Estrogen receptor-beta potency-selective ligands: structure-activity relationship studies of diarylpropionitriles and their acetylene and polar analogues

Antiproliferative Role of Natural and Semi-Synthetic Tocopherols on Colorectal Cancer Cells Overexpressing the Estrogen Receptor β

Estrogen receptor β (ERβ) is the most highly expressed subtype in the colon epithelium and mediates the protective effect of estrogen against the development of colon cancer. Indeed, the expression of this receptor is inversely related to colorectal cancer progression. Structurally estrogen-like compounds, including vitamin E components, affect cell growth by binding to ERs. In the present study, cell proliferation was measured by cell counting in a Bürker hemocytometer, and ERβ expression was measured by Real-Time qPCR and immunoenzymatic methods. The results obtained show that natural δ-tocopherol (δ-Toc) and two of its semi-synthetic derivatives, bis-δ-tocopheryl sulfide (δ-Toc)2S and bis-δ-tocopheryl disulfide (δ-Toc)2S2, play an antiproliferative role and upregulate ERβ expression, similar to 17-β-estradiol (17β-E2), in human colon adenocarcinoma HCT8 cells engineered to overexpress ERβ protein (HCT8-β8). These events are not present in HCT8-pSV2neo and in HCT8-β8 pretreated with ICI 182,780, suggesting that they are mediated by the binding of compounds to ERβ, as also boosted by an in silico assay. The antiproliferative effect is independent of the intracellular redox state and (δ-Toc)2S and (δ-Toc)2S2 reduce cell proliferation at concentrations lower than that of δ-Toc and all tested compounds are also able to upregulate ERβ expression. Taken together, the data indicate that, through the involvement of ERβ activity and expression, δ-Toc, (δ-Toc)2S, and (δ-Toc)2S2 may provide potential therapeutic support against colorectal cancer.

Signaling crosstalk of Galectin-3, β-catenin, and estrogen receptor in androgen-independent prostate cancer DU-145 cells

The aims of this study were to investigate the localization of non-phosphorylated β‑catenin and Galectin-3 (GAL-3), the regulation of the expression of both proteins by activation of estrogen receptors (ERs) and their role in tumorigenic characteristics of androgen-independent prostate cancer DU-145 cells. DU-145 cells were cultured in the absence (control), and presence of 17β-estradiol (E2). Cells were also untreated or pre-treated with the inhibitor of GAL‑3, VA03, or with a compound that disrupts the complex β-catenin-TCF/LEF transcription factor, PKF 118-310. Immunofluorescence assay for non-phosphorylated β-catenin and GAL-3, cell proliferation, wound healing and cell invasion assays were performed. 17β-estradiol (E2, 4 h) increased the expression of non-phosphorylated β-catenin and GAL-3. E2 also increased (2-fold) the co-localization of the fluorescence of non-phosphorylated β-catenin and GAL‑3 in the whole cells compared to the control. The up-regulation of non-phosphorylated β-catenin expression was blocked by VA03, suggesting that GAL-3 is upstream protein involved in this process. E2 (24 h) increased the cell number, migration, and invasion of the DU‑145 cells compared to control. Furthermore, PKF 118-310 completely blocked the proliferation, migration, and invasion of the DU-145 cells induced by activation of ERs. The activation of ERs increases the expression, co-localization and signaling of the GAL-3 and non-phosphorylated β-catenin in DU-145 cells. Non-phosphorylated β-catenin is downstream protein involved in proliferation, migration, and invasion of the DU‑145 cells.

Hypoxia drives estrogen receptor β-mediated cell growth via transcription activation in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is a highly malignant tumor with a poor prognosis. Hypoxia conditions affect multiple cellular processes promoting the adaptation and progression of cancer cells via the activation of hypoxia-inducible factors (HIF) and subsequent transcription activation of their target genes. Preliminary studies have suggested that estrogen receptor β (ERβ) might play a promoting role in the progression of NSCLC. However, the precise mechanisms, particularly its connection to HIF-1α-mediated modulation under hypoxia, remain unclear. Our findings demonstrated that the overexpression of ERβ, not ERα, increased cell proliferation and inhibition of apoptosis in NSCLC cells and xenografts. Tissue microarray staining revealed a strong correlation between the protein expression of HIF-1α and ERβ. HIF-1α induced ERβ gene transcription and protein expression in CoCl2-induced hypoxia, 1% O2 incubation, or HIF-1α overexpressing cells. ChIP identified HIF-1α binding to a hypoxia response element in the ESR2 promoter. The suppression of HIF-1α and ERβ both in vitro and in vivo effectively reduced the tumor growth, thus emphasizing the promising prospects of targeting HIF-1α and ERβ as a therapeutic approach for the treatment of NSCLC. KEY MESSAGES: ERβ, not ERα, increases cell proliferation and inhibition of apoptosis in NSCLC cells and xenografts. A strong correlation exists between the protein expression of HIF-1α and ERβ. HIF-1α induced ERβ gene transcription and protein expression in hypoxic cells via binding to HRE in the ESR2 promoter. The suppression of HIF-1α and ERβ both in vitro and in vivo effectively reduced the NSCLC tumor growth.

Diarylpropionitrile-stimulated ERβ nuclear accumulation promotes MyoD-induced muscle regeneration in mdx mice by interacting with FOXO3A

Duchenne muscular dystrophy (DMD) is an X-linked recessive progressive degenerative disease of skeletal muscle, characterized by intramuscular inflammation, muscle regeneration disorder and replacement of muscle with fibroadipose tissue. DMD is caused by the absence of normal dystrophy. Impaired self-renew ability and limited differentiation capacity of satellite cells are proved as main reasons for muscle regeneration failure. The deficiency of estrogen impedes the process of muscle regeneration. However, the role of estrogen receptor β (ERβ) in muscle regeneration is still unclear. This study aims to investigate the role and the pharmacological effect of ERβ activation on muscle regeneration in mdx mice. This study showed that mRNA levels of ERβ and myogenic-related genes both witnessed increasing trends in dystrophic context. Our results revealed that treatment with selective ERβ agonist (DPN, diarylpropionitrile) significantly increased myogenic differentiation 1 (MyoD-1) level and promoted muscle regeneration in mdx mice. Similarly, in mdx mice with muscle-specific estrogen receptor α (ERα) ablation, DPN treatment still promoted muscle regeneration. Moreover, we demonstrated that myoblasts differentiation was accompanied by raised nuclear accumulation of ERβ. DPN treatment augmented the nuclear accumulation of ERβ and, thus, contributed to myotubes formation. One important finding was that forkhead box O3A (FOXO3A), as a pivotal transcription factor in Myod-1 transcription, participated in the ERβ-promoted muscle regeneration. Overall, we offered an interesting explanation about the crucial role of ERβ during myogenesis.

Estrogen receptor beta signaling enhances extinction memory recall for heroin-conditioned cues in a sex- and region-specific manner

Return to use, or relapse, is a major challenge in the treatment of opioid use disorder (OUD). Relapse can be precipitated by several factors, including exposure to drug-conditioned cues. Identifying successful treatments to mitigate cue-induced relapse has been challenging, perhaps due to extinction memory recall (EMR) deficits. Previously, inhibition of estradiol (E2) signaling in the basolateral amygdala (BLA) impaired heroin-cue EMR. This effect was recapitulated by antagonism of BLA estrogen receptors (ER) in a sex-specific manner such that blocking ERα in males, but ERβ in females, impaired EMR. However, it is unclear whether increased E2 signaling, in the BLA or systemically, enhances heroin-cue EMR. We hypothesized that ERβ agonism would enhance heroin-cue EMR in a sex- and region-specific manner. To determine the capacity of E2 signaling to improve EMR, we pharmacologically manipulated ERβ across several translationally designed experiments. First, male and female rats acquired heroin or sucrose self-administration. Next, during a cued extinction session, we administered diarylpropionitrile (DPN, an ERβ agonist) and tested anxiety-like behavior on an open field. Subsequently, we assessed EMR in a cue-induced reinstatement test and, finally, measured ERβ expression in several brain regions. Across all experiments, females took more heroin and sucrose than males and had greater responses during heroin-cued extinction. Administration of DPN in the BLA enhanced EMR in females only, driven by ERβ's impacts on memory consolidation. Interestingly, however, systemic DPN administration improved EMR for heroin cues in both sexes across several different tests, but did not impact sucrose-cue EMR. Immunohistochemical analysis of ERβ expression across several different brain regions showed that females only had greater expression of ERβ in the basal nucleus of the BLA. Here, in several preclinical experiments, we demonstrated that ERβ agonism enhances heroin-cue EMR and has potential utility in combatting cue-induced relapse.

ERβ-activated LINC01018 promotes endometriosis development by regulating the CDC25C/CDK1/CyclinB1 pathway

Endometriosis refers to as an estrogen-dependent disease. Estrogen receptor β (ERβ), the main estrogen receptor subtype which is encoded by the estrogen receptor 2 (ESR2) gene, can mediate the action of estrogen in endometriosis. Although selective estrogen receptor modulators can target the ERβ, they are not specific due to the wide distribution of ERβ. Recently, long noncoding RNAs have been implicated in endometriosis. Therefore, we aim to explore and validate the downstream regulatory mechanism of ERβ, and to investigate the potential role of long intergenic noncoding RNA 1018 (LINC01018) as a nonhormonal treatment for endometriosis. Our study demonstrates that the expression levels of ESR2 and LINC01018 are increased in ectopic endometrial tissues and reveals a significant positive correlation between the ESR2 and LINC01018 expression. Mechanistically, ERβ directly binds to an estrogen response element located in the LINC01018 promoter region and activates LINC01018 transcription. Functionally, ERβ can regulate the CDC25C/CDK1/CyclinB1 pathway and promote ectopic endometrial stromal cell proliferation via LINC01018 in vitro. Consistent with these findings, the knockdown of LINC01018 inhibits endometriotic lesion proliferation in vivo. In summary, our study demonstrates that the ERβ/LINC01018/CDC25C/CDK1/CyclinB1 signaling axis regulates endometriosis progression.

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.

Evaluation of structural and thermodynamic insight of ERβ with DPN and derivatives through MMGBSA/MMPBSA methods

Estrogen receptors (ERs) are nuclear factors that exist as two subtypes: ERα and ERβ. Among the different selective ERβ agonist ligands, the widely used ERβ-selective agonist DPN (diarylpropionitrile) is highlighted. Recent experimental and thermodynamic information between R-DPN and S-DPN enantiomers with ERβ is important for evaluating further the ability of MD simulations combined with end-point methods to reproduce experimental binding affinity and generate structural insight not provided through crystallographic data. In this research, starting from crystallographic data and experimental binding affinities, we explored the structural and thermodynamic basis of the molecular recognition of ERβ with DPN and derivatives through triplicate MD simulations combined with end-point methods. Conformational analysis showed some regions with the highest mobility linked to ligand association that, at the time, impacted the total protein fluctuation. Binding free energy (ΔG) analysis revealed that the Molecular Mechanics Generalized-Born Surface Area (MMGBSA) approach was able to reproduce the experimental tendency with a strong correlation (R = 0.778), whereas per-residue decomposition analysis revealed that all the systems interacted strongly with eight residues (L298, E305, L339, M340, L343, F356, H475, and L476). The comparison between theoretical studies using the MMGBSA approach with experimental results provides new insights for drug designing of new DPN derivatives.

The steroid hormone ADIOL promotes learning by reducing neural kynurenic acid levels

Reductions in brain kynurenic acid levels, a neuroinhibitory metabolite, improve cognitive function in diverse organisms. Thus, modulation of kynurenic acid levels is thought to have therapeutic potential in a range of brain disorders. Here we report that the steroid 5-androstene 3β, 17β-diol (ADIOL) reduces kynurenic acid levels and promotes associative learning in Caenorhabditis elegans We identify the molecular mechanisms through which ADIOL links peripheral metabolic pathways to neural mechanisms of learning capacity. Moreover, we show that in aged animals, which normally experience rapid cognitive decline, ADIOL improves learning capacity. The molecular mechanisms that underlie the biosynthesis of ADIOL as well as those through which it promotes kynurenic acid reduction are conserved in mammals. Thus, rather than a minor intermediate in the production of sex steroids, ADIOL is an endogenous hormone that potently regulates learning capacity by causing reductions in neural kynurenic acid levels.

Estrogen dysregulation, intraocular pressure, and glaucoma risk

Characterized by optic nerve atrophy due to retinal ganglion cell (RGC) death, glaucoma is the leading cause of irreversible blindness worldwide. Of the major risk factors for glaucoma (age, ocular hypertension, and genetics), only elevated intraocular pressure (IOP) is modifiable, which is largely regulated by aqueous humor outflow through the trabecular meshwork. Glucocorticoids such as dexamethasone have long been known to elevate IOP and lead to glaucoma. However, several recent studies have reported that steroid hormone estrogen levels inversely correlate with glaucoma risk, and that variants in estrogen signaling genes have been associated with glaucoma. As a result, estrogen dysregulation may contribute to glaucoma pathogenesis, and estrogen signaling may protect against glaucoma. The mechanism for estrogen-related protection against glaucoma is not completely understood but likely involves both regulation of IOP homeostasis and neuroprotection of RGCs. Based upon its known activities, estrogen signaling may promote IOP homeostasis by affecting extracellular matrix turnover, focal adhesion assembly, actin stress fiber formation, mechanosensation, and nitric oxide production. In addition, estrogen receptors in the RGCs may mediate neuroprotective functions. As a result, the estrogen signaling pathway may offer a therapeutic target for both IOP control and neuroprotection. This review examines the evidence for a relationship between estrogen and IOP and explores the possible mechanisms by which estrogen maintains IOP homeostasis.

Cisplatin-activated ERβ/DCAF8 positive feedback loop induces chemoresistance in non-small cell lung cancer via PTEN/Akt axis

High levels of the estrogen receptor β (ERβ) predict poor prognosis following platinum-containing adjuvant chemotherapies in patients with non-small cell lung cancer (NSCLC). However, the precise role of ERβ remains elusive. In this study, we demonstrated that targeting ERβ could significantly increase the cytotoxicity of cisplatin both in vitro and in vivo. Mechanically, cisplatin directly binds to ERβ, which facilitates its homodimerization and nuclear translocation. ERβ activation transcriptionally represses the expression of DCAF8, an adaptor of CRL4 E3 ubiquitin ligase, which in turn attenuates the proteasomal degradation of ERβ, leading to ERβ accumulation; this positive feedback loop results in Akt activation and eventually cisplatin resistance in NSCLC through PTEN inhibition. Moreover, low expression of DCAF8 and high expression of ERβ are associated with treatment resistance in patients receiving cisplatin-containing adjuvant chemotherapy. The present results provide insights into the underlying mechanism of ERβ-induced cisplatin resistance and offer an alternative therapeutic strategy to improve the efficacy of platinum-based chemotherapy in patients with NSCLC.

The G protein-coupled oestrogen receptor GPER in health and disease: an update

Oestrogens and their receptors contribute broadly to physiology and diseases. In premenopausal women, endogenous oestrogens protect against cardiovascular, metabolic and neurological diseases and are involved in hormone-sensitive cancers such as breast cancer. Oestrogens and oestrogen mimetics mediate their effects via the cytosolic and nuclear receptors oestrogen receptor-α (ERα) and oestrogen receptor-β (ERβ) and membrane subpopulations as well as the 7-transmembrane G protein-coupled oestrogen receptor (GPER). GPER, which dates back more than 450 million years in evolution, mediates both rapid signalling and transcriptional regulation. Oestrogen mimetics (such as phytooestrogens and xenooestrogens including endocrine disruptors) and licensed drugs such as selective oestrogen receptor modulators (SERMs) and downregulators (SERDs) also modulate oestrogen receptor activity in both health and disease. Following up on our previous Review of 2011, we herein summarize the progress made in the field of GPER research over the past decade. We will review molecular, cellular and pharmacological aspects of GPER signalling and function, its contribution to physiology, health and disease, and the potential of GPER to serve as a therapeutic target and prognostic indicator of numerous diseases. We also discuss the first clinical trial evaluating a GPER-selective drug and the opportunity of repurposing licensed drugs for the targeting of GPER in clinical medicine.

Estrogenic flavonoids and their molecular mechanisms of action

Flavonoids are a major group of phytoestrogens associated with physiological effects, and ecological and social impacts. Although the estrogenic activity of flavonoids was reported by researchers in the fields of medical, environmental and food studies, their molecular mechanisms of action have not been comprehensively reviewed. The estrogenic activity of the respective classes of flavonoids, anthocyanidins/anthocyanins, 2-arylbenzofurans/3-arylcoumarins/α-methyldeoxybenzoins, aurones/chalcones/dihydrochalcones, coumaronochromones, coumestans, flavans/flavan-3-ols/flavan-4-ols, flavanones/dihydroflavonols, flavones/flavonols, homoisoflavonoids, isoflavans, isoflavanones, isoflavenes, isoflavones, neoflavonoids, oligoflavonoids, pterocarpans/pterocarpenes, and rotenone/rotenoids, was summarized through a comprehensive literature search, and their structure-activity relationship, biological activities, signaling pathways, and applications were discussed. Although the respective classes of flavonoids contained at least one chemical mimicking estrogen, the mechanisms varied, such as those with estrogenic, anti-estrogenic, non-estrogenic, and biphasic activities, and additional activities through crosstalk/bypassing, which exert biological activities through cell signaling pathways. Such mechanistic variations of estrogen action are not limited to flavonoids and are observed among other broad categories of chemicals, thus this group of chemicals can be termed as the "estrogenome". This review article focuses on the connection of estrogen action mainly between the outer and the inner environments, which represent variations of chemicals and biological activities/signaling pathways, respectively, and form the basis to understand their applications. The applications of chemicals will markedly progress due to emerging technologies, such as artificial intelligence for precision medicine, which is also true of the study of the estrogenome including estrogenic flavonoids.

Machine-Learning Classification for the Prediction of Catalytic Activity of Organic Photosensitizers in the Nickel(II)-Salt-Induced Synthesis of Phenols

Catalytic systems using a small amount of organic photosensitizer for the activation of an inorganic (on-demand ligand-free) nickel(II) salt represent a cost-effective method for cross-coupling reactions, while C(sp² )-O bond formation remains less developed. Herein, we report a strategy for the synthesis of phenols with a nickel(II) salt and an organic photosensitizer, which was identified via an investigation into the catalytic activity of 60 organic photosensitizers consisting of various electron donor and acceptor moieties. To examine the effect of multiple intractable parameters on the catalytic activity of photosensitizers, machine-learning (ML) models were developed, wherein we embedded descriptors representing their physical and structural properties, which were obtained from DFT calculations and RDKit, respectively. The study clarified that integrating both DFT- and RDKit-derived descriptors in ML models balances higher "precision" and "recall" across a wide range of search space relative to using only one of the two descriptor sets.

In vivo potentiation of muscle torque is enhanced in female mice through estradiol-estrogen receptor signaling

Estradiol affects several properties of skeletal muscle in females including strength. Here, we developed an approach to measure in vivo posttetanic twitch potentiation (PTP) of the anterior crural muscles of anesthetized mice and tested the hypothesis that 17β-estradiol (E2) enhances PTP through estrogen receptor (ER) signaling. Peak torques of potentiated twitches were ∼40%-60% greater than those of unpotentiated twitches and such PTP was greater in ovary-intact mice, or ovariectomized (Ovx) mice treated with E2, compared with Ovx mice (P ≤ 0.047). PTP did not differ between mice with and without ERα ablated in skeletal muscle fibers (P = 0.347). Treatment of ovary-intact and Ovx mice with ERβ antagonist and agonist (PHTPP and DPN, respectively) did not affect PTP (P ≥ 0.258). Treatment with G1, an agonist of the G protein-coupled estrogen receptor (GPER), significantly increased PTP in Ovx mice from 41 ± 10% to 66 ± 21% (means ± SD; P = 0.034). Collectively, these data indicate that E2 signals through GPER, and not ERα or ERβ, in skeletal muscles of female mice to augment an in vivo parameter of strength, namely, PTP.NEW & NOTEWORTHY A novel in vivo approach was developed to measure potentiation of skeletal muscle torque in female mice and highlight another parameter of strength that is impacted by estradiol. The enhancement of PTP by estradiol is mediated distinctively through the G-protein estrogen receptor, GPER.

Spinal dopaminergic D1-and D2-like receptors have a sex-dependent effect in an experimental model of fibromyalgia

There is evidence about the importance of sex in pain. The purpose of this study was to investigate the effect of sex in the antiallodynic activity of spinal dopamine D₁-and D₂-like receptors in a model of fibromyalgia-type pain in rats. Reserpine induced the same extent of tactile allodynia in female and male rats. Intrathecal injection of SCH- 23390 (3-30 nmol, D₁-like receptor antagonist), pramipexole (0.15-15 nmol) or quinpirole (1-10 nmol D₂-like receptor agonists) increased withdrawal threshold in reserpine-treated female rats. Those drugs induced a greater antiallodynic effect in female rats. Sex-difference was also observed in a nerve injury model. Ovariectomy abated the antiallodynic effect of SCH- 23390 (30 nmol) in reserpine-treated rats, while systemic reconstitution of 17β-estradiol levels or intrathecal injection estrogen receptor-α agonist protopanaxatriol in ovariectomized reserpine-treated females restored the antiallodynic effect of SCH- 23390. Intrathecal administration of ICI-182,780 (estrogen receptor-α/β antagonist) or methyl-piperidino-pyrazole hydrate (estrogen receptor-α antagonist) abated 17β-estradiol-restored antiallodynic effect of SCH- 23390 in rats. In contrast, ovariectomy slightly reduced the effect of pramipexole (15 nmol) or quinpirole (10 nmol) in reserpine-treated rats, whereas systemic reconstitution of 17β-estradiol levels did not modify the antiallodynic effect of both drugs. Combination 17β-estradiol/progesterone, but not 17β-estradiol nor progesterone alone, restored the antiallodynic effect of pramipexole and quinpirole in the rats. Mifepristone (progesterone receptor antagonist) abated 17β-estradiol + progesterone restoration of antiallodynic effect of pramipexole and quinpirole. These data suggest that the antiallodynic effect of dopamine D₁-and D₂-like receptors in fibromyalgia-type pain depends on spinal 17β-estradiol/estrogen receptor-α and progesterone receptors, respectively.

Repeated exposure to 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) accelerates ligand-independent activation of estrogen receptors in long-term estradiol-deprived MCF-7 cells

It was previously identified that there may be an active metabolite of bisphenol A (BPA), 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP). An in vitro system was developed to detect MBP toxicity to the Michigan Cancer Foundation-7 (MCF-7) cells that had been repeatedly exposed to a low dose of the metabolite. MBP profoundly activated estrogen receptor (ER)-dependent transcription as a ligand, with an EC₅₀ of 2.8 nM. Women are continuously exposed to numerous estrogenic environmental chemicals; but their susceptibility to these chemicals may be significantly altered after menopause. Long-term estrogen-deprived (LTED) cells, which display ligand-independent ER activation, are a postmenopausal breast cancer model derived from MCF-7 cells. In this study, we investigated the estrogenic effects of MBP on LTED cells in a repeated exposure in vitro model. The results suggest that i) nanomolar levels of MBP reciprocally disrupt the balanced expression of ERα and ERβ proteins, leading to the dominant expression of ERβ, ii) MBP stimulates ERs-mediated transcription without acting as an ERβ ligand, and iii) MBP utilizes mitogen-activated protein kinase and phosphatidylinositol-3 kinase signaling to evoke its estrogenic action. Moreover, the repeated exposure strategy was effective for detecting low-dose estrogenic-like effects caused by MBP in LTED cells.

ERβ1 Sensitizes and ERβ2 Desensitizes ERα-Positive Breast Cancer Cells to the Inhibitory Effects of Tamoxifen, Fulvestrant and Their Combination with All-Trans Retinoic Acid

Adjuvant endocrine therapy (AET) is the treatment of choice for early-stage estrogen receptor alpha (ERα)-positive breast cancer (BC). However, almost 40% of tamoxifen-treated cases display no response or a partial response to AET, thus increasing the need for new treatment options and strong predictors of the therapeutic response of patients at high risk of relapse. In addition to ERα, BC research has focused on ERβ1 and ERβ2 (isoforms of ERβ), the second ER isotype. At present, the impact of ERβ isoforms on ERα-positive BC prognosis and treatment remains elusive. In the present study, we established clones of MCF7 cells constitutively expressing human ERβ1 or ERβ2 and investigated their role in the response of MCF7 cells to antiestrogens [4-hydroxytamoxifen (OHΤ) and fulvestrant (ICI182,780)] and retinoids [all-trans retinoic acid (ATRA)]. We show that, compared to MCF7 cells, MCF7-ERβ1 and MCF7-ERβ2 cells were sensitized and desensitized, respectively, to the antiproliferative effect of the antiestrogens, ATRA and their combination and to the cytocidal effect of the combination of OHT and ATRA. Analysis of the global transcriptional changes upon OHT-ATRA combinatorial treatment revealed uniquely regulated genes associated with anticancer effects in MCF7-ERβ1 cells and cancer-promoting effects in MCF7-ERβ2 cells. Our data are favorable to ERβ1 being a marker of responsiveness and ERβ2 being a marker of resistance of MCF7 cells to antiestrogens alone and in combination with ATRA.

Heart Failure in Menopause: Treatment and New Approaches

Aging is an important risk factor for the development of heart failure (HF) and half of patients with HF have preserved ejection fraction (HFpEF) which is more common in elderly women. In general, sex differences that lead to discrepancies in risk factors and to the development of cardiovascular disease (CVD) have been attributed to the reduced level of circulating estrogen during menopause. Estrogen receptors adaptively modulate fibrotic, apoptotic, inflammatory processes and calcium homeostasis, factors that are directly involved in the HFpEF. Therefore, during menopause, estrogen depletion reduces the cardioprotection. Preclinical menopause models demonstrated that several signaling pathways and organ systems are closely involved in the development of HFpEF, including dysregulation of the renin-angiotensin system (RAS), chronic inflammatory process and alteration in the sympathetic nervous system. Thus, this review explores thealterations observed in the condition of HFpEF induced by menopause and the therapeutic targets with potential to interfere with the disease progress.

An overview on Estrogen receptors signaling and its ligands in breast cancer

Estrogen governs the regulations of various pathological and physiological actions throughout the body in both males and females. Generally, 17β-estradiol an endogenous estrogen is responsible for different health problems in pre and postmenopausal women. The major activities of endogenous estrogen are executed by nuclear estrogen receptors (ERs) ERα and ERβ while non-genomic cytoplasmic pathways also govern cell growth and apoptosis. Estrogen accomplished a fundamental role in the formation and progression of breast cancer. In this review, we have hyphenated different studies regarding ERs and a thorough and detailed study of estrogen receptors is presented. This review highlights different aspects of estrogens ranging from receptor types, their isoforms, structures, signaling pathways of ERα, ERβ and GPER along with their crystal structures, pathological roles of ER, ER ligands, and therapeutic strategies to overcome the resistance.

Membrane estrogen receptor ERα activation improves tau clearance via autophagy induction in a tauopathy cell model

Alzheimer's disease (AD) is the most prevalent aging-associated neurodegenerative disease, with a higher incidence in women than men. There is evidence that sex hormone replacement therapy, particularly estrogen, reduces memory loss in menopausal women. Neurofibrillary tangles are associated with tau protein aggregation, a characteristic of AD and other tauopathies. In this sense, autophagy is a promising cellular process to remove these protein aggregates. This study evaluated the autophagy mechanisms involved in neuroprotection induced by 17β-estradiol (E2) in a Tet-On inducible expression tauopathy cell model (EGFP-tau WT or with the P301L mutation, 0N4R isoform). The results indicated that 17β-estradiol induces autophagy by activating AMPK in a concentration-dependent manner, independent of mTOR signals. The estrogen receptor α (ERα) agonist, PPT, also induced autophagy, while the ERα antagonist, MPP, substantially attenuated the 17β-estradiol-mediated autophagy induction. Notably, 17β-estradiol increased LC3-II levels and phosphorylated and total tau protein clearance in the EGFP-tau WT cell line but not in EGPF-tau P301L. Similar results were observed with E2-BSA, a plasma membrane-impermeable estrogen, suggesting membrane ERα involvement in non-genomic estrogenic pathway activation. Furthermore, 17β-estradiol-induced autophagy led to EGFP-tau protein clearance. These results demonstrate that modulating autophagy via the estrogenic pathway may represent a new therapeutic target for treating AD.

Molecular characterization and functional analysis of Esr1 and Esr2 in gonads of Chinese soft-shelled turtle (Pelodiscus sinensis)

Estrogens and their receptors play crucial roles in regulating the gonadal development of vertebrates. To clarify the roles of estrogen receptors in the gonadal development of turtles, estrogen receptors (Esr1 and Esr2) in Chinese soft-shelled turtle (Pelodiscus sinensis) were identified and characterized, and their function in gonads was investigated by intraperitoneal injection of agonist propylpyrazoletriol (PPT) and diarylpropionitrile (DPN), and antagonist ICI 182,780 (ICI). Ps-Esr1 encoded a 588 amino acid protein and Ps-Esr2 encoded a 556 amino acid protein. The two receptors contained classic domains, including the DNA-binding domain and ligand-binding domain, and amino acid sequences showed high homology with other turtles. Ps-Esr1 showed the highest expression in the testis, followed by the ovary and liver. However, Ps-Esr2 showed the highest expression in the ovary, followed by the brain and testis. Ps-Esr1 expression showed an up-regulation trend in gonadal differentiation. Histomorphometric analysis showed that the number of follicles increased in female juvenile turtles treated with DPN or PPT. In addition, Tsc2, GnRH, and Fshβ were up-regulated in ovaries of turtles treated with agonists, while Sycp3 and Picalm were up-regulated in testes of turtles treated with agonists. Treatment with the antagonist decreased the number of sperm in matured turtles. Stra8, Scyp3, Dmc1, Picalm, Evl, Boule, and Cdk1 were up-regulated in testis after antagonist treatment. The results indicated that Esr1 might play an important role in gonadal differentiation, and the two estrogen receptors might be involved in the spermatogenesis of the turtle. These results could provide a reference for further research on the function of the estrogen signal in male vertebrates.

Evaluating the correlation of binding affinities between isothermal titration calorimetry and fragment molecular orbital method of estrogen receptor beta with diarylpropionitrile (DPN) or DPN derivatives

Estrogen receptors (ERs) are ligand-activated transcription factors, with two subtypes ERα and ERβ. The endogenous ligand of ERs is the common 17β-estradiol, and the ligand-binding pocket of ERα and ERβ is very similar. Nevertheless, some ERβ-selective agonist ligands have been reported. DPN (diarylpropionitrile) is a widely used ERβ-selective agonist; however, the structure of the ERβ-DPN complex has not been solved. Therefore, the bound-state conformation of DPN and its enantioselectivity remain unresolved. In this report, we present the structures of the complexes of ERβ with DPN or its derivatives that include a chlorine atom by the X-ray crystallography. Additionally, we measured the binding affinity between ERβ and DPN or derivatives by isothermal titration calorimetry (ITC) and estimated the binding affinity by fragment molecular orbital (FMO) calculations. We also examined the correlation between the ITC data and results from the FMO calculations. FMO calculations showed that S-DPN interacts strongly with three amino acids (Glu305, Phe356, and His475) of ERβ, and ITC measurements confirmed that the chlorine atom of the DPN derivatives enhances binding affinity. The enthalpy change by ITC correlated strongly with the interaction energy (total IFIEs; inter-fragment interaction energies) calculated by FMO (R = 0.870). We propose that FMO calculations are a valuable approach for enhancing enthalpy contributions in drug design, and its scope of applications includes halogen atoms such as chlorine. This study is the first quantitative comparison of thermodynamic parameters obtained from ITC measurements and FMO calculations, providing new insights for future precise drug design.

Insight into Isomeric Effect on the Photoluminescence and Mechanoluminescence of Cyanostilbene Derivatives

Molecular structures, packings, and intermolecular interactions significantly affect the photophysical properties of organic luminogens. In this work, the photoluminescence (PL) and mechanoluminescence (ML) of two pairs of isomers, 1/2 and 3/4, were systematically explored. The fluorescence of crystals 1c and 4c is much brighter than that of their isomers 2c and 3c, respectively. Only 1c is ML-active among all four molecules. Single-crystal structural analysis revealed that isomerization of a substituent group affected their molecular packing and intermolecular interactions. Stronger intermolecular interaction and intact three-dimensional hydrogen-bonded networks were formed only in crystal 1c, which were essential for preventing slippage of molecular layers and generating ML; the other molecules were either lacking π-π interactions or C-H···π interactions. Theoretical calculation suggested that the energy barrier between the Franck-Condon (FC) structure and minimum energy crossing point (MECP) structure of 2/3 was much lower than that of 1/4. Nonradiative decay channels of molecules 2 and 3 were thus more easily activated, which led to their lower quantum yield.

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.

Estrogen modulation of the pronociceptive effects of serotonin on female rat trigeminal sensory neurons is timing dependent and dosage dependent and requires estrogen receptor alpha

ABSTRACT

The role of the major estrogen estradiol (E2) on orofacial pain conditions remains controversial with studies reporting both a pronociceptive and antinociceptive role of E2. E2 modulation of peripheral serotonergic activity may be one mechanism underlying the female prevalence of orofacial pain disorders. We recently reported that female rats in proestrus and estrus exhibit greater serotonin (5HT)-evoked orofacial nocifensive behaviors compared with diestrus and male rats. Further coexpression of 5HT 2A receptor mRNA in nociceptive trigeminal sensory neurons that express transient receptor potential vanilloid 1 ion channels contributes to pain sensitization. E2 may exacerbate orofacial pain through 5HT-sensitive trigeminal nociceptors, but whether low or high E2 contributes to orofacial pain and by what mechanism remains unclear. We hypothesized that steady-state exposure to a proestrus level of E2 exacerbates 5HT-evoked orofacial nocifensive behaviors in female rats, explored the transcriptome of E2-treated female rats, and determined which E2 receptor contributes to sensitization of female trigeminal sensory neurons. We report that a diestrus level of E2 is protective against 5HT-evoked orofacial pain behaviors, which increase with increasing E2 concentrations, and that E2 differentially alters several pain genes in the trigeminal ganglia. Furthermore, E2 receptors coexpressed with 5HT 2A and transient receptor potential vanilloid 1 and enhanced capsaicin-evoked signaling in the trigeminal ganglia through estrogen receptor α. Overall, our data indicate that low, but not high, physiological levels of E2 protect against orofacial pain, and we provide evidence that estrogen receptor α receptor activation, but not others, contributes to sensitization of nociceptive signaling in trigeminal sensory neurons.

Synthesis and Evaluation of (1,4-Disubstituted)-1,2,3-triazoles as Estrogen Receptor Beta Agonists

Estrogen receptors (ER) are nuclear hormone receptors which are responsible for sex hormone signaling in women. A series of (1,4-disubstituted)-1,2,3-triazoles 5–21 were prepared by reaction of azidophenols with terminal alkynes under Fokin reaction conditions. The products were purified by column chromatography or recrystallization and characterized by NMR and HRMS. The compounds were tested for binding to ERβ via a ligand displacement assay, and 1-(4-hydroxyphenyl)-α-phenyl-1,2,3-triazole-4-ethanol (21) was found to be the most potent analog (EC50 = 1.59 μM). Molecular docking of 5–21 within the ligand binding pocket of ERβ (pdb 2jj3) was performed and the docking scores exhibited a general qualitative trend consistent with the measured EC50 values.

Hypothalamic Expression of Estrogen Receptor Isoforms Underlies Estradiol Control of Luteinizing Hormone in Female Rats

Luteinizing hormone (LH) secretion during the ovarian cycle is governed by fluctuations in circulating estradiol (E2) that oppositely regulate kisspeptin neurons in the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC) of the hypothalamus. However, how these effects are orchestrated to achieve fertility is unknown. Here, we have tested the hypothesis that AVPV and ARC neurons have different sensitivities to E2 to coordinate changes in LH secretion. Cycling and ovariectomized rats with low and high E2 levels were used. As an index of E2 responsiveness, progesterone receptor (PR) was expressed only in the AVPV of rats with high E2, showing the preovulatory LH surge. On the other hand, kisspeptin neurons in the ARC responded to low E2 levels sufficient to suppress LH release. Notably, the Esr1/Esr2 ratio of gene expression was higher in the ARC than AVPV, regardless of E2 levels. Accordingly, the selective pharmacological activation of estrogen receptor α (ERα) required lower doses to induce PR in the ARC. The activation of ERβ, in turn, amplified E2-induced PR expression in the AVPV and the LH surge. Thus, ARC and AVPV neurons are differently responsive to E2. Lower E2 levels activate ERα in the ARC, whereas ERβ potentiates the E2 positive feedback in the AVPV, which appears related to the differential Esr1/Esr2 ratio in these 2 brain areas. Our findings provide evidence that the distinct expression of ER isoforms in the AVPV and ARC plays a key role in the control of periodic secretion of LH required for fertility in females.

Diarylpropionitrile inhibits melanogenesis via protein kinase A/cAMP-response element-binding protein/microphthalmia-associated transcription factor signaling pathway in α-MSH-stimulated B16F10 melanoma cells

Diarylpropionitrile (DPN), a selective agonist for estrogen receptor β (ERβ), has been reported to regulate various hormonal responses through activation of ERβ in tissues including the mammary gland and brain. However, the effect of DPN on melanogenesis independent of ERβ has not been studied. The aim of this study is to examine the possibility of anti-melanogenic effect of DPN and its underlying mechanism. Melanin contents and cellular tyrosinase activity assay indicated that DPN inhibited melanin biosynthesis in alpha-melanocyte stimulating hormone-stimulated B16F10 melanoma cell line. However, DPN had no direct influence on in vitro tyrosinase catalytic activity. On the other hand, 17β-estradiol had no effect on inhibition of melanogenesis, suggesting that the DPN-mediated suppression of melanin production was not related with estrogen signaling pathway. Immunoblotting analysis showed that DPN down-regulated the expression of microphthalmia-associated transcription factor (MITF), a central transcription factor of melanogenesis and its down-stream genes including tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2. Also, DPN attenuated the phosphorylation of protein kinase A (PKA) and cAMP-response element-binding protein (CREB). Additionally, DPN suppressed the melanin synthesis in UVB-irradiated HaCaT conditioned media culture system suggesting that DPN has potential as an anti-melanogenic activity in physiological conditions. Collectively, our data show that DPN inhibits melanogenesis via down-regulation of PKA/CREB/MITF signaling pathway.

ERα, but not ERβ and GPER, Mediates Estradiol-Induced Secretion of TSH in Mouse Pituitary

Although estradiol (E2) plays a critical role in the promotion of pituitary development and in the regulation of various pituitary hormones, its effects on the thyroid-stimulating hormone (TSH) remain unaddressed. The actions of E2 are mediated by two classical nuclear estrogen receptors α (ERα) and β (ERβ) and the G protein-coupled estrogen receptor (GPER). However, the types of estrogen receptor involvement in the regulation of thyrotropes are still limited. In this study, we demonstrate that ERα, but not ERβ and GPER, is localized to thyrotropes in the pituitary of female mouse. In agreement with the presence of ERα in thyrotropes, E2 was shown to stimulate TSH release in vitro from primary culture of female mouse pituitary cells. PPT, a ERα-selective agonist, but not DPN (a ERβ-selective agonist) and G-1 (a GPER-selective agonist), was shown to stimulate TSH release in mouse pituitary cells. This effect could be prevented by the specific ER antagonist fulvestrant and the selective ERα antagonist MPP. The findings of this study suggest that E2 may bind to ERα to trigger TSH release and provide novel information on the differential regulation of multiple estrogen receptors in the pituitary.

SERMs (selective estrogen receptor modulator), acting as estrogen receptor β agonists in hepatocellular carcinoma cells, inhibit the transforming growth factor-α-induced migration via specific inhibition of AKT signaling pathway

Selective estrogen receptor modulator (SERM) interacts with estrogen receptors and acts as both an agonist or an antagonist, depending on the target tissue. SERM is widely used as a safer hormone replacement therapeutic medicine for postmenopausal osteoporosis. Regarding hepatocellular carcinoma (HCC), accumulating evidence indicates gender differences in the development, and that men are at higher morbidity risk than premenopausal women, suggesting that estrogen protects against HCC. However, it remains unclear whether SERM affects the HCC progression. Previously, we have shown that transforming growth factor (TGF)-α promotes the migration of HCC cells via p38 mitogen-activated protein kinases (MAPK), c-Jun N-terminal kinase and AKT. In the present study, we investigated whether SERM such as tamoxifen, raloxifene and bazedoxifene, affects the HCC cell migration using human HCC-derived HuH7 cells. Raloxifene and bazedoxifene but not tamoxifen, significantly suppressed the TGF-α-induced HuH7 cell migration. ERB041 and DPN, estrogen receptor (ER) β agonists, inhibited the TGF-α-induced cell migration whereas PPT, an ERα agonist, did not show the suppressive effect on the cell migration. ERB041 attenuated the TGF-α-induced phosphorylation of AKT without affecting the phosphorylation of p38 MAPK and c-Jun N-terminal kinase. Raloxifene and bazedoxifene also inhibited the phosphorylation of AKT by TGF-α. Furthermore, PHTPP, an ERβ antagonist, significantly reversed the suppression by both raloxifene and bazedoxifene of the TGF-α-induced cell migration. Taken together, our results strongly indicate that raloxifene and bazedoxifene, SERMs, suppress the TGF-α-induced migration of HCC cells through ERβ-mediated inhibition of the AKT signaling pathway.

Synthesis of Unsymmetrical Diarylfumaronitriles via Tandem Michael Addition and Oxidation under K3Fe(CN)6/O2 System

An efficient formal alkenyl C-H cyanation reaction has been developed for the general synthesis of unsymmetrical diarylfumaronitriles in good to excellent yields. The reaction was achieved through tandem Michael addition and an oxidative process. The merits of this transformation include the use of K₃Fe(CN)₆ as a safe and nontoxic cyanide source, without an external noble metal catalyst, oxygen-involved reactions, easily available raw materials, good functional group tolerance, high stereoselectivity, and potential further application of the products.

Estradiol promotes cell survival and induces Greb1 expression in granulosa cell tumors of the ovary through an ERα-dependent mechanism

Granulosa cell tumor (GCT) is a form of ovarian tumor characterized by its tendency to recur years after surgical ablation. Little is known on the mechanisms involved in GCT development and progression. GCTs can produce estradiol (E2), but whether this hormone could play a role in this cancer through its nuclear receptors, i.e., ERα and ERβ, remains unknown. Here, we addressed this issue by cell-based and molecular studies on human GCTs and GCT cell lines. Importantly, we observed that E2 significantly increased the growth of GCT cells by promoting cell survival. The use of selective agonists of each type of receptor, together with Esr1 (ERα) or Esr2 (ERβ)-deleted GCT cells revealed that E2 mediated its effects through ERα-dependent genomic mechanisms and ERβ/ERα-dependent extra-nuclear mechanisms. Notably, the expression of Greb1, a prototypical ER target gene, was dose-dependently up-regulated by E2 specifically through ERα in GCT cells. Accordingly, using GCTs from patients, we found that GREB1 mRNA abundance was positively correlated to intra-tumoral E2 concentrations. Tissue microarrays analyses showed that there were various combinations of ER expression in primary and recurrent GCTs, and that ERα expression persisted only in combination with ERβ in ~40% of recurrent tumors. Altogether, this study demonstrates that E2 can promote the progression of GCTs, with a clear dependence on ERα. In addition to demonstrating that GCTs can be classified as a hormone-related cancer, our results also highlight that the nature of ER forms present in recurrent GCTs could underlie the variable efficiency of endocrine therapies. This article is protected by copyright. All rights reserved.

Cyanogenic Derivatives as Chemical Markers for the Authentication of Commercial Products of Bamboo Shoots

The authentication of bamboo shoots found in the marketplace is complex because the chemical profile of processed and unprocessed material is different. During processing, heat derivatives of the potentially toxic cyanogenic glycoside taxiphyllin are produced. Here, we report the isolation and structure elucidation of the two major diarylbutenedinitrile derivatives, which are cis and trans isomers of the rare 2,3-bis(4-hydroxyphenyl)but-2-enedinitrile from a commercial extract of bamboo shoots. These compounds, absent in fresh bamboo shoots, were produced by boiling the shoots of Bambusa vulgaris and were associated with a decrease in levels of taxiphyllin. Furthermore, (E)-2,3-bis(4-hydroxyphenyl)but-2-enedinitrile was quantified in all 16 of the commercial products tested. Its abundance was found to be highly variable, ranging from 1 to 3 mg/g in preserved bamboo shoots and from 10 to 160 mg/mL in commercial aqueous extracts. Of the 15 authenticated bamboo samples tested for taxiphyllin, it was found only in the shoots of B. vulgaris and Gigantochloa verticillata, which represent two edible bamboo species. Our results indicate that diarylbutenedinitriles can be used as markers for the authentication of boil-processed bamboo shoots obtained from taxiphyllin-containing edible species and organs.

Targeting Nuclear Receptors in Neurodegeneration and Neuroinflammation

Nuclear receptors, also known as ligand-activated transcription factors, regulate gene expression upon ligand signals and present as attractive therapeutic targets especially in chronic diseases. Despite the therapeutic relevance of some nuclear receptors in various pathologies, their potential in neurodegeneration and neuroinflammation is insufficiently established. This perspective gathers preclinical and clinical data for a potential role of individual nuclear receptors as future targets in Alzheimer's disease, Parkinson's disease, and multiple sclerosis, and concomitantly evaluates the level of medicinal chemistry targeting these proteins. Considerable evidence suggests the high promise of ligand-activated transcription factors to counteract neurodegenerative diseases with a particularly high potential of several orphan nuclear receptors. However, potent tools are lacking for orphan receptors, and limited central nervous system exposure or insufficient selectivity also compromises the suitability of well-studied nuclear receptor ligands for functional studies. Medicinal chemistry efforts are needed to develop dedicated high-quality tool compounds for the therapeutic validation of nuclear receptors in neurodegenerative pathologies.

Structure-Activity Relationship of para-Carborane Selective Estrogen Receptor β Agonists

Selective agonism of the estrogen receptor (ER) subtypes, ERα and ERβ, has historically been difficult to achieve due to the high degree of ligand-binding domain structural similarity. Multiple efforts have focused on the use of classical organic scaffolds to model 17β-estradiol geometry in the design of ERβ selective agonists, with several proceeding to various stages of clinical development. Carborane scaffolds offer many unique advantages including the potential for novel ligand/receptor interactions but remain relatively unexplored. We synthesized a series of para-carborane estrogen receptor agonists revealing an ERβ selective structure-activity relationship. We report ERβ agonists with low nanomolar potency, greater than 200-fold selectivity for ERβ over ERα, limited off-target activity against other nuclear receptors, and only sparse CYP450 inhibition at very high micromolar concentrations. The pharmacological properties of our para-carborane ERβ selective agonists measure favorably against clinically developed ERβ agonists and support further evaluation of carborane-based selective estrogen receptor modulators.

The oxysterome and its receptors as pharmacological targets in inflammatory diseases

Oxysterols have gained attention over the last decades and are now considered as fully fledged bioactive lipids. The study of their levels in several conditions, including atherosclerosis, obesity and neurodegenerative diseases, led to a better understanding of their involvement in (patho)physiological processes such as inflammation and immunity. For instance, the characterization of the cholesterol-7α,25-dihydroxycholesterol/GPR183 axis and its implication in immunity represents an important step in the oxysterome study. Besides this axis, others were identified as important in several inflammatory pathologies (such as colitis, lung inflammation and atherosclerosis). However, the oxysterome is a complex system notably due to a redundancy of metabolic enzymes and a wide range of receptors. Indeed, deciphering oxysterol roles and identifying the potential receptor(s) involved in a given pathology remain challenging. Oxysterol properties are very diverse, but most of them could be connected by a common component: inflammation. Here, we review the implication of oxysterol receptors in inflammatory diseases.

Long-term oral administration of a novel estrogen receptor beta agonist enhances memory and alleviates drug-induced vasodilation in young ovariectomized mice

Development of estrogen therapies targeting the β (ERβ) but not α (ERα) estrogen receptor is critically needed for the treatment of negative menopausal symptoms, as ERα activation increases health risks like cancer. Here, we determined the effects of long-term oral treatment with EGX358, a novel highly selective ERβ agonist, on memory, vasodilation, and affect in young ovariectomized mice. Mice were orally gavaged daily for 9 weeks with vehicle, 17β-estradiol (E₂), the ERβ agonist diarylpropionitrile (DPN), or EGX358 at doses that enhance memory when delivered acutely. Tail skin temperature was recorded as a proxy for vasodilation following injection of vehicle or senktide, a tachykinin receptor 3 agonist used to model hot flashes. Anxiety-like behavior was assessed in the open field (OF) and elevated plus maze (EPM), and depression-like behavior was measured in the tail suspension (TST) and forced swim tests (FST). Finally, memory was assessed in object recognition (OR) and object placement (OP) tasks. E₂, DPN, and EGX358 reduced senktide-mediated increases in tail skin temperature compared to vehicle. All three treatments also enhanced memory in the OR and OP tasks, whereas vehicle did not. Although E₂ increased time spent in the center of the OF, no other treatment effects were observed in the OF, EPM, TST, or FST. These data suggest that long-term ERβ activation can reduce hot flash-like symptoms and enhance spatial and object recognition memories in ovariectomized mice. Thus, the highly selective ERβ agonist EGX358 may be a promising avenue for reducing menopause-related hot flashes and memory dysfunction.

G Protein-Coupled Estrogen Receptor in Cancer and Stromal Cells: Functions and Novel Therapeutic Perspectives

Estrogen is involved in numerous physiological and pathophysiological systems. Its role in driving estrogen receptor-expressing breast cancers is well established, but it also has important roles in a number of other cancers, acting both on tumor cells directly as well as in the function of multiple cells of the tumor microenvironment, including fibroblasts, immune cells, and adipocytes, which can greatly impact carcinogenesis. One of its receptors, the G protein-coupled estrogen receptor (GPER), has gained much interest over the last decade in both health and disease. Increasing evidence shows that GPER contributes to clinically observed endocrine therapy resistance in breast cancer while also playing a complex role in a number of other cancers. Recent discoveries regarding the targeting of GPER in combination with immune checkpoint inhibition, particularly in melanoma, have led to the initiation of the first Phase I clinical trial for the GPER-selective agonist G-1. Furthermore, its functions in metabolism and corresponding pathophysiological states, such as obesity and diabetes, are becoming more evident and suggest additional therapeutic value in targeting GPER for both cancer and other diseases. Here, we highlight the roles of GPER in several cancers, as well as in metabolism and immune regulation, and discuss the therapeutic value of targeting this estrogen receptor as a potential treatment for cancer as well as contributing metabolic and inflammatory diseases and conditions.

Estrogen Receptor Signaling Pathways Involved in Invasion and Colony Formation of Androgen-Independent Prostate Cancer Cells PC-3

Castration-resistant prostate cancer (CRPC) is an advanced and androgen-independent form of prostate cancer. Recent studies of rapid actions mediated by estrogen in the prostate and its relationship with CRPC are emerging. We have previously shown that estrogen receptor (ER) promotes migration and invasion of the androgen-independent prostate cancer cells PC-3, but the signaling pathways involved in these events remain to be elucidated. Therefore, this study aimed to analyze the role of ERα and ERβ in the activation of SRC, and the involvement of SRC and PI3K/AKT on invasion and colony formation of the PC-3 cells. Our results showed that the activation of ERα (using ERα-selective agonist PPT) and ERβ (using ERβ-selective agonist DPN) increased phosphorylation of SRC in PC-3 cells. In the presence of the selective inhibitor for SRC-family kinases PP2, the effects of DPN and PPT on transmigration and soft agar colony formation assays were decreased. Furthermore, SRC is involved in the expression of the non-phosphorylated β-catenin. Finally, using PI3K specific inhibitor Wortmannin and AKT inhibitor MK2206, we showed that PI3K/AKT are also required for invasion and colony formation of PC-3 cells simulated by ER. This study provides novel insights into molecular mechanisms of ER in PC-3 cells by demonstrating that ER, located outside the cell nucleus, activates rapid responses molecules, including SRC and PI3K/AKT, which enhance the tumorigenic potential of prostate cancer cells, increasing cell proliferation, migration, invasion, and tumor formation.

Growth and Bone Mineral Density Changes in Ovariectomized Rats Treated with Estrogen Receptor Alpha or Beta Agonists

BACKGROUND

Estrogen controls the pubertal growth spurt, growth plate closure, and accretion of bone mineral density (BMD) of long bones after biding estrogen receptor (ER). There are two subtypes of ER, ERα and ERβ. If each ER subtype has different effects, we may control those actions by manipulating the estrogen binding intensity to each ER subtype and increase the final adult height without markedly reducing BMD or impairing reproductive functions. The purpose of our study was to compare these effects of ERα and ERβ on long bones in ovariectomized rats.

METHODS

Thirty female rats were ovariectomized and randomly divided into 3 groups. The control, propylpyrazole triol (PPT), and 2,3-bis (4-hydroxyphenyl) propionitrile (DPN) groups were subcutaneously injected for 5 weeks with sesame oil, PPT as an ERα agonist, and DPN as an ERβ agonist, respectively. The crown-lump length and body weight were measured weekly. BMD, serum levels of growth hormone (GH) and estradiol were checked before and after 5 weeks of injections. Pituitary GH1 expression levels were determined with quantitative real-time polymerase chain reaction, the proximal tibias were dissected, decalcified and stained with hematoxylin-eosin, and the thicknesses of epiphyseal plates including proliferative and hypertrophic zones were measured in 20-evenly divided sites after 5 weeks of injections. Comparisons for auxological data, serum hormone and pituitary GH1 expression levels, BMD, and epiphyseal plate thicknesses among 3 groups before and after injections were conducted.

RESULTS

There was no significant difference in body lengths among 3 groups. The body weights were significantly lower, but, serum GH, pituitary GH1 expression levels, and BMDs were higher in PPT group than the other 2 groups after 5 weeks of injections. There was no significant difference in the thicknesses of the total epiphyseal plate, proliferative, and hypertrophic zone among 3 groups.

CONCLUSION

ERα is more involved in pituitary GH secretion and bone mineral deposition than ERβ. Weight gain might be prevented with the ERα agonist.

The role of estrogen receptors in rat Sertoli cells at different stages of development

The aim of the study was to investigate the effects of estrogen receptors (ESR1 and ESR2) on the expression of the proteins involved with proliferation (CCND1) and differentiation (CDKN1B and CTNNB) of Sertoli cells from rat in different stages of development. ESR1-selective agonist PPT, but not ESR2-selective agonist DPN, increased CCND1 expression in Sertoli cells from 5- and 15-day old rats. PPT did not have any effect on CCND1 expression in Sertoli cells from 20- and 30-day-old rats. DPN, but not PPT, increased CDKN1B expression in Sertoli cells from 15-, 20-, 30-day-old rats. DPN did not have any effect on Sertoli cells from 5-day-old rats. 17β-estradiol (E2) and PPT enhanced the [Methyl-³H] thymidine incorporation in Sertoli cells from 15-day-old rats, whereas the treatment did not have any effect in 20-day-old rats. E2 and DPN, but not PPT, increased non-phosphorylated CTNNB expression in Sertoli cells from 20-day-old rats. This upregulation was blocked by ESR2-selective antagonist PHTPP. The activation of ESR1 and ESR2, respectively, plays a role in the proliferation and differentiation of Sertoli cells in a critical period of testicular development. Furthermore, in Sertoli cells from 20-day-old rats, upregulation of non-phosphorylated CTNNB by E2/ESR2, via c-SRC/ERK1/2 and PI3K/AKT, may play a role in the interaction between Sertoli cells and/or in cell-germ cell adhesion and/or in the stabilization and accumulation of CTNNB in the cytosol. CTNNB could be translocated to the nucleus and modulate the transcriptional activity of specific target genes. The present study reinforces the important role of estrogen in normal testis development.

The peri-menopause in a woman's life: a systemic inflammatory phase that enables later neurodegenerative disease

The peri-menopause or menopausal transition—the time period that surrounds the final years of a woman’s reproductive life—is associated with profound reproductive and hormonal changes in a woman’s body and exponentially increases a woman’s risk of cerebral ischemia and Alzheimer’s disease. Although our understanding of the exact timeline or definition of peri-menopause is limited, it is clear that there are two stages to the peri-menopause. These are the early menopausal transition, where menstrual cycles are mostly regular, with relatively few interruptions, and the late transition, where amenorrhea becomes more prolonged and lasts for at least 60 days, up to the final menstrual period. Emerging evidence is showing that peri-menopause is pro-inflammatory and disrupts estrogen-regulated neurological systems. Estrogen is a master regulator that functions through a network of estrogen receptors subtypes alpha (ER-α) and beta (ER-β). Estrogen receptor-beta has been shown to regulate a key component of the innate immune response known as the inflammasome, and it also is involved in regulation of neuronal mitochondrial function. This review will present an overview of the menopausal transition as an inflammatory event, with associated systemic and central nervous system inflammation, plus regulation of the innate immune response by ER-β-mediated mechanisms.

Design and Synthesis of Small Molecules as Potent Staphylococcus aureus Sortase A Inhibitors

The widespread and uncontrollable emergence of antibiotic-resistant bacteria, especially methicillin-resistant Staphylococcus aureus, has promoted a wave of efforts to discover a new generation of antibiotics that prevent or treat bacterial infections neither as bactericides nor bacteriostats. Due to its crucial role in virulence and its nonessentiality in bacterial survival, sortase A has been considered as a great target for new antibiotics. Sortase A inhibitors have emerged as promising alternative antivirulence agents against bacteria. Herein, the structural and preparative aspects of some small synthetic organic compounds that block the pathogenic action of sortase A have been described.

Male and female immediate fear reaction to white noise in a semi-natural environment: A detailed behavioural analysis of the role of sex and oestrogen receptors

In classical rodent anxiety models, females usually display lower anxiety than males, whereas anxiety disorders are more prevalent in women. Perhaps this contradiction is caused by the use of behavioural models with low external validity. Therefore, we analysed immediate reactions to a sudden 90-dB white noise in a semi-natural environment. We observed mixed-sex groups of rats for the 60 seconds preceding noise onset and the first 60 seconds of exposure. White noise elicited fear-specific behaviours hiding alone and huddling. It also increased exploratory and ambulatory behaviours, although only in the burrow zone farthest from the open area. Thus, in a semi-natural environment, white noise enhanced motor activity as a product of fear-induced general arousal. Then, we compared male and female sexual, social, exploratory and anxiety-related behaviour, and found little sex difference. This absence of behavioural effect, also observed in other studies, might be a result of our study design, a familiar environment with an ecologically relevant social context. Fear and anxiety responses are modulated by oestrogens through the activation of oestrogen receptors α and β. Thus, in a third part of out study, we analysed how treatment with either oil, oestradiol benzoate (EB), an agonist to the oestrogen receptor α (propylpyrazoletriol [PPT]) or β (diarylpropionitrile [DPN]) influenced female behaviour. The effect of treatment was limited, both EB and PPT stimulated motor activity in the open area before white noise, probably because of sexual activity. PPT increased the probability of fleeing from the noise, and decreased the latency to do so, which is consistent with a pattern of anxiogenic properties found in previous studies. Contrary to reports in classical procedures, we failed to detect any effect of DPN on immediate fear reactions in a semi-natural environment.

Synthesis and evaluation of 17α-triazolyl and 9α-cyano derivatives of estradiol

A variety of 17α-triazolyl and 9α-cyano derivatives of estradiol were prepared and evaluated for binding to human ERβ in both a TR-FRET assay, as well as ERβ and ERα agonism in cell-based functional assays. 9α-Cyanoestradiol (5) was nearly equipotent as estradiol as an agonist for both ERβ and ERα. The potency of the 17α-triazolylestradiol analogs is considerably more variable and depends on the nature of the 4-substituent of the triazole ring. While rigid protein docking simulations exhibited significant steric clashing, induced fit docking providing more protein flexibility revealed that the triazole linker of analogs 2d and 2e extends outside of the traditional ligand binding domain with the benzene ring located in the loop connecting helix 11 to helix 12.

Key role of estrogen receptor β in the organization of brain and behavior of the Japanese quail

Estrogens play a key role in the sexual differentiation of the brain and behavior. While early estrogen actions exert masculinizing effects on the brain of male rodents, a diametrically opposite effect is observed in birds where estrogens demasculinize the brain of females. Yet, the two vertebrate classes express similar sex differences in the brain and behavior. Although ERα is thought to play a major role in these processes in rodents, the role of ERβ is still controversial. In birds, the identity of the estrogen receptor(s) underlying the demasculinization of the female brain remains unclear. The aim of the present study was thus to determine in Japanese quail the effects of specific agonists of ERα (propylpyrazole triol, PPT) and ERβ (diarylpropionitrile, DPN) administered at the beginning of the sensitive period (embryonic day 7, E7) on the sexual differentiation of male sexual behavior and on the density of vasotocin-immunoreactive (VT-ir) fibers, a known marker of the organizational action of estrogens on the quail brain. We demonstrate that estradiol benzoate and the ERβ agonist (DPN) demasculinize male sexual behavior and decrease the density of VT-ir fibers in the medial preoptic nucleus and the bed nucleus of the stria terminalis, while PPT has no effect on these measures. These results clearly indicate that ERβ, but not ERα, is involved in the estrogen-induced sexual differentiation of brain and sexual behavior in quail.

Estradiol Induces Epithelial to Mesenchymal Transition of Human Glioblastoma Cells

The mesenchymal phenotype of glioblastoma multiforme (GBM), the most frequent and malignant brain tumor, is associated with the worst prognosis. The epithelial–mesenchymal transition (EMT) is a cell plasticity mechanism involved in GBM malignancy. In this study, we determined 17β-estradiol (E2)-induced EMT by changes in cell morphology, expression of EMT markers, and cell migration and invasion assays in human GBM-derived cell lines. E2 (10 nM) modified the shape and size of GBM cells due to a reorganization of actin filaments. We evaluated EMT markers expression by RT-qPCR, Western blot, and immunofluorescence.We found that E2 upregulated the expression of the mesenchymal markers, vimentin, and N-cadherin. Scratch and transwell assays showed that E2 increased migration and invasion of GBM cells. The estrogen receptor-α (ER-α)-selective agonist 4,4’,4’’-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT, 10 nM) affected similarly to E2 in terms of the expression of EMT markers and cell migration, and the treatment with the ER-α antagonist methyl-piperidino-pyrazole (MPP, 1 μM) blocked E2 and PPT effects. ER-β-selective agonist diarylpropionitrile (DNP, 10 nM) and antagonist 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazole[1,5-a]pyrimidin-3-yl]phenol (PHTPP, 1 μM) showed no effects on EMT marker expression. These data suggest that E2 induces EMT activation through ER-α in human GBM-derived cells.