RNA fine-tunes estrogen receptor-alpha binding on low-affinity DNA motifs for transcriptional regulation.

Transcription factors (TFs) regulate gene expression by binding with varying strengths to DNA via their DNA-binding domain. Additionally, some TFs also interact with RNA, which modulates transcription factor binding to chromatin. However, whether RNA-mediated TF binding results in differential transcriptional outcomes remains unknown. In this study, we demonstrate that estrogen receptor α (ERα), a ligand-activated TF, interacts with RNA in a ligand-dependent manner. Defects in RNA binding lead to genome-wide loss of ERα recruitment, particularly at weaker ERα-motifs. Furthermore, ERα mobility in the nucleus increases in the absence of its RNA-binding capacity. Unexpectedly, this increased mobility coincides with robust polymerase loading and transcription of ERα-regulated genes that harbor low-strength motifs. However, highly stable binding of ERα on chromatin negatively impacts ligand-dependent transcription. Collectively, our results suggest that RNA interactions spatially confine ERα on low-affinity sites to fine-tune gene transcription.

Running the Female Power Grid Across Lifespan Through Brain Estrogen Signaling.

The role of central estrogen in cognitive, metabolic, and reproductive health has long fascinated the lay public and scientists alike. In the last two decades, insight into estrogen signaling in the brain and its impact on female physiology is beginning to catch up with the vast information already established for its actions on peripheral tissues. Using newer methods to manipulate estrogen signaling in hormone-sensitive brain regions, neuroscientists are now identifying the molecular pathways and neuronal subtypes required for controlling sex-dependent energy allocation. However, the immense cellular complexity of these hormone-sensitive brain regions makes it clear that more research is needed to fully appreciate how estrogen modulates neural circuits to regulate physiological and behavioral end points. Such insight is essential for understanding how natural or drug-induced hormone fluctuations across lifespan affect women's health.

Role of estrogen signaling in fibroblastic reticular cells for innate and adaptive immune responses in antigen-induced arthritis.

Women are more prone to develop rheumatoid arthritis, with peak incidence occurring around menopause. Estrogen has major effects on the immune system and is protective against arthritis. We have previously shown that treatment with estrogen inhibits inflammation and joint destruction in murine models of arthritis, although the mechanisms involved remain unclear. Fibroblastic reticular cells (FRCs) are specialized stromal cells that generate the three-dimensional structure of lymph nodes (LNs). FRCs are vital for coordinating immune responses from within LNs and are characterized by the expression of the chemokine CCL19, which attracts immune cells. The aim of this study was to determine whether the influence of estrogen on innate and adaptive immune cells in arthritis is mediated by estrogen signaling in FRCs. Conditional knockout mice lacking estrogen receptor α (ERα) in CCL19-expressing cells (Ccl19-CreERαfl/fl) were generated and tested. Ccl19-CreERαfl/fl mice and littermate controls were ovariectomized, treated with vehicle or estradiol and subjected to the 28-day-long antigen-induced arthritis model to enable analyses of differentiated T- and B-cell populations and innate cells in LNs by flow cytometry. The results reveal that while the response to estradiol treatment in numbers of FRCs per LN is significantly reduced in mice lacking ERα in FRCs, estrogen does not inhibit joint inflammation or markedly affect immune responses in this arthritis model. Thus, this study validates the Ccl19-CreERαfl/fl strain for studying estrogen signaling in FRCs within inflammatory diseases, although the chosen arthritis model is deemed unsuitable for addressing this question.

Estrogen receptor alpha (ERα) regulates PARN-mediated nuclear deadenylation and gene expression in breast cancer cells.

The estrogen signalling pathway is highly dynamic and primarily mediated by estrogen receptors (ERs) that transcriptionally regulate the expression of target genes. While transcriptional functions of ERs have been widely studied, their roles in RNA biology have not been extensively explored. Here, we reveal a novel biological role of ER alpha (ERα) in mRNA 3' end processing in breast cancer cells, providing an alternative mechanism in regulating gene expression at the post-transcriptional level. We show that ERα activates poly(A) specific ribonuclease (PARN) deadenylase using in vitro assays, and that this activation is further increased by tumour suppressor p53, a factor involved in mRNA processing. Consistent with this, we confirm ERα-mediated activation of nuclear deadenylation by PARN in samples from MCF7 and T47D breast cancer cells that vary in expression of ERα and p53. We further show that ERα can form complex(es) with PARN and p53. Lastly, we identify and validate expression of common mRNA targets of ERα and PARN known to be involved in cell invasion, metastasis and angiogenesis, supporting the functional overlap of these factors in regulating gene expression in a transactivation-independent manner. Together, these results show a new regulatory mechanism by which ERα regulates mRNA processing and gene expression post-transcriptionally, highlighting its contribution to unique transcriptomic profiles and breast cancer progression.

Interaction of Per- and Polyfluoroalkyl Substances with Estrogen Receptors in Rainbow Trout (Oncorhynchus mykiss): An In Silico Investigation.

Fresh water sources, including lakes, such as the Great Lakes, are some of the most important ecosystems in the world. Despite the importance of these lakes, there is increasing concern about the presence of per- and polyfluoroalkyl substances (PFAS)─among the most prevalent contaminants of our time─due to the ability of PFAS to bioaccumulate and persist in the environment, as well as to its linkages to detrimental human and animal health effects. In this study, PFAS exposure on rainbow trout (Oncorhynchus mykiss) is examined at the molecular level, focusing on the impact of PFAS binding on the alpha (α) and beta (ß) estrogen receptors (ERs) using molecular dynamics simulations, binding free energy calculations, and structural analysis. ERs are involved in fundamental physiological processes, including reproductive system development, muscle regeneration, and immunity. This study shows that PFAS binds to both the estrogen α and estrogen ß receptors, albeit via different binding modes, due to a modification of an amino acid in the binding site as a result of a reorientation of residues in the binding pocket. As ER overactivation can occur through environmental toxins and pollutants, this study provides insights into the influence of different types of PFAS on protein function.

COPD-Like Phenotypes in TBC-Treated Mice Can be Effectively Alleviated via Estrogen Supplement.

Tris(2,3-dibromopropyl) isocyanurate (TBC), recognized as an endocrine disruptor, can cause inflammatory injury to the lung tissue of mice. To investigate the specific respiratory effects of TBC, male C57BL/6J mice were administered a daily dose of 20 mg/kg of TBC over 14 days. Postexposure, these mice developed chronic obstructive pulmonary disease (COPD)-like symptoms characterized by inflammatory lung damage and functional impairment. In light of the antiestrogenic properties of TBC, we administrated estradiol (E2) to investigate its potential protective role against TBC-induced damage and found that the coexposure of E2 notably mitigated the COPD-like phenotypes. Immunohistochemical analysis revealed that TBC exposure reduced estrogen receptor alpha (ERα) expression and increased nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) expression, while E2 treatment rebalanced the expression levels of ERα and NF-κB to their normative states. Our findings indicate that TBC, as an antiestrogenic agent, may contribute to the pathogenesis of COPD through an ERα-mediated inflammatory pathway, but that E2 treatment could reverse the impairment, providing a potentially promising remedial treatment. Given the lung status as a primary target of air pollution, the presence of antiestrogenic compounds like TBC in atmospheric particulates presents a significant concern, with the potential to exacerbate respiratory conditions such as COPD and pneumonia.

Stimulation of estrogen receptor-alpha by hydroxyanilide fungicide, fenhexamid promotes lipid accumulation in 3 T3-L1 adipocyte.

Fenhexamid are fungicides that act against plant pathogens by inhibiting sterol biosynthesis. Nonetheless, it can trigger endocrine disruption and promote breast cancer cell growth. In a recent study, we investigated the mechanism underlying the lipid accumulation induced by fenhexamid hydroxyanilide fungicides in 3 T3-L1 adipocytes. To examine the estrogen receptor alpha (ERα)-agonistic effect, ER transactivation assay using the ERα-HeLa-9903 cell line was applied, and fenhexamid-induced ERα agonist effect was confirmed. Further confirmation that ERα-dependent lipid accumulation occurred was provided by treating 3 T3-L1 adipocytes with Methyl-piperidino-pyrazole hydrate (MPP), an ERα-selective antagonist. Fenhexamid mimicked the actions of ERα agonists and impacted lipid metabolism, and its mechanism involves upregulation of the expression of transcription factors that facilitate adipogenesis and lipogenesis. Additionally, it stimulated the expression of peroxisome proliferator-activated receptor (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), fatty acid synthase (FAS), and sterol regulatory element-binding protein 1 (SREBP1) and significantly elevated the expression of fatty acid-binding protein 4 (FABP4). In contrast, in combination with an ERα-selective antagonist, fenhexamid suppressed the expression of adipogenic/lipogenic transcription factors. These results suggest that fenhexamid affects the endocrine system and leads to lipid accumulation by interfering with processes influenced by ERα activation.

Comprehensive Computational Screening and Analysis of Natural Compounds Reveals Promising Estrogen Receptor Alpha Inhibitors for Breast Cancer Therapy.

Breast cancer remains a leading cause of death among women, with estrogen receptor alpha (ERα) overexpression playing a pivotal role in tumor growth and progression. This study aimed to identify novel ERα inhibitors from a library of 561 natural compounds using computational techniques, including virtual screening, molecular docking, and molecular dynamics simulations. Four promising candidates-Protopine, Sanguinarine, Pseudocoptisine, and Stylopine-were selected based on their high binding affinities and interactions with key ERα residues. Molecular dynamics simulations conducted over 500 nanoseconds revealed that Protopine and Sanguinarine exhibited more excellent stability with minimal fluctuations, suggesting strong and stable binding. In contrast, Pseudocoptisine and Stylopine showed higher flexibility, indicating less stable interactions. Binding free energy calculations further supported the potential of Protopine and Sanguinarine as ERα inhibitors, though their binding strength was slightly lower than that of the reference compound. These findings highlight Protopine and Sanguinarine as leading candidates for further investigation, and in vitro and in vivo studies are recommended to evaluate their therapeutic potential in breast cancer treatment.

An ESR1-Related Gene Signature Identifies Head and Neck Squamous Cell Carcinoma with Imputed Susceptibility to Endocrine Therapy.

Head and neck squamous cell carcinoma (HNSCC) is associated with high morbidity and mortality. New personalized treatment strategies represent an unmet medical need to improve the overall survival and the quality of life of patients, which are often limited by the toxicity of established multimodal treatment protocols. Several studies have reported an increased expression of the estrogen receptor 1 (ESR1) in HNSCC, but its potential role in the disease outcome of these tumors remains elusive. Using an integrative analysis of multiomics and clinical data from The Cancer Genome Atlas (TCGA)-HNSC, we established a prognostic risk model based on an ESR1-related 25-gene set. The prognostic value was confirmed in an independent cohort of HNSCC and other solid tumors from TCGA. Finally, we performed in silico drug sensitivity modeling to explore potential vulnerabilities for both risk groups. This approach predicted a higher sensitivity for HNSCC, with prominent ESR1 pathway activity under treatment with specific estrogen receptor modulators. In conclusion, our data confirm the involvement of ESR1-related pathway activity in the progression of a defined subset of HNSCC, provide compelling evidence that these tumors share a specific vulnerability to endocrine therapy, and pave the way for preclinical studies and clinical trials to demonstrate the efficacy of this new therapeutic option.

ERα/LKB1 complex upregulates E-cadherin expression and stimulates breast cancer growth and progression upon adiponectin exposure.

Adiponectin is the major adipocytes-secreted protein involved in obesity-related breast cancer growth and progression. We proved that adiponectin promotes proliferation in ERα-positive breast cancer cells, through ERα transactivation and the recruitment of LKB1 as ERα-coactivator. Here, we showed that adiponectin-mediated ERα transactivation enhances E-cadherin expression. Thus, we investigated the molecular mechanism through which ERα/LKB1 complex may modulate the expression of E-cadherin, influencing tumor growth, progression and distant metastasis. We demonstrated that adiponectin increases E-cadherin expression in ERα-positive 2D and higher extent in 3D cultures. This occurs through a direct activation of E-cadherin gene promoter by ERα/LKB1-complex. The impact of E-cadherin on ERα-positive breast cancer cell proliferation comes from the evidence that in the presence of E-cadherin siRNA the proliferative effects of adiponectin is no longer noticeable. Since E-cadherin connects cell polarity and growth, we investigated if the adiponectin-enhanced E-cadherin expression could influence the localization of proteins cooperating in cell polarity, such as LKB1 and Cdc42. Surprisingly, immunofluorescence showed that, in adiponectin-treated MCF-7 cells, LKB1 and Cdc42 mostly colocalize in the nucleus, impairing their cytosolic cooperation in maintaining cell polarity. The orthotopic implantation of MCF-7 cells revealed an enhanced E-cadherin-mediated breast cancer growth induced by adiponectin. Moreover, tail vein injection of MCF-7 cells showed a higher metastatic burden in the lungs of mice receiving adiponectin-treated cells compared to control. From these findings it emerges that adiponectin treatment enhances E-cadherin expression, alters cell polarity and stimulates ERα-positive breast cancer cell growth in vitro and in vivo, sustaining higher distant metastatic burden.

The hypothalamic paraventricular nucleus as a central hub for the estrogenic modulation of neuroendocrine function and behavior.

Estradiol and hypothalamic paraventricular nucleus (PVN) help coordinate reproduction with body physiology, growth and metabolism. PVN integrates hormonal and neural signals originating in the periphery, generating an output mediated both by its long-distance neuronal projections, and by a variety of neurohormones produced by its magnocellular and parvocellular neurosecretory cells. Here we review the cyto-and chemo-architecture, the connectivity and function of PVN and the sex-specific regulation exerted by estradiol on PVN neurons and on the expression of neurotransmitters, neuromodulators, neuropeptides and neurohormones in PVN. Classical and non-classical estrogen receptors (ERs) are expressed in neuronal afferents to PVN and in specific PVN interneurons, projecting neurons, neurosecretory neurons and glial cells that are involved in the input-output integration and coordination of neurohormonal signals. Indeed, PVN ERs are known to modulate body homeostatic processes such as autonomic functions, stress response, reproduction, and metabolic control. Finally, the functional implications of the estrogenic modulation of the PVN for body homeostasis are discussed.

Clinical Implications and Treatment Strategies for ESR1 Fusions in Hormone Receptor-Positive Metastatic Breast Cancer: A Case Series.

In hormone receptor-positive metastatic breast cancer (HR+ MBC), endocrine resistance is commonly due to genetic alterations of ESR1, the gene encoding estrogen receptor alpha (ERα). While ESR1 point mutations (ESR1-MUT) cause acquired resistance to aromatase inhibition (AI) through constitutive activation, far less is known about the molecular functions and clinical consequences of ESR1 fusions (ESR1-FUS). This case series discusses 4 patients with HR+ MBC with ESR1-FUS in the context of the existing ESR1-FUS literature. We consider therapeutic strategies and raise the hypothesis that CDK4/6 inhibition (CDK4/6i) may be effective against ESR1-FUS with functional ligand-binding domain swaps. These cases highlight the importance of screening for ESR1-FUS in patients with HR+ MBC while continuing investigation of precision treatments for these genomic rearrangements.

Membrane expression of the estrogen receptor ERα is required for intercellular communications in the mammary epithelium.

17ß-Estradiol induces the postnatal development of mammary gland and influences breast carcinogenesis by binding to the estrogen receptor ERα. ERα acts as a transcription factor but also elicits rapid signaling through a fraction of ERα expressed at the membrane. Here, we have used the C451A-ERα mouse model mutated for the palmitoylation site to understand how ERα membrane signaling affects mammary gland development. Although the overall structure of physiological mammary gland development is slightly affected, both epithelial fragments and basal cells isolated from C451A-ERα mammary glands failed to grow when engrafted into cleared wild-type fat pads, even in pregnant hosts. Similarly, basal cells purified from hormone-stimulated ovariectomized C451A-ERα mice did not produce normal outgrowths. Ex vivo, C451A-ERα basal cells displayed reduced matrix degradation capacities, suggesting altered migration properties. More importantly, C451A-ERα basal cells recovered in vivo repopulating ability when co-transplanted with wild-type luminal cells and specifically with ERα-positive luminal cells. Transcriptional profiling identified crucial paracrine luminal-to-basal signals. Altogether, our findings uncover an important role for membrane ERα expression in promoting intercellular communications that are essential for mammary gland development.

GDNF-RET signaling and EGR1 form a positive feedback loop that promotes tamoxifen resistance via cyclin D1.

BACKGROUND: Rearranged during transfection (RET) tyrosine kinase signaling has been previously implicated in endocrine resistant breast cancer, however the mechanism by which this signaling cascade promotes resistance is currently not well described. We recently reported that glial cell-derived neurotrophic factor (GDNF)-RET signaling appears to promote a positive feedback loop with the transcription factor early growth response 1 (EGR1). Here we investigate the mechanism behind this feedback loop and test the hypothesis that GDNF-RET signaling forms a regulatory loop with EGR1 to upregulate cyclin D1 (CCND1) transcription, leading to cell cycle progression and tamoxifen resistance. METHODS: To gain a better understanding of the GDNF-RET-EGR1 resistance mechanism, we studied the GDNF-EGR1 positive feedback loop and the role of GDNF and EGR1 in endocrine resistance by modulating their transcription levels using CRISPR-dCAS9 in tamoxifen sensitive (TamS) and tamoxifen resistant (TamR) MCF-7 cells. Additionally, we performed kinetic studies using recombinant GDNF (rGDNF) treatment of TamS cells. Finally, we performed cell proliferation assays using rGDNF, tamoxifen (TAM), and Palbociclib treatments in TamS cells. Statistical significance for qPCR and chromatin immunoprecipitation (ChIP)-qPCR experiments were determined using a student's paired t-test and statistical significance for the cell viability assay was a one-way ANOVA. RESULTS: GDNF-RET signaling formed a positive feedback loop with EGR1 and also downregulated estrogen receptor 1 (ESR1) transcription. Upregulation of GDNF and EGR1 promoted tamoxifen resistance in TamS cells and downregulation of GDNF promoted tamoxifen sensitivity in TamR cells. Additionally, we show that rGDNF treatment activated GDNF-RET signaling in TamS cells, leading to recruitment of phospho-ELK-1 to the EGR1 promoter, upregulation of EGR1 mRNA and protein, binding of EGR1 to the GDNF and CCND1 promoters, increased GDNF protein expression, and subsequent upregulation of CCND1 mRNA levels. We also show that inhibition of cyclin D1 with Palbociclib, in the presence of rGDNF, decreases cell proliferation and resensitizes cells to TAM. CONCLUSION: Outcomes from these studies support the hypotheses that GDNF-RET signaling forms a positive feedback loop with the transcription factor EGR1, and that GDNF-RET-EGR1 signaling promotes endocrine resistance via signaling to cyclin D1. Inhibition of components of this signaling pathway could lead to therapeutic insights into the treatment of endocrine resistant breast cancer.

Endometrial cancer (EC) derived G3BP1 overexpression and mutant promote EC tumorigenesis and metastasis via SPOP/ERα axis.

BACKGROUND: Ras-GTPase-activating protein binding protein 1 (G3BP1) is an oncogenic factor, which highly expressed in a variety of cancers. In recent years, G3BP1 has been reported to promote the development of prostate cancer by inhibiting the degradation of AR through inhibiting SPOP. However, whether G3BP1 contributes in a similar manner to the abnormal accumulation of ERα, which is also an important target for hormone therapy, remains unknown. This article addresses this issue and explores potential mechanisms. METHODS: Bioinformatics tools were used for G3BP1 expression analysis, survival analysis, and clinical association analysis. Immunohistochemical staining was used to examine the correlation between G3BP1 and ERα in EC patients. In addition, western blot and co-immunoprecipitation were used to detect the half-life of G3BP1 and mutant, and the effect of G3BP1 and mutant on the ubiquitination and degradation of ERα mediated by SPOP. Then, the oncogenic functions of G3BP1 dependent on the SPOP/ERα axis were determined by CCK8 cell proliferation assay, colony formation assay and cell migration assay. Finally, we established the EC cells treated or untreated with fulvestrant, exploring the possibility of fulvestrant combined with the reduction of G3BP1 to improve the efficacy of fulvestrant. RESULTS: G3BP1 is abnormally high expressed and characterized by high-frequency mutation in EC. In addition, there is a positive correlation between G3BP1 protein and ERα protein. Mechanistically, both G3BP1 and mutant, the latter is displaying the longer half-life, competitively bind SPOP with ERα, thereby inhibiting SPOP-mediated ubiquitination and degradation of ERα. Functionally, G3BP1 and mutant promote the proliferation and migration of EC cells by regulating the G3BP1/SPOP/ERα axis. However, fulvestrant can reverse the cancer-promoting effects of G3BP1 and mutant. CONCLUSIONS: G3BP1 and its mutant positively regulate ERα signaling pathway by inhibiting SPOP-mediated ubiquitination and degradation of ERα, indicating the promising effect of fulvestrant on the suppression the occurrence and development of EC with high expressed G3BP1 and G3BP1 mutants. Video Abstract.

Sex differences in androgen receptor, estrogen receptor alpha, and c-Fos co-expression with corticotropin releasing factor expressing neurons in restrained adult mice.

Gonadal hormone actions through androgen receptor (AR) and estrogen receptor alpha (ERα) regulate sex differences in hypothalamic-pituitary-adrenal (HPA) axis responsivity and stress-related behaviors. Here we tested whether corticotropin releasing factor (CRF) expressing neurons, which are widely known to regulate neuroendocrine and behavioral stress responses, co-express AR and ERα as a potential mechanism for gonadal hormone regulation of these responses. Using Crh-IRES-Cre::Ai9 reporter mice we report high co-localization of AR in CRF neurons within the medial preoptic area (MPOA), bed nucleus of the stria terminalis (BST), medial amygdala (MeA), and ventromedial hypothalamus (VMH), moderate levels within the central amygdala (CeA) and low levels in the paraventricular hypothalamus (PVN). Sex differences in CRF/AR co-expression were found in the principal nucleus of the BST (BSTmpl), CeA, MeA, and VMH (males>females). CRF co-localization with ERα was generally lower relative to AR co-localization. However, high co-expression was found within the MPOA, AVPV, and VMH, with moderate co-expression in the arcuate nucleus (ARC), BST, and MeA and low levels in the PVN and CeA. Sex differences in CRF/ERα co-localization were found in the BSTmpl and PVN (males>females). Finally, we assessed neural activation of CRF neurons in restraint-stressed mice and found greater CRF/c-Fos co-expression in females in the BSTmpl and periaqueductal gray, while co-expression was higher in males within the ARC and dorsal CA1. Given the known role of CRF in regulating behavioral stress responses and the HPA axis, AR/ERα co-expression and sex-specific activation of CRF cell groups indicate potential mechanisms for modulating sex differences in these functions.

Estrogen receptor alpha mediates 17ß-estradiol, up-regulates autophagy and alleviates hydrogen peroxide-induced vascular senescence.

Atherosclerosis threatens human health by developing cardiovascular diseases, the deadliest disease world widely. The major mechanism contributing to the formation of atherosclerosis is mainly due to vascular endothelial cell (VECs) senescence. We have shown that 17ß-estradiol (17ß-E2) may protect VECs from senescence by upregulating autophagy. However, little is known about how 17ß-E2 activates the autophagy pathway to alleviate cellular senescence. Therefore, the aim of this study is to determine the role of estrogen receptor (ER) α and ß in the effects of 17ß-E2 on vascular autophagy and aging through in vitro and in vivo models. Hydrogen peroxide (H2O2) was used to establish Human Umbilical Vein Endothelial Cells (HUVECs) senescence. Autophagy activity was measured through immunofluorescence and immunohistochemistry staining of light chain 3 (LC3) expression. Inhibition of ER activity was established using shRNA gene silencing and ER antagonist. Compared with ER-ß knockdown, we found that knockdown of ER-α resulted in a significant increase in the extent of HUVEC senescence and senescence-associated secretory phenotype (SASP) secretion. ER-α-specific shRNA was found to reduce 17ß-E2-induced autophagy, promote HUVEC senescence, disrupt the morphology of HUVECs, and increase the expression of Rb dephosphorylation and SASP. These in vitro findings were found consistent with the in vivo results. In conclusion, our data suggest that 17ß-E2 activates the activity of ER-α and then increases the formation of autophagosomes (LC3 high expression) and decreases the fusion of lysosomes with autophagic vesicles (P62 low expression), which in turn serves to decrease the secretion of SASP caused by H2O2 and consequently inhibit H2O2-induced senescence in HUVEC cells.

The Aryl Hydrocarbon Receptor Ligand 6-Formylindolo(3,2-b)carbazole Promotes Estrogen Receptor Alpha and c-Fos Protein Degradation and Inhibits MCF-7 Cell Proliferation and Migration.

INTRODUCTION: Worldwide, breast cancer is the most common cancer in women and is the main cause of death among all neoplasia in this group. Luminal A breast cancer represents approximately 70% of all breast cancers and is treated with hormone therapies targeting estrogen receptor alpha (ERα). Unfortunately, patients develop drug resistance leading to recurrence of neoplasia due to estrogen-independent ERα reactivation. Therefore, it is crucial to identify new molecular targets downstream ERα signaling pathway that allows the implementation of better treatments to improve the outcome of breast cancer patients. Overexpression of c-Fos, an ERα gene target, has been associated with increased cell motility, malignancy, metastasis, and invasion while its neutralization results in decreased breast cancer tumorigenesis. The aryl hydrocarbon receptor (AHR) ligands halogenated and polycyclic aromatic hydrocarbons, highly toxic compounds, down regulate c-Fos and ERα levels. The present study aimed to evaluate whether 6-formylindolo(3,2-b)carbazole (FICZ), a no toxic AHR agonist, modifies c-Fos levels in MCF-7 mammary carcinoma cells as well as to determine its effects on cell proliferation and migration. In addition, the possible mechanism through which FICZ mediates c-Fos levels in MCF-7 cells was investigated. METHODS: Initially, the effect of FICZ on c-Fos mRNA and protein levels in MCF-7 cells, untreated or treated with estradiol, was evaluated by qPCR and Western blot. 2,3,7,8-Tetrachloro-dibenzo-p-dioxin, an AHR prototype agonist, was used as a positive control. Next, we examined the effect of FICZ on MCF-7 cell proliferation and migration by cell counting, MTT, 3H-thymidine incorporation, and scratch-wound assays. Finally, the involvement of proteasome 26S on ERα and c-Fos protein degradation was investigated by the use of MG132 and Western blot. RESULTS: The data show that FICZ treatment downregulates c-Fos mRNA and protein levels, most likely by promoting ERα proteasome degradation, blocking MCF-7 cell proliferation and migration. The results also demonstrate that liganded ERα was required for FICZ-mediated ERα degradation. CONCLUSIONS: Activation of AHR results in a decreased MCF-7 cell proliferation and migration by ERα and c-Fos down regulation. Targeting AHR might be a promising therapy for breast cancer treatment, particularly when estrogen-independent ERα reactivation presents.

Estrogen receptor alpha-mediated mitochondrial damage in intrahepatic bile duct epithelial cells leading to the pathogenesis of primary biliary cholangitis.

This study investigated the effects of estrogen and estrogen receptor alpha (ERα) on the pathogenesis of primary biliary cholangitis (PBC) in human intrahepatic bile duct epithelial cells (HiBECs). The researchers measured serum levels of ERα, oxidative stress indicators, and cytokines in PBC patients and healthy controls. They examined the expression of ERα, pyruvate dehydrogenase complex E2-component (PDC-E2), and apoptosis-related proteins in the small bile ducts. In vitro experiments with HiBECs showed that estrogen had a dual effect on cell viability, increasing it at low concentrations but reducing it at higher concentrations. ERα activation led to mitochondrial damage, apoptosis, and upregulation of ERα and PDC-E2 expression. These findings suggest that the high expression of ERα in the bile ducts contributes to mitochondrial damage, inflammation, and apoptosis in PBC. The study highlights ERα as a potential target for understanding and treating estrogen-mediated PBC pathogenesis.

Evaluation of tooth eruption rate of incisor teeth in rats with estrogen deficiency.

OBJECTIVES: To assess the influence of estrogen deficiency on tooth eruption rate (TER) and gene expression of estrogen receptor alpha and beta (ERα and ERß) in the odontogenic region of teeth with continuous formation in a rat model. MATERIALS AND METHODS: Ovariectomies (OVX; n = 25) and sham surgeries (SHAM; n = 25) were performed in female Wistar rats when animals were 25 days old. The TER of the lower incisors, both in impeded (hyperfunction condition) and unimpeded (trimmed incisal edge-hypofunction condition) conditions, was evaluated using standardized digital photographs acquired every 48-72 h for 3 weeks (35th-53rd day of life), using a camera coupled to a stereomicroscope. Quantitative real-time PCR was performed to evaluate the relative gene expression of ERα and ERß in the odontogenic region. RESULTS: The OVX group showed a significant reduction in TER when compared to the SHAM group, only in the impeded condition (p = 0.03). There was no statistically significant difference between the groups in ERα gene expression (p = 0.33). ERß showed a significantly higher gene expression in the OVX group (p ≤ 0.05). CONCLUSIONS: Estrogen deficiency decreases TER in teeth under impeded condition. Estrogen deficiency also increases ERß gene expression in the odontogenic region of teeth with continuous formation. CLINICAL RELEVANCE: Hormonal disturbances affecting estrogen levels can cause alterations in dental formation and teeth eruption.