index (BMI) of participants were recorded and serum samples were collected. Serum GPER1 levels were measured by enzyme-linked immunosorbent assays.

RESULTS

Serum GPER1 level was significantly higher in GDM (p=0.03) and non-pregnant women (p=0.005) than those of normal pregnancy. There was no significant correlation between the serum GPER1 levels age (r=0.18, p=0.34), gestational age (r=-0.22, p=0.47), and BMI (r=0.004, p=0.975).

CONCLUSIONS

Our results suggest that changes in serum GPER1 levels in pregnancy and GDM may be associated with estrogen. More detailed studies should be conducted to monitor the changes and their interactions in serum sex hormones and serum GPER1 levels during GDM.

Bisphenol A Analogues Suppress Spheroid Attachment on Human Endometrial Epithelial Cells through Modulation of Steroid Hormone Receptors Signaling Pathway

Bisphenol A (BPA) is a well-known endocrine disruptor, widely used in various consumer products and ubiquitously found in air, water, food, dust, and sewage leachates. Recently, several countries have restricted the use of BPA and replaced them with bisphenol S (BPS) and bisphenol F (BPF), which have a similar chemical structure to BPA. Compared to BPA, both BPS and BPF have weaker estrogenic effects, but their effects on human reproductive function including endometrial receptivity and embryo implantation still remain largely unknown. We used an in vitro spheroid (blastocyst surrogate) co-culture assay to investigate the effects of BPA, BPS, and BPF on spheroid attachment on human endometrial epithelial cells, and further delineated their role on steroid hormone receptor expression. We also used transcriptomics to investigate the effects of BPA, BPS, and BPF on the transcriptome of human endometrial cells. We found that bisphenol treatment in human endometrial Ishikawa cells altered estrogen receptor alpha (ERα) signaling and upregulated progesterone receptors (PR). Bisphenols suppressed spheroid attachment onto Ishikawa cells, which was reversed by the downregulation of PR through PR siRNA. Overall, we found that bisphenol compounds can affect human endometrial epithelial cell receptivity through the modulation of steroid hormone receptor function leading to impaired embryo implantation.

Profiling the expression and function of oestrogen receptor isoform ER46 in human endometrial tissues and uterine natural killer cells

STUDY QUESTION

Does the oestrogen receptor isoform, ER46, contribute to regulation of endometrial function?

SUMMARY ANSWER

ER46 is expressed in endometrial tissues, is the predominant ER isoform in first trimester decidua and is localised to the cell membrane of uterine natural killer (uNK) cells where activation of ER46 increases cell motility.

WHAT IS KNOWN ALREADY

Oestrogens acting via their cognate receptors are essential regulators of endometrial function and play key roles in establishment of pregnancy. ER46 is a 46-kDa truncated isoform of full length ERα (ER66, encoded by ESR1) that contains both ligand- and DNA-binding domains. Expression of ER46 in the human endometrium has not been investigated previously. ER46 is located at the cell membrane of peripheral blood leukocytes and mediates rapid responses to oestrogens. uNK cells are a phenotypically distinct (CD56brightCD16-) population of tissue-resident immune cells that regulate vascular remodelling within the endometrium and decidua. We have shown that oestrogens stimulate rapid increases in uNK cell motility. Previous characterisation of uNK cells suggests they are ER66-negative, but expression of ER46 has not been characterised. We hypothesise that uNK cells express ER46 and that rapid responses to oestrogens are mediated via this receptor.

STUDY DESIGN, SIZE, DURATION

This laboratory-based study used primary human endometrial (n = 24) and decidual tissue biopsies (n = 30) as well as uNK cells which were freshly isolated from first trimester human decidua (n = 18).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Primary human endometrial and first trimester decidual tissue biopsies were collected using methods approved by the local institutional ethics committee (LREC/05/51104/12 and LREC/10/51402/59). The expression of ERs (ER66, ER46 and ERβ) was assessed by quantitative PCR, western blot and immunohistochemistry. uNK cells were isolated from first-trimester human decidua by magnetic bead sorting. Cell motility of uNK cells was measured by live cell imaging: cells were treated with 17β-oestradiol conjugated to bovine serum albumin (E2-BSA, 10 nM equivalent), the ERβ-selective agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN; 10 nM) or dimethylsulphoxide vehicle control.

MAIN RESULTS AND THE ROLE OF CHANCE

ER46 was detected in proliferative and secretory phase tissues by western blot and was the predominant ER isoform in first-trimester decidua samples. Immunohistochemistry revealed that ER46 was co-localised with ER66 in cell nuclei during the proliferative phase but detected in both the cytoplasm and cell membrane of stromal cells in the secretory phase and in decidua. Triple immunofluorescence staining of decidua tissues identified expression of ER46 in the cell membrane of CD56-positive uNK cells which were otherwise ER66-negative. Profiling of isolated uNK cells confirmed expression of ER46 by quantitative PCR and western blot and localised ER46 protein to the cell membrane by immunocytochemistry. Functional analysis of isolated uNK cells using live cell imaging demonstrated that activation of ER46 with E2-BSA significantly increased uNK cell motility.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Expression pattern in endometrial tissue was only determined using samples from proliferative and secretory phases. Assessment of first trimester decidua samples was from a range of gestational ages, which may have precluded insights into gestation-specific changes in these tissues. Our results are based on in vitro responses of primary human cells and we cannot be certain that similar mechanisms occur in situ.

WIDER IMPLICATIONS OF THE FINDINGS

E2 is an essential regulator of reproductive competence. This study provides the first evidence for expression of ER46 in the human endometrium and decidua of early pregnancy. We describe a mechanism for regulating the function of human uNK cells via expression of ER46 and demonstrate that selective targeting with E2-BSA regulates uNK cell motility. These novel findings identify a role for ER46 in the human endometrium and provide unique insight into the importance of membrane-initiated signalling in modulating the impact of E2 on uNK cell function in women. Given the importance of uNK cells to regulating vascular remodelling in early pregnancy and the potential for selective targeting of ER46, this may be an attractive future therapeutic target in the treatment of reproductive disorders.

STUDY FUNDING/COMPETING INTEREST(S)

These studies were supported by Medical Research Council (MRC) Programme Grants G1100356/1 and MR/N024524/1 to PTKS. H.O.D.C. was supported by MRC grant G1002033. The authors declare no competing interests related to the published work.

Lipolysis by downregulating miR-92a activates the Wnt/β-catenin signaling pathway in hypoxic rats

The aim of the present study was to investigate the role of miR-92a in lipid metabolism in hypoxic rats. Microarray analysis and reverse transcription-quantitative (RT-q)PCR were used to detect changes in the mRNA expression levels of miR-92a in the epididymal fat of hypoxic and normoxic rats. The downstream target mRNA of miR-92a was predicted using bioinformatics analysis and verified using a dual luciferase reporter assay. Changes in the expression of frizzled (Fzd)10 and c-Myc in the epididymal fat were detected using RT-qPCR and western blotting. Microarray analysis and RT-qPCR results showed that the expression of miR-92a was significantly lower in the fat tissues of the hypoxic rats compared with the normoxic rats. The results of the dual luciferase reporter assay showed that the target gene of miR-92a was Fzd10, which is an acceptor in the Wnt pathway. Fzd10 expression was upregulated in the hypoxic rats. The mRNA expression levels of c-Myc, which is located downstream of the Wnt pathway, was increased significantly. The increase in the mRNA and protein expression levels of Fzd10 and c-Myc may be associated with miR-92a downregulation. Downregulation of miR-92a in-turn may result in lipolysis through the regulation of the Wnt/β-catenin signaling pathway, and thus weight loss in the rats.

Estrogen Receptors and Estrogen-Induced Uterine Vasodilation in Pregnancy

Normal pregnancy is associated with dramatic increases in uterine blood flow to facilitate the bidirectional maternal–fetal exchanges of respiratory gases and to provide sole nutrient support for fetal growth and survival. The mechanism(s) underlying pregnancy-associated uterine vasodilation remain incompletely understood, but this is associated with elevated estrogens, which stimulate specific estrogen receptor (ER)-dependent vasodilator production in the uterine artery (UA). The classical ERs (ERα and ERβ) and the plasma-bound G protein-coupled ER (GPR30/GPER) are expressed in UA endothelial cells and smooth muscle cells, mediating the vasodilatory effects of estrogens through genomic and/or nongenomic pathways that are likely epigenetically modified. The activation of these three ERs by estrogens enhances the endothelial production of nitric oxide (NO), which has been shown to play a key role in uterine vasodilation during pregnancy. However, the local blockade of NO biosynthesis only partially attenuates estrogen-induced and pregnancy-associated uterine vasodilation, suggesting that mechanisms other than NO exist to mediate uterine vasodilation. In this review, we summarize the literature on the role of NO in ER-mediated mechanisms controlling estrogen-induced and pregnancy-associated uterine vasodilation and our recent work on a “new” UA vasodilator hydrogen sulfide (H₂S) that has dramatically changed our view of how estrogens regulate uterine vasodilation in pregnancy.

Spatial and temporal changes in the expression of steroid hormone receptors in mouse model of endometriosis

PURPOSE

Endometriosis is recognized as a steroid hormone-dependent disorder. However, controversies exist regarding the status of the steroid hormone receptor expression in endometriotic tissues. The purpose of this study was to determine the ontogeny of cellular changes in the expression of estrogen receptors (ERα, ERβ), G protein-coupled estrogen receptor 1 (GPER1), and progesterone receptors (PRs) in endometriosis using a mouse model.

METHODS

We used the autologous uterine tissue transfer mouse model and studied the mRNA and protein expression of ERα, ERβ, GPER1, and PR in ectopic lesions at 2, 4, and 8 weeks of induction of endometriosis.

RESULT

As compared to endometrium of controls, in the ectopic endometrium, ERα is reduced while ERβ was elevated in stromal cells; however, Gper1 and PR levels are reduced in both stromal and epithelial cells in a time-specific manner. There is a high inter-animal variation in the levels of these receptors in ectopic endometrium as compared to controls; the levels also varied by almost 100-fold within the same lesion resulting in "micro-heterogeneity." The expression of all these receptors also deferred between two lesions from the same animal.

CONCLUSION

In the endometriotic tissue, there is extensive inter-animal and intra-lesion heterogeneity in the expression of ERα, ERβ, GPER1, and PR. These changes are not due to the influence of the peritoneal environment but appear to be tissue intrinsic. We propose that the variable outcomes in hormonal therapy for endometriosis could be possibly due to heterogeneity in the expression of steroid hormone receptors in the ectopic endometrium.

Expression and Role of the G Protein-Coupled Estrogen Receptor (GPR30/GPER) in the Development and Immune Response in Female Reproductive Cancers

Cancer is a major public health issue and represents the second leading cause of death in women worldwide, as female reproductive-related neoplasms are the main cause of incidence and mortality. Female reproductive cancers have a close relationship to estrogens, the principal female sex steroid hormones. Estrogens exert their actions by the nuclear estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ). ERα, and ERβ act as transcription factors mediating genomic effects. Besides, the G protein-coupled estrogen receptor (GPER, formerly known as GPR30) was recently described as a seven-transmembrane receptor that mediates non-genomic estrogenic signaling, including calcium mobilization, cAMP synthesis, cleavage of matrix metalloproteinases, transactivation of epidermal growth factor receptor (EGFR), and the subsequent activation of PI3K and MAPK signaling pathways, which are the reasons why it is related to cellular processes, such as cell-cycle progression, cellular proliferation, differentiation, apoptosis, migration, and invasion. Since its discovery, selective agonists and antagonists have been found and developed. GPER has been implicated in a variety of hormone-responsiveness tumors, such as breast, endometrial, ovarian, cervical, prostate, and testicular cancer as well as lung, hepatic, thyroid, colorectal, and adrenocortical cancers. Nevertheless, GPER actions in cancer are still debatable due to the conflicting information that has been reported to date, since many reports indicate that activation of this receptor can modulate carcinogenesis. In contrast, many others show that its activation inhibits tumor activity. Besides, estrogens play an essential role in the regulation of the immune system, but little information exists about the role of GPER activation on its modulation within cancer context. This review focuses on the role that the stimulation of GPER plays in female reproductive neoplasms, specifically breast, endometrial, ovarian, and cervical cancers, in its tumor activity and immune response regulation.

Aberrant DNA methylation profiling affecting the endometrial receptivity in recurrent implantation failure patients undergoing in vitro fertilization

PROBLEM

DNA methylation profile in mid-secretory phase of endometrium is reported to be varied from other phases in natural menstrual cycle. Therefore, we intended to study the impairment in endometrial receptivity by performing whole-genome methylation and gene expression profiling in endometrium of recurrent implantation failure patients (RIF) during IVF under controlled ovarian stimulation (COS).

METHOD OF STUDY

Endometrial biopsies were collected from IVF-RIF patients (cases, n = 6) and healthy fertile oocyte donors (controls, n = 6) undergoing COS after 6/7th day of human chorionic gonadotropin administration. The whole-genome methylation and gene expression microarray were performed and analysed by GenomeStudio software (P < .05 by Illumina Custom Model), whereas the enrichment analysis was performed using "Database for Annotation, Visualization and Integrated Discovery" (DAVID, V6.8). Significant differentially methylated genes were correlated with dys-regulated genes using Pearson's correlation.

RESULTS

Differential methylation in RIF patients revealed 448 CpG sites. The enrichment analysis showed aberrant methylation in genes involved in immunological response and G protein activity. Methylation in NLRP2 gene in inflammatory pathway had significant negative correlation with gene expression (P = .008), whereas SERPINA5 gene that is already known to be involved in endometrial receptivity was observed to be hypomethylated in promoter region with highest delta beta value and up-regulated in gene expression analysis.

CONCLUSION

The aberrant methylation of genes involved in immunological functions and G protein activation was found to be prevalent which might suggest a role in endometrial receptivity. However, the findings need to be further validated on a larger cohort of IVF-RIF patients.

Association of a reduction of G‑protein coupled receptor 30 expression and the pathogenesis of preeclampsia

Preeclampsia is a pregnancy‑specific disorder, which is a leading cause of maternal and perinatal mortality and morbidity. A lower increase of estrogen, compared with the increase in progesterone, is associated with pathogenesis of the disease during pregnancy. G‑protein‑coupled receptor 30 (GPR30) mediates the action of estrogen, however remains to be investigated in preeclampsia. The levels of GPR30 were measured in placentae from uncomplicated pregnancies and pregnancies complicated by preeclampsia using immunohistochemistry and western blotting. GPR30 expression was additionally measured in placental HTR8/SVneo cells following 17β‑estrogen (E2) treatment in normal or hypoxia‑reoxygenation conditions by western blotting. In addition, the outgrowth of HTR8/SVneo cells following E2 treatment in hypoxia‑reoxygenation conditions was measured. Levels of GPR30 were significantly reduced in placentae from women with preeclampsia as compared with uncomplicated pregnancies. Treatment with E2 significantly increased the expression of GPR30 in HTR8/SVneo cells, in normal and hypoxia‑reoxygenation conditions. Furthermore, treatment with E2 increased the outgrowth of HTR8/SVneo cells in hypoxia‑reoxygenation conditions. The present study demonstrated lowered placental expression of GPR30 in preeclampsia. Estrogen treatment increases GPR30 expression in extravillous trophoblast and GPR30 may be involved in extravillous trophoblast invasion.

GPER-novel membrane oestrogen receptor

The recent discovery of the G protein-coupled oestrogen receptor (GPER) presents new challenges and opportunities for understanding the physiology, pathophysiology and pharmacology of many diseases. This review will focus on the expression and function of GPER in hypertension, kidney disease, atherosclerosis, vascular remodelling, heart failure, reproduction, metabolic disorders, cancer, environmental health and menopause. Furthermore, this review will highlight the potential of GPER as a therapeutic target.

Hyper-methylation of the upstream CpG island shore is a likely mechanism of GPER1 silencing in breast cancer cells

GPER1, also known as GPR30, is a novel seven-transmembrane G-protein coupled estrogen receptor that mediates both short-term (non-genomic) and long-term (genomic) effects of estrogen in target cells and tissues. A substantial body of work over the last two decades has highlighted its therapeutic or prognostic utility. However, the clinical data on the expression of GPER1 in breast tissue is ambiguous. Analysis of TCGA RNAseq data revealed significantly lower mean expression of GPER1 mRNA in primary breast tumors compared to that in normal breast tissues. This provides support to the tumor suppressor role for GPER1. However, the mechanisms underlying the reduced expression are not completely understood. We analyzed the expression levels of GPER1 mRNA variants in MCF-7 and MDA-MB-231 cells by RT-PCR, and the methylation status of two CpG islands in the GPER1 locus by modified COBRA assays and bisulfite sequencing. Our results show that MCF-7 cells express higher levels of GPER1 mRNA variants compared to MDA-MB-231 cells. Modified COBRA assays revealed differential methylation in the upstream CpG island (upCpGi) that overlaps with the first exon of two GPER1 variants (GPER1v2 and v3) but not in the downstream CpG island (dnCpGi) that overlaps with the coding region common to all variants. Bisulfite sequencing results showed that the core upCpGi was hypo-methylated in both MCF-7 and MDA-MB-231 cells. However, eight CpGs in the 3' end of the upCpGi were hyper-methylated in MDA-MB-231 cells. 5-Azacytidine, a DNA methyltransferase inhibitor, induced the expression levels of GPER1 mRNA variants in MDA-MB-231 cells. Expression-methylation correlation analysis of TCGA breast cancer data revealed that methylation of CpGs in the regions flanking the upCpGi significantly correlated negatively with GPER1 mRNA expression. Taken together, our results demonstrate the role of DNA methylation in GPER1 repression, implicate the flanking regions (shore) of the upCpGi, and suggest a potential mechanism of GPER1 silencing in breast tumors.

Rs4265085 in GPER1 gene increases the risk for unexplained recurrent spontaneous abortion in Dai and Bai ethnic groups in China

Oestrogen receptors are implicated in the pathogenesis of recurrent spontaneous abortion (RSA). Non-genomic oestrogen responses can be mediated by GPER. The prevalence of polymorphisms in GPER1 gene in RSA was assessed in 747 Chinese women from Yunnan province (171 Bai, 258 Chinese Han, 234 Dai, 33 Achang and 51 Jingpo patients). Snapshot technology was used for genotyping the polymorphisms of the GPER1 gene. The rs4265085G was significantly increased in the Dai and Bai groups versus controls (Dai: P < 0.0001, P_adj < 0.0001, OR 95% CI 2.34 [1.79 to 3.05]; Bai: P = 0.0004, P_adj = 0.0012, OR 95% CI 1.71 [1.27 to 2.31]); recessive model of rs4265085 in the Dai (P = 0.003, P_adj = 0.009, OR 95% CI 2.71 [1.38 to 5.30]); Bai (P < 0.0001, P_adj < 0.0001, OR 95% CI 3.37 [1.93 to 5.91]). Haplotype frequencies containing rs10269151G-rs4265085G-rs11544331C were separately significantly different in Dai and Bai ethnic groups (Dai: P = 0.0002, P_adj = 0.001, OR 95% CI = 2.12 [1.43 to 3.17]; Bai: P = 0.005, P_adj = 0.025, OR 95% CI = 1.82 [1.18 to 2.78]) compared with controls. The intron variant rs4265085 may confer risk for RSA in Dai and Bai ethnic groups.

Functional expression of G protein-coupled receptor 30 in immature rat epididymal epithelium

The aim of this study is to investigate the functional role of G protein-coupled receptor 30 (GPR30) in the epididymis. We found that GPR30 is expressed in the epithelium of the immature rat epididymis and is involved in chloride secretion into the caudal epididymis lumen. The short-circuit current (Isc) experiments showed that in primary cultured caudal epididymis epithelium, activation of GPR30 by its specific agonist G1 induced a mono-phasic current increase, and G15, the specific antagonist of GPR30, could completely inhibit the current induced by G1. The G1-induced Isc was largely blocked by application of the non-specific chloride channel inhibitor diphenylamine-dicarboxylic acid (DPC), or by the cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor CFTR_inh-172 , suggesting that the current was mainly mediated through CFTR. In addition, after stimulating GPR30 by G1, the intracellular concentration of cAMP in the epithelium was significantly increased, indicating that the cAMP signal pathway is involved and could be responsible for the CFTR activation. Finally, to further investigate the function of GPR30 in vivo, G15 was administrated into rats subcutaneously. The osmotic pressure of the micro perfusion solution from epididymis was measured and the sperms were collected. Results showed that there was an osmotic pressure increase of the perfusion solution from G15 treated rats. When the GPR30 was inhibited by G15 endogenously, the motility of sperms decreased. Our data demonstrated that GPR30 is involved in the formation of caudal epididymis fluid micro-environment thus affecting sperm motility.

Imbalance between proliferation and apoptosis-related impaired GPR30 expression is involved in preeclampsia

The proliferation and apoptosis of cells in the placenta play a critical role in preeclampsia (PE) in which estrogen has been implicated via estrogen receptors (ERs). A novel ER, G-protein-coupled receptor 30 (GPR30), has recently been shown to be involved in PE. We investigated the basic levels of proliferation and apoptosis in normal placentae and placentae with PE and compared GPR30 expression levels between the two groups. We demonstrated that low GPR30 expression levels, more apoptosis, and less proliferation were associated with PE. Moreover, our in vitro study showed that both the selective GPR30 agonist G1 and the general ER agonist 17-β-estradiol were able to protect the placenta from hypoxia-reoxygenation injuries, resulting in decreased apoptosis and increased proliferation. Furthermore, this protective effect was abolished by the addition of the selective GPR30 inhibitor G15. These results provide evidence that (1) GPR30 is involved in regulating cell proliferation and apoptosis; (2) pharmacologic upregulation of GPR30 is beneficial for PE management; (3) GPR30 may therefore be an interventional target for pregnancies complicated by PE.

Validation data of a rabbit antiserum and affinity purified polyclonal antibody against the N-terminus of human GPR30

Rabbit antiserum was generated against the N-terminus of human GPR30 followed by peptide affinity purification. In this article, the methodology used and validation data are presented. The peptide affinity purified polyclonal antibody specifically detects human GPR30 in ELISA and on western blots of total protein prepared from human breast cancer cell lines.

miRNAs regulated by estrogens, tamoxifen, and endocrine disruptors and their downstream gene targets

MicroRNAs (miRNAs) are short (22 nucleotides), single-stranded, non-coding RNAs that form complimentary base-pairs with the 3' untranslated region of target mRNAs within the RNA-induced silencing complex (RISC) and block translation and/or stimulate mRNA transcript degradation. The non-coding miRBase (release 21, June 2014) reports that human genome contains ∼ 2588 mature miRNAs which regulate ∼ 60% of human protein-coding mRNAs. Dysregulation of miRNA expression has been implicated in estrogen-related diseases including breast cancer and endometrial cancer. The mechanism for estrogen regulation of miRNA expression and the role of estrogen-regulated miRNAs in normal homeostasis, reproduction, lactation, and in cancer is an area of great research and clinical interest. Estrogens regulate miRNA transcription through estrogen receptors α and β in a tissue-specific and cell-dependent manner. This review focuses primarily on the regulation of miRNA expression by ligand-activated ERs and their bona fide gene targets and includes miRNA regulation by tamoxifen and endocrine disrupting chemicals (EDCs) in breast cancer and cell lines.

Differential expression of upstream stimulatory factor (USF) 2 variants in eutopic endometria from women with endometriosis: estradiol regulation

BACKGROUND

Endometriosis, pro-inflammatory and invasive benign disease estrogen dependent, abnormally express in endometria the enzyme P450Arom, positively regulated by steroid factor-1 (SF-1). Our objective was to study the nuclear protein contents of upstream stimulating factor 2 (USF2a and USF2b), a positive regulator of SF-1, throughout the menstrual cycle in eutopic endometria from women with and without (control) endometriosis and the involvement of nuclear estrogen receptors (ER) and G-coupled protein estrogen receptor (GPER)-1.

RESULTS

Upstream stimulating factor 2 protein contents were higher in mid (USF2b) and late (USF2a and USF2b) secretory phase in eutopic endometria from endometriosis than control (p < 0.05). In isolated control epithelial cells incubated with E2 and PGE2, to resemble the endometriosis condition, the data showed: (a) significant increase of USF2a and USF2b nuclear protein contents when treated with E2, PPT (specific agonist for ERα) or G1 (specific agonist for GPER1); (b) no increase in USF2 binding to SF-1 E-Box/DNA consensus sequence in E2-treated cells; (c) USF2 variants protein contents were not modified by PGE2; (d) SF-1 nuclear protein content was significantly higher than basal when treated with PGE2, E2 or G1, stimulation unaffected by ICI (nuclear ER antagonist); and (e) increased (p < 0.05) cytosolic protein contents of P450Arom when treated with PGE2, E2, PPT or G1 compared to basal, effect that was additive with E2 + PGE2 together. Nevertheless, in endometriosis cells, the high USF2, SF-1 and P450Arom protein contents in basal condition were unmodified.

CONCLUSION

These data strongly suggest that USF2 variants and P450Arom are regulated by E2 through ERα and GPER1, whereas SF-1 through GPER1, visualized by the response of the cells obtained from control endometria, being unaffected the endogenously stimulated cells from endometriosis origin. The lack of E2 stimulation on USF2/SF-1 E-Box/DNA-sequence binding and the absence of PGE2 effect on USF2 variants opposite to the strong induction that they exert on SF1 and P450 proteins suggest different mechanisms and indirect regulations. The sustained USF2 variants protein expression during the secretory phase in eutopic endometria from women with endometriosis may participate in the pathophysiology of this disease strongly associated with infertility and its characteristic endometrial invasion to ectopic sites in the pelvic cavity.

Placental development during early pregnancy in sheep: estrogen and progesterone receptor messenger RNA expression in pregnancies derived from in vivo-produced and in vitro-produced embryos

Sex steroids are important regulators of angiogenesis and growth in reproductive tissues, including the placenta. In experiment (exp.) 1, to examine the expression of a suite of sex steroid receptors throughout early pregnancy, maternal (caruncular [CAR]) and fetal (fetal membranes [FM]) placental tissues were collected on days 14 to 30 after mating and on day 10 after estrus (nonpregnant controls). In exp. 2, to examine the hypothesis that assisted reproductive technology would affect the expression of the same suite of sex steroid receptors, pregnancies were achieved through natural mating (NAT) or transfer of embryos from natural mating (NAT-ET), in vitro fertilization (IVF), or in vitro activation (IVA), and CAR and FM were collected on day 22. In exp. 1, for CAR messenger RNA (mRNA) expression of estrogen receptors (ESR) 1 and 2, nuclear (n) progesterone receptors (PGR) and membrane (m) PGRα, β, and γ were affected (P < 0.02) by pregnancy stage, as were ESR1, nPGR, and mPGRα, β, and γ for FM (P < 0.03). In exp. 2, for CAR, mRNA expression of ESR1 and nPGR was decreased (P < 0.001) in NAT-ET, IVF, and IVA groups compared with NAT. For FM, mRNA expression of ESR1 tended to be greater (P = 0.10) in the IVA group compared with NAT and NAT-ET, and GPER1 was greater (P < 0.05) in NAT-ET and IVF compared with NAT. These data establish the normal pattern of sex steroid receptor mRNA expression in maternal and fetal placenta during early pregnancy in sheep, and in addition, suggest that altered expression of placental sex steroid receptors may be an early event leading to poor placental vascularization and growth after assisted reproductive technology.

G-protein Coupled Estrogen Receptor (GPER/GPR30) and Women's Health

Estrogen - the female sexual hormone playing the most important role - plays a physiologically significant role, not only regulating in cell signals with second messenger but also being active in regulating transcription. Estrogen receptor (ER) which is a protein accepting estrogen not only play the role of a transcription factor combining with other genes to regulate their activity like other nuclear receptors but also performs external activities, combining with DNA, etc. G-protein coupled ER (GPER) that has been recently discovered exists as 7-membrane and has non-genomic (rapid) signaling. These functions, however, are not extensively addressed. This paper discusses the roles of GPER and its physiological mechanism.

Lack of cyclical fluctuations of endometrial GLUT4 expression in women with polycystic ovary syndrome: Evidence for direct regulation of GLUT4 by steroid hormones

Background Determination of the role of steroid hormones in expression and regulation of endometrial glucose transport 4 (GLUT4) in humans is important for understanding endometrial disorders such as polycystic ovary syndrome (PCOS), a common hormone-imbalance disease. Methods Endometrial biopsy samples were collected from non-PCOS patients with regular menstrual cycles or with hyperplasia and from PCOS patients with or without hyperplasia. In addition, endometrial tissues from postmenopausal women were incubated with human chorionic gonadotropin (hCG, 10 IU/ml), 17β-estradiol (E2, 10 nM), progesterone (P4, 100 nM), or a combination of E2 and P4 for 24 h. The expression of GLUT4 was measured at the mRNA level using quantitative real-time polymerase chain reaction (qRT-PCR) and at the protein level using Western blot analysis and immunohistochemistry. Results A cyclical change in GLUT4 expression pattern was observed in non-PCOS patients, and a high level of GLUT4 expression was seen in the proliferative phase compared to the secretory phase. Low levels of GLUT4 expression were found in PCOS patients compared to menstrual cycle phase-matched non-PCOS patients, and there was no significant change in GLUT4 expression in PCOS patients during the menstrual cycle. GLUT4 was localized in both epithelial and stromal cells, with notable changes in epithelial cells. We postulate that decreased GLUT4 expression might be regulated by steroid hormones. In support of this, we showed that in cultured endometrial tissues hCG and E2 alone had no effect on GLUT4 expression. However, P4 alone and P4 in combination with E2 decreased GLUT4 expression. Compared with non-PCOS controls, PCOS patients with endometrial hyperplasia exhibited decreased GLUT4 expression in particular in the epithelial cells. Conclusion We conclude that P4 can induce changes in endometrial GLUT4 expression during the menstrual cycle and that abnormal hormonal conditions such as PCOS disrupt normal patterns of GLUT4 expression in endometrial cells.

GPER mediates estrogen-induced signaling and proliferation in human breast epithelial cells and normal and malignant breast

17β-Estradiol (estrogen), through receptor binding and activation, is required for mammary gland development. Estrogen stimulates epithelial proliferation in the mammary gland, promoting ductal elongation and morphogenesis. In addition to a developmental role, estrogen promotes proliferation in tumorigenic settings, particularly breast cancer. The proliferative effects of estrogen in the normal breast and breast tumors are attributed to estrogen receptor α. Although in vitro studies have demonstrated that the G protein-coupled estrogen receptor (GPER, previously called GPR30) can modulate proliferation in breast cancer cells both positively and negatively depending on cellular context, its role in proliferation in the intact normal or malignant breast remains unclear. Estrogen-induced GPER-dependent proliferation was assessed in the immortalized nontumorigenic human breast epithelial cell line, MCF10A, and an ex vivo organ culture model employing human breast tissue from reduction mammoplasty or tumor resections. Stimulation by estrogen and the GPER-selective agonist G-1 increased the mitotic index in MCF10A cells and proportion of cells in the cell cycle in human breast and breast cancer explants, suggesting increased proliferation. Inhibition of candidate signaling pathways that may link GPER activation to proliferation revealed a dependence on Src, epidermal growth factor receptor transactivation by heparin-bound EGF and subsequent ERK phosphorylation. Proliferation was not dependent on matrix metalloproteinase cleavage of membrane-bound pro-HB-EGF. The contribution of GPER to estrogen-induced proliferation in MCF10A cells and breast tissue was confirmed by the ability of GPER-selective antagonist G36 to abrogate estrogen- and G-1-induced proliferation, and the ability of siRNA knockdown of GPER to reduce estrogen- and G-1-induced proliferation in MCF10A cells. This is the first study to demonstrate GPER-dependent proliferation in primary normal and malignant human tissue, revealing a role for GPER in estrogen-induced breast physiology and pathology.

Macrophages: are they involved in endometriosis, abortion and preeclampsia and how?

Macrophages hold a key role in both regulating and executing the body's own immune response under various conditions. Hence, although endometriosis, preeclampsia and abortions are clinically different, all three are regarded to involve highly complex immunological processes. The aim of our current work was to evaluate the role of macrophages within these gynaecological disorders. Macrophages have been shown to invade endometriosis lesions and to mediate propagation of endometriotic cyst growth. However this is the first time that significant GPER up-regulation in macrophages is demonstrated. This highlights a potential alternative way through which estrogen may modulate immune response of macrophages in endometriosis. In addition, during spontaneous miscarriages the macrophage population increases significantly. This deregulation may possibly support an inflammatory scheme further triggering abortive procedures. Macrophage-mediated apoptosis of extravillous trophoblasts (EVT) has been associated with preeclampsia. Larger numbers of apoptotic EVT were detected in preeclamptic placentas compared with normal. In preeclamptic placentas, decidual macrophages were found to be Fas ligand (FasL)-positive. Our results highlight a new aspect of macrophage biology in endometriosis and pregnancy physiology and patho-physiology. Further studies with larger samples are needed to verify the current results and evaluate their clinical impact. Our data strongly indicate that macrophages hold key roles in various gynaecological disorders and might be crucial to further elucidate their patho-physiology.

Altered expression of ERs, aromatase, and COX2 connected to estrogen action in type 1 endometrial cancer biology

In order to study estrogen-driven microenvironment associated with type 1 endometrial carcinoma, we evaluated estrogen receptors (ERs), aromatase, and cyclooxygenase II (COX2) molecular and immunohistochemical profiles with correlation to clinicopathological features. We investigated aromatase, ERα, ERβ, and COX2 expression at the mRNA and protein levels using quantitative real-time PCR and immunohistochemical method in 51 endometrial carcinomas and 16 normal endometria. All the studied tumors, as well as normal endometria, expressed ERα, ERβ, and COX2 mRNAs. Five endometrial carcinoma tissues and one normal endometrium showed no aromatase mRNA expression. The majority of tumors expressed ERα (82%), aromatase (80%), and COX2 (88%) proteins. Forty-one percent of the studied tumors were ERβ-negative. ERα and ERβ showed significantly decreased mRNA and protein expression levels in endometrial carcinoma as compared to normal endometrium. An opposite trend was shown for COX2 and aromatase proteins. ERα expression correlated positively with COX2 expression at both mRNA and protein levels (P < 0.005, r = 0.398; P < 0.0005, r = 0.510, respectively). There was also a positive correlation between COX2 and aromatase expression in cancer tissue (P < 0.002, r = 0.433 for transcriptional level; P < 0.0005, r = 0.614 for protein level). We observed positive correlations between ERβ and ERα, as well as between ERβ and COX2 at the transcriptional level only (P < 0.0005, r = 0.644; P < 0.002, r = 0.444, respectively). Negative correlations were found between pT category of primary tumor and levels of ERα and ERβ transcripts (P < 0.02, r = -0.332; P < 0.02, r = -0.348, respectively). A negative association between ERβ and the International Federation of Gynecology and Obstetrics (FIGO) staging was also found. The growth of EC1 with the presence of ERα and overexpression of aromatase and COX2 is dependent on estrogens. We believe that ERβ may be considered as a potential marker in the progression of disease in endometrial cancer patients.

G protein-coupled estrogen receptor 1 expression in human vocal fold

OBJECTIVES/HYPOTHESIS

Besides the classical sexual receptors, the expression of a recently clarified transmembrane G protein-coupled receptor (GPR30) has not been reported in the vocal fold so far. We aimed to study whether GPR30 is expressed in the human vocal fold.

STUDY DESIGN

Experimental study using pathologic human vocal fold tissues.

METHODS

Reverse-transcription polymerase chain reaction and immunohistochemistry were used to detect the GPR30 expression in a total of 83 vocal fold samples.

RESULTS

A total of 66% of the specimens tested were GPR30 mRNA positive, and 54% of the sections were revealed to be GPR30 immunostaining positive in the plasma membrane as well as the nucleus in the epithelial cells.

CONCLUSIONS

The GPR30 expression both in mRNA and protein level could be detected in the human vocal fold.

The expression status of G protein-coupled receptor GPR30 is associated with the clinical characteristics of endometriosis

INTRODUCTION

GPR30 is a seven-transmembrane G protein-coupled estrogen receptor that regulates endometrial cellular responses to estrogen. GPR30 is often highly expressed in cancer cells from aggressive tumors. The aim of this study was to evaluate the expression patterns of GPR30 in endometriosis during medical treatment.

PATIENTS

A total of 38 females, 28 patients with endometriosis and 10 patients with leiomyoma who underwent laparoscopic surgery were included this study.

INTERVENTION

Eutopic endometrial tissue sampling from women without endometriosis and ectopic endometrial tissue sampling from women with endometriosis.

MAIN OUTCOME MEASURE

A quantitative real-time polymerase chain reaction analysis of the mRNA expression in eutopic and ectopic endometrial tissues with or without GnRH agonist treatment. The expression of GPR30 was confirmed by immunohistochemistry.

RESULTS

There was an increased level of GPR30 mRNA in eutopic endometrium during the proliferative phase, whereas higher expression was observed in the ectopic endometrium during the secretory phase. Increased GPR30 mRNA was observed in ectopic endometrium in comparison to eutopic endometrium. GnRH agonist treatment before laparoscopic surgery decreased GPR30 mRNA in ectopic endometrium. The immunohistochemical analysis also revealed that GPR30 was strongly expressed in epithelial cells in ectopic endometrium, whereas GnRH agonist treatment decreased the GPR30 expression.

CONCLUSION

High levels of GPR30 expression can play an important role in the progression of endometriosis.

Estrogen biosynthesis and signaling in endometriosis

Endometriosis is an estrogen-dependent gynecological disease where endometrium-like tissue grows outside uterine cavity. Endometriotic cell proliferation is stimulated by estrogens acting predominantly via their nuclear receptors. Estrogen receptors (ESR1, ESR2) are ligand activated transcription factors whose activation is dependent on the cell-specific dynamic expression of the receptors, on the interacting proteins and on the ligand availability. The different types of endometriotic lesions, peritoneal, deep, and ovarian endometriosis, may respond to estrogens differentially due to differences in the expression of the receptors and interacting proteins, and due to potential differences in the ligand availability regulated by the local estrogen synthesis. This review summarizes the current knowledge of estrogen synthesizing enzymes and estrogen receptors in different types of endometriosis lesions. Further studies are still needed to define the possible differences in steroid metabolism in different types of endometriotic lesions.

G protein-coupled estrogen receptor (GPER) expression in normal and abnormal endometrium

Rapid estrogen effects are mediated by membrane receptors, and evidence suggests a role for both a membrane-associated form of estrogen receptor alpha (ESR1; ERα) and G-protein coupled receptor 30 (GPER; GPR30). Considering estrogen's importance in endometrial physiology and endometriosis pathophysiology, we hypothesized that GPER could be involved in both cyclic changes in endometrial estrogen action and that aberrant expression might be seen in the eutopic endometrium of women with endometriosis. Using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemical analysis of normal endometrium, endometrial samples demonstrated cycle-regulated expression of GPER, with maximal expression in the proliferative phase. Eutopic and ectopic endometrium from women with endometriosis overexpressed GPER as compared to eutopic endometrium of normal participants. Ishikawa cells, an adenocarcinoma cell line, expressed GPER, with increased expression upon treatment with estrogen or an ESR1 agonist, but not with a GPER-specific agonist. Decreased expression was seen in Ishikawa cells stably transfected with progesterone receptor A. Together, these data suggest that normal endometrial GPER expression is cyclic and regulated by nuclear estrogen and progesterone receptors, while expression is dysregulated in endometriosis.

Expression of the G protein-coupled estrogen receptor (GPER) in endometriosis: a tissue microarray study

BACKGROUND

The G protein-coupled estrogen receptor (GPER) is thought to be involved in non-genomic estrogen responses as well as processes such as cell proliferation and migration. In this study, we analyzed GPER expression patterns from endometriosis samples and normal endometrial tissue samples and compared these expression profiles to those of the classical sex hormone receptors.

METHODS

A tissue microarray, which included 74 samples from different types of endometriosis (27 ovarian, 19 peritoneal and 28 deep-infiltrating) and 30 samples from normal endometrial tissue, was used to compare the expression levels of the GPER, estrogen receptor (ER)-alpha, ER-beta and progesterone receptor (PR). The immunoreactive score (IRS) was calculated separately for epithelium and stroma as the product of the staining intensity and the percentage of positive cells. The expression levels of the hormonal receptors were dichotomized into low (IRS < 6) and high (IRS > = 6) expression groups.

RESULTS

The mean epithelial IRS (+/- standard deviation, range) of cytoplasmic GPER expression was 1.2 (+/- 1.7, 0-4) in normal endometrium and 5.1 (+/- 3.5, 0-12) in endometriosis (p < 0.001), of nuclear GPER 6.4 (+/- 2.6, 0-12) and 6.8 (+/- 2.9, 2-12; p = 0.71), of ER-alpha 10.6 (+/- 2.4, 3-12) and 9.8 (+/- 3.0, 2-12; p = 0.26), of ER-beta 2.4 (+/- 2.2; 0-8) and 5.6 (+/- 2.6; 0-10; p < 0.001), and of PR 11.5 (+/- 1.7; 3-12) and 8.1 (+/- 4.5; 0-12; p < 0.001), respectively. The mean stromal IRS of nuclear GPER expression was 7.7 (+/- 3.0; 2-12) in endometrium and 10.8 (+/- 1.7; 6-12) in endometriosis (p < 0.001), of ER-alpha 8.7 (+/- 3.1; 2-12) and 10.6 (+/- 2.4; 2-12; p = 0.001), of ER-beta 1.8 (+/- 2.0; 0-8) and 5.4 (+/- 2.5; 0-10; p < 0.001), and of PR 11.7 (+/- 0.9; 8-12) and 10.9 (+/- 2.0; 3-12; p = 0.044), respectively. Cytoplasmic GPER expression was not detectable in the stroma of endometrium and endometriosis. The observed frequency of high epithelial cytoplasmic GPER expression levels was 50% (n = 30/60) in the endometriosis and none (0/30) in the normal endometrium samples (p < 0.001). High epithelial cytoplasmic GPER expression levels were more frequent in endometriomas (14/20, 70%; p = 0.01), as compared to peritoneal (9/18, 50%) or deep-infiltrating endometriotic lesions (7/22, 31.8%). The frequency of high stromal nuclear GPER expression levels was 100% (n = 74/74) in endometriosis and 76.7% (n = 23/30) in normal endometrium (p < 0.001). The frequency of high epithelial nuclear GPER expression levels did not differ between endometriosis and normal endometrium.

CONCLUSIONS

The present data indicate a unique GPER expression pattern in endometriosis, especially in endometriomas as compared to the normal endometrium. The overexpression of GPER in endometriotic lesions suggests a potential role for GPER in the hormonal regulation of endometriosis, which should be taken into consideration for future hormonal treatment strategies.

The G protein-coupled estrogen receptor 1 (GPER/GPR30) does not predict survival in patients with ovarian cancer

Background

Even though ovarian tumors are not generally considered estrogen-sensitive, estrogens may still have an impact on ovarian tumor progression. The recently identified trans-membrane estrogen receptor GPER is involved in rapid estrogen signaling. Furthermore, it binds selective estrogen receptor modulators with agonistic effect, which could explain tamoxifen controversies.

Methods

GPER mRNA was assayed with quantitative real-time PCR (qPCR) in 42 primary ovarian tumors and 7 ovarian cancer cell lines. ERα and ERβ mRNA were analyzed for comparison. GPER protein was semi-quantified with densitometric scanning of Western blots and its tissue distribution analyzed with immunohistochemistry (IHC) in 40 ovarian tumors. In addition, IHC was evaluated in a tissue microarray (TMA) of 150 primary malignant ovarian tumors.

Results

All tumor samples contained GPER mRNA. The content of mRNA was not different between benign and malignant tumors, but one third of malignant samples over-expressed GPER mRNA. The content of ERα mRNA was higher in malignant than in benign tumors, whereas ERβ mRNA was higher in benign than in malignant tumors. GPER mRNA was detected in all seven ovarian cancer cell lines with highest levels in TOV21G and TOV112D cells. Similar expression pattern was seen for ERβ mRNA. Western blot demonstrated GPER protein in all tumor samples. Semi-quantification showed no difference between benign and malignant tumors, but about one third of malignant samples over-expressed GPER protein. GPER staining was localized mainly in epithelial cells. In the TMA study we found no correlation between GPER staining and clinical stage, histological grade or patient survival.

Conclusions

GPER mRNA as well as GPER protein is present in both benign and malignant ovarian tumor tissue. About one third of malignant tumors over-expressed both GPER mRNA and protein. This, however, correlated neither with histological or clinical parameters nor with patient survival.

Estrogen receptor (ER) expression and function in the pregnant human myometrium: estradiol via ERα activates ERK1/2 signaling in term myometrium

Estrogens are thought to promote labor by increasing the expression of pro-contraction genes in myometrial cells. The specific estrogen receptors ((ERs: ERα and ERβ (also known as ESR1 and ESR2)) and G protein-coupled receptor 30 (GPR30; also known as G protein-coupled estrogen receptor 1)) and signaling pathways that mediate these actions are not clearly understood. In this study, we identified the ERs expressed in the pregnant human myometrium and determined a key extranuclear signaling pathway through which estradiol (E(2)) modulates expression of the gene encoding the oxytocin receptor (OXTR), a major pro-contraction protein. Using quantitative RT-PCR, we found that ERα and GPR30 mRNAs were expressed in the human pregnant myometrium while ERβ mRNA was virtually undetectable. While mRNA encoding ERα was the predominant ER transcript in the pregnant myometrium, ERα protein was largely undetectable in myometrial tissue by immunoblotting. Pharmacological inhibition of 26S proteasome activity increased ERα protein abundance to detectable levels in term myometrial explants, however, indicating rapid turnover of ERα protein by proteasomal processing in the pregnant myometrium. E(2) stimulated rapid extranuclear signaling in myometrial explants, as evidenced by increased extracellularly regulated kinase (ERK1/2) phosphorylation within 10 min. This effect was inhibited by pre-treatment with an ER antagonist, ICI 182 780, indicating the involvement of ERα. Inhibition of ERK signaling abrogated the ability of E(2) to stimulate OXTR gene expression in myometrial explants. We conclude that estrogenic actions in the human myometrium during pregnancy, including the stimulation of contraction-associated gene expression, can be mediated by extranuclear signaling through ERα via activation of the ERK/mitogen-activated protein kinase pathway.

Sex-hormone receptors pattern on regulatory T-cells: clinical implications for multiple sclerosis

Cellular mechanisms underlying sexual dimorphism in the immune response remain largely unknown. Concerning the interactions among the nervous, endocrine and immune systems, we reported that during gestation, a period during which multiple sclerosis (MS) clearly ameliorates, there is a physiological expansion of regulatory T-lymphocytes (T(Reg)). Given that alterations in T(Reg) proportions and suppressive function are involved in MS pathophysiology, we investigated the in vitro effect of sex hormones on T(Reg). Here, we show that both E2 and progesterone (P2) enhance T(Reg) function in vitro, although only E2 further induces a T(Reg) phenotype in activated responder T-cells (CD4(+)CD25(-)) (P < 0.01). E2 receptor beta (ERβ) percentages and mean fluorescence intensity (MFI) on T(Reg) were lower in MS patients than in controls (P < 0.05), in parallel with lower E2 plasma levels (P < 0.05). Importantly, percentages and MFI of ERβ were higher in T(Reg) than in T-responder cells (P < 0.0001) both in MS patients and controls. We show a unique differential pattern of higher ER and PR levels in T(Reg), which may be relevant for the in vivo responsiveness of these cells to sex hormones and hence to MS physiopathology.

Unraveling the mechanisms underlying the rapid vascular effects of steroids: sorting out the receptors and the pathways

Aldosterone, oestrogens and other vasoactive steroids are important physiological and pathophysiological regulators of cardiovascular and metabolic function. The traditional view of the cardiovascular actions of these vasoactive steroids has focused on their roles as regulators of transcription via activation of their 'classical' receptors [mineralocorticoid receptors (MR) and oestrogen receptors (ER)]. However, based on a series of observations going back more than half a century, scientists have speculated that a range of steroids, including oestrogen and aldosterone, might have effects on regulation of smooth muscle contractility, cell growth and differentiation that are too rapid to be accounted for by transcriptional regulation. Recent studies performed in our laboratories (and those of others) have begun to elucidate the mechanism of rapid steroid-mediated cardiometabolic regulation. GPR30, now designated as GPER-1 (http://www.iuphar-db.org/DATABASE/FamilyIntroductionForward?familyId=22), a newly characterized 'orphan receptor', has been implicated in mediating the rapid effects of estradiol and most recently those of aldosterone. Studies to date have taught us that to understand the rapid vascular mechanisms of steroids, one must (i) know which vascular 'compartment' the steroid is acting; (ii) know which receptor the steroid hormone is activating; and (iii) not assume the receptor specificity of a steroid receptor ligand based solely on its selectivity for its traditional 'transcriptional' steroid receptor. Our newfound appreciation of the rapid effects of steroids such as aldosterone and oestrogens opens up a new vista for advancing our understanding of the biology and pathobiology of vascular regulation.

Delineating the receptor mechanisms underlying the rapid vascular contractile effects of aldosterone and estradiol

It is increasingly appreciated that steroid hormones such as aldosterone and estradiol can mediate important cardiovascular effects. Many of these effects occur over a time course not consistent with the genomic actions of these hormones acting through classical nuclear receptors / transcription factors. Further, multiple receptors have been implicated in mediating these rapid effects of both aldosterone and estradiol, including a newly appreciated G-protein-coupled receptor, GPR30. In previous studies we demonstrated that both aldosterone and estradiol mediate contraction in vascular smooth muscle cells, as assessed in single cell assays. However, the receptor mechanisms underlying these effects remained unclear. Therefore, we studied the actions of estradiol and aldosterone on rat aortic vascular smooth muscle cells. Both aldosterone and estradiol mediated a concentration-dependent increase in contraction, as assessed in substrate deformation assays with EC50s in the range of nanomoles per litre. These effects paralleled increased myosin light chain phosphorylation. The effects of aldosterone were inhibited by the mineralocorticoid selective antagonist eplerenone. Further, aldosterone’s contractile effects were enhanced by increased expression of the mineralocorticoid receptor. The contractile effects of estradiol were inhibited by estrogen receptor (ER)-selective antagonists, tamoxifen, and ICI 182780, as well as eplerenone. Further, estradiol’s effects were enhanced by the increased expression of both ERα and the mineralocorticoid receptor (MR). To assess the potential role of GPR30 in mediating the effects of aldosterone and estradiol, GPR30 was re-introduced, since these cells lose endogenous GPR30 expression in culture. Re-expression of GPR30 enhanced both estradiol- and aldosterone-mediated contraction. These studies demonstrate that in rat aortic vascular smooth muscle cells, both aldosterone and estradiol mediate vascular smooth muscle contraction and that these effects can be mediated by MR, ERα, and by GPR30.

G-1-activated membrane estrogen receptors mediate increased contractility of the human myometrium

Estrogens are key mediators of increased uterine contractility at labor. We sought to determine whether membrane-associated estrogen receptors, such as the recently described seven-transmembrane receptor G protein-coupled receptor 30 (GPR30), mediated some of this effect. Using human myometrium obtained at term cesarean section before or after the onset of labor, we demonstrated the presence of GPR30 mRNA and protein using quantitative RT-PCR and Western blotting. GPR30 receptor was localized to the cell membrane and often colocalized with calveolin-1. Using the specific estrogen membrane receptor agonist G-1 and myometrial explants, we showed that membrane receptor activation led to phosphorylation of MAPK and the actin-modifying small heat shock protein 27. Using myometrial strips incubated with G-1 or vehicle we demonstrated that estrogen membrane receptor activation increased the myometrial contractile response to oxytocin. These data suggest that activation of the plasma membrane estrogen receptor GPR30 likely participates in the physiology of the human myometrium during pregnancy and identifies it as a potential target to modify uterine activity.

GPR30 activation opposes estrogen-dependent uterine growth via inhibition of stromal ERK1/2 and estrogen receptor alpha (ERα) phosphorylation signals

Although estradiol-17β (E2)-regulated early and late phase uterine responses have been well defined, the molecular mechanisms linking the phases remain poorly understood. We have previously shown that E2-regulated early signals mediate cross talk with estrogen receptor (ER)-α to elicit uterine late growth responses. G protein-coupled receptor (GPR30) has been implicated in early nongenomic signaling mediated by E2, although its role in E2-dependent uterine biology is unclear. Using selective activation of GPR30 by G-1, we show here a new function of GPR30 in regulating early signaling events, including the inhibition of ERK1/2 and ERα (Ser118) phosphorylation signals and perturbation of growth regulation under the direction of E2 in the mouse uterus. We observed that GPR30 primarily localizes in the uterine epithelial cells, and its activation alters gene expression and mediates inhibition of ERK1/2 and ERα (Ser118) phosphorylation signals in the stromal compartment, suggesting a paracrine signaling is involved. Importantly, viral-driven manipulation of GPR30 or pharmacological inhibition of ERK1/2 activation effectively alters E2-dependent uterine growth responses. Overall, GPR30 is a negative regulator of ERα-dependent uterine growth in response to E2. Our work has uncovered a novel GPR30-regulated inhibitory event, which may be physiologically relevant in both normal and pathological situations to negatively balance ERα-dependent uterine growth regulatory functions induced by E2.

G protein-coupled estrogen receptor 1/G protein-coupled receptor 30 localizes in the plasma membrane and traffics intracellularly on cytokeratin intermediate filaments

G protein-coupled receptor 30 [G protein-coupled estrogen receptor 1 (GPER1)], has been introduced as a membrane estrogen receptor and a candidate cancer biomarker and therapeutic target. However, several questions surround the subcellular localization and signaling of this receptor. In native cells, including mouse myoblast C(2)C(12) cells, Madin-Darby canine kidney epithelial cells, and human ductal breast epithelial tumor T47-D cells, G-1, a GPER1 agonist, and 17β-estradiol stimulated GPER1-dependent cAMP production, a defined plasma membrane (PM) event, and recruitment of β-arrestin2 to the PM. Staining of fixed and live cells showed that GPER1 was localized both in the PM and on intracellular structures. One such intracellular structure was identified as cytokeratin (CK) intermediate filaments, including those composed of CK7 and CK8, but apparently not endoplasmic reticulum, Golgi, or microtubules. Reciprocal coimmunoprecipitation of GPER1 and CKs confirmed an association of these proteins. Live staining also showed that the PM receptors constitutively internalize apparently to reach CK filaments. Receptor localization was supported using FLAG- and hemagglutinin-tagged GPER1. We conclude that GPER1-mediated stimulation of cAMP production and β-arrestin2 recruitment occur in the PM. Furthermore, the PM receptors constitutively internalize and localize intracellularly on CK. This is the first observation that a G protein-coupled receptor is capable of associating with intermediate filaments, which may be important for GPER1 regulation in epithelial cells and the relationship of this receptor to cancer.