Estradiol Binding Research Articles

Abstract PO3-29-03: An Emerging Class of ER mutations Enhances ER Dimerization and Promotes ER Activity

Abstract Physiological activation of estrogen receptor alpha (ERα) requires the binding of estradiol (E2) to the ligand binding domain (LBD) of the receptor. This interaction triggers a repositioning of helix 12 (H12), facilitating the recruitment of coactivator proteins to the unoccupied coactivator binding groove. However, in the context of breast cancer, point mutations of ERα at H12 lead to its repositioning and self-activation in the absence of E2. Through MSK clinical sequencing breast cancer cohort (MSK-IMPACT), we assayed 8302 samples of ER+ breast cancer patients and identified 649 mutations within the LBD of ERα. 471 of these mutations (73%) were located at H11-H12 loops (D538, Y537, L536), while the remaining 27% were located near the dimer interface of ERα (V422, G442, F461, S463P, L469). Through in vitro biochemical and cell assays, we identified that these mutations promote dimer formation and hormone-independent transcriptional activity. Tumors expressing these mutations exhibited significantly accelerated growth compared to their wild-type controls. Unlike Y537S, cells harboring mutations at the dimer interface maintain their sensitivity to Selective Estrogen Receptor Degraders (SERDs), including Fulvestrant, recently FDA-approved Elacestrant, and Camizestrant, as well as Selective Estrogen Receptor Modulators (SERMs) including Tamoxifen and Raloxifene. By utilizing machine learning and computational structural analyses, we uncovered that these mutants, unlike Y537 repositions H12, act distinctly through conformational change across the ERα dimer interface. Further cell assays proved that the dimerization leads to increased stability of the receptor and facilitates its nuclear localization, which is required for ERα activation. Collectively, our finding unveiled a new class of ER mutations that enforce receptor dimerization and activation of the ER signaling pathway. The discovery opens up a new therapeutic interventional possibility, suggesting that targeting dimerization could emerge as a new strategy to combat these malignancies. Citation Format: Seema Irani, Wuwei Tan, Qing Li, Weiyi Toy, Catherine Jones, Mayur Gadiya, Antonio Marra, John Katzenellenbogen, Kathryn Carlson, Benita S. Katzenellenbogen, Yang Shen, Sarat Chandarlapaty. An Emerging Class of ER mutations Enhances ER Dimerization and Promotes ER Activity [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-29-03.

Genistein Ameliorated Vascular Endothelial Growth Factor-A (VEGF-A) and Estrogen Receptor-Alpha (ER-α) in Endometriosis Mice Model, In Vivo and In Silico.

Endometriosis (EM) is a gynecological disorder that causes morbidity in women and is characterized by endometrial tissue in the uterus cavity. This study investigated the mechanism of genistein in the VEGF-A and ER-α expression through in vivo and in silico approaches. An in vivo study was conducted by thirty-six mice that were divided into six groups including control, EM, and EM treatment with genistein with the doses of 1.3, 1.95, 2.6, and 3.25 mg/day for 14 days. Peritoneal tissues with lesions were collected and analyzed by immunohistochemistry to measure the VEGF-A and ER-α expression. The data were analyzed using a statistical approach using one-way ANOVA followed by Tukey HSD test with a significant value p < 0.05. In silico study was conducted for investigating the inhibition mechanism of genistein in VEGF-A and ER-α protein. Genistein significantly reduced the VEGF-A and ER-α expression with the optimum dose of 3.25 mg/day. Molecular docking showed that genistein inhibited VEGF-A in several active site residues of VEGF-A, also blocked the ER-α protein in estradiol binding sites. This study concluded that genistein prevented endometriosis by performing the antiangiogenic activity and showed a similar function to estradiol.

Nuclear receptor superfamily structural diversity in pacific oyster: In silico identification of estradiol binding candidates

The increasing presence of anthropogenic contaminants in aquatic environments poses challenges for species inhabiting contaminated sites. Due to their structural binding characteristics to ligands that inhibit or activate gene transcription, these xenobiotic compounds frequently target the nuclear receptor superfamily. The present work aims to understand the potential interaction between the hormone 17-β-estradiol, an environmental contaminant, and the nuclear receptors of Crassostrea gigas, the Pacific oyster. This filter-feeding, sessile oyster species is subject to environmental changes and exposure to contaminants. In the Pacific oyster, the estrogen-binding nuclear receptor is not able to bind this hormone as it does in vertebrates. However, another receptor may exhibit responsiveness to estrogen-like molecules and derivatives. We employed high-performance in silico methodologies, including three-dimensional modeling, molecular docking and atomistic molecular dynamics to identify likely binding candidates with the target moecule. Our approach revealed that among the C. gigas nuclear receptor superfamily, candidates with the most favorable interaction with the molecule of interest belonged to the NR1D, NR1H, NR1P, NR2E, NHR42, and NR0B groups. Interestingly, NR1H and NR0B were associated with planktonic/larval life cycle stages, while NR1P, NR2E, and NR0B were associated with sessile/adult life stages. The application of this computational methodological strategy demonstrated high performance in the virtual screening of candidates for binding with the target xenobiotic molecule and can be employed in other studies in the field of ecotoxicology in non-model organisms.

Influence of the receptor apparatus of the mammary gland on the content of estrogens during the lactation process in rats

Purpose : To study the mechanisms of reducing the concentration of estrogens in the mammary gland. Materials and methods . In the experiment, breast preparations obtained from lactating rats were used. Estradiol receptors were detected using autoradiographic study and biochemical method in the cytosolic fraction. The specificity of estradiol binding was determined as the difference between the total binding during incubation in a medium containing 10-9 M ³H-17 β estradiol and binding during incubation in a medium containing, in addition to the labeled hormone, a 100-fold excess of unlabeled estradiol. During the washing process, structures with significant affinity for the hormone were revealed. Results . As a result of the study, the reception of estradiol by the cells of the alveolar part of the mammary gland during lactation was established. In the alveoli of the mammary gland, there is an intense binding of labeled estradiol by glandular cells and leukocytes. At high values of specific binding of estradiol, intensely labeled cells are located in the form of a close cluster. An indicator of the membrane binding of estradiol is the numerous silver granules accumulating over the cell border. Conclusion . The study made it possible to analyze the reception of estradiol in hormone-dependent tissue (mammary gland). Leukocyte cells have estrogen receptors, which reduce the level of the hormone as a result of lactation. In the mammary gland, there is a mechanism for reducing the concentration of estrogens. The ability of leukocyte receptor binding allows us to speak about the role of milk and colostrum cells in reducing the level of estrogens, which is one of the important factors in reducing the development of pathological processes in breast tissues.

A rapid synthesis of molecularly imprinted polymer nanoparticles for the extraction of performance enhancing drugs (PIEDs).

It is becoming increasingly more significant to detect and separate hormones from water sources, with the development of synthetic recognition materials becoming an emerging field. The delicate nature of biological recognition materials such as the antibodies means the generation of robust viable synthetic alternatives has become a necessity. Molecularly imprinted nanoparticles (NanoMIPs) are an exciting class that has shown promise due the generation of high-affinity and specific materials. While nanoMIPs offer high affinity, robustness and reusability, their production can be tricky and laborious. Here we have developed a simple and rapid microwaveable suspension polymerisation technique to produce nanoMIPs for two related classes of drug targets, Selective Androgen Receptor Modulators (SARMs) and steroids. These nanoMIPs were produced using one-pot microwave synthesis with methacrylic acid (MAA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as a suitable cross-linker, producing particles of an approximate range of 120-140 nm. With the SARMs-based nanoMIPs being able to rebind 94.08 and 94.46% of their target molecules (andarine, and RAD-140, respectively), while the steroidal-based nanoMIPs were able to rebind 96.62 and 96.80% of their target molecules (estradiol and testosterone, respectively). The affinity of nanoMIPs were investigated using Scatchard analysis, with Ka values of 6.60 × 106, 1.51 × 107, 1.04 × 107 and 1.51 × 107 M-1, for the binding of andarine, RAD-140, estradiol and testosterone, respectively. While the non-imprinted control polymer (NIP) shows a decrease in affinity with Ka values of 3.40 × 104, 1.01 × 104, 1.83 × 104, and 4.00 × 104 M-1, respectively. The nanoMIPs also demonstrated good selectivity and specificity of binding the targets from a complex matrix of river water, showing these functional materials offer multiple uses for trace compound analysis and/or sample clean-up.

Potential Disruption of Systemic Hormone Transport by Tobacco Alkaloids Using Computational Approaches.

Tobacco/nicotine is one of the most toxic and addictive substances and continues to pose a significant threat to global public health. The harmful effects of smoking/nicotine affect every system in the human body. Nicotine has been associated with effects on endocrine homeostasis in humans such as the imbalance of gonadal steroid hormones, adrenal corticosteroid hormones, and thyroid hormones. The present study was conducted to characterize the structural binding interactions of nicotine and its three important metabolites, cotinine, trans-3'-hydroxycotinine, and 5'-hydroxycotinine, against circulatory hormone carrier proteins, i.e., sex-hormone-binding globulin (SHBG), corticosteroid-binding globulin (CBG), and thyroxine-binding globulin (TBG). Nicotine and its metabolites formed nonbonded contacts and/or hydrogen bonds with amino acid residues of the carrier proteins. For SHBG, Phe-67 and Met-139 were the most important amino acid residues for nicotine ligand binding showing the maximum number of interactions and maximum loss in ASA. For CBG, Trp-371 and Asn-264 were the most important amino acid residues, and for TBG, Ser-23, Leu-269, Lys-270, Asn-273, and Arg-381 were the most important amino acid residues. Most of the amino acid residues of carrier proteins interacting with nicotine ligands showed a commonality with the interacting residues for the native ligands of the proteins. Taken together, the results suggested that nicotine and its three metabolites competed with native ligands for binding to their carrier proteins. Thus, nicotine and its three metabolites may potentially interfere with the binding of testosterone, estradiol, cortisol, progesterone, thyroxine, and triiodothyronine to their carrier proteins and result in the disbalance of their transport and homeostasis in the blood circulation.

Sex Differences in Acute Neuroendocrine Responses to Stressors in Rodents and Humans.

Sex differences in the neuroendocrine response to acute stress occur in both animals and humans. In rodents, stressors such as restraint and novelty induce a greater activation of the hypothalamic-pituitary-adrenal axis (HPA) in females compared to males. The nature of this difference arises from steroid actions during development (organizational effects) and adulthood (activational effects). Androgens decrease HPA stress responsivity to acute stress, while estradiol increases it. Androgenic down-regulation of HPA responsiveness is mediated by the binding of testosterone (T) and dihydrotestosterone (DHT) to the androgen receptor, as well as the binding of the DHT metabolite, 3β-diol, to the β form of the estrogen receptor (ERβ). Estradiol binding to the α form of the estrogen receptor (ERα) increases HPA responsivity. Studies of human sex differences are relatively few and generally employ a psychosocial paradigm to measure stress-related HPA activation. Men consistently show greater HPA reactivity than women when being evaluated for achievement. Some studies have found greater reactivity in women when being evaluated for social performance. The pattern is inconsistent with rodent studies but may involve the differential nature of the stressors employed. Psychosocial stress is nonphysical and invokes a significant degree of top-down processing that is not easily comparable to the types of stressors employed in rodents. Gender identity may also be a factor based on recent work showing that it influences the neural processing of positive and negative emotional stimuli independent of genetic sex. Comparing different types of stressors and how they interact with gender identity and genetic sex will provide a better understanding of sex steroid influences on stress-related HPA reactivity.

Forskolin Stimulates Estrogen Receptor (ER) α Transcriptional Activity and Protects ER from Degradation by Distinct Mechanisms.

Estradiol action is mediated by estrogen receptors (ERs), a and ß. Estradiol binding initiates ER-mediated transcription and ER degradation, the latter of which occurs via the ubiquitin-proteasome pathway. Inhibition of proteasome activity prevents estradiol-induced ERα degradation and transactivation. In ER-positive GH3 cells (a rat pituitary prolactinoma cell line), forskolin, acting via protein kinase A (PKA), stimulates ERα transcriptional activity without causing degradation, and proteasome inhibition does not block forskolin-stimulated transcription. Forskolin also protects liganded ERα from degradation. In the current study, we first examined ERα and ERβ transcriptional activity in ER-negative HT22 cells and found that forskolin stimulated ERα-, but not ERβ-dependent transcription, through the ligand-binding domain (LBD). We also identified four mutations (L396R, D431Y, Y542F, and K534E/M548V) on the ERα LBD that selectively obliterated the response to forskolin. In GH3 cells, transfected ERα mutants and ERβ were protected from degradation by forskolin. Ubiquitination of ERα and ERβ was increased by forskolin or estradiol. ERα ubiquitination was diminished by a mutated ubiquitin (K48R) that prevents elongation of polyubiquitin chains for targeting the proteasome. Increased ERα ubiquitination was not affected by the deletion of the A/B domain but significantly diminished in the F domain deletion mutant. Our results indicate distinct and novel mechanisms for forskolin stimulation of ERα transcriptional activity and protection from ligand-induced degradation. It also suggests a unique mechanism by which forskolin increases unliganded and liganded ERα and ERβ ubiquitination but uncouples them from proteasome-mediated degradation regardless of their transcriptional responses to forskolin.

No Differences in Value-Based Decision-Making Due to Use of Oral Contraceptives

Fluctuating ovarian hormones have been shown to affect decision-making processes in women. While emerging evidence suggests effects of endogenous ovarian hormones such as estradiol and progesterone on value-based decision-making in women, the impact of exogenous synthetic hormones, as in most oral contraceptives, is not clear. In a between-subjects design, we assessed measures of value-based decision-making in three groups of women aged 18 to 29 years, during (1) active oral contraceptive intake (N = 22), (2) the early follicular phase of the natural menstrual cycle (N = 20), and (3) the periovulatory phase of the natural menstrual cycle (N = 20). Estradiol, progesterone, testosterone, and sex-hormone binding globulin levels were assessed in all groups via blood samples. We used a test battery which measured different facets of value-based decision-making: delay discounting, risk-aversion, risk-seeking, and loss aversion. While hormonal levels did show the expected patterns for the three groups, there were no differences in value-based decision-making parameters. Consequently, Bayes factors showed conclusive evidence in support of the null hypothesis. We conclude that women on oral contraceptives show no differences in value-based decision-making compared to the early follicular and periovulatory natural menstrual cycle phases.

Estrogen receptor expression is modulated in human and mouse prostate epithelial cells during cancer progression

Substantial data posit estrogen receptors (ERs) as promising targets for prostate cancer (PCa) therapeutics. However, the trials on assessing the chemo-preventive or therapeutic potential of ER targeting drugs or selective estrogen receptor modulators (SERMs) have not yet established their clinical benefits. This could be ascribed to a possible modulation in the ER expression during PCa progression. Further it is warranted to test various ER targeting drugs in appropriate preclinical models that simulate human ER expression pattern during PCa progression. The study was undertaken to revisit the existing data on the epithelial ER expression pattern in human cancerous prostates and experimentally determine whether these patterns are replicated in TRAMP (Transgenic Adenocarcinoma of Mouse Prostate) mice, a model for human PCa. Estradiol (E2) binding to the plasma membrane of the epithelial cells and its modulation during the PCa progression in TRAMP were also investigated.A reassessment of the existing data revealed a trend towards downregulation in the epithelial expression of wild-type ESR1 transcripts in high-grade PCa, compared to non-cancerous prostate in humans. Next, epithelial cell-enriched populations from TRAMP prostates (TP) displaying low-grade prostatic intraepithelial neoplasia (LGPIN), high-grade PIN (HGPIN), HGPIN with well-differentiated carcinoma (PIN + WDC), WDC (equivalent to grade 2/3 human PCa), and poorly-differentiated carcinoma (PDC-equivalent to grade 4/5 human PCa) revealed significantly higher Esr1 and Esr2 levels in HGPIN and significantly reduced levels in WDC, compared to respective age-matched control prostates. These patterns for the nuclear ERs were similar to the trend shown by E2 binding to the plasma membrane of the epithelial cells during PCa progression in TRAMP. E2 binding to epithelial cells (EpCAM+), though significantly higher in TPs displaying LGPIN, decreased significantly as the disease progressed to WDC. The study highlights a reduction in the epithelial ESR level with the PCa progression and this pattern was evident in both humans and TRAMP. These observations may have major implications in refining PCa therapeutics targeting ER.

The relationship between sex hormones and glycated hemoglobin in a non-diabetic middle-aged and elderly population

BackgroundSex hormones are strongly linked to the occurrence and development of diabetes, and influence glycated hemoglobin (HbA1c) levels in diabetic population; but, the relationship between sex hormones and HbA1c in non-diabetic population remains unknown. This study aimed to explore the extent of influence of sex hormones on HbA1c levels in non-diabetic population.MethodsA total of 1409 non–diabetic subjects, including 601 men and 808 postmenopausal women were recruited from Shanghai community. HbA1c was detected using high performance liquid chromatography, and hemoglobin level was determined by sodium lauryl sulfate colorimetry. Serum estradiol (E2), total testosterone (TT), and sex hormone binding globulin (SHBG) were measured by chemiluminescent microparticle immunoassays.ResultsThe level of HbA1c was 5.6 (5.4–5.9) % in all subjects, with 5.6 (5.4–5.8) % in men and 5.7 (5.5–5.9) % in postmenopausal women. After adjusting for age, body mass index (BMI), and hemoglobin, E2 was positively correlated with HbA1c in men (r = 0.122, P = .003), and SHBG was inversely correlated with HbA1c (r = − 0.125, P < .001) in women. Other hormones were not correlated with HbA1c (all P > .05). Multivariate linear regression analysis showed that, except for traditional factors, such as age, hemoglobin, and BMI, E2 was another determinant of HbA1c (standardized β = 0.137, P = .003) in men; besides, in women, SHBG was another determinant of HbA1c (standardized β = − 0.178, P < .001), except for age and systolic blood pressure.ConclusionAfter controlling for confounding factors, two sex hormones, as E2 and SHBG could influence HbA1c levels in non-diabetic population.

In Vitro and In Silico Determination of Some N-ferrocenylmethylaniline Derivatives as Anti-Proliferative Agents Against MCF-7 Human Breast Cancer Cell Lines.

Since the binding of estradiol to its receptor promotes breast cancer cell proliferation (in the ER+ tumours), many molecules targeting this protein have been synthesized to counteract the estradiol action. Ferrocene derivatives have proved their efficiency against hormone-dependent breast cancer cells (MCF-7). In this study, we aimed to find new ferrocene derivatives having pharmacochemistry properties as potential drugs against human breast cancer cells. A series of 29 N-ferrocenylmethylaniline derivatives A0-A28 were synthesised, and their anti-proliferative activity against both hormone-dependent (MCF-7) and independent (MDA-MB 231) human breast cancer cell lines were performed using the MTT test. Molecular docking and drug-likeness prediction were also performed for the five most active derivatives towards MCF-7. A QSAR model was also developed for the perdition of the anti-proliferative activity against MCF-7 cell lines using molecular descriptors and MLR analysis. All studied derivatives demonstrated better cytotoxicity against MCF-7 compared to the MDA-MB-231 cell lines, and compounds A2, A9, A14, A17 and A27 were the most potent ones but still less active than the standard anticancer drug, crizotinib. The QSAR study revealed good predictive ability, as shown by R2 cv = 0.848. In vitro and in silico results indicated that derivatives A2, A9, A14, A17, and A27 possess the highest anti-proliferative activity; these results can be used to design more potent N-ferrocenylmethylaniline derivatives as anti-proliferative agents.

Abstract OT2-11-08: AMEERA-5 : A randomized, double-blind phase 3 study of amcenestrant (SAR439859) + palbociclib versus letrozole + palbociclib for previously untreated ER+/HER2- advanced breast cancer

Abstract Background Selective estrogen receptor degraders (SERDs) block estrogen receptor (ER) associated signaling and have created interest for treating patients (pts) with advanced ER+ breast cancer (BC). Fulvestrant is currently the only SERD available for advanced BC but requires intramuscular administration, limiting the applied dose, exposure and receptor engagement. Amcenestrant (SAR439859) is an oral SERD that binds with high affinity to both wild-type and mutant ER, blocking estradiol binding and promoting up to 98% ER degradation in preclinical studies. In the phase I AMEERA-1 study of pretreated pts with ER+/HER2- advanced BC, amcenestrant 150-600 mg once daily (QD) showed a mean ER occupancy of 94% with plasma concentrations &amp;gt; 100 ng/mL and a favorable safety profile (Bardia, 2019; data on file). Combination therapy with amcenestrant + palbociclib (palbo) was also evaluated as part of this ongoing phase I study. CDK 4/6 inhibitors (CDK4/6i) combined with an aromatase inhibitor (AI), the gold standard for first line treatment for advanced breast cancer, prolong progression free survival (PFS) in pts with no prior treatment for ER+/HER2- advanced BC, but OS benefit has not been shown yet in postmenopausal pts. There remains a clinical need for more effective treatments in this setting. Methods AMEERA-5 (NCT04478266) is an ongoing, prospective, randomized, double-blind phase III study comparing the efficacy and safety of amcenestrant + palbo with that of letrozole + palbo in pts with advanced, locoregional recurrent or metastatic ER+/HER2- BC who have not received prior systemic therapy for advanced disease. The study includes men, pre/peri-menopausal (with goserelin) and post-menopausal women. Pts with progression during or within 12 months of (neo)adjuvant endocrine therapy using any of the following agents are excluded: AI, selective estrogen receptor modulators, CDK4/6i. Pts are randomized 1:1 to either continuous amcenestrant 200 mg or letrozole 2.5 mg QD orally with matching placebos; both combined with palbo 125 mg QD orally (d1-21 every 28-d cycle). Randomization is stratified according to disease type (de novo metastatic vs recurrent disease), the presence of visceral metastasis, and menopausal status. The primary endpoint is investigator assessed progression free survival (PFS) (RECIST v1.1). Secondary endpoints are overall survival, PFS2, objective response rate, duration of response, clinical benefit rate, pharmacokinetics of amcenestrant and palbo, health-related quality of life, time to chemotherapy, and safety. Biomarkers will be measured in paired tumor biopsies and cell free deoxyribonucleic acid (cfDNA) over time. Target enrolment = 1066 pts; enrolment as of 6/2021 = 415 pts. Bardia A, et al., J Clin Oncol. 2019; 37 (15 suppl):1054. Funding: Sanofi. This abstract was accepted and previously presented at the 2021 American Society of Clinical Oncology Annual Meeting. All rights reserved. Citation Format: Aditya Bardia, Javier Cortes, Sara Hurvitz, Suzette Delaloge, Hiroji Iwata, Zhi-Ming Shao, Dheepak Kanagavel, Patrick Cohen, Qianying Liu, Sylvaine Cartot-Cotton, Vasiliki Pelekanou, Joyce O’Shaughnessy. AMEERA-5 : A randomized, double-blind phase 3 study of amcenestrant (SAR439859) + palbociclib versus letrozole + palbociclib for previously untreated ER+/HER2- advanced breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT2-11-08.

Insights into the substrate binding mechanism of SULT1A1 through molecular dynamics with excited normal modes simulations

Sulfotransferases (SULTs) are phase II drug-metabolizing enzymes catalyzing the sulfoconjugation from the co-factor 3′-phosphoadenosine 5′-phosphosulfate (PAPS) to a substrate. It has been previously suggested that a considerable shift of SULT structure caused by PAPS binding could control the capability of SULT to bind large substrates. We employed molecular dynamics (MD) simulations and the recently developed approach of MD with excited normal modes (MDeNM) to elucidate molecular mechanisms guiding the recognition of diverse substrates and inhibitors by SULT1A1. MDeNM allowed exploring an extended conformational space of PAPS-bound SULT1A1, which has not been achieved up to now by using classical MD. The generated ensembles combined with docking of 132 SULT1A1 ligands shed new light on substrate and inhibitor binding mechanisms. Unexpectedly, our simulations and analyses on binding of the substrates estradiol and fulvestrant demonstrated that large conformational changes of the PAPS-bound SULT1A1 could occur independently of the co-factor movements that could be sufficient to accommodate large substrates as fulvestrant. Such structural displacements detected by the MDeNM simulations in the presence of the co-factor suggest that a wider range of drugs could be recognized by PAPS-bound SULT1A1 and highlight the utility of including MDeNM in protein–ligand interactions studies where major rearrangements are expected.

Perfluoroalkyl and polyfluoroalkyl substance exposure and association with sex hormone concentrations: results from the NHANES 2015\u20132016

BackgroundThere is increasing global concern regarding the health impacts of perfluoroalkyl and polyfluoroalkyl substances (PFAS), which are emerging environmental endocrine disruptors. Results from previous epidemiological studies on the associations between PFAS exposure and sex hormone levels are inconsistent.ObjectiveWe examined the associations between serum PFAS compounds (PFDeA, PFHxS, PFNA, PFOA, PFOS) and sex hormones, including total testosterone (TT), free testosterone (FT), estradiol (E), and serum hormone binding globulin (SHBG).ResultsAfter adjusting for potential confounders, PFDeA, PFOS, and PFHxS exposures were significantly associated with increased serum testosterone concentrations in males. PFDeA, PFOA, and PFOS exposures were positively correlated with FT levels in 20–49-year-old women, while PFOS exposure was negatively associated with TT levels in 12–19-year-old girls. PFAS exposure was negatively associated with estradiol levels including: PFDeA in all females, PFHxS, PFNA, PFOS, and PFOA in 12–19-year-old girls, PFNA in women above 50 years, and PFOA in 12–19-year-old boys, while PFDeA and PFOS exposures were positively associated with estradiol levels in these boys. n-PFOS exposure was positively associated with SHBG levels in men older than 20 and in all females.ConclusionsUsing a large cohort of males and females aged from 12 to 80, we found that PFAS exposure appears to disrupt sex hormones in a sex-, age-, and compound-specific manner. Future work is warranted to clarify the causality and mechanisms involved.

1266-PUB: Correlation of Sex Hormones Levels and Glycated Hemoglobin in Nondiabetic Middle-Aged and Elderly

Aims: Sex hormones are strongly linked to the occurrence and development of diabetes, and influence glycated hemoglobin (HbA1c) levels in diabetic population; but, the relationship between sex hormones and HbA1c in nondiabetic population remains unknown. This study aimed to explore the extent of influence of sex hormones on HbA1c levels in nondiabetic population. Methods: A total of 1409 nondiabetic subjects, including 601 men and 808 postmenopausal women were recruited from Shanghai community. HbA1c was detected using high performance liquid chromatography, and hemoglobin level was determined by sodium lauryl sulfate colorimetry. Serum estradiol (E2), total testosterone (TT), and sex hormone binding globulin (SHBG) were measured by chemiluminescent microparticle immunoassays. Results: The level of HbA1c was 5.6 (5.4-5.9) % in all subjects, with 5.6 (5.4-5.8) % in men and 5.7 (5.5-5.9) % in postmenopausal women. After adjusting for age, body mass index (BMI), and hemoglobin, E2 was positively correlated with HbA1c in men (r = 0.122, P = 0.003), and SHBG was inversely correlated with HbA1c (r = -0.125, P &amp;lt; 0.001) in women. Other hormones were not correlated with HbA1c (all P &amp;gt; 0.05). Multivariate linear regression analysis showed that, except for traditional factors, such as age, hemoglobin, and BMI, E2 was another determinant of HbA1c (standardized β = 0.137, P = 0.003) in men and the regression equation was HbA1c (%) = 0.001×E2 (pmol/ L) +5.465. In women, SHBG was another determinant of HbA1c (standardized β = -0.178, P &amp;lt; 0.001), except for age and systolic blood pressure (SBP), and the regression equation was HbA1c (%) = -0.002×SHBG (nmol)/L) +5.772. Conclusion: After controlling for confounding factors, E2 is positively correlated with HbA1c in men, and SHBG is inversely correlated with HbA1c in postmenopausal women. Sex hormones influence HbA1c levels in nondiabetic population, but it is very limited to affect the level of HbA1c in the diagnose of diabetes. Disclosure Y. Bao: None. Y. Xu: None. W. Cao: None. Y. Shen: None. J. Tang: None. Y. Wang: None. X. Ma: None.

AMEERA-5: A randomized, double-blind phase III study of amcenestrant (SAR439859) + palbociclib versus letrozole + palbociclib for previously untreated ER+/HER2- advanced breast cancer.

TPS1104 Background: Selective estrogen receptor degraders (SERDs) block estrogen receptor (ER) associated signaling and have created interest for treating patients (pts) with advanced ER+ breast cancer (BC). Fulvestrant is currently the only SERD available for advanced BC but requires intramuscular administration, limiting the applied dose, exposure and receptor engagement. Amcenestrant (SAR439859) is an oral SERD that binds with high affinity to both wild-type and mutant ER, blocking estradiol binding and promoting up to 98% ER degradation in preclinical studies. In the phase I AMEERA-1 study of pretreated pts with ER+/HER2- advanced BC, amcenestrant 150–600 mg once daily (QD) showed a mean ER occupancy of 94% with plasma concentrations &gt; 100 ng/mL and a favorable safety profile (Bardia, 2019; data on file). Combination therapy with amcenestrant + palbociclib (palbo) was also evaluated as part of this ongoing phase I study. CDK 4/6 inhibitors (CDK4/6i) combined with an aromatase inhibitor (AI), the gold standard for first line treatment for advanced breast cancer, prolong progression free survival (PFS) in pts with no prior treatment for ER+/HER2- advanced BC, but OS benefit has not been shown yet in postmenopausal pts. There remains a clinical need for more effective treatments in this setting. Methods: AMEERA-5 (NCT04478266) is an ongoing, prospective, randomized, double-blind phase III study comparing the efficacy and safety of amcenestrant + palbo with that of letrozole + palbo in pts with advanced, locoregional recurrent or metastatic ER+/HER2- BC who have not received prior systemic therapy for advanced disease. The study includes men, pre/peri-menopausal (with goserelin) and post-menopausal women. Pts with progression during or within 12 months of (neo)adjuvant endocrine therapy using any of the following agents are excluded: AI, selective estrogen receptor modulators, CDK4/6i. Pts are randomized 1:1 to either continuous amcenestrant 200 mg or letrozole 2.5 mg QD orally with matching placebos; both combined with palbo 125 mg QD orally (d1–21 every 28-d cycle). Randomization is stratified according to disease type (de novo metastatic vs recurrent disease), the presence of visceral metastasis, and menopausal status. The primary endpoint is investigator assessed progression free survival (PFS) (RECIST v1.1). Secondary endpoints are overall survival, PFS2, objective response rate, duration of response, clinical benefit rate, pharmacokinetics of amcenestrant and palbo, health-related quality of life, time to chemotherapy, and safety. Biomarkers will be measured in paired tumor biopsies and cell free deoxyribonucleic acid (cfDNA) over time. Target enrolment = 1066 pts; enrolment as of 1/2021 = 33 pts. Bardia A, et al., J Clin Oncol. 2019; 37 (15 suppl):1054 Clinical trial information: NCT04478266 .

Estradiol induces allosteric coupling and partitioning of sex-hormone-binding globulin monomers among conformational states

SummarySex-hormone-binding globulin (SHBG) regulates the transport and bioavailability of estradiol. The dynamics of estradiol's binding to SHBG are incompletely understood, although it is believed that estradiol binds to each monomer of SHBG dimer with identical affinity (Kd ∼2 nM). Contrary to the prevalent view, we show that estradiol's binding to SHBG is nonlinear, and the "apparent" Kd changes with varying estradiol and SHBG concentrations. Estradiol's binding to each SHBG monomer influences residues in the ligand-binding pocket of both monomers and differentially alters the conformational and energy landscapes of both monomers. Monomers are not energetically or conformationally equivalent even in fully bound state.Estradiol's binding to SHBG involves bidirectional, inter-monomeric allostery that changes the distribution of both monomers among various energy and conformational states. Inter-monomeric allostery offers a mechanism to extend the binding range of SHBG and regulate hormone bioavailability as estradiol concentrations vary widely during life.

Estradiol activates ERK phosphorylation by binding to ERβ to inhibit proliferation and promote apoptosis of human chondrocytes

To explore the effect of estradiol (E2) binding to its receptor ERβ on the proliferation and apoptosis of C28I2 cells. We cloned the sequence of ESR2 into a recombinant adenovirus plasmid (pAd-ESR2) and packaged the plasmid in HEK293 cells. Normal human chondrocyte C28I2 cells were transfected with Ad-ESR2 or small interfering RNA targeting ESR2-siRNA (ESR2-siRNA), and the effects of treatment with DMSO or E2 on the expression of the proteins associated with endoplasmic reticulum (ER) stress and cell apoptosis were determined using Western blotting. qRT-PCR was used to detect the expressions of proliferation-related marker genes, and an EdU kit and flow cytometry were used to assess cell proliferation and apoptosis. We also tested the effects of U0126 (an ERK pathway inhibitor) and E2, alone or in combination, on ER stress, apoptosis and the ERK signaling pathway in C28I2 cells infected with Ad-ESR2 using Western blotting. Overexpression of Ad-ESR2 in C28I2 cells significantly promoted the expressions of IRE1α, PERK, XBP1s, and cleaved caspase-12, inhibited proliferation related marker genes PCNA, cyclin B1, cyclin D1, and decreased the level of ERK phosphorylation following E2 treatment (all P < 0.05). Interference of ESR2 caused significant reduction in the expressions of ER stress-related proteins and apoptosis-related proteins, up-regulated the genes related to cell proliferation, and increased intracellular pERK/ERK ratio in C28I2 cells. The effect of E2 binding to ERβ, which promoted the expressions of ER stress associated proteins and apoptosis related proteins, was obviously antagonized by treatment of the cells with U0126. The binding of E2 to ERβ promotes ER stress and apoptosis in human chondrocytes by activating ERK pathway phosphorylation inhibit cell proliferation.

Interaction of Cytochrome C Oxidase with Steroid Hormones.

Estradiol, testosterone and other steroid hormones inhibit cytochrome c oxidase (CcO) purified from bovine heart. The inhibition is strongly dependent on concentration of dodecyl-maltoside (DM) in the assay. The plots of Ki vs [DM] are linear for both estradiol and testosterone which may indicate an 1:1 stoichiometry competition between the hormones and the detergent. Binding of estradiol, but not of testosterone, brings about spectral shift of the oxidized CcO consistent with an effect on heme a33+. We presume that the hormones bind to CcO at the bile acid binding site described by Ferguson-Miller and collaborators. Estradiol is shown to inhibit intraprotein electron transfer between hemes a and a3. Notably, neither estradiol nor testosterone suppresses the peroxidase activity of CcO. Such a specific mode of action indicates that inhibition of CcO activity by the hormones is associated with impairing proton transfer via the K-proton channel.