Search Results (21)

Parkinson’s disease (PD) is characterized by degeneration of nigrostriatal dopaminergic neurons (DNs) and movement disorders. Low efficiency of pharmacotherapy requires improvement, e.g., using receptor agonists or antagonists as drugs. Our work aims to initiate these developments by studying the expression levels of genes encoding neurotransmitters, neuropeptides and hormone receptors in substantia nigra pars compacta (SNpc) cells and in isolated DNs in intact mice, and changes in expression of these genes in MPTP mouse models of PD at preclinical and clinical stages. Expression of all 12 studied genes was detected in the SNpc and only 10 in DNs—Cckar and Glp1r were undetectable. In intact mice, the expression of Drd2, Grin2b, Grm1 and Ntsr2 predominates in SNpc tissue, whereas that of Gria2, Chrnb2, Gper1, Igf1r is higher in DNs. In PD models, change in receptor gene expression was detected in DNs but not in SNpc tissue. In the preclinical PD, Drd2 expression increased and Gria2 decreased, whereas in a clinical model, Drd2, Grm1, Ntsr2 expression decreased. Thus, the above genes are expressed in DNs and other cells of SNpc; expression of some genes changes in PD models, which opens up prospects for development of therapy using receptor agonists and antagonists. Full article

Cutaneous melanoma (CM) is the most aggressive and fatal malignancy among other skin cancers and its incidence has risen steadily recently around the world. Hormone-related therapy, particularly estrogen (E2) has been used as a prospective strategy for CM treatment. Quercetin and luteolin are flavonoids with antitumor effects against a wide range of cancers including CM. However, the underlying mechanism of their actions through GPER in CM is not fully understood. We examined the anti-tumor effects of quercetin and luteolin on the A375 CM cell line through activation of the G-protein coupled estrogen receptor (GPER). MTT assay was performed to assess the impact of flavonoids on cell viability. Apoptosis and cell cycle were studied by flow cytometry. Cell migration was evaluated by transwell assay. GPER expression and the effect of the flavonoids on the key signaling proteins were confirmed by immunofluorescence staining and Western blot, respectively. Results showed that quercetin and luteolin inhibited proliferation and migration, induced apoptosis, and blocked the cell cycle at S and G2/M in A375 cells. Immunofluorescence and immunoblotting data demonstrated the presence of GPER in this cell line and the two flavonoids enhanced its expression except at the high concentration of 100 µM. Quercetin and luteolin enhanced P-ERK and c-Myc expression, an effect abolished by the GPER antagonist G15, confirming GPER-mediated signaling. In conclusion, quercetin and luteolin exhibited anti-tumor effects on A375 melanoma cells via GPER activation, suggesting their potential as anti-melanoma therapeutics. Full article

Estrogen is a steroid hormone that plays a key role in regulating many physiological processes, such as follicle activation and development and oocyte maturation in mammals. Ca²⁺ is crucial in oogenesis, oocyte maturation, ovulation, and fertilization. However, the mechanism by which estrogen regulates Ca²⁺ during oocyte maturation in mice has not been reported. This study revealed that Ca²⁺ levels in oocytes significantly increase during the 4–12 h period in vitro. Oocytes treated with 0.1 µM estrogen and 1 µM G1, a G-protein-coupled estrogen receptor (GPER) agonist, showed significantly increased Ca²⁺ levels, while treatment with 1 µM G15, an antagonist of GPER, significantly decreased Ca²⁺ levels. Notably, estrogen regulates Ca²⁺ in oocytes through the GPER pathway and promotes the expression of the Ca²⁺-producing protein EPAC1. In addition, estrogen alleviates the inhibitory effect of the Ca²⁺ chelator BAPTA-AM during oocyte maturation by promoting Ca²⁺ production. Furthermore, estrogen can promote the expression of the mitochondrial generation-associated protein SIRT1 through the GPER pathway, alleviate mitochondrial oxidative damage caused by BAPTA-AM, and restore the mitochondrial membrane potential level. Collectively, this study demonstrates that estrogen can regulate Ca²⁺ through the GPER-EPAC1 pathway and promote the expression of SIRT1, which promotes oocyte mitochondrial function during oocyte maturation. Full article

The prevalence of obesity-induced asthma increases in women after menopause. We hypothesized that the increase in obese asthma in middle-aged women results from estrogen loss. In particular, we focused on the acute action of estrogen through the G protein-coupled estrogen receptor 1 (GPER), previously known as GPR30. We investigated whether GPER activation ameliorates obesity-induced asthma with a high-fat diet (HFD) using G-1, the GPER agonist, and G-36, the GPER antagonist. Administration of G-1 (0.5 mg/kg) suppressed HFD-induced airway hypersensitivity (AHR), and increased immune cell infiltration, whereas G-36 co-treatment blocked it. Histological analysis showed that G-1 treatment inhibited HFD-induced inflammation, fibrosis, and mucus hypersecretion in a GPER-dependent manner. G-1 inhibited the HFD-induced rise in the mRNA levels of pro-inflammatory cytokines in the gonadal white adipose tissue and lungs, whereas G-36 co-treatment reversed this effect. G-1 increased anti-inflammatory M2 macrophages and inhibited the HFD-induced rise in pro-inflammatory M1 macrophages in the lungs. In addition, G-1 treatment reversed the HFD-induced increase in leptin expression and decrease in adiponectin expression in the lungs and gonadal white adipose tissue. The results suggest that activation of GPER could be a therapeutic option for obesity-induced asthma. Full article

Tamoxifen, a selective estrogen receptor modulator (SERM), exhibits dual agonist or antagonist effects contingent upon its binding to either G-protein-coupled estrogen receptor (GPER) or estrogen nuclear receptor (ESR). Estrogen signaling plays a pivotal role in initiating epigenetic alterations and regulating estrogen-responsive genes in breast cancer. Employing three distinct breast cancer cell lines—MCF-7 (ESR+; GPER+), MDA-MB-231 (ESR−; GPER−), and SkBr3 (ESR−; GPER+)—this study subjected them to treatment with two tamoxifen derivatives: 4-hydroxytamoxifen (4-HT) and endoxifen (Endox). Through 2D high-performance liquid chromatography with tandem mass spectrometry detection (HPLC-MS/MS), varying levels of 5-methylcytosine (5-mC) were found, with MCF-7 displaying the highest levels. Furthermore, TET3 mRNA expression levels varied among the cell lines, with MCF-7 exhibiting the lowest expression. Notably, treatment with 4-HT induced significant changes in TET3 expression across all cell lines, with the most pronounced increase seen in MCF-7 and the least in MDA-MB-231. These findings underscore the influence of tamoxifen derivatives on DNA methylation patterns, particularly through modulating TET3 expression, which appears to be contingent on the presence of estrogen receptors. This study highlights the potential of targeting epigenetic modifications for personalized anti-cancer therapy, offering a novel avenue to improve treatment outcomes. Full article

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. Full article

Esophageal carcinoma is a male-dominant malignancy worldwide, and esophageal adenocarcinoma (EAC) shows more significant sex bias than esophageal squamous cell carcinoma (ESCC) in morbidity and mortality. The G protein-coupled estrogen receptor 1 (GPER1) is involved in several sex-related cancers; however, its expression level in esophageal carcinoma has been poorly investigated and its role is not precisely defined, depending on histological types. In the present study, the mRNA levels of GPER1 in esophageal carcinoma were collected from GEPIA and Oncomine databases for meta-analyses. The protein expression levels of GPER1 were detected by immunohistochemistry in the tissue microarray of EAC and ESCC. The GPER1 selective agonist G1, antagonist G15, and siRNA were applied in vitro to investigate their impacts on esophageal cell lines. Analysis of the RNA levels from the databases showed a decreased expression of GPER1 in overall esophageal carcinoma, and low expression levels of GPER1 were found to be associated with low survival of tumor patients. However, in the subgroup of EAC and its precancerous lesion, Barrett’s esophagus, overexpression of GPER1 RNA was increased when compared with the normal tissues. The average staining scores of GPER1 protein in the tissue microarray of EAC were significantly higher than normal esophageal samples, and the rate of positive staining increased with the grade of poor tumor differentiation. The scores of GPER1 protein in ESCC tissues were lower than those in the normal tissues. The results from cell line experiments in vitro showed that the GPER1 agonist G1 inhibited proliferation and promoted apoptosis of ESCC cells EC109 with positive expression of GPER1. G1 had no obvious effect on normal esophageal NE2 cells with weak expression of GPER1. In addition, GPER1 RNA knockdown and application of antagonist G15 reversed the effects of G1 on EC109. The results of this study indicate that the expression levels of GPER1 are higher in EAC than in ESCC, which might be correlated with the dimorphic estrogen signaling pathway in different types of esophageal carcinoma. Full article

Whether G protein-coupled estrogen receptor 1 (GPER1) is tumor-promoting or tumor-suppressive depends in part on tumor entity. Little is known about the function of GPER1 in vulvar carcinoma. In this work, we aim to clarify what role GPER1 plays in vulvar cancer, tumor-promoting or tumor-suppressive. Localization of GPER1 in A431 and CAL-39 vulvar carcinoma cells was examined by immunofluorescence. Using a tissue microarray of vulvar neoplasias, the correlation between GPER1 expression and grade of malignancy was investigated. A431 and CAL-39 cells were treated either with GPER1 agonist G1 or antagonist G36. Proliferation was quantified by BrdU assay and viability examined using Resazurin assay. Morphological changes were analyzed by microscopy and measured using ImageJ. Cell migration was analyzed by gap closure assay. Clonogenic potential was tested by colony and sphere formation. Expression of estrogen receptors was examined by Western blot. GPER1 was found consistently expressed in vulvar neoplasia tissues. The immune-reactive score was found to be significantly higher in tissue samples of lymph node metastases and neoplasias with grade 3. In A431 and CAL-39 vulvar carcinoma cells, GPER1 expression was mainly found in the cytoplasm and nuclei. Treatment of A431 and CAL-39 cells with GPER1 agonist G1 resulted in a decrease in proliferation and migration. In addition, colony formation and tumor sphere formation were reduced. Furthermore, morphological signs of necrosis and reduction in cell viability after G1 treatment were observed. The GPER1 antagonist G36 did not have significant effects on vulvar carcinoma cells. Neither agonist G1 nor antagonist G36 treatment resulted in altered expression of estrogen receptors. Activation of GPER1 with GPER1 agonist G1 reduces the tumorigenic potential of the vulvar carcinoma cells. It can be deduced from this that GPER1 appears to have a tumor-suppressive effect in vulvar carcinoma. Full article

Global cerebral ischemia can elicit rapid innate neuroprotective mechanisms that protect against delayed neuronal death. Brain-derived 17β-estradiol (BDE2), an endogenous neuroprotectant, is synthesized from testosterone by the enzyme aromatase (Aro) and is upregulated by brain ischemia and inflammation. Our recent study revealed that G1, a specific G-protein-coupled estrogen receptor 1 (GPER) agonist, exerts anti-inflammatory and anti-apoptotic roles after global cerebral ischemia (GCI). Herein, we aimed to elucidate whether G1 modulates the early inflammatory process and the potential underlying mechanisms in the ovariectomized rat hippocampal CA1 region. G1 was found to markedly reduce pro-inflammatory (iNOS, MHCII, and CD68) and to enhance anti-inflammatory (CD206, Arginase 1, IL1RA, PPARγ, and BDNF) markers after 1 and 3 days of reperfusion after GCI. Intriguingly, the neuroprotection of G1 was blocked by the Aro inhibitor, letrozole. Conversely, the GPER antagonist, G36, inhibited Aro-BDE2 signaling and exacerbated neuronal damage. As a whole, this work demonstrates a novel anti-inflammatory role of GPER, involving a synergistic mediation with BDE2 during the early stage of GCI. Full article

S100A7 has received extensive attention in the prevention and treatment of mastitis across a broad spectrum, yet there is a little information about its mechanism, especially in the immunomodulatory effects of estrogen. In the present study, based on the milk bacteriological culture (BC) of 30 dairy goats, the concentration of both estrogen and S100A7 in the BC-positive samples was not significantly different than in the BC-negative samples; the estrogen abundance in subclinical and clinical mastitis samples also showed only a limited difference; compared with healthy samples, the S100A7 abundance in subclinical mastitis samples differed little, while it was significantly decreased in clinical mastitis samples. Moreover, the relationship between estrogen and S100A7 was positive, and the regression equation was y = 0.3206x + 23.459. The goat mammary epithelial cells (gMECs) were isolated and treated with 1, 10, 100 nM E2 and/or 5 μg/mL lipopolysaccharide (LPS), respectively, for 6 h. Compared with control samples, 5 μg/mL LPS, 10 nM E2 and 100 nM E2 markedly induced S100A7 expression and secretion. More than separated treatment, the cooperation of LPS and E2 also significantly increased S100A7 expression, rather than S100A7 secretion. The p-ERK was up-regulated markedly with 100 nM E2 treatment, while the expression of p-JNK, p-p38 and p-Akt had little effect. The G protein-coupled estrogen receptor 1(GPER1) agonist G1 markedly induced S100A7 expression and secretion in gMECs, and the estrogen nuclear receptor antagonist ICI and GPER1 antagonist G15 significantly repressed this process. In conclusion, E2 binds to nuclear and membrane receptors to regulate the expression and secretion of S100A7 via the ERK1/2-signaling pathway in gMECs. Full article

The G-protein-coupled receptor for estrogen (GPER1) is a transmembrane receptor involved in the progression and development of various neoplasms whose ligand is estradiol (E2). 17β-aminoestrogens (17β-AEs) compounds, analogs to E2, are possible candidates for use in hormone replacement therapy (HRT), but our knowledge of their pharmacological profile is limited. Thus, we explored the molecular recognition of GPER1 with different synthetic 17β-AEs: prolame, butolame, and pentolame. We compared the structure and ligand recognition sites previously reported for a specific agonist (G1), antagonists (G15 and G36), and the natural ligand (E2). Then, the biological effects of 17β-AEs were analyzed through cell viability and cell-cycle assays in two types of female cancer. In addition, the effect of 17β-AEs on the phosphorylation of the oncoprotein c-fos was evaluated, because this molecule is modulated by GPER1. Molecular docking analysis showed that 17β-AEs interacted with GPER1, suggesting that prolame joins GPER1 in a hydrophobic cavity, similarly to G1, G15, and E2. Prolame induced cell proliferation in breast (MCF-7) and cervical cancer (SIHA) cells; meanwhile, butolame and pentolame did not affect cell proliferation. Neither 17β-AEs nor E2 changed the activation of c-fos in MCF-7 cells. Meanwhile, in SIHA cells, E2 and 17β-AEs reduced c-fos phosphorylation. Thus, our data suggest that butolame and pentolame, but not prolame, could be used for HRT without presenting a potential risk of inducing breast- or cervical-cancer-cell proliferation. The novelty of this work lies in its study of compound analogs to E2 that may represent important therapeutic strategies for women in menopause, with non-significant effects on the cell viability of cancer cells. The research focused on the interactions of GPER1, a molecule recently associated with promoting and maintaining various neoplasms. Full article

The present study was designed to evaluate how estradiol alone or in combination with G protein-coupled estrogen receptor (GPER) agonists and GPER and peroxisome proliferator-activated receptor (PPAR) antagonists alter the expression of tumor growth factor β (TGF-β), cyclooxygenase-2 (COX-2), hypoxia inducible factor 1-alpha (HIF-1α), and vascular endothelial growth factor (VEGF) in mouse testis explants and MA-10 mouse tumor Leydig cells. In order to define the hormone-associated signaling pathway, the expression of MAPK and PI3K/Akt was also examined. Tissue explants and cells were treated with estradiol as well as GPER agonist (ICI 182,780), GPER antagonist (G-15), PPARα antagonist (GW6471), and PPARγ antagonist (T00709072) in various combinations. First, we showed that in testis explants GPER and PPARα expressions were activated by the GPER agonist and estradiol (either alone or in mixtures), whereas PPARγ expression was activated only by GPER agonist. Second, increased TGF-β expression and decreased COX-2 expression were found in all experimental groups of testicular explants and MA-10 cells, except for up-regulated COX-2 expression in estradiol-treated cells, compared to respective controls. Third, estradiol treatment led to elevated expression of HIF-1α and VEGF, while their lower levels versus control were noted in the remaining groups of explants. Finally, we demonstrated the up-regulation of MAPK and PI3Kp85/Akt expressions in estradiol-treated groups of both ex vivo and in vitro models, whereas estradiol in mixtures with compounds of agonistic or antagonistic properties either up-regulated or down-regulated signaling kinase expression levels. Our results suggest that a balanced estrogen level and its action together with proper GPER and PPAR signaling play a key role in the maintenance of testis homeostasis. Moreover, changes in TGF-β and COX-2 expressions (that disrupted estrogen pathway) as well as disturbed GPER-PPAR signaling observed after estradiol treatment may be involved in testicular tumorigenesis. Full article

Stroke is the third leading cause of mortality in women and it kills twice as many women as breast cancer. A key role in the pathophysiology of stroke plays the disruption of the blood–brain barrier (BBB) within the neurovascular unit. While estrogen induces vascular protective actions, its influence on stroke remains unclear. Moreover, experiments assessing its impact on endothelial cells to induce barrier integrity are non-conclusive. Since pericytes play an active role in regulating BBB integrity and function, we hypothesize that estradiol may influence BBB by regulating their activity. In this study using human brain vascular pericytes (HBVPs) we investigated the impact of estradiol on key pericyte functions known to influence BBB integrity. HBVPs expressed estrogen receptors (ER-α, ER-β and GPER) and treatment with estradiol (10 nM) inhibited basal cell migration but not proliferation. Since pericyte migration is a hallmark for BBB disruption following injury, infection and inflammation, we investigated the effects of estradiol on TNFα-induced PC migration. Importantly, estradiol prevented TNFα-induced pericyte migration and this effect was mimicked by PPT (ER-α agonist) and DPN (ER-β agonist), but not by G1 (GPR30 agonist). The modulatory effects of estradiol were abrogated by MPP and PHTPP, selective ER-α and ER-β antagonists, respectively, confirming the role of ER-α and ER-β in mediating the anti-migratory actions of estrogen. To delineate the intracellular mechanisms mediating the inhibitory actions of estradiol on PC migration, we investigated the role of AKT and MAPK activation. While estradiol consistently reduced the TNFα-induced MAPK and Akt phosphorylation, only the inhibition of MAPK, but not Akt, significantly abrogated the migratory actions of TNFα. In transendothelial electrical resistance measurements, estradiol induced barrier function (TEER) in human brain microvascular endothelial cells co-cultured with pericytes, but not in HBMECs cultured alone. Importantly, transcriptomics analysis of genes modulated by estradiol in pericytes showed downregulation of genes known to increase cell migration and upregulation of genes known to inhibit cell migration. Taken together, our findings provide the first evidence that estradiol modulates pericyte activity and thereby improves endothelial integrity. Full article

Autocrine/paracrine factors generated in response to 17β-estradiol (E2) within the fallopian tube (FT) facilitate fertilization and early embryo development for implantation. Since cyclic AMP (cAMP) plays a key role in reproduction, regulation of its synthesis by E2 may be of biological/pathophysiological relevance. Herein, we investigated whether cAMP production in FT cells (FTCs) is regulated by E2 and environmental estrogens (EE’s; xenoestrogens and phytoestrogens). Under basal conditions, low levels of extracellular cAMP were detectable in bovine FTCs (epithelial cells and fibroblasts; 1:1 ratio). Treatment of FTCs with forskolin (AC; adenylyl cyclase activator), isoproterenol (β-adrenoceptor agonist) and IBMX (phosphodiesterase (PDE) inhibitor) dramatically (>10 fold) increased cAMP; whereas LRE1 (sAC; soluble AC inhibitor) and 2’,5’-dideoxyadenosine (DDA; transmembrane AC (tmAC)) inhibitor decreased cAMP. Comparable changes in basal and stimulated intracellular cAMP were also observed. Ro-20-1724 (PDE-IV inhibitor), but not milrinone (PDE-III inhibitor) nor mmIBMX (PDE-I inhibitor), augmented forskolin-stimulated cAMP levels, suggesting that PDE-IV dominates in FTCs. E2 increased cAMP levels and CREB phosphorylation in FTCs, and these effects were mimicked by EE’s (genistein, 4-hydroxy-2’,4’,6’-trichlorobiphenyl, 4-hydroxy-2’,4’,6’-dichlorobiphenyl). Moreover, the effects of E2 and EE were blocked by the tmAC inhibitor DDA, but not by the ERα/β antagonist ICI182780. Moreover, BAPTA-AM (intracellular-Ca²⁺ chelator) abrogated the effects of E2, but not genistein, on cAMP suggesting differential involvement of Ca²⁺. Treatment with non-permeable E2-BSA induced cAMP levels and CREB-phosphorylation; moreover, the stimulatory effects of E2 and EEs on cAMP were blocked by G15, a G protein-coupled estrogen receptor (GPER) antagonist. E2 and IBMX induced cAMP formation was inhibited by LRE1 and DDA suggesting involvement of both tmAC and sAC. Our results provide the first evidence that in FTCs, E2 and EE’s stimulate cAMP synthesis via GPER. Exposure of the FT to EE’s and PDE inhibitors may result in abnormal non-cyclic induction of cAMP levels which may induce deleterious effects on reproduction. Full article

Histone H3 lysine 4 trimethylation (H3K4me3) is one of the most recognized epigenetic regulators of transcriptional activity representing, an epigenetic modification of Histone H3. Previous reports have suggested that the broad H3K4me3 domain can be considered as an epigenetic signature for tumor-suppressor genes in human cells. G-protein-coupled estrogen receptor (GPER), a new membrane-bound estrogen receptor, acts as an inhibitor on cell growth via epigenetic regulation in breast and ovarian cancer cells. This study was conducted to evaluate the relationship of GPER and H3K4me3 in ovarian cancer tissue samples as well as in two different cell lines (Caov3 and Caov4). Silencing of GPER by a specific siRNA and two selective regulators with agonistic (G1) and antagonistic (G15) activity were applied for consecutive in vitro studies to investigate their impacts on tumor cell growth and the changes in phosphorylated ERK1/2 (p-ERK1/2) and H3K4me3. We found a positive correlation between GPER and H3K4me3 expression in ovarian cancer patients. Patients overexpressing GPER as well as H3K4me3 had significantly improved overall survival. Increased H3K4me3 and p-ERK1/2 levels and attenuated cell proliferation and migration were observed in Caov3 and Caov4 cells via activation of GPER by G1. Conversely, antagonizing GPER activity by G15 resulted in opposite effects in the Caov4 cell line. In conclusion, interaction of GPER and H3K4me3 appears to be of prognostic significance for ovarian cancer patients. The results of the in vitro analyses confirm the biological rationale for their interplay and identify GPER agonists, such as G1, as a potential therapeutic approach for future investigations. Full article