Genetic variants of GPER/GPR30, a novel estrogen-related G protein receptor, are associated with human seminoma

Advances in immune regulation of the G protein-coupled estrogen receptor

Estrogen and related receptors have been shown to have a significant impact on human development, reproduction, metabolism and immune regulation and to play a critical role in tumor development and treatment. Traditionally, the nuclear estrogen receptors (nERs) ERα and ERβ have been thought to be involved in mediating the estrogenic effects. However, our group and others have previously demonstrated that the G protein-coupled estrogen receptor (GPER) is the third independent ER, and estrogen signaling mediated by GPER is known to play an important role in normal physiology and a variety of abnormal diseases. Interestingly, recent studies have progressively revealed GPER involvement in the maintenance of the normal immune system, abnormal immune diseases, and inflammatory lesions, which may be of significant clinical value primarily in the immunotherapy of tumors. In this article, we review current advances in GPER-related immunomodulators and provide a theoretical basis and potential clinical targets to ameliorate immune-related diseases and immunotherapy for tumors.

Activation of estrogen receptor induces differential proteomic responses mainly involving migration, invasion, and tumor development pathways in human testicular embryonal carcinoma NT2/D1 cells

The aims of the present study were to investigate the global changes on proteome of human testicular embryonal carcinoma NT2/D1 cells treated with 17β-estradiol (E2), and the effects of this hormone on migration, invasion, and colony formation of these cells. A quantitative proteomic analysis identified the presence of 1230 proteins in both E2-treated and control cells. The analysis revealed 75 differentially abundant proteins (DAPs), out of which 43 proteins displayed a higher abundance and, 30 proteins showed a lower abundance in E2-treated NT2/D1 cancer cells. Functional analysis using IPA highlighted some activation processes such as migration, invasion, metastasis, and tumor growth. Interestingly, the treatment with E2 and ERβ-selective agonist DPN increased the migration of NT2/D1 cells. On the other hand, ERα-selective agonist PPT did not modify cell migration, indicating that ERβ is the upstream receptor involved in this process. The activation of ERβ increased the invasion and anchorage‑independent growth of NT2/D1 cells more intensely than ERα. ERα and ERβ may play overlapping roles on invasion and colony formation of these cells. Further studies are required to clarify the mechanism underlying these effects. The molecular mechanisms revealed by proteomic and functional studies might also guide the development of potential targets for a better understanding of the biology of these cells and novel treatments for non-seminoma in the future.

Utility of G protein-coupled oestrogen receptor 1 as a biomarker for pan-cancer diagnosis, prognosis and immune infiltration: a comprehensive bioinformatics analysis

BACKGROUND

The G protein-coupled oestrogen receptor (GPER) 1 mediates non-genomic oestrogen-related signalling and plays an important role in the regulation of cell growth and programmed cell death through multiple downstream pathways. Despite the increasing interest in the role of GPER1 in cancer development, no pan-cancer analysis has been available for GPER1.

METHODS

In this study we performed a comprehensive analysis of the role of GPER1 in pan-cancer via Human Protein Atlas (HPA), The Cancer Genome Atlas (TCGA), University of California, Santa Cruz Xena (UCSC XENA), Genotype-Tissue Expression (GTEx), MethSurv, The University of Alabama at Birmingham CANcer data analysis Portal (UALCAN), cBioPortal, STRING and TISIDB detabases, followed by enrichment analysis using R software.

RESULTS

GPER1 was widely expressed in tissues and organs and differed in expression from normal tissue in a variety of cancers. In diagnostic assessment, it's Area Under the Curve (AUC) surpassed 0.9 in nine cancer types. Survival analysis showed that GPER1 was correlated with the prognosis of 11 cancer types. Moreover, GPER1 expression was associated with immune infiltration in multiple cancers.

CONCLUSIONS

In summary, GPER1 has good diagnostic or prognostic value across various malignancies. Together with its extensive correlation with immune components, the aforementioned results suggests that GPER1 shows promise in tumour diagnosis and prognosis, providing new ideas for precise and personalised anti-tumour strategies.

Estrogen Receptor Genes, Cognitive Decline, and Alzheimer Disease

BACKGROUND AND OBJECTIVES

Lifetime risk of Alzheimer disease (AD) dementia is twofold higher in women compared with men, and low estrogen levels in postmenopause have been suggested as a possible contributor. We examined 3 ER (GPER1, ER2, and ER1) variants in association with AD traits as an indirect method to test the association between estrogen and AD in women. Although the study focus was on women, in a comparison, we separately examined ER molecular variants in men.

METHODS

Participants were followed for an average of 10 years in one of the 2 longitudinal clinical pathologic studies of aging. Global cognition was assessed using a composite score derived from 19 neuropsychological tests' scores. Postmortem pathologic assessment included examination of 3 AD (amyloid-β and tau tangles determined by immunohistochemistry, and a global AD pathology score derived from diffuse and neurotic plaques and neurofibrillary tangle count) and 8 non-AD pathology indices. ER molecular genomic variants included genotyping and examining ER DNA methylation and RNA expression in brain regions including the dorsolateral prefrontal cortex (DLPFC) that are major players in cognition and often have AD pathology.

RESULTS

The mean age of women (N = 1711) at baseline was 78.0 (SD = 7.7) years. In women, GPER1 molecular variants had the most consistent associations with AD traits. GPER1 DNA methylation was associated with cognitive decline, tau tangle density, and global AD pathology score. GPER1 RNA expression in DLPFC was related to cognitive decline and tau tangle density. Other associations included associations of ER2 and ER1 sequence variants and DNA methylation with cognition. RNA expressions in DLPFC of genes involved in signaling mechanisms of activated ERs were also associated with cognitive decline and tau tangle density in women. In men (N = 651, average age at baseline: 77.4 [SD = 7.3]), there were less robust associations between ER molecular genomic variants and AD cognitive and pathologic traits. No consistent association was seen between ER molecular genomic variations and non-AD pathologies in either of the sexes.

DISCUSSION

ER DNA methylation and RNA expression, and to some extent ER polymorphisms, were associated with AD cognitive and pathologic traits in women, and to a lesser extent in men.

The long non-coding RNA transcript, LOC100130460 (CAND1.11) gene, encodes a novel protein highly expressed in cancer cells and tumor human testis tissues

BACKGROUND

Testis-specific genes encoding for long non-coding RNA (lncRNA) have been detected in several cancers; many produce proteins with restricted or aberrant expression patterns in normal or cancer tissues.

OBJECTIVE

To characterize new lncRNA involved in normal and/or pathological differentiation of testicular cells.

METHODS

Using bioinformatics analysis, we found that lncRNA LOC100130460 (CAND1.11) is expressed in normal and tumor testis; its expression was assessed in several human cell lines by qRT-PCR. CAND1.11 protein, produced by a single nucleotide mutation, was studied by western blot and immunofluorescence analysis on normal, classic seminoma, and Leydig cell tumor testicular tissues.

RESULTS

CAND1.11 gene is primate-specific; its expression was low in SH-SY5Y cells and increased when differentiated with retinoic acid treatment. CAND1.11 expression in PC3 cells was higher than in PNT2 cells. CAND1.11 protein is present in the human testis and overexpressed in testicular cancer tissues.

CONCLUSIONS

This report is one of the few providing evidence that a lncRNA produces a protein expressed in normal human tissues and overexpressed in several testicular cancers, suggesting its involvement in regulating cell proliferation and differentiation. Although further studies are needed to validate the results, our data indicate that CAND1.11 could be a potential new prognostic biomarker to use in proliferation and cancer.

Membrane estrogen receptor and follicle-stimulating hormone receptor

Follicle-stimulating hormone (FSH) and estrogens are fundamental to support reproductive functions. Beside the well-known FSH membrane receptor (FSHR), a G protein-coupled estrogen receptor (GPER) has been found, over the last two decades, in several tissues. It may trigger rapid, non-genomic responses of estradiol, activating proliferative and survival stimuli. The two receptors were co-characterized in the ovary, where they modulate different intracellular signaling cascades, according to the expression level and developmental stage of ovarian follicles. Moreover, they may physically interact to form heteromeric assemblies, suggestive of a new mode of action to regulate FSH-specific signals, and likely determining the follicular fate between atresia and dominance. The knowledge of FSH and estrogen membrane receptors provides a new, deeper level of comprehension of human reproduction.

Comparative G-Protein-Coupled Estrogen Receptor (GPER) Systems in Diabetic and Cancer Conditions: A Review

For many patients, diabetes Mellitus and Malignancy are frequently encountered comorbidities. Diabetes affects approximately 10.5% of the global population, while malignancy accounts for 29.4 million cases each year. These troubling statistics indicate that current treatment approaches for these diseases are insufficient. Alternative therapeutic strategies that consider unique signaling pathways in diabetic and malignancy patients could provide improved therapeutic outcomes. The G-protein-coupled estrogen receptor (GPER) is receiving attention for its role in disease pathogenesis and treatment outcomes. This review aims to critically examine GPER' s comparative role in diabetes mellitus and malignancy, identify research gaps that need to be filled, and highlight GPER's potential as a therapeutic target for diabetes and malignancy management. There is a scarcity of data on GPER expression patterns in diabetic models; however, for diabetes mellitus, altered expression of transport and signaling proteins has been linked to GPER signaling. In contrast, GPER expression in various malignancy types appears to be complex and debatable at the moment. Current data show inconclusive patterns of GPER expression in various malignancies, with some indicating upregulation and others demonstrating downregulation. Further research should be conducted to investigate GPER expression patterns and their relationship with signaling pathways in diabetes mellitus and various malignancies. We conclude that GPER has therapeutic potential for chronic diseases such as diabetes mellitus and malignancy.

First Evidence of the Expression and Localization of Prothymosin α in Human Testis and Its Involvement in Testicular Cancers

Prothymosin α (PTMA) is a phylogenetically conserved polypeptide in male gonads of Vertebrates. In Mammals, it is a ubiquitous protein, and, possessing a random-coil structure, it interacts with many other partners, in both cytoplasmic and nuclear compartments. PTMA has been widely studied during cell progression in different types of cancer because of its anti-apoptotic and proliferative properties. Here, we provided the first evidence of PTMA expression and localization in human testis and in two testicular cancers (TC): classic seminoma (CS) and Leydig cell tumor (LCT). Data showed that its protein level, together with that of proliferating cell nuclear antigen (PCNA), a cell cycle progression marker, increased in both CS and LCT samples, as compared to non-pathological (NP) tissue. Moreover, in the two-cancer tissue, a decreased apoptotic rate and an increased autophagic flux was also evidenced. Results confirmed the anti-apoptotic action of PTMA, also suggesting that it can act as a switcher from apoptosis to autophagy, to favor the survival of testicular cancer cells when they develop in adverse environments. Finally, the combined data, even if they need to be further validated, add new insight into the role of PTMA in human normal and pathological testicular tissue.

Activation of estrogen receptor ESR1 and ESR2 induces proliferation of the human testicular embryonal carcinoma NT2/D1 cells

The aims of the present study were to investigate the expression of the classic estrogen receptors ESR1 and ESR2, the splicing variant ESR1-36 and GPER in human testicular embryonal carcinoma NT2/D1 cells, and the effects of the activation of the ESR1 and ESR2 on cell proliferation. Immunostaining of ESR1, ESR2, and GPER were predominantly found in the nuclei, and less abundant in the cytoplasm. ESR1-36 isoform was predominantly expressed in the perinuclear region and cytoplasm, and some weakly immunostained in the nuclei. In nonstimulated NT2/D1 cells (control), proteins of the cell cycle CCND1, CCND2, CCNE1 and CDKN1B are present. Activation of ESR1 and ESR2 increases, respectively, CCND2 and CCNE1 expression, but not CCND1. Activation of ESR2 also mediates upregulation of the cell cycle inhibitor CDKN1B. This protein co-immunoprecipitated with CCND2. Also, E2 induces an increase in the number and viability of the NT2/D1 cells. These effects are blocked by simultaneous pretreatment with ESR1-and ESR2-selective antagonists, confirming that both estrogen receptors regulate NT2/D1 cell proliferation. In addition, E2 increases SRC phosphorylation, and SRC mediates cell proliferation. Our study provides novel insights into the signatures and molecular mechanisms of estrogen receptor in NT2/D1 cells.

G protein-coupled estrogen receptor activation by bisphenol-A disrupts the protection from apoptosis conferred by the estrogen receptors ERα and ERβ in pancreatic beta cells

17β-estradiol protects pancreatic β-cells from apoptosis via the estrogen receptors ERα, ERβ and GPER. Conversely, the endocrine disruptor bisphenol-A (BPA), which exerts multiple effects in this cell type via the same estrogen receptors, increased basal apoptosis. The molecular-initiated events that trigger these opposite actions have yet to be identified. We demonstrated that combined genetic downregulation and pharmacological blockade of each estrogen receptor increased apoptosis to a different extent. The increase in apoptosis induced by BPA was diminished by the pharmacological blockade or the genetic silencing of GPER, and it was partially reproduced by the GPER agonist G1. BPA and G1-induced apoptosis were abolished upon pharmacological inhibition, silencing of ERα and ERβ, or in dispersed islet cells from ERβ knockout (BERKO) mice. However, the ERα and ERβ agonists PPT and DPN, respectively, had no effect on beta cell viability. To exert their biological actions, ERα and ERβ form homodimers and heterodimers. Molecular dynamics simulations together with proximity ligand assays and coimmunoprecipitation experiments indicated that the interaction of BPA with ERα and ERβ as well as GPER activation by G1 decreased ERαβ heterodimers. We propose that ERαβ heterodimers play an antiapoptotic role in beta cells and that BPA- and G1-induced decreases in ERαβ heterodimers lead to beta cell apoptosis. Unveiling how different estrogenic chemicals affect the crosstalk among estrogen receptors should help to identify diabetogenic endocrine disruptors.

Estrogen Receptors-Mediated Apoptosis in Hormone-Dependent Cancers

It is known that estrogen stimulates growth and inhibits apoptosis through estrogen receptor(ER)-mediated mechanisms in many cancer cell types. Interestingly, there is strong evidence that estrogens can also induce apoptosis, activating different ER isoforms in cancer cells. It has been observed that E2/ERα complex activates multiple pathways involved in both cell cycle progression and apoptotic cascade prevention, while E2/ERβ complex in many cases directs the cells to apoptosis. However, the exact mechanism of estrogen-induced tumor regression is not completely known. Nevertheless, ERs expression levels of specific splice variants and their cellular localization differentially affect outcome of estrogen-dependent tumors. The goal of this review is to provide a general overview of current knowledge on ERs-mediated apoptosis that occurs in main hormone dependent-cancers. Understanding the molecular mechanisms underlying the induction of ER-mediated cell death will be useful for the development of specific ligands capable of triggering apoptosis to counteract estrogen-dependent tumor growth.

Association between GPER gene polymorphisms and GPER expression levels with cancer predisposition and progression

Estrogen is a female sex steroid hormone that plays a significant role in physiological functions. Evidence suggests that estrogen-signaling pathways are closely linked to cancer development and progression. The novel G protein-coupled estrogen receptor (GPER or GPR30) has been shown to influence cancer predisposition and progression, although results of related studies remain equivocal. Thus, this meta-analysis aimed to estimate the relationship between GPER gene polymorphisms and GPER expression levels, with cancer predisposition and progression. The pooled results showed that two GPER polymorphisms, rs3808350 and rs3808351, were significantly associated with cancer predisposition, especially in the Asian population, but no significant association was detected for rs11544331. In parallel, we also found that cancer aggressiveness and progression correlated with rs3808351 and GPER expression in cancerous tissues. Altogether, our findings suggest that GPER plays a pivotal role in cancer pathogenesis and progression. We suggest that rs3808350 and rs3808351 may be used as a prospective biomarker for cancer screening; while rs3808351 and GPER expression can be used to examine the prognosis of patients with cancer. Further biological studies are warranted to confirm our findings.

Estrogen Receptors: Therapeutic Perspectives for the Treatment of Cardiac Dysfunction after Myocardial Infarction

Estrogen receptors (ER) mediate functions beyond their endocrine roles, as modulation of cardiovascular, renal, and immune systems through anti-inflammatory and anti-apoptotic effects, preventing necrosis of cardiomyocytes and endothelial cells, and attenuating cardiac hypertrophy. Estradiol (E2) prevents cardiac dysfunction, increases nitric oxide synthesis, and reduces the proliferation of vascular cells, yielding protective effects, regardless of gender. Such actions are mediated by ER (ER-alpha (ERα), ER-beta (ERβ), or G protein-coupled ER (GPER)) through genomic or non-genomic pathways, which regulate cardiovascular function and prevent tissue remodeling. Despite the extensive knowledge on the cardioprotective effects of estrogen, clinical studies conducted on myocardial infarction (MI) and cardiovascular diseases still include favorable and unfavorable profiles. The purpose of this review is to provide up-to-date information regarding molecular, preclinical, and clinical aspects of cardiovascular E2 effects and ER modulation as a potential therapeutic target for the treatment of MI-induced cardiac dysfunction.

Mutations in G Protein-Coupled Receptors: Mechanisms, Pathophysiology and Potential Therapeutic Approaches

There are approximately 800 annotated G protein-coupled receptor (GPCR) genes, making these membrane receptors members of the most abundant gene family in the human genome. Besides being involved in manifold physiologic functions and serving as important pharmacotherapeutic targets, mutations in 55 GPCR genes cause about 66 inherited monogenic diseases in humans. Alterations of nine GPCR genes are causatively involved in inherited digenic diseases. In addition to classic gain- and loss-of-function variants, other aspects, such as biased signaling, trans-signaling, ectopic expression, allele variants of GPCRs, pseudogenes, gene fusion, and gene dosage, contribute to the repertoire of GPCR dysfunctions. However, the spectrum of alterations and GPCR involvement is probably much larger because an additional 91 GPCR genes contain homozygous or hemizygous loss-of-function mutations in human individuals with currently unidentified phenotypes. This review highlights the complexity of genomic alteration of GPCR genes as well as their functional consequences and discusses derived therapeutic approaches. SIGNIFICANCE STATEMENT: With the advent of new transgenic and sequencing technologies, the number of monogenic diseases related to G protein-coupled receptor (GPCR) mutants has significantly increased, and our understanding of the functional impact of certain kinds of mutations has substantially improved. Besides the classical gain- and loss-of-function alterations, additional aspects, such as biased signaling, trans-signaling, ectopic expression, allele variants of GPCRs, uniparental disomy, pseudogenes, gene fusion, and gene dosage, need to be elaborated in light of GPCR dysfunctions and possible therapeutic strategies.

Role of GPER-Mediated Signaling in Testicular Functions and Tumorigenesis

Estrogen signaling plays important roles in testicular functions and tumorigenesis. Fifteen years ago, it was discovered that a member of the G protein-coupled receptor family, GPR30, which binds also with high affinity to estradiol and is responsible, in part, for the rapid non-genomic actions of estrogens. GPR30, renamed as GPER, was detected in several tissues including germ cells (spermatogonia, spermatocytes, spermatids) and somatic cells (Sertoli and Leydig cells). In our previous review published in 2014, we summarized studies that evidenced a role of GPER signaling in mediating estrogen action during spermatogenesis and testis development. In addition, we evidenced that GPER seems to be involved in modulating estrogen-dependent testicular cancer cell growth; however, the effects on cell survival and proliferation depend on specific cell type. In this review, we update the knowledge obtained in the last years on GPER roles in regulating physiological functions of testicular cells and its involvement in neoplastic transformation of both germ and somatic cells. In particular, we will focus our attention on crosstalk among GPER signaling, classical estrogen receptors and other nuclear receptors involved in testis physiology regulation.

GPER and Testicular Germ Cell Cancer

The G protein-coupled estrogen receptor (GPER), also known as GPR30, is a widely conserved 7-transmembrane-domain protein which has been identified as a novel 17β-estradiol-binding protein that is structurally distinct from the classic oestrogen receptors (ERα and ERβ). There are still conflicting data regarding the exact role and the natural ligand of GPER/GPR30 in reproductive tracts as both male and female knock-out mice are fertile and have no abnormalities of reproductive organs. Testicular germ cell cancers (TGCCs) are the most common malignancy in young males and the most frequent cause of death from solid tumors in this age group. Clinical and experimental studies suggested that estrogens participate in the physiological and pathological control of male germ cell proliferation. In human seminoma cell line, while 17β-estradiol (E2) inhibits in vitro cell proliferation through an ERβ-dependent mechanism, an impermeable E2 conjugate (E2 coupled to BSA), in vitro cell proliferation is stimulated by activating ERK1/2 and protein kinase A through a membrane GPCR that we further identified as GPER/GPR30. The same effect was observed with low but environmentally relevant doses of BPA, an estrogenic endocrine disrupting compound. Furthermore, GPER/GPR30 is specifically overexpressed in seminomas but not in non-seminomas and this overexpression is correlated with an ERβ-downregulation. This GPER/GPR30 overexpression could be linked to some genetic variations, as single nucleotide polymorphisms, which was also reported in other hormone-dependent cancers. We will review here the implication of GPER/GPR30 in TGCCs pathophysiology and the arguments to consider GPER/GPR30 as a potential therapeutic target in humans.

Is Testicular Germ Cell Cancer Estrogen Dependent? The Role of Endocrine Disrupting Chemicals

Testicular germ cell cancer (TGCC) is the most frequent cancer of the young male, with an increasing incidence worldwide. The pathogenesis and reasons for this increase remain unknown. However, epidemiological and experimental data have suggested that, similar to genital malformations and sperm impairment, it could result from the interaction of genetic and environmental factors including fetal exposure to endocrine-disrupting chemicals (EDCs) with estrogenic effects. In this review, we analyze the expression of classic and nonclassic estrogen receptors by TGCC cells, the way they may influence germ cell proliferation induced by EDCs, and discuss how this estrogen dependency supports the developmental and environmental hypothesis.

Transmembrane G protein-coupled receptor 30 gene polymorphisms and uterine adenomyosis in Korean women

To compare the genetic distributions of 14G protein-coupled receptor 30 (GPR30) single-nucleotide polymorphisms (SNPs) between women with and without uterine adenomyosis. The study population comprised 69 Korean women. Uterine tissues from the adenomyosis and non-adenomyosis groups were used for DNA extraction. Pre-designed PCR/Sanger or Sequencing Primer and TaqMan^® SNP Genotyping Assays were used for the SNP genotyping of the GPR30 gene. Immunohistochemical staining was performed to confirm the GPR30 expression. Differences in genotype and allele frequencies between the two groups were calculated using Fisher's exact test. The rs3802141 CT genotype was more common in the control group (p = .02), and the rs4266553 CC genotype was more common in the adenomyosis group (p = .02). The C allele of the SNP rs4266553 was more common in the adenomyosis group (p = .02). GPR30 expression was confirmed in 69 individuals in both groups. GPR30 gene polymorphism is presumed to affect the risk of adenomyosis with limited sample size. Further large-scale study is needed to explain the genetic influence of GPR30 gene polymorphism.

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.

The G protein-coupled estrogen receptor as a modulator of neoplastic transformation

Estrogens play a crucial role in the regulation of physiological and pathophysiological processes. These hormones act through specific receptors, most notably the canonical estrogen receptors α and β (ERα and ERβ) and their truncated forms as well as the G protein-coupled estrogen receptor (GPER). Several studies have shown that GPER is expressed in many normal and cancer cells, including those of the breast, endometrium, ovary, testis and lung. Hormonal imbalance is one possible cause of cancer development. An accumulating body of evidence indicates that GPER is involved in the regulation of cancer cell proliferation, migration and invasion, it may act as a mediator of microRNA, and is believed to modulate the inflammation associated with neoplastic transformation. Furthermore, used in various treatment regimens anti-estrogens such as tamoxifen, raloxifen and fulvestrant (ICI 182.780), antagonists/modulators of canonical estrogen receptors, were found to be GPER agonists. This review presents the current knowledge about the potential role of GPER in neoplastic transformation.

Not lost in translation: Emerging clinical importance of the G protein-coupled estrogen receptor GPER

It has been 20years that the G protein-coupled estrogen receptor (GPER) was cloned as the orphan receptor GPR30 from multiple cellular sources, including vascular endothelial cells. Here, I will provide an overview of estrogen biology and the historical background leading to the discovery of rapid vascular estrogen signaling. I will also review the recent advances in the understanding of the mechanisms underlying GPER function, its role in physiology and disease, some of the currently available GPER-targeting drugs approved for clinical use such as SERMs (selective estrogen receptor modulators) and SERDs (selective estrogen receptor downregulators). Many of currently used drugs such as tamoxifen, raloxifene, or faslodex™/fulvestrant were discovered targeting GPER many years after they had been introduced to the clinics for entirely different purposes. This has important implications for the clinical use of these drugs and their modes of action, which I have termed 'reverse translational medicine'. In addition, environmental pollutants known as 'endocrine disruptors' have been found to bind to GPER. This article also discusses recent evidence in these areas as well as opportunities in translational clinical medicine and GPER research, including medical genetics, personalized medicine, prevention, and its theranostic use.

G-protein-coupled estrogen receptor-30 gene polymorphisms are associated with uterine leiomyoma risk

The G-protein-coupled estrogen receptor (GPR30, GPER-1) is a member of the G-protein-coupled receptor 1 family and is expressed significantly in uterine leiomyomas. To understand the relationship between GPR30 single nucleotide polymorphisms and the risk of leiomyoma, we measured the follicle-stimulating hormone (FSH) and estradiol (E2) levels of 78 perimenopausal healthy women and 111 perimenopausal women with leiomyomas. The participants' leiomyoma number and volume were recorded. DNA was extracted from whole blood with a GeneJET Genomic DNA Purification Kit. An amplification-refractory mutation system polymerase chain reaction approach was used for genotyping of the GPR30 gene (rs3808350, rs3808351, and rs11544331). The differences in genotype and allele frequencies between the leiomyoma and control groups were calculated using the chi-square (χ2) and Fischer's exact test. The median FSH level was higher in controls (63 vs. 10 IU/L, p=0.000), whereas the median E2 level was higher in the leiomyoma group (84 vs. 9.1 pg/mL, p=0.000). The G allele of rs3808351 and the GG genotype of both the rs3808350 and rs3808351 polymorphisms and the GGC haplotype increased the risk of developing leiomyoma. There was no significant difference in genotype frequencies or leiomyoma volume. However, the GG genotype of the GPR30 rs3808351 polymorphism and G allele of the GPR30 rs3808351 polymorphism were associated with the risk of having a single leiomyoma. Our results suggest that the presence of the GG genotype of the GPR30 rs3808351 polymorphism and the G allele of the GPR30 rs3808351 polymorphism affect the characteristics and development of leiomyomas in the Turkish population.

International Union of Basic and Clinical Pharmacology. XCVII. G Protein-Coupled Estrogen Receptor and Its Pharmacologic Modulators

Estrogens are critical mediators of multiple and diverse physiologic effects throughout the body in both sexes, including the reproductive, cardiovascular, endocrine, nervous, and immune systems. As such, alterations in estrogen function play important roles in many diseases and pathophysiological conditions (including cancer), exemplified by the lower prevalence of many diseases in premenopausal women. Estrogens mediate their effects through multiple cellular receptors, including the nuclear receptor family (ERα and ERβ) and the G protein-coupled receptor (GPCR) family (GPR30/G protein-coupled estrogen receptor [GPER]). Although both receptor families can initiate rapid cell signaling and transcriptional regulation, the nuclear receptors are traditionally associated with regulating gene expression, whereas GPCRs are recognized as mediating rapid cellular signaling. Estrogen-activated pathways are not only the target of multiple therapeutic agents (e.g., tamoxifen, fulvestrant, raloxifene, and aromatase inhibitors) but are also affected by a plethora of phyto- and xeno-estrogens (e.g., genistein, coumestrol, bisphenol A, dichlorodiphenyltrichloroethane). Because of the existence of multiple estrogen receptors with overlapping ligand specificities, expression patterns, and signaling pathways, the roles of the individual receptors with respect to the diverse array of endogenous and exogenous ligands have been challenging to ascertain. The identification of GPER-selective ligands however has led to a much greater understanding of the roles of this receptor in normal physiology and disease as well as its interactions with the classic estrogen receptors ERα and ERβ and their signaling pathways. In this review, we describe the history and characterization of GPER over the past 15 years focusing on the pharmacology of steroidal and nonsteroidal compounds that have been employed to unravel the biology of this most recently recognized estrogen receptor.

The G-protein-coupled estrogen receptor (GPER/GPR30) in ovarian granulosa cell tumors

Ovarian granulosa cell tumors (GCTs) are thought to arise from cells of the ovarian follicle and comprise a rare entity of ovarian masses. We recently identified the G-protein-coupled estrogen receptor (GPER/GPR30) to be present in granulosa cells, to be regulated by gonadotropins in epithelial ovarian cancer and to be differentially expressed throughout folliculogenesis. Thus, supposing a possible role of GPER in GCTs, this study aimed to analyze GPER in GCTs. GPER immunoreactivity in GCTs (n = 26; n (primary diagnosis) = 15, n (recurrence) = 11) was studied and correlated with the main clinicopathological variables. Positive GPER staining was identified in 53.8% (14/26) of GCTs and there was no significant relation of GPER with tumor size or lymph node status. Those cases presenting with strong GPER intensity at primary diagnosis showed a significant reduced overall survival (p = 0.002). Due to the fact that GPER is regulated by estrogens, as well as gonadotropins, GPER may also be affected by endocrine therapies applied to GCT patients. Moreover, with our data supposing GPER to be associated with GCT prognosis, GPER might be considered as a possible confounder when assessing the efficacy of hormone-based therapeutic approaches in GCTs.

Estrogen biology: new insights into GPER function and clinical opportunities

Estrogens play an important role in the regulation of normal physiology, aging and many disease states. Although the nuclear estrogen receptors have classically been described to function as ligand-activated transcription factors mediating genomic effects in hormonally regulated tissues, more recent studies reveal that estrogens also mediate rapid signaling events traditionally associated with G protein-coupled receptors. The G protein-coupled estrogen receptor GPER (formerly GPR30) has now become recognized as a major mediator of estrogen's rapid cellular effects throughout the body. With the discovery of selective synthetic ligands for GPER, both agonists and antagonists, as well as the use of GPER knockout mice, significant advances have been made in our understanding of GPER function at the cellular, tissue and organismal levels. In many instances, the protective/beneficial effects of estrogen are mimicked by selective GPER agonism and are absent or reduced in GPER knockout mice, suggesting an essential or at least parallel role for GPER in the actions of estrogen. In this review, we will discuss recent advances and our current understanding of the role of GPER and the activity of clinically used drugs, such as SERMs and SERDs, in physiology and disease. We will also highlight novel opportunities for clinical development towards GPER-targeted therapeutics, for molecular imaging, as well as for theranostic approaches and personalized medicine.