Regulation Of Estrogen Receptor Expression Research Articles

Sexual dimorphism of early transcriptional reprogramming in degenerating peripheral nerves.

Sexual dimorphism is a powerful yet understudied factor that influences the timing and efficiency of gene regulation in axonal injury and repair processes in the peripheral nervous system. Here, we identified common and distinct biological processes in female and male degenerating (distal) nerve stumps based on a snapshot of transcriptional reprogramming 24 h after axotomy reflecting the onset of early phase Wallerian degeneration (WD). Females exhibited transcriptional downregulation of a larger number of genes than males. RhoGDI, ERBB, and ERK5 signaling pathways increased activity in both sexes. Males upregulated genes and canonical pathways that exhibited robust baseline expression in females in both axotomized and sham nerves, including signaling pathways controlled by neuregulin and nerve growth factors. Cholesterol biosynthesis, reelin signaling, and synaptogenesis signaling pathways were downregulated in females. Signaling by Rho Family GTPases, cAMP-mediated signaling, and sulfated glycosaminoglycan biosynthesis were downregulated in both sexes. Estrogens potentially influenced sex-dependent injury response due to distinct regulation of estrogen receptor expression. A crosstalk of cytokines and growth hormones could promote sexually dimorphic transcriptional responses. We highlighted prospective regulatory activities due to protein phosphorylation, extracellular proteolysis, sex chromosome-specific expression, major urinary proteins (MUPs), and genes involved in thyroid hormone metabolism. Combined with our earlier findings in the corresponding dorsal root ganglia (DRG) and regenerating (proximal) nerve stumps, sex-specific and universal early phase molecular triggers of WD enrich our knowledge of transcriptional regulation in peripheral nerve injury and repair.

The effect of hormonal levels and oxidative stress on bisphenol A and soy isoflavone reproductive toxicity in murine offspring.

Previous studies have suggested that human exposure to bisphenolA (BPA) and soy isoflavones (SIFs) can occur during pregnancy. The combination of these chemicals is hypothesized to have a toxic impact on the fetus. While BPA is an industrial chemical used widely in the manufacture of polycarbonate plastics and epoxy resins, SIFs are naturally occurring estrogen‑like phytoestrogens. To determine the impact of the combination of BPA and SIFs on fetal development, the body weight, organ weight, anogenital distance and histopathological changes in the testes of F1 offspring were assessed in mice. Hormonal effects were determined by measuring serum levels of estrogen receptor(ESR), follicle‑stimulating hormone (FSH), luteinizing hormone(LH) and testosterone (T). Additionally, mitochondrial DNA copy numbers, and the serum levels of malondialdehyde and superoxide dismutase, were determined to evaluate alterations in oxidative stress and potential toxicity. Exposure to BPA increased the body weight of the pups and reduced the ratio of anogenital distance to body weight, as well as testes weight. Moreover, BPA exposure also induced testicular lesions. The seminiferous tubules of testis were denatured in varying degrees and the lumen wall structure was disordered. The levels of ESR in all offspring and the Tlevels in male offspring significantly increased, compared with controls. Co‑exposure to BPA and SIFs exacerbated these changes in body weight, testicular lesions and hormonal levels, relative to BPA exposure alone. Additionally, oxidative damage was only induced by high‑dose BPA. Collectively, these findings suggested that BPA and SIFs could have synergistic effect on the reproductive system, which could be mediated by the regulation of ESR expression and testosterone release.

Hormonal Regulation of Estrogen Receptors

BackgroundWe previously showed that estrogen has beneficial effects on cardiovascular function via the novel G‐protein coupled estrogen receptor (GPER). Selectively activating GPER may elicit beneficial cardiovascular effects of estrogen without eliciting deleterious effects. Receptor expression is important in developing targeted pharmacological therapies, but the regulation and expression of estrogen receptors is still not fully understood.ObjectiveOur goal was to study the effects androgens, glucocorticoids, and progesterone on the expression of the classical estrogen receptor ERα and novel estrogen receptor GPER.MethodsMouse aortic smooth muscle cells (MOVAS) were grown in 10% FBS media to 80% confluency and then starved for 24 h in charcoal‐stripped 0.5% FBS. The plates were treated for 24 h with 100 nm of dexamethasone (DEX), dihydrotestosterone (DHT), medroxyprogesterone acetate (MPA), or vehicle. After treatment, RNA was extracted and droplet digital PCR was used to quantify the expression of both GPER and ERα. Results were analyzed using a one‐way ANOVA.ResultsGPER expression was decreased by both DHT (66% of control, p=0.006, n=9) and MPA (70% of control, p=0.012, n=6). The impact of DEX on GPER was not statistically significant (89% of control, p=0.245, n=9). ERα expression was significantly reduced by DEX (65% of control, p=0.0046, n=9), DHT (56% of control, p=0.004, n=9), and MPA (52% of control, p=0.005, n=6) as compared to controls.ConclusionsIn cultured vascular smooth muscle cells, DHT and MPA decreased the expression GPER, while DEX, DHT, and MPA downregulated ERα. These results suggest that androgens, glucocorticoids, and progesterone act at the transcriptional level to decrease the expression of GPER and ERα. This decrease in receptor expression could lessen beneficial effects of GPER and/or ERα on cardiovascular function. Future studies will address the impact of androgens, glucocorticoids, and progesterone on the molecular mechanisms and in vivo cardiovascular responses to estrogen. The regulation of estrogen receptor expression is important for understanding the clinical interactions that may alter the response to hormone therapy.Support or Funding InformationFunding was provided by NIH HL133619 to SHL.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Activation of pro-survival metabolic networks by 1,25(OH)2D3 does not hamper the sensitivity of breast cancer cells to chemotherapeutics

BackgroundWe have previously identified 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], the bioactive form of vitamin D3, as a potent regulator of energy-utilization and nutrient-sensing pathways in prostate cancer cells. In the current study, we investigated the effects of 1,25(OH)2D3 on breast cancer (BCa) cell metabolism using cell lines representing distinct molecular subtypes, luminal (MCF-7 and T-47D), and triple-negative BCa (MDA-MB-231, MDA-MB-468, and HCC-1143).Methods1,25(OH)2D3’s effect on BCa cell metabolism was evaluated by employing a combination of real-time measurements of glycolysis/oxygen consumption rates using a biosensor chip system, GC/MS-based metabolomics, gene expression analysis, and assessment of overall energy levels. The influence of treatment on energy-related signaling molecules was investigated by immunoblotting.ResultsWe show that 1,25(OH)2D3 significantly induces the expression and activity of the pentose phosphate pathway enzyme glucose-6-phosphate dehydrogenase (G6PD) in all BCa cell lines, however differentially influences glycolytic and respiratory rates in the same cells. Although 1,25(OH)2D3 treatment was found to induce seemingly anti-oxidant responses in MCF-7 cells, such as increased intracellular serine levels, and reduce the expression of its putative target gene thioredoxin-interacting protein (TXNIP), intracellular reactive oxygen species levels were found to be elevated. Serine accumulation in 1,25(OH)2D3-treated cells was not found to hamper the efficacy of chemotherapeutics, including 5-fluorouracil. Detailed analyses of the nature of TXNIP’s regulation by 1,25(OH)2D3 included genetic and pharmacological inhibition of signaling molecules and metabolic enzymes including AMP-activated protein kinase and G6PD, as well as by studying the ITCH (E3 ubiquitin ligase)-TXNIP interaction. While these investigations demonstrated minimal involvement of such pathways in the observed non-canonical regulation of TXNIP, inhibition of estrogen receptor (ER) signaling by tamoxifen mirrored the reduction of TXNIP levels by 1,25(OH)2D3, demonstrating that the latter’s negative regulation of ER expression is a potential mechanism of TXNIP modulation.ConclusionsAltogether, we propose that regulation of energy metabolism contributes to 1,25(OH)2D3’s anti-cancer effects and that combining 1,25(OH)2D3 with drugs targeting metabolic networks in tumor cells may lead to synergistic effects.

PI3K/mTOR mediate mitogen-dependent HDAC1 phosphorylation in breast cancer: a novel regulation of estrogen receptor expression.

Histone deacetylase 1 (HDAC1) is an important epigenetic controller involved in transcriptional regulation through modification of chromatin structure. Genetic and epigenetic changes and deregulation of signal transduction pathways have been implicated in the development of breast cancer. Downregulation of estrogen receptor α (ERα) expression is one of the mechanisms behind the acquisition of endocrine resistance. Sustained and increased hormone and growth factor receptor signaling in breast cancer cells contribute to resistance to endocrine therapy. Both HDACs and the PI3K/mTOR signaling pathway are becoming promising targets in breast cancer, reversing also acquired hormone resistance. Here we show how mitogens, activating the PI3K/mTOR pathway, trigger the phosphorylation of HDAC1 in breast cancer cells, which is completely dependent on the activity of the p70 S6 kinase (S6K1). Our findings show that S6K1, overexpressed in many breast cancers, controls HDAC1-dependent transcriptional regulation of ERα levels upon mitogenic stimuli, controlling HDAC1 recruitment to the ERα promoter. Furthermore, cell treatment with both mTOR and HDACs inhibitors shows an additive effect in inhibiting breast cancer proliferation. This confirms the novel cross-talk between the HDAC1 and PI3K pathways with clinical implications towards the treatment of this malignant disease.

Abstract B108: The novel HDAC inhibitor PCI-24781 synergizes with tamoxifen in ER-positive breast cancer by concertedly downregulating AKT1 expression.

Abstract Breast cancer continues to be the most frequently diagnosed malignancy in women, and is second only to lung cancer as the cause of cancer death. While aromatase inhibitors are more commonly used in postmenopausal women, tamoxifen remains the only approved hormonal therapy for premenopausal patients presenting with estrogen receptor (ER)-positive disease. However, the effectiveness of tamoxifen is limited, as many tumors develop resistance. As such, substantial effort has been made to improve and extend the effectiveness of tamoxifen. To this end, we have demonstrated that histone deacetylase (HDAC) inhibitors potentiate the anti-tumor activity of tamoxifen in preclinical models, and in an early phase trial durable responses were achieved in a heavily pre-treated patient cohort. Mechanistic studies have revealed that HDAC inhibition directs breast cancer cells into mitochondrial-mediated apoptosis in part by altering the balance of apoptotic gatekeepers (e.g. Bax, Bak, and Bcl-2). In the current study, we extend our mechanistic understanding of this combination in ER-positive cells using the novel hydroxamic acid type HDAC inhibitor PCI-24781. Early clinical evaluation suggests that PCI-24781 is a potent HDAC inhibitor and is well tolerated at doses exceeding those needed for preclinical synergy. Here we demonstrate that PCI-24781 and tamoxifen act individually to additively abrogate AKT cell signaling by down regulating AKT1 mRNA and protein expression. Furthermore, PCI-24781 represses ESR1 transcription and thus exerts its effect on AKT1 expression in part through the regulation of ER expression. Attenuated AKT signaling manifests in elevated GSK3α/β phosphorylation, Bim, and p21 and a reduction in cyclin D. Cells exhibit an induction of an array of pro-apoptotic drivers, mitochondrial release of cytochrome C, caspase activation, and cell death. These results suggest that HDACs regulate the response of AKT to tamoxifen and that the cooperative effects of HDAC inhibitors and tamoxifen lead to enhance cell death. Therefore, early introduction of an HDAC inhibitor into hormonal therapy in patients with ER-positive breast cancer may counter the emergence of tamoxifen resistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B108.

Nuclear Factor-κB Regulates Estrogen Receptor-α Transcription in the Human Heart

Estrogen receptor (ER)-mediated effects have been associated with the modulation of myocardial hypertrophy in animal models and in humans, but the regulation of ER expression in the human heart has not yet been analyzed. In various cell lines and tissues, multiple human estrogen receptor alpha (hERalpha) mRNA isoforms are transcribed from distinct promoters and differ in their 5'-untranslated regions. Using PCR-based strategies, we show that in the human heart the ERalpha mRNA is transcribed from multiple promoters, namely, A, B, C, and F, of which the F-promoter is most frequently used variant. Transient transfection reporter assays in a human cardiac myocyte cell line (AC16) with F-promoter deletion constructs demonstrated a negative regulatory region within this promoter. Site-directed mutagenesis and electrophoretic mobility shift assays indicated that NF-kappaB binds to this region. An inhibition of NF-kappaB activity by parthenolide significantly increased the transcriptional activity of the F-promoter. Increasing NF-kappaB expression by tumor necrosis factor-alpha reduced the expression of ERalpha, indicating that the NF-kappaB pathway inhibits expression of ERalpha in human cardiomyocytes. Finally, 17beta-estradiol induced the transcriptional activity of hERalpha promoters A, B, C, and F. In conclusion, inflammatory stimuli suppress hERalpha expression via activation and subsequent binding of NF-kappaB to the ERalpha F-promoter, and 17beta-estradiol/hERalpha may antagonize the inhibitory effect of NF-kappaB. This suggests interplay between estrogen/estrogen receptors and the pro-hypertrophic and inflammatory responses to NF-kappaB.

Melatonin as a chronobiotic/anticancer agent: cellular, biochemical, and molecular mechanisms of action and their implications for circadian-based cancer therapy.

Melatonin, as a new member of an expanding group of regulatory factors that control cell proliferation and loss, is the only known chronobiotic, hormonal regulator of neoplastic cell growth. At physiological circulating concentrations, this indoleamine is cytostatic and inhibits cancer cell proliferation in vitro via specific cell cycle effects. At pharmacological concentrations, melatonin exhibits cytotoxic activity in cancer cells. At both physiological and pharmacological concentrations, melatonin acts as a differentiating agent in some cancer cells and lowers their invasive and metastatic status through alterations in adhesion molecules and maintenance of gap junctional intercellular communication. In other cancer cell types, melatonin, either alone or in combination with other agents, induces apoptotic cell death. Biochemical and molecular mechanisms of melatonin's oncostatic action may include regulation of estrogen receptor expression and transactivation, calcium/calmodulin activity, protein kinase C activity, cytoskeletal architecture and function, intracellular redox status, melatonin receptor-mediated signal transduction cascades, and fatty acid transport and metabolism. A major mechanism mediating melatonin's circadian stage-dependent tumor growth inhibitory action is the suppression of epidermal growth factor receptor (EGFR)/mitogen-activated protein kinase (MAPK) activity. This occurs via melatonin receptor-mediated blockade of tumor linoleic acid uptake and its conversion to 13-hydroxyoctadecadienoic acid (13-HODE) which normally activates EGFR/MAPK mitogenic signaling. This represents a potentially unifying model for the chronobiological inhibitory regulation of cancer growth by melatonin in the maintenance of the host/cancer balance. It also provides the first biological explanation of melatonin-induced enhancement of the efficacy and reduced toxicity of chemo- and radiotherapy in cancer patients.

The regulation of estrogen receptor expression and function in human breast cancer.

Estrogen and estrogen receptor (ER) play an important role in the development and function of the mammary gland. During mammary gland development, the hypothalamus and pituitary gland signal changes in the level of plasma estrogen, which is associated with proliferation of the mammary epithelial cells, leading to branching of ducts and formation of alveolar structures called lobules. Normal mammary epithelial cells express low basal levels (0-37 fmol/mg cytosol protein) of ER, and immunohistochemical studies show that about 7% of normal breast epithelial cells stain positively for ER [1,2]. These levels fluctuate during the menstrual cycle in conjunction with the cyclic changes in estrogen [3]. Definitive evidence that ER plays a pivotal role in normal mammary development was demonstrated using transgenic mice that were homozygously deleted for the gene. Adult female ER knockout mice develop mammary glands with only vestigial ducts present at the nipples [4].KeywordsEstrogen ReceptorHuman Breast Cancer Cell LineEstrogen Receptor GeneHuman Estrogen ReceptorEstrogen Receptor ProteinThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Immunohistochemical analysis of estrogen receptors in cystic-endometritis-pyometra complex in the bitch

Monoclonal antibodies to human estrogen receptor were used with an indirect immunohistochemical technique to localize in formalin-fixed, paraffin-embedded sections of the genital tract of the bitch. The presence of estrogen receptors in the uterus of dogs with cystic hyperplasia endometritis complex (CHE) was compared with normal uteri from dogs at the same stage of estrous cycle. Lower estrogen receptor expression was found in the squamous metaplastic epithelium covering the luminal surface of the endometrium from dogs with CHE than in the columnar epithelium from normal dogs. In contrast, the basal glands from uteri of CHE group dogs contained more estrogen receptor than glands from normal dogs at the same stage of estrous cycle. This was most pronounced and statistically significant in the late secretary stage of the estrous cycle. When the glands presented cystic degeneration, the estrogen receptor labeling was less pronounced. The highest estrogen receptor score was present in normal glands from dogs treated with progestins. In this group even cystic degenerated glands contained high estrogen receptor concentrations compared with those of the other groups. From this study it was concluded that the down regulation of estrogen receptor expression in the endometrial glands under the influence of rising progesterone concentrations is defective in dogs with CHE. Therefore it is suggested that the regulation of estrogen receptor expression in endometrial glands may play an important role in the pathogenesis of CHE in the bitch.

The role of transforming growth factor-beta in the regulation of estrogen receptor expression in the MCF-7 breast cancer cell line.

The role of transforming growth factor-beta1 (TGFbeta1) in the regulation of estrogen receptor (ER) expression in MCF-7 cells was investigated. After treatment of the cells with 100 pM TGFbeta1, ER protein declined by about 30% at 6 h from a concentration of 413.5 fmol/mg protein in control cells to 289.5 fmol/mg protein in treated cells. The concentration of receptor remained suppressed for 24 h. Scatchard analysis demonstrated that the decrease in ER protein corresponded to a decrease in estradiol-binding sites, with no effect on the binding affinity of the ER. The dissociation constant of the estradiol-ER complex was 0.117 nM in TGFbeta1-treated cells compared to 0.155 nM in control cells. Treatment with TGFbeta1 did not influence the half-life of the ER. In TGFbeta1-treated cells, as well as in control cells, the half-life of the receptor was approximately 4 h. In contrast to the effect on ER concentration, TGFbeta1 treatment resulted in a greater decrease in the steady state level of ER messenger RNA (approximately 75%) at 6 h. By 24 h, a small recovery in the amount of messenger RNA was observed. Transcription run-on experiments demonstrated a decrease of approximately 70% in the level of ER gene transcription at 3 h. Transient transfections using an ER promoter-chloramphenicol acetyltransferase construct demonstrated that after TGFbeta1 treatment, chloramphenicol acetyltransferase activity decreased by 50%, suggesting that TGFbeta1 inhibition of the ER gene transcription is mediated through the ER promoter. Although treatment with TGFbeta1 decreased the ER concentration, the growth factor had no effect on the activity of ER, as measured by its effects on estradiol induction of progesterone receptor and pS2, suggesting that TGFbeta1 does not inhibit proliferation of MCF-7 cells by blocking ER activity.

The Role of Transforming Growth Factor- in the Regulation of Estrogen Receptor Expression in the MCF-7 Breast Cancer Cell Line

The Role of Transforming Growth Factor- in the Regulation of Estrogen Receptor Expression in the MCF-7 Breast Cancer Cell Line

Up-regulation of estrogen receptor mRNA and estrogen receptor activity by estradiol in liver of rainbow trout and other teleostean fish

Injection of estradiol (E 2) into immature rainbow trout resulted in the induction of the hepatic vitellogenin gene mediated by the nuclear estrogen receptor (ER). Liver ER mRNA rose markedly on E 2 treatment in three groups of trout kept at different temperatures. Only in the group kept at 4 °C did the total cellular ER, as measured by [ 3H]estradiol-binding activity in nuclear and cytosol fractions, parallel the ER mRNA level. In fish kept at 9 °C and 15 °C, the ratio of total ER activity to ER mRNA fell during chronic E 2 treatment, probably reflecting translational or post-translational control mechanisms. Upregulation of ER mRNA also occurred in sea raven, sculpin, winter flounder, and Atlantic salmon after E 2 treatment. Intrahepatic ER activity rose proportionately in Atlantic salmon kept at 6–9 °C but not in sea raven, sculpin, or flounder. We conclude that the regulation of ER expression in teleosts is complex and includes transcriptional, translational, and post-translational elements and is influenced by environmental temperature.

Regulation of estrogen receptor expression.

Regulation of estrogen receptor expression.

Regulation of estrogen receptor expression in breast cancer.

One of the most prevalent of cancers, breast cancer, is characterized by hormonal control of its growth. Expression of the estrogen receptor (ER) in MCF-7 breast cancer cells appears to be a complex process involving multiple steps subject to hormonal regulation by estrogen. Treatment of MCF-7 cells with estradiol results in the suppression of estrogen receptor protein. By 6 hours, the receptor protein declined by about 60% from a level of approximately 3.6 to 1.2 fmol/micrograms DNA and remained suppressed for 24-48 hours. Similar results were obtained with an estrogen receptor binding assay. Estrogen treatment also resulted in a decrease of receptor mRNA to approximately 10% of control values by 6 hours. Estrogen receptor remained at the suppressed level for up to 48 hours. Transcription run-on experiments demonstrated a transient decrease of about 90% in receptor gene transcription after 1 hour. By 3-6 hours transcription increased approximately 2-fold and remained elevated for at least 48 hours. These data suggest that estrogen suppresses ER mRNA by inhibition of ER gene transcription at early times and by a post-transcriptional effect on receptor mRNA at later times. To determine whether post-transcriptional regulation of ER gene expression is mediated by an ER-dependent mechanism independent of protein synthesis, we used the competitive estrogen antagonist, 4-hydroxytamoxifen, and the inhibitor of protein synthesis, cycloheximide, to study the regulation of ER mRNA by estradiol. 4-Hydroxytamoxifen had no effect on the steady-state level of receptor mRNA and effectively blocked the suppression of ER mRNA by estradiol. The metabolic inhibitor, cycloheximide, was unable to prevent the estrogen induced decrease in ER mRNA. These data provide evidence that the post-transcriptional suppression of ER expression through estradiol is mediated through the ER independent of protein synthesis.

Capacity of adipose tissue to promote growth and metastasis of a murine mammary carcinoma: effect of estrogen and progesterone.

Previously we have shown that a murine mammary carcinoma cell line, designated SPI, grows and metastasizes more efficiently in the mammary gland than in the subcutis. In this report, we examine the tissue specificity of this phenomenon. Our results show that SPI cells grow best in the mesenteric and ovarian fat pads and well in the mammary gland, but very poorly in the subcutis or peritoneal cavity. Massive dissemination of tumors from the ovarian and mesenteric sites occurs to the liver, spleen and diaphragm. In contrast, metastases from the mammary site occur primarily in the lung. Co-transplantation of a threshold number of SPI cells with mammary or ovarian fat fragments into the subcutis results in increased tumor growth, whereas very few tumors form in sham controls receiving no fat fragments. Removal of the ovaries of donor and recipient mice abrogates tumor growth in adipose tissue transplants. Estrogen can stimulate growth of SPI in adipose tissue sites, whereas progesterone inhibits growth. In contrast, in vivo growth of a stable metastatic variant selected from SPI cells was not inhibited by progesterone. SPI cells growing in ovarian and mesenteric fat pads showed increased expression of estrogen receptors and progesterone receptors, as well as detectable levels of epidermal-growth-factor receptors, whereas receptor levels decreased to baseline on tumors in the subcutis. The levels of estrogen-receptor mRNA reflect the corresponding functional expression of receptors; this finding suggests that the regulation of estrogen-receptor expression in this system is, at least in part, at the mRNA level. Our results are consistent with the model that adipose tissue exerts an estrogen-dependent positive regulatory effect on primary SPI tumor growth, and promotes the formation of metastases.