Role Of ERα Research Articles

Estrogen enhances the proliferation, migration, and invasion of papillary thyroid carcinoma via the ERα/KRT19 signaling axis.

Estrogen is thought to be the reason for the higher prevalence of papillary thyroid carcinoma (PTC) in fertile women; however, more study is required to completely comprehend how estrogen affects PTC development at the cellular level. Therefore, we combined Oxford Nanopore Technologies (ONT) sequencing to explore molecular markers of PTC and to investigate the molecular mechanisms by which estrogen promotes PTC development. The expression levels of ESR1 (ERα) and KRT19 in normal thyroid tissues and cancer tissues as well as in different cancer stages, races, genders, age groups, histological subtypes and nodular metastasis status of the TCGA database were analyzed online by Ualcan; the relationship between ESR1, KRT19 and the survival of THCA patients was analyzed. A PTC xenograft tumor model was established. An ERα specific inhibitor (MPP) was administered and an EDU cell proliferation assay was used to verify the effect of estrogen on PTC proliferation. KRT19 was knocked down in KTC-1 cells, and the proliferation, migration, and invasion abilities of PTC cells were determined using CCK-8, immunofluorescence labeling, Western blot for EMT-related proteins, scratch assay, and Transwell assay. The role of ERα in relation to KRT19 was investigated by Western blot and immunofluorescence. The effects of ERα/KRT19 signaling axis on the proliferation, migration and invasion ability of PTC cells were evaluated using EDU cell proliferation assay and Transwell. Using ONT sequencing, 15 pairs of PTC tissue and paracancer tissue samples were collected. A PPI network was constructed to validate the differential expression of KRT19 in combination with biosignature analysis, and the protein interaction between KRT19 and ESR1 was verified using STRING. Ualcan showed that the expression of ESR1 and KRT19 was higher in THCA tissues than in normal thyroid tissues. E2 activation of ERα promoted the growth of PTC cells and tissues. si-KRT19 inhibited the proliferation, migration and invasion of PTC cells. KRT19 together with ERα formed the ERα/KRT19 signaling axis. E2 activation of the ERα/KRT19 signaling axis promoted the proliferation, migration, and invasion of PTC cells. ONT sequencing and STRING website verified that KRT19 is significantly differentially expressed in PTC and that ESR1 and KRT19 have protein interactions and are related to the estrogen signaling pathway. Using public databases, RNA sequencing, and bioinformatics, we discovered that E2 stimulates the ERα/KRT19 signaling axis to stimulate PTC proliferation, migration, and invasion.

Role of ERα and Aromatase in Juvenile Gigantomastia.

Approximately 150 patients with juvenile gigantomastia have been reported in the literature but the underlying biologic mechanisms remain unknown. To conduct extensive clinical, biochemical, immunochemical, and genetic studies in 3 patients with juvenile gigantomastia to determine causative biologic factors. We examined clinical effects of estrogen by blockading estrogen synthesis or its action. Breast tissue aromatase expression and activity were quantitated in 1 patient and 5 controls. Other biochemical markers, including estrogen receptor α (ERα), cyclin D1 and E, p-RB, p-MAPK, p-AKT, BCL-2, EGF-R, IGF-IR β, and p-EGFR were assayed by Western blot. Immunohistochemical analyses for aromatase, ERα and β, PgR, Ki67, sulfotransferase, estrone sulfatase, and 17βHD were performed in all 3 patients. The entire genomes of the mother, father, and patient in the 3 families were sequenced. Blockade of estrogen synthesis or action in patients resulted in demonstrable clinical effects. Biochemical studies on fresh frozen tissue revealed no differences between patients and controls, presumably due to tissue dilution from the large proportion of stroma. However, immunohistochemical analysis of ductal breast cells in the 3 patients revealed a high percent of ERα (64.1% ± 7.8% vs reference women 9.6%, range 2.3-15%); aromatase score of 4 (76%-100% of cells positive vs 30.4% ± 5.6%); PgR (69.5% ± 15.2% vs 6.0%, range 2.7%-11.9%) and Ki67 (23.7% ± 0.54% vs 4.2%). Genetic studies were inconclusive although some intriguing variants were identified. The data implicate an important biologic role for ERα to increase tissue sensitivity to estrogen and aromatase to enhance local tissue production as biologic factors involved in juvenile gigantomastia.

The Role of ERα and ERβ in Castration-Resistant Prostate Cancer and Current Therapeutic Approaches.

Castration-resistant prostate cancer, or CRPC, is an aggressive stage of prostate cancer (PCa) in which PCa cells invade nearby or other parts of the body. When a patient with PCa goes through androgen deprivation therapy (ADT) and the cancer comes back or worsens, this is called CRPC. Instead of androgen-dependent signalling, recent studies show the involvement of the estrogen pathway through the regulation of estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) in CRPC development. Reduced levels of testosterone due to ADT lead to low ERβ functionality in inhibiting the proliferation of PCa cells. Additionally, ERα, which possesses androgen independence, continues to promote the proliferation of PCa cells. The functions of ERα and ERβ in controlling PCa progression have been studied, but further research is needed to elucidate their roles in promoting CRPC. Finding new ways to treat the disease and stop it from becoming worse will require a clear understanding of the molecular processes that can lead to CRPC. The current review summarizes the underlying processes involving ERα and ERβ in developing CRPC, including castration-resistant mechanisms after ADT and available medication modification in mitigating CRPC progression, with the goal of directing future research and treatment.

The Isoforms of Estrogen Receptor Alpha and Beta in Thyroid Cancer

The incidence of thyroid cancer was predominant in women, indicating that the sex hormone may have a role in thyroid cancer development. Generally, the sex hormone exerts its function by binding to the correspondent nuclear receptors. Therefore, aberrant of these receptors may be involved in the development of thyroid cancer. Estrogen receptor alpha (ERα) and beta (ERβ), two main estrogen receptors, have been reported to have an important role in the pathogenesis of thyroid cancer. When the ERα and ERβ genes undergo the alternative RNA splicing, some ERα and ERβ isoforms with incomplete functional domains may be formed. To date, several isoforms of ERα and ERβ have been identified. However, their expression and roles in thyroid cancer are far from clear. In this review, we summarized the expressions and roles of ERα and ERβ isoforms in thyroid cancer, aiming to provide the perspective of modulating the alternative RNA splicing of ERα and ERβ against thyroid cancer.

151-OR: 27-Hydroxycholesterol Inhibits Food Intake through ERa-Mediated Activation of POMC Neurons

Oxysterols are metabolites of cholesterol produced in peripheral tissues as a means to eliminate cholesterol. 27-hydroxycholesterol (27HC) is the most abundant oxysterols and can cross the blood-brain barrier. Interestingly, 27HC has recently been identified as an endogenous selective estrogen receptor modulator (SERM) for both estrogen receptor α and β (ERα/β) . Considering the regulatory effects of brain estrogen/ERα signaling on energy metabolism, we hypothesize that the endogenous SERM 27HC binds with ERα in the arcuate nucleus of hypothalamus (ARH) of brain to modulate energy homeostasis.In supporting this point of view, we found that a single acute intracerebroventricular (ICV) injection of 27HC inhibited food intake in both male and female mice. The reduced food intake was attributed to decreased meal size and increased intermeal intervals. This anorexigenic effect was also associated with the increased c-fos expression in the pro-opiomelanocortin neurons in ARH (POMCARH) . Using brain slice patch-clamp recording, we consistently showed that 27HC dose-dependently actives POMCARH in an ERα-dependent manner, suggesting a mediating role of ERα expressed by POMCARH neurons. Notably, we further revealed that the inhibitory effects of 27HC on food intake were blocked by antagonists for ERα or POMC downstream melanocortin 3/4 receptors. In addition, chemogenetic inhibition of POMCARH neurons also blunted the anorexigenic effects of 27HC in mice. Collectively, these results support a model that 27HC acutely inhibits food intake by acting on ERα to stimulate POMCARH neuronal activity. This 27HC/ERα/POMC signaling pathway may serve as a critical defending mechanism against high-fat diet-induced obesity. Disclosure H. Ye: None. B. Feng: None. D. Dixit: None. Y. He: None. P. Xu: None.

Bone mass and adaptation to mechanical loading are sexually dimorphic in adult osteoblast-specific ERα knockout mice.

Estrogen receptor-alpha (ERα) regulates bone mass and is implicated in bone tissue's response to mechanical loading. The effects of ERα deletion in mice depend on sex, anatomical location, and the cellular stage at which ERα is removed. Few studies have investigated the effect of age on the role of ERα in skeletal maintenance and functional adaptation. We previously demonstrated that bone mass and adaptation to loading were altered in growing 10-week-old female and male mice lacking ERα in mature osteoblasts and osteocytes (pOC-ERαKO). Here our goal was to determine the effects of ERα and mechanical loading in skeletally-mature adult mice. We subjected 26-week-old skeletally-mature adult pOC-ERαKO and littermate control (LC) mice of both sexes to two weeks of in vivo cyclic tibial loading. ERα deletion in male mice did not alter bone mass or the response to loading. Adult female pOC-ERαKO mice had reduced cancellous and cortical bone mass and increased adaptation to high-magnitude mechanical loading compared to LC mice. Thus, ERα deletion from mature osteoblasts reduced the bone mass and increased the mechanoadaptation of adult female but not male mice. Additionally, compared to our previous work in young mice, adult female mice had greatly reduced mechanoadaptation and adult male mice retained most of their mechanoadaptation with age.

Estrogen Biosynthesis and Signal Transduction in Ovarian Disease.

Estrogen mainly binds to estrogen receptors (ERs) to regulate menstrual cycles and reproduction. The expression of ERalpha (ERα), ERbeta (ERβ), and G-protein-coupled estrogen receptor (GPER) mRNA could be detected in ovary, suggesting that they play an important role in estrogen signal transduction in ovary. And many studies have revealed that abnormal expression of estrogen and its receptors is closely related to ovarian disease or malignant tumors. With the continuous development and research of animal models, tissue-specific roles of both ERα and ERβ have been demonstrated in animals, which enable people to have a deeper understanding of the potential role of ER in regulating female reproductive diseases. Nevertheless, our current understanding of ERs expression and function in ovarian disease is, however, incomplete. To elucidate the biological mechanism behind ERs in the ovary, this review will focus on the role of ERα and ERβ in polycystic ovary syndrome (PCOS), ovarian cancer and premature ovarian failure (POF) and discuss the major challenges of existing therapies to provide a reference for the treatment of estrogen target tissue ovarian diseases.

Anthocyanins Activate Membrane Estrogen Receptors With Nanomolar Potencies to Elicit a Nongenomic Vascular Response Via NO Production.

BackgroundThe vascular pharmacodynamics of anthocyanins is only partially understood. To examine whether the anthocyanin‐induced vasorelaxation is related to membrane estrogen receptor activity, the role of ERα or GPER antagonism was ascertained on anthocyanins or 17‐β estradiol‐(E2) induced vasodilatations and NO production.Methods and ResultsThe rat arterial mesenteric bed was perfused with either anthocyanins or corresponding 3‐O‐glycosides, or E2, to examine rapid concentration‐dependent vasorelaxations. The luminally accessible fraction of NO in mesenteric perfusates before and after anthocyanins or E2 administration was quantified. Likewise, NO‐DAF signal detected NO production in primary endothelial cells cultures incubated with anthocyanins or E2 in the absence and presence of ERα (ICI 182,780) or GPER (G‐36) selective antagonists. Anthocyanins or corresponding glycosides elicited, within minutes, vasodilation with nanomolar potencies; half maximal anthocyanin response reached 50% to 60% efficacy, in contrast to acetylcholine. The vasorelaxation is of rapid onset and exclusively endothelium‐dependent; NOS inhibition annulled the vasorelaxation. The delphinidin vascular response was not modified by 100 nmol/L atropine but significantly attenuated by joint application of ICI plus G‐36 (52±4.6 versus 8.5±1.5%), revealing the role of membrane estrogen receptors. Moreover, the anthocyanin or E2‐induced NO production was antagonized up to 70% by these antagonists. NO‐DAF signal elicited by anthocyanins was annulled by NOS inhibition or by ICI plus G‐36 addition.ConclusionsThe biomedical effect of anthocyanins or 3‐O‐glycosylates derivatives contained in naturally purple‐colored foods or berries is due to increased NO production, and not to the phytochemical's antioxidant potential, highlighting the nutraceutical role of natural products in cardiovascular diseases.

Oestrogen receptors: A potential therapeutic target in oesophageal adenocarcinoma?

Oesophageal cancer is the seventh most common cancer in the world and adenocarcinoma is the dominant subtype in Western industrialised nations. The global 5-year relative survival rate for oesophageal adenocarcinoma is 12%. Chemotherapy is a standard treatment offered to patients with both resectable and unresectable disease. However, there are only a few established chemotherapeutic drug options and progress in this area is limited. Recent efforts have focused on targeted molecular therapies. Epidemiological evidence points towards hormonal influences on disease development, particularly sex hormones. Several research studies have demonstrated oestrogen receptor (ER) expression in oesophageal adenocarcinoma tissue, making them a possible option for targeting with ER modulating agents. ERs are also present in laboratory models of the disease and experiments in ER-positive cell lines suggest that ER modulator therapy may be effective. A deeper understanding of the roles of ERα and ERβ in this disease would be valuable for future translation into clinical practice. In this review, we discuss the association between oestrogens and the development of oesophageal adenocarcinoma and the potential to modulate ER signalling networks for therapeutic benefit.

ERα down-regulates carbohydrate responsive element binding protein and decreases aerobic glycolysis in liver cancer cells.

Deregulated metabolism is one of the characteristics of hepatocellular carcinoma. Sex hormone receptor signalling has been involved in the marked gender dimorphism of hepatocellular carcinoma pathogenesis. Oestrogen receptor (ER) has been reported to reduce the incidence of liver cancer. However, it remains unclear how oestrogen and ER regulate metabolic alterations in liver tumour cells. Our previous work revealed that ERα interacted with carbohydrate responsive element binding protein (ChREBP), which is a transcription factor promoting aerobic glycolysis and proliferation of hepatoma cells. Here, the data showed that ERα overexpression with E2 treatment reduced aerobic glycolysis and cell proliferation of hepatoma cells. In addition to modestly down‐regulating ChREBP transcription, ERα promoted ChREBP degradation. ERα co‐immunoprecipitated with both ChREBP‐α and ChREBP‐β, the two known subtypes of ChREBP. Although E2 promoted ERα to translocate to the nucleus, it did not change subcellular localization of ChREBP. In addition to interacting with ChREBP‐β and promoting its degradation, ERα decreased ChREBP‐α–induced ChREBP‐β transcription. Taken together, we confirmed an original role of ERα in suppressing aerobic glycolysis in liver cancer cells and elucidated the mechanism by which ERα and ChREBP‐α together regulated ChREBP‐β expression.

The Cell-Free Expression of MiR200 Family Members Correlates with Estrogen Sensitivity in Human Epithelial Ovarian Cells.

Exposure to physiological estrogens or xenoestrogens (e.g., zearalenone or bisphenol A) increases the risk for cancer. However, little information is available on their significance in ovarian cancer. We present a comprehensive study on the effect of estradiol, zearalenone and bisphenol A on the phenotype, mRNA, intracellular and cell-free miRNA expression of human epithelial ovarian cell lines. Estrogens induced a comparable effect on the rate of cell proliferation and migration as well as on the expression of estrogen-responsive genes (GREB1, CA12, DEPTOR, RBBP8) in the estrogen receptor α (ERα)-expressing PEO1 cell line, which was not observable in the absence of this receptor (in A2780 cells). The basal intracellular and cell-free expression of miR200s and miR203a was higher in PEO1, which was accompanied with low ZEB1 and high E-cadherin expression. These miRNAs showed a rapid but intermittent upregulation in response to estrogens that was diminished by an ERα-specific antagonist. The role of ERα in the regulation of the MIR200B-MIR200A-MIR429 locus was further supported by publicly available ChIP-seq data. MiRNA expression of cell lysates correlated well with cell-free miRNA expression. We conclude that cell-free miR200s might be promising biomarkers to assess estrogen sensitivity of ovarian cells.

Abstract 4380: Positive expression of estrogen receptor alpha correlates with poor prognosis and metastasis in colorectal cancer

Abstract Background: The estrogen receptor beta (ERβ) is the predominant estrogen receptor in the normal colon mucosa, and its expression is downregulated in colorectal cancer (CRC). On the other hand, ER alpha (ERα) is very little expressed in the normal colon tissue. An increased ERα/β ratio has been shown in colon carcinomas. However, the role of ERα in CRC development and progression needs further evaluation. Aim: To investigate the role of ERα expression in CRC prognosis. Methods: A tumor tissue microarray of primary CRCs from 351 patients was stained for the expression of ERα. The nuclear staining intensity was evaluated using the Immuno-Reactive Score (IRS). Cox regression analysis and Kaplan-Meier curves were used to evaluate overall (OS) and disease-free survival (DFS). Colon cancer (CC) cells lines, SW-480, HCT-116 and HT-29 were used for in-vitro investigations. Two CC mouse models were used to investigate the expression of ERα. The zebrafish xenograft model was used to study CC cell metastasis. Untreated and ERα specific agonist (PPT, 40 nM) treated colon cancer cells were injected into the zebrafish perivitelline space. After 48 h the tale was checked for the presence of the metastasized cells. Results: ERα nuclear expression was negative in 232 and positive in 119 CRC patients, with a significantly higher expression in cancer tissue compared to normal tissue. Patients with positive ERα expression had higher TNM stage and more lymph node and distant metastasis. Positive ERα expression was independently associated with worse OS (HR=0.42; 95% CI: 0.26-0.51) and DFS (HR=0.32; 95% CI: 0.18-0.56), after adjustment for age and TNM stage. Moreover, patients with positive ERα expression had higher frequency of activated K-RAS mutation and higher expression levels of cysteinyl leukotriene receptor 1 (CysLT1R) and nuclear β-catenin, both with potent pro-tumorigenic properties. In the colon tissue from the colitis-associated colon cancer (CAC) mouse model with the Cysltr1 gene disruption, ERα expression was significantly decreased compared to wild-type (WT) mice, while in the colon of ApcMin/+ mice the ERα expression was significantly increased. In-vitro, PPT treatment significantly increased cell migration and wound closure compared to untreated cells. The zebrafish xenograft model showed that fish injected with PPT stimulated CC cells had significantly more tail metastasis compared with the control group (80% versus 67% respectively). Conclusion: Positive ERα expression correlates with poor prognosis and metastasis in colorectal cancer. Our results suggest that ERα-selective antagonists might be beneficial to combine therapeutic opportunities for improving the prognosis of CRC patients. Citation Format: Geriolda Topi, Shakti R Satapathy, Roy Roy Ehrnström, Marie-Louise Lydrup, Anita Sjölander. Positive expression of estrogen receptor alpha correlates with poor prognosis and metastasis in colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4380.

Abstract 3435: Characterizing the dependence of AP-1 transcription factors on Estrogen Receptor Alpha transcriptional activity and Fulvestrant sensitivity in ovarian cancer cells

Abstract Ovarian cancer is the leading cause of death among gynecologic malignancies. Epidemiological evidence has suggested a role for steroid hormones in the pathogenesis of ovarian cancer, however, their precise role in ovarian cancer remains unknown. We hypothesized that Estrogen Receptor α (ERα) drives a transcriptional program that is sufficient to promote ovarian cancer cell proliferation in ER+ ovarian cancers. Preliminary data generated in our laboratory has suggested that estradiol (E2) treatment increases cell proliferation in PEO1 and OVKATE cells, ERα+ ovarian cancer cell lines. This increase in cell proliferation can be inhibited by co-administration with the selective estrogen receptor modulator, Tamoxifen, and the selective estrogen receptor degrader, Fulvestrant. To further interrogate the mechanism of action of ERα in ovarian cancer, we performed RNA-seq on PEO1 cells treated with Vehicle, 10 nM E2, 100 nM Fulvestrant, and E2+Fulvestrant for 4 and 24 hours. We identified 86 significantly differentially expressed genes following 4 hr E2 treatment and 659 significantly differentially expressed genes following 24 hr E2 treatment. Fulvestrant inhibited the majority of E2-induced differentially expressed genes, confirming that these genes are dependent upon ERα. Gene Set Enrichment Analysis (GSEA) indicated that the Hallmark early and late estrogen responses and G2/M checkpoint as positively enriched in our dataset, indicating that classical ER pathways are intact in these cells. To further characterize the transcriptional role of ERα in ovarian cancer cells, ChIP-seq was performed on PEO1 cells treated with Vehicle, E2, Tamoxifen, or E2+Tamoxifen for 45 minutes. E2 treatment robustly increased ER recruitment to its regulatory regions when compared to Vehicle or Tamoxifen alone. Motif analysis of these ERα binding sites demonstrated a significant enrichment in members of the AP-1 transcription factor family, but not in known ERα cofactors FOXA1 and GATA3. Furthermore, using GIGGLE analysis to identify similar ChIP-seq datasets to the PEO1 dataset, we identified FOSL1, FOSL2, JUND, JUN, and FOS as among the datasets with the highest similarity scores to the E2 PEO1 dataset. In order to identify potential combinatorial endocrine therapies for ovarian cancer, we performed a genome-wide CRISPR screen in the presence of Fulvestrant in PEO1 cells. Among the top positively selected genes in the presence of Fulvestrant was the AP-1 family member, FOSL2, indicating that loss of FOSL2 contributes to Fulvestrant resistance and further confirmed the role of AP-1 factors in estrogen function. We also identified genes that confer sensitivity to Fulvestrant treatment; the E2F, PI3K/mTOR, and steroid hormone biosynthesis pathways are enriched in the Fulvestrant sensitizer genes. Further analysis is currently underway to determine synergistic combinations with Fulvestrant for the treatment of ovarian cancer. Citation Format: Irene I. Lee, Myles Brown. Characterizing the dependence of AP-1 transcription factors on Estrogen Receptor Alpha transcriptional activity and Fulvestrant sensitivity in ovarian cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3435.

The role of the estrogen receptor-α gene, Esr1, in maternal-like behavior in juvenile female and male rats

The estrogen receptor-alpha (ER-α) is an important ligand activated transcription factor that works to control gene transcription in many species. Previous studies have shown estrogen to be an important hormone in the regulation of maternal behavior. Like adult female rats, both male and female juvenile rats exhibit increased level of maternal-like behavior when exposed to pups. The aim of this study was to determine whether ER-α is critical for the expression of maternal-like behavior in juvenile male and female rats. ER-α knock-out and wildtype (WT) juvenile male and female rats were generated and tested for maternal behaviors. Latencies to display maternal-like behaviors that included retrieval, grouping and crouching responses, revealed no genotype differences between KO and WT subjects. Male juvenile rats exhibited slightly shorter latencies than WT juvenile female rats indicating a sex difference in the latency to display these responses. Additionally, ER-α KO females exhibited a delay in onset of vaginal opening compared to WT females, indicating a role for ER-α in sexual maturation. The behavioral findings indicate that ER-α is not obligatory for the expression of full maternal-like behavior in male and female juvenile rats. Understanding this neurobiological system will help to elucidate the developmental involvement of the endocrine and brain networks in the regulation of maternal behaviors in mammals.

Abstract GMM-038: DECIPHERING THE ROLE OF ESTROGEN RECEPTOR ALPHA IN OVARIAN CANCER

Abstract Ovarian cancer is the leading cause of death among gynecologic malignancies. Despite years of research, the 5-year survival rate for ovarian cancer patients has remained poor and the standard of care is largely the same as it was decades ago. Epidemiological evidence and previous studies have suggested a role for steroid hormones in the pathogenesis of ovarian cancer, however, the role of steroid hormones in ovarian cancer remains understudied. We hypothesized that Estrogen Receptor α (ERα) is transcriptionally active and drives a transcriptional program that is sufficient to promote ovarian cancer cell proliferation and survival in a subset of ER+ ovarian cancers. Preliminary data generated in our laboratory has suggested that estradiol (E2) treatment increases cell proliferation in PEO1 cells, an ERα+ ovarian cancer cell line. This increase in cell proliferation can be inhibited by co-administration with the selective estrogen receptor modulator, Tamoxifen, and the selective estrogen receptor degrader, Fulvestrant. To further interrogate the mechanism of action of ERα in ovarian cancer, we performed RNA-seq on PEO1 cells treated with Vehicle, 10 nM E2, 100 nM Fulvestrant, and E2+Fulvestrant for 24 hours. We identified 659 significantly differentially expressed genes following E2 treatment. Fulvestrant inhibited the majority of E2-induced differentially expressed genes, confirming that these genes are dependent upon ERα. Gene Set Enrichment Analysis (GSEA) indicated that the Hallmark early and late estrogen responses are enriched in the E2 dataset, confirming that classical ER activity is intact in these cells. Furthermore, we identified G2/M checkpoint as positively enriched in our dataset, indicating that proliferation genes are upregulated by ERα in these cells. Additionally, we found that apoptosis was negatively enriched in our dataset, indicating that apoptosis pathway genes are suppressed by E2 treatment. To further characterize the transcriptional role of ERα in ovarian cancer cells, ChIP-seq was performed on PEO1 cells treated with Vehicle, E2, Tamoxifen, or E2+Tamoxifen for 45 minutes. E2 treatment robustly increased ER recruitment to its regulatory regions (25,717 binding sites) when compared to Vehicle (8,370 binding sites) or Tamoxifen (18,935 binding sites) alone. Motif analysis of these ERα binding sites demonstrated a significant enrichment in members of the AP-1 transcription factor family, but not in known ERα cofactors FOXA1 and GATA3. FOXA1 and GATA3 are important regulators of ERα-dependent transcription in breast cancer cells; our results may suggest that mechanisms governing ERα transcriptional activity are lineage dependent. Finally, Binding and expression target analysis (BETA) was performed in order to predict the activating and repressing function of ERα. This analysis demonstrated that ERα has significant repressive function in PEO1 cells, indicating that ER may be acting as a strong transcriptional repressor in ovarian cancer cells. Future investigation in this project will center on the role of AP-1 in mediating ERα-dependent transcription. Additionally, we will use CRISPR/Cas9 screening to determine genetic sensitizers to ER antagonists. We believe that these studies will provide additional drug targets that may suggest a combinatorial therapeutic approach in conjunction with endocrine therapies for the treatment of ovarian cancer. Citation Format: Irene I Lee, Myles Brown. DECIPHERING THE ROLE OF ESTROGEN RECEPTOR ALPHA IN OVARIAN CANCER [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr GMM-038.

Chronic cadmium exposure decreases the dependency of MCF7 breast cancer cells on ER\u03b1

Cadmium is an environmental contaminant that can activate estrogen receptor alpha (ERα) and contribute to the development and progression of breast cancer. Our lab previously demonstrated that chronic cadmium exposure alters the expression of several ERα-responsive genes and increases the malignancy of breast cancer cells. Although these studies support cadmium’s function as a hormone disrupter, the role of ERα in cadmium-induced breast cancer progression remains unclear. To address this, we modulated the expression of ERα and found that while the loss of ERα significantly impaired cancer cell growth, migration, invasion and anchorage-independent growth in both MCF7 and MCF7-Cd cells, cadmium-exposed cells retained a significant advantage in cell growth, migration, and invasion, and partially circumvented the loss of ERα. ERα knockout in MCF7 and MCF7-Cd cells significantly reduced the expression of classical ERα-regulated genes, while non-classical ERα-regulated genes were less impacted by the loss of ERα in MCF7-Cd cells. This is the first study to show that chronic cadmium exposure, even at low levels, can increase the malignancy of breast cancer cells by decreasing their dependency on ERα and increasing the adaptability of the cancer cells.

Estradiol Induced Estrogen Receptor-mediated Transcription and Expression of Aquaporin5

In this study, we constructed the recombinant plasmid of pGL2/Aquaporin5(AQP5) promoter (pGL2/AQP5p) luciferase reporter, then found estradiol(E2) induced AQP5 promoter activation in a dose-dependent manner. Further, we identified endogenous estrogen receptors(ER), including ERα and ERβ, expressed in human submandibular gland(HSG) cells, which responded to E2. Then demonstrated by the stimulation of E2, AQP5 was upregulated in protein level, meanwhile AQP5 located in cytomembrane was elevated in immunofluorescence. Furthermore, we revealed the roles of ERα and ERβ in AQP5 upregulation by E2. When ERα and ERβ were overexpressed, the AQP5 transcription level and protein expression were augmented obviously. While when knockdown ER by ERα-shRNA or ERβ-shRNA, AQP5 transcription and expression attenuated. Moreover, we detected the effect of E2 in Sjogren’s syndrome(SS) mice model in vivo. SS mice models were constructed by injecting submandibular gland antigen immune induction combined with estrogen deprivation, which were administrated with saline and E2. The salivary secretion was decreased, and the AQP5 expression downregulated in the submandibular gland in the SS model group. When SS mice were administrated with E2, the salivary secretion was significantly increased, and the AQP5 expression upregulated in the submandibular gland. These results suggest E2 activates AQP5p transcription and upregulates AQP5 protein expression, and E2 promotes salivary secretion in SS model in vivo. Taken together, we provided the evidence that E2 increased salivary secretion by activating AQP5 transcription and expression.

Dysregulation of hypothalamic-pituitary estrogen receptor α-mediated signaling causes episodic LH secretion and cystic ovary.

Polycystic ovary syndrome (PCOS) is a hypothalamic-pituitary-gonadal (HPG) axis disorder. PCOS symptoms most likely result from a disturbance in the complex feedback regulation system of the HPG axis, which involves gonadotrophic hormones and ovarian steroid hormones. However, the nature of this complex and interconnecting feedback regulation makes it difficult to dissect the molecular mechanisms responsible for PCOS phenotypes. Global estrogen receptor α (ERα) knockout (KO) mice exhibit a disruption of the HPG axis, resulting in hormonal dysregulation in which female ERα KO mice have elevated levels of serum estradiol (E2), testosterone, and LH. The ERα KO females are anovulatory and develop cystic hemorrhagic ovaries that are thought to be due to persistently high circulating levels of LH from the pituitary. However, the role of ERα in the pituitary is still controversial because of the varied phenotypes reported in pituitary-specific ERα KO mouse models. Therefore, we developed a mouse model where ERα is reintroduced to be exclusively expressed in the pituitary on the background of a global ERα-null (PitERtgKO) mouse. Serum E2 and LH levels were normalized in PitERtgKO females and were comparable to wild-type serum levels. However, the ovaries of PitERtgKO adult mice displayed a more overt cystic and hemorrhagic phenotype when compared with ERα KO littermates. We determined that anomalous sporadic LH secretion caused the severe ovarian phenotype of PitERtgKO females. Our observations suggest that pituitary ERα is involved in the estrogen negative feedback regulation, whereas hypothalamic ERα is necessary for the precise control of LH secretion. Uncontrolled, irregular LH secretion may be the root cause of the cystic ovarian phenotype with similarities to PCOS.-Arao, Y., Hamilton, K. J., Wu, S.-P., Tsai, M.-J., DeMayo, F. J., Korach, K. S. Dysregulation of hypothalamic-pituitary estrogen receptor α-mediated signaling causes episodic LH secretion and cystic ovary.

Significance of BRCA1 expression in breast and ovarian cancer patients with brain metastasis – A multicentre study

PurposeCerebral metastases develop in 10–30% of patients with breast cancer (BC) and in around 3.3 to 4% of patients with ovarian cancer (OC). The aim of the multicenter study is to investigate the correlation between the expression of estrogen alpha receptors (ERα), progesterone receptors (PR), human epidermal growth factor receptor 2 (HER2), stromal cell-derived factor 1 (SDF1) and its receptor C-X-C chemokine receptor type 4 (CXCR4), breast cancer metastasis suppressor 1 (BRMS1), astrocyte elevated gene 1 (AEG1), depending on the status of BRCA1 protein, in patients suffering from OC and BC with brain metastases. Patients and methodsThe analysis included 51 patients: 29 with BC and 22 with OC, in whom brain metastases were disclosed. ResultsIn most patients (65.5% of BC patients and 68.2% of patients with OC tumors) BRCA1 protein loss was found. No correlation was disclosed between the levels of ERα, PR receptors, HER2, SDF1, CXCR4, AEG1, BRMS1 and BRCA1 status, patient age, stage of disease advancement, grade of histological maturity of the cells, presence of metastases to lymph nodes. A statistically significant correlation was disclosed between the negative expression of PR receptors and a high expression of CXCR4 in patients with BC. High values of the AEG1 protein (linked to metastases) were detected alongside a high expression of BRMS1 (a suppressor of metastases). ConclusionsPatients with BC and OC and brain metastases have a frequent loss of BRCA1 expression. The role of ERα, PR, HER2, SDF1, CXCR4, AEG1, BRMS1 in metastatic process needs further studies.

Abstract P1-04-01: Estrogen receptor β agonists inhibits syngeneic mammary tumor growth through cell-cycle arrest by modulating cell-cycle regulators

Abstract Breast Cancer is the main cause of cancer-associated mortality in women worldwide. The estrogen receptors (ER's) play an important role in normal mammary gland development, as well as in breast cancer. Estrogen Receptor α is expressed in 70% of breast cancers, where it contributes to increased cell proliferation and decreased cell death. Endocrine therapies such as anti-estrogens and aromatase inhibitors target ERα signaling and improve outcomes of these patients. Syngeneic, immunocompetent mouse models are essential for elucidating the mechanisms and for evaluating novel strategies for the treatment of breast cancer. In contrast to the tumor-inducing role of ERα, ERβ has been shown to have tumor suppressive activities in various cancer, including the breast cancer. Compounds that selectively activate ERβ hold promise because they could potentially avoid the unwanted effects of ERα activation, while exploiting the tumor-suppressive function of ERβ. In the present study, we assessed the antitumor effects of ERβ agonists using three different syngeneic mouse models; D2A1 (BALB/c) and MM51 (FVB) syngeneic models and ex-vivo culture of highly metastatic cell line E0771 (C57/B6). Effect on in vitro cancer cell growth was evaluated by cell proliferation and clonogenic assays. Cell cycle distribution was analysed by flow cytometry. Our results demonstrate that ERβ agonists LY500307 and S-Equol not only inhibited the growth of all three mouse mammary tumor cell lines, but also reduced the colony formation ability. ERβ agonists also induced the cell-cycle arrest in time and dose-dependent manner. In mechanistic studies, ERβ agonists LY500307 and S-Equol, modulated the protein levels of cyclin-dependent kinases (CDKs) (4, 6, and 2), cyclins (D1 and E), in a differential manner in these three cell lines. Our in vivo studies of D2A1 and MM51 cells demonstrates that ERβ agonist LY500307 inhibited the tumor growth and the effect was more pronounce in combination with aromatase inhibitor letrozole. Ex-vivo model of E0771 cells showed that LY500307 has potential to dramatically reduce the proliferation of mouse mammary tumor growth.Together, these results identify potential molecular targets and anticancer effects of ERβ agonists in mouse mammary tumors. Citation Format: Ramasamy K, Samayoa C, Krishnegowda NK, Thurlapati A, Vadlamudi RK, Tekmal RR. Estrogen receptor β agonists inhibits syngeneic mammary tumor growth through cell-cycle arrest by modulating cell-cycle regulators [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-04-01.