ERRα Expression Research Articles

ERRα Expression in Bone Metastases Leads to an Exacerbated Antitumor Immune Response.

Bone is the most common metastatic site for breast cancer. Although the estrogen-related receptor alpha (ERRα) has been implicated in breast cancer cell dissemination to the bone from the primary tumor, its role after tumor cell anchorage in the bone microenvironment remains elusive. Here, we reveal that ERRα inhibits the progression of bone metastases of breast cancer cells by increasing the immune activity of the bone microenvironment. Overexpression of ERRα in breast cancer bone metastases induced expression of chemokines CCL17 and CCL20 and repressed production of TGFβ3. Subsequently, CD8+ T lymphocytes recruited to bone metastases escaped TGFβ signaling control and were endowed with exacerbated cytotoxic features, resulting in significant reduction in metastases. The clinical relevance of our findings in mice was confirmed in over 240 patients with breast cancer. Thus, this study reveals that ERRα regulates immune properties in the bone microenvironment that contributes to decreasing metastatic growth. SIGNIFICANCE: This study places ERRα at the interplay between the immune response and bone metastases of breast cancer, highlighting a potential target for intervention in advanced disease.

Effect of the Combination of Training and ERRα Inhibition on Liver Metabolism by Modulation of PDK4 and LXR-α Expression in STZ-Induced Diabetic and Healthy Rats

Diabetes is a public health problem that affects life quality. Exercise training (ET) and controlled dietary habits improve metabolic diseases such as diabetes. The mechanisms by which exercise training ameliorate metabolic diseases are not fully clear. We designed the current study to evaluate the combination of ERRα suppression and ET effects on the expression of LXR-α, PDK4, and PPARα in healthy and STZ-induced diabetic rats. Fifty-six male Wistar rats were divided into 8 groups (n = 7) as follows; control, diabetic control (a single dose of 45 mg/kg of STZ), ERRα inhibition group (received 0.48 mg/kg of XCT790), endurance training, diabetic rats which received XCT790, diabetic rats which performed endurance training, rats which received XCT790 and performed endurance training, and diabetic rats which received XCT790 and also performed endurance training. Expression of the target gene and protein was carried out on the liver tissue. Our results showed that ET significantly increased PDK4, PPARα, and ERRα expression. ERRα suppression significantly increased LXR-α and PDK4 expression in healthy rats compared to the healthy control group. In the diabetic group with ERRα suppression, LXR-α expression significantly upregulated. The combination of ET and ERRα suppression did not change LXR-α expression compared to healthy and diabetic groups (CTL/ERR), but the expression of PDK4, PPARα, and ERRα was significantly upregulated.

A novel non-invasive molecular biomarker in ovarian endometriosis: estrogen-related receptor α.

This study aimed to explore whether estrogen-related receptors α (ERRα) can prognosticate the occurrence and development of ovarian endometriosis (EMs) as a non-invasive biomarker. The ectopic and its' correspond eutopic endometria from 47 patients with ovarian EMs and the control normal endometria from 32 cases were collected and detected the mRNA expression of ERRα by RT-qPCR. The serum protein of ERRα were tested by ELISA. The menstrual cycle, ovarian cyst sizes, relative clinical tumour markers, such as CA125, CA19-9 and HE-4, and other demographic data were also involved into analysis in these patients by SPSS 22.0 (IBM, Chicago, IL, USA). The ERRα mRNA expression in ectopic endometria were significantly lower than it in eutopic endometria (P < 0.05) and the normal endometria (P < 0.05). Similarly, the serum ERRα levels in patients with EMs were significantly lower than it in control group (P < 0.01). Moreover, the serum ERRα levels were decreasing with the increasing of the pathological stages and ovarian cyst sizes. While, the serum CA125, CA19-9, CA125/ERRα ratio and CA19-9/ERRα ratio in the study group were significantly higher than those in the control group (all P < 0.01). The expression of ERRα is correlated with the development of ovarian EMs pathological stages and ovarian cyst sizes and can be used as a novel and non-invasive biomarker for evaluating the progression of ovarian EMs.

A Critical Role for Estrogen-Related Receptor Signaling in Cardiac Maturation.

The heart undergoes dramatic developmental changes during the prenatal to postnatal transition, including maturation of cardiac myocyte energy metabolic and contractile machinery. Delineation of the mechanisms involved in cardiac postnatal development could provide new insight into the fetal shifts that occur in the diseased heart and unveil strategies for driving maturation of stem cell-derived cardiac myocytes. To delineate transcriptional drivers of cardiac maturation. We hypothesized that ERR (estrogen-related receptor) α and γ, known transcriptional regulators of postnatal mitochondrial biogenesis and function, serve a role in the broader cardiac maturation program. We devised a strategy to knockdown the expression of ERRα and γ in heart after birth (pn-csERRα/γ [postnatal cardiac-specific ERRα/γ]) in mice. With high levels of knockdown, pn-csERRα/γ knockdown mice exhibited cardiomyopathy with an arrest in mitochondrial maturation. RNA sequence analysis of pn-csERRα/γ knockdown hearts at 5 weeks of age combined with chromatin immunoprecipitation with deep sequencing and functional characterization conducted in human induced pluripotent stem cell-derived cardiac myocytes (hiPSC-CM) demonstrated that ERRγ activates transcription of genes involved in virtually all aspects of postnatal developmental maturation, including mitochondrial energy transduction, contractile function, and ion transport. In addition, ERRγ was found to suppress genes involved in fibroblast activation in hearts of pn-csERRα/γ knockdown mice. Disruption of Esrra and Esrrg in mice during fetal development resulted in perinatal lethality associated with structural and genomic evidence of an arrest in cardiac maturation, including persistent expression of early developmental and noncardiac lineage gene markers including cardiac fibroblast signatures. Lastly, targeted deletion of ESRRA and ESRRG in hiPSC-CM derepressed expression of early (transcription factor 21 or TCF21) and mature (periostin, collagen type III) fibroblast gene signatures. ERRα and γ are critical regulators of cardiac myocyte maturation, serving as transcriptional activators of adult cardiac metabolic and structural genes, an.d suppressors of noncardiac lineages including fibroblast determination.

Early B Cell Factor Activity Controls Developmental and Adaptive Thermogenic Gene Programming in Adipocytes

SUMMARYBrown adipose tissue (BAT) activity protects animals against hypothermia and represents a potential therapeutic target to combat obesity. The transcription factor early B cell factor-2 (EBF2) promotes brown adipocyte differentiation, but its roles in maintaining brown adipocyte fate and in stimulating BAT recruitment during cold exposure were unknown. We find that the deletion of Ebf2 in adipocytes of mice ablates BAT character and function, resulting in cold intolerance. Unexpectedly, prolonged exposure to cold restores the thermogenic profile and function of Ebf2 mutant BAT. Enhancer profiling and genetic assays identified EBF1 as a candidate regulator of the cold response in BAT. Adipocyte-specific deletion of both Ebf1 and Ebf2 abolishes BAT recruitment during chronic cold exposure. Mechanistically, EBF1 and EBF2 promote thermogenic gene transcription through increasing the expression and activity of ERRα and PGC1α. Together, these studies demonstrate that EBF proteins specify the developmental fate and control the adaptive cold response of brown adipocytes.

Estrogen-related receptor-α promotes gallbladder cancer development by enhancing the transcription of Nectin-4.

Estrogen‐related receptor‐α (ERRα) is a nuclear receptor of transcription factor that binds to estrogen responsive elements and estrogen‐related responsive elements. Estrogen‐related receptor‐α is involved in metabolic processes and implicated in the progression and growth of several human malignancies. However, the biologic role and clinical significance of ERRα in gallbladder cancer (GBC) remains to be clarified. Here, we reported that ERRα protein expression was notably higher in GBC tissues than in cholecystitis tissues, and that the aberrantly higher ERRα expression was positively correlated with advanced TNM stage and indicated dismal prognosis of GBC (P < .01). In GBC cell lines NOZ and OCUG, the targeted depletion of ERRα retarded the growth and suppressed the migration and invasive capabilities of GBC cells, and inhibited epithelial‐mesenchymal transition by decreasing the expression of mesenchymal markers and elevating the expression of epithelial markers. Moreover, ERRα knockdown inhibited tumor growth in nude mice and led to decreased expression levels of Nectin‐4, p‐PI3K p85α, and p‐AKT. Overexpression of ERRα in the GBC‐SD cell line showed exactly the opposite effect. The targeted inhibition of Nectin‐4 antagonized GBC cell proliferation and invasion, which were induced by ERRα upregulation. Moreover, Nectin‐4 depletion inhibited the ERRα‐induced activation of the PI3K/AKT pathway. Chromatin immunoprecipitation analysis and dual‐luciferase reporter gene assays showed that ERRα enhanced the transcription of Nectin‐4 by binding to the promoter of Nectin‐4. In conclusion, our data indicated that ERRα could be a potential target for the genetic treatment of GBC.

Expression of Estrogen-Related Receptors in Localized Provoked Vulvodynia.

Eight percent of women suffer from vulvodynia, a chronic pain condition with unknown etiology. Inflammation and dysregulation of estrogen signaling have been suggested to play a role in the pathogenesis of localized provoked vulvodynia (LPV). Therefore, the aim of the study was to analyze protein expression levels of estrogen-related receptors ERRα, ERRß, ERRγ, estrogen receptor (ERα), and progesterone receptor (PRα) and CD3-positive T cells in the vulvar vestibulum obtained from women suffering from LPV in comparison to healthy, unaffected controls. Vulvar vestibulum tissue specimens were obtained from LPV patients (n = 12) who had undergone modified posterior vestibulectomy and from 15 healthy controls. Protein expression of ERRα, ERRß, ERRγ, ERα, and PRα and CD3-positive T cells was analyzed by immunohistochemistry (IHC). Expression of ERRß was significantly more pronounced in samples from LPV compared to healthy controls (p = 0.006). No significant difference in the expression patterns of ERRα, ERRγ, ERα, PRα, or CD3 cells was detected. To our knowledge, this is the first study reporting ERR expression in normal vestibulum and in vestibulectomy samples from LPV patients. The higher level of ERRß expression detected by IHC may reflect dysregulation of estrogen signaling in LPV.

ERRα activates SHMT2 transcription to enhance the resistance of breast cancer to lapatinib via modulating the mitochondrial metabolic adaption.

Lapatinib, a tyrosine kinase inhibitor, can initially benefit the patients with breast tumors but fails in later treatment due to the inevitable development of drug resistance. Estrogen-related receptor α (ERRα) modulates the metabolic adaptations in lapatinib-resistant cancer cells; however, the underlying mechanism remains unclear. ERRα was predicted to bind to the serine hydroxymethyltransferase 2 (SHMT2) transcription initiation site in the ER- and HER2-positive cell line BT-474; thus, we hypothesize that ERRα might modulate the resistance of breast cancer to lapatinib via regulating SHMT2. In the present study, we revealed that 2.5 and 5 µM lapatinib treatment could significantly decrease the expression and protein levels of ERRα and SHMT2; ERRα and SHMT2 expression and protein levels were significantly up-regulated in breast cancer cells, in particularly in breast cancer cells with resistance to lapatinib. ERRα knockdown restored the inhibitory effects of lapatinib on the BT-474R cell viability and migration; in the meantime, ERRα knockdown rescued the production of reactive oxygen species (ROS) whereas decreased the ratio of glutathione (GSH)/oxidized glutathione (GSSG) upon lapatinib treatment. Via targeting SHMT2 promoter region, ERRα activated the transcription of SHMT2. The effects of ERRα knockdown on BT-474R cells under lapatinib treatment could be significantly reversed by SHMT2 overexpression. In conclusion, ERRα knockdown suppresses the detoxification and the mitochondrial metabolic adaption in breast cancer resistant to lapatinib; ERRα activates SHMT2 transcription via targeting its promoter region, therefore enhancing breast cancer resistance to lapatinib.

Effects of estrogen-related receptor alpha on inflammatory response in pulmonary microvascular endothelial cells

Objective To investigate the effect of estrogen-related receptor alpha(ERRα)on lipopolysaccharide-induced inflammatory response in rat pulmonary microvascular endothelial cells (PMVECs) and its mechanism. Methods PMVECs were cultured in vitro. When the cells were in the logarithmic growth phase, the cell were ransfected with lentivirus, and a stable low-expression ERRα cell line was constructed. The cells were divided into four groups: Ctr group (normal control group), Ctr+LPS group (normal cell+LPS treatment group), shERRα1 (shERRα1 gene knockdown group), and shERRα1+LPS group (shERRα1 gene knockdown +LPS treatment group). After 20 μg/mL LPS stimulated cells in the control group and shERRα1 group for 6, 12 and 24 h, cell counting kit-8 (cck-8) was used to detect the cell proliferation ability of each group, and enzyme-linked immunosorbent assay (ELISA) was used to detect the concentrations of tumor necrosis factor alpha (TNF-α) and Interleukin-1β (IL-1β) in cell culture fluid. After 12 h LPS stimulation, the expression levels of ERRα and NF-κB related proteins (p-p65, p65, P-IKBα, IKBα) were measured by Western blot. Pairwise comparisons were performed with SNK-q test (two-tailed), and multiple-group comparisons were performed with one-way ANOVA. The non-parametric test of rank transformation was used when homogeneity of variance were not met. P value<0.05 was considered significantly different. Results Compared with the control group, ERRα expression in the shERRα group was significantly decreased (0.09±0.01 vs 0.15±0.01). At 6, 12 and 24 h after LPS stimulation, compared with the control group, the cell proliferation ability (%) of the shERRα1+LPS group was significantly reduced (99.68±4.53 vs 48.62±1.60) and the concentration of TNF-α (ng/mL) (15.76±3.38 vs 5 498.91±367.95) and IL-1β (ng/mL) (14.41±3.86 vs 6 014.92±277.33) in the cell culture supernatant were significantly increased. The change was most obvious after 12 h stimulation. Meanwhile the expression of p-p65 (0.30±0.50 vs 1.05±0.07) and p-IKBα (0.27±0.04 vs 0.77±0.06) were increased significantly, while the expression of IKBα (0.96±0.07 vs 0.14±0.04) was decreased significantly in the shERRα1+LPS group (all P<0.05). Conclusion ERRα gene attenuates LPS-induced inflammatory response in rat pulmonary microvascular endothelial cells by inhibiting NF-κB signaling pathway activation. Key words: Sepsis; Estrogen-related receptor alpha; NF-κB pathway; Gene knockdown

A novel miR-1291-ERRα-CPT1C axis modulates tumor cell proliferation, metabolism and tumorigenesis.

Rationale: MicroRNAs are known to influence the development of a variety of cancers. Previous studies revealed that miR-1291 has antiproliferative functions in cancer cells. Carnitine palmitoyltransferase 1C (CPT1C) has a vital role in mitochondrial energy metabolism and modulation of cancer cell proliferation. Since both miR-1291 and CPT1C regulate tumor cell metabolism and cancer progression, we hypothesized that they might be regulated synergistically.Methods: A series of cell phenotype indicators, such as BrdU, colony formation, cell cycle, ATP production, ROS accumulation and cell ability to resist metabolic stress, were performed to clarify the effects of miR-1291 and ERRα expression on tumor cell proliferation and metabolism. A xenograft tumor model was used to evaluate cell tumorigenesis. Meta-analysis and bioinformatic prediction were applied in the search for the bridge-link between miR-1291 and CPT1C. RT-qPCR, western-blot and IHC analysis were used for the detection of mRNA and protein expression. Luciferase assays and ChIP assays were conducted for in-depth mechanism studies.Results: The expression of miR-1291 inhibited growth and tumorigenesis as a result of modulation of metabolism. CPT1C expression was indirectly and negatively correlated with miR-1291 levels. ESRRA was identified as a prominent differentially expressed gene in both breast and pancreatic cancer samples, and estrogen-related receptor α (ERRα) was found to link miR-1291 and CPT1C. MiR-1291 targeted ERRα and CPT1C was identified as a newly described ERRα target gene. Moreover, ERRα was found to influence cancer cell metabolism and proliferation, consistent with the cellular changes caused by miR-1291.Conclusion: This study demonstrated the existence and mechanism of action of a novel miR-1291-ERRα-CPT1C cancer metabolism axis that may provide new insights and strategies for the development of miRNA-based therapies for malignant cancers.

Nuclear receptor ERRα contributes to castration-resistant growth of prostate cancer via its regulation of intratumoral androgen biosynthesis.

Enhanced intratumoral androgen biosynthesis and persistent androgen receptor (AR) signaling are key factors responsible for the relapse growth of castration-resistant prostate cancer (CRPC). Residual intraprostatic androgens can be produced by de novo synthesis of androgens from cholesterol or conversion from adrenal androgens by steroidogenic enzymes expressed in prostate cancer cells via different steroidogenic pathways. However, the dysregulation of androgen biosynthetic enzymes in CRPC still remains poorly understood. This study aims to elucidate the role of the nuclear receptor, estrogen-related receptor alpha (ERRα, ESRRA), in the promotion of androgen biosynthesis in CRPC growth.Methods: ERRα expression in CRPC patients was analyzed using Gene Expression Omnibus (GEO) datasets and validated in established CRPC xenograft model. The roles of ERRα in the promotion of castration-resistant growth were elucidated by overexpression and knockdown studies and the intratumoral androgen levels were measured by UPLC-MS/MS. The effect of suppression of ERRα activity in the potentiation of sensitivity to androgen-deprivation was determined using an ERRα inverse agonist.Results: ERRα exhibited an increased expression in metastatic CRPC and CRPC xenograft model, could act to promote castration-resistant growth via direct transactivation of two key androgen synthesis enzymes CYP11A1 and AKR1C3, and hence enhance intraprostatic production of dihydrotestosterone (DHT) and activation of AR signaling in prostate cancer cells. Notably, inhibition of ERRα activity by an inverse agonist XCT790 could reduce the DHT production and suppress AR signaling in prostate cancer cells.Conclusion: Our study reveals a new role of ERRα in the intratumoral androgen biosynthesis in CRPC via its transcriptional control of steroidogenic enzymes, and also provides a novel insight that targeting ERRα could be a potential androgen-deprivation strategy for the management of CRPC.

Expression of fatty-acid-binding protein 5 in intrahepatic and extrahepatic cholangiocarcinoma: the possibility of different energy metabolisms in anatomical location.

The biliary tract cancer (BTC) covers a range of carcinomas, including intrahepatic cholangiocarcinoma (ICC), cholangiolocellular carcinoma (CoCC), perihilar cholangiocarcinoma (perihilar CC), extrahepatic cholangiocarcinoma (ECC), and gallbladder cancer (GBC), defined according to the anatomical location. These adenocarcinomas mostly comprise biliary epithelial cell-derived malignant cells. In addition to anatomical differences, there are morphological and biological differences in BTC starting from embryonic development of the tissues extending to physiological differences. Fatty acid-binding proteins (FABPs) are closely associated with the energy metabolism. Using surgical specimens from 74 BTCs, we performed immunohistochemistry for FABP5 and its associated molecules, including peroxisome proliferator-activated receptor γ (PPARγ), PPARγ coactivator 1 (PGC-1), and estrogen-related receptor α (ERRα). We found that the expression patterns of small BTCs (ICC and CoCC) considerably differed from those of large BTCs (perihilar CC, ECC, and GBC). Expression of FABP5 and PGC-1 in large BTCs was high compared with those of small BTCs, but no difference in the expression of PPARγ and ERRα was observed. FABP5 appears to play a role in malignant progression in large BTCs. Small and large BTCs possess different energy metabolism systems owing to their different anatomical locations and course of carcinogenesis, although all BTCs originate from biliary epithelial cells.

Dual targeting of estrogen receptor α and estrogen-related receptor α: a novel endocrine therapy for endometrial cancer.

BackgroundEndometrial cancer (EC) is a hormone dependent carcinoma that may involve complex molecular mechanisms. Endocrine therapy by blocking the estrogen and estrogen receptor α (ERα) has been effective in breast cancer, while it is still controversial in EC. Recently, estrogen-related receptor α (ERRα) was proven to be another endocrine therapy target.MethodsThe anti-tumor effect of selective estrogen receptor modulators (SERMs) and XCT790 (XCT) used alone or in combination were evaluated in both of ERα-positive (ERα+) and ERα-negative (ERα-) EC cells. ERα and ERRα mRNA were tested by qPCR, while the protein was detected by Western blot. The proliferation was tested by MTS and cell cycle, apoptosis rate were analyzed by flow cytometry.ResultsA relatively high dose (10 μM) of tamoxifen (TAM) suppressed the expression of ERα and ERRα in two types of EC cells. However, 10 μM raloxifene (RAL) exhibited no effect on ERα and ERRα, while 10 μM XCT down regulated ERRα specifically, but not ERα in all EC cells. When dual targeting on ERα and ERRα by combining TAM with XCT, the proliferation inhibitory effect and apoptosis reached the strongest in all EC cells (P<0.05). Moreover, the inhibitory effect of proliferation was attributed significantly to the G0/G1 arrest (P<0.05). Interestingly, the apoptosis induced by combining TAM with XCT were obviously higher in ERα+ EC cells than ERα- EC cells (P<0.05).ConclusionTaken together, the results indicate that dual targeting on ERα and ERRα represents a better anti-tumor effect, which provides a novel endocrine based therapy strategy for EC.

Abstract 5253: Regulation of estrogen related receptor α by ING4 and its potential role in breast cancer pathogenesis

Abstract Breast cancer is one of the most frequently diagnosed tumors in the United States that affects one in eight women during their lifetime. It is second only to lung cancer as cause of cancer death in women. The orphan members of the nuclear receptor superfamily, estrogen-related receptors ERRα and γ (ERRs) isoforms are considered the master regulators of energy metabolism and their transcriptional pathways are highly associated with the cancer phenotype. Realizing the important function of co-regulators on ERRs transcriptional activity and their impact on cancer development and progression, we have identified the tumor growth family member 4 (ING4), a protein that has been implicated in several solid tumors and physically interacts with ERRα in breast cancer cellular models and modulates its transcriptional activity. Examination of the Oncomine database revealed that both ING4 and ERRα gene expression were significantly higher in invasive ductal and lobular breast carcinomas compared to normal ones, and their increased expression is inversely correlated with the overall patient survival rate in The Cancer Genome Atlas (TCGA) database. Knocking down ING4 in a breast cancer cell line using siRNA technology significantly decreased the expression of ERRα, and overexpression of ING4 upregulates the endogenous expression of ERRα. Well-defined ERRα target genes were also regulated by ING4 in the same manner as ERRα. Also, depleting ING4 expression significantly increased breast cancer cell migration in in vitro scratch assays, while both ING4 and ERRα knockdown decreased breast cancer cell proliferation. Collectively, these findings provide evidence for positive regulation of ERRα by ING4. Understanding the mechanism by which ING4/ERRα interaction regulates cellular pathways in breast cancer, underscores the impact of such regulation on biological and pharmacological actions. Thus, they can be used for the development of improved novel pharmaceuticals that target ERRα/ING4 complex or its downstream pathways. Citation Format: Aymen A. Shatnawi, Vincent Giguere. Regulation of estrogen related receptor α by ING4 and its potential role in breast cancer pathogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5253.

719-P: Inducible Estrogen-Related Receptor Alpha Overexpression Stimulates Skeletal Muscle Oxidative Metabolism and Improves Exercise Endurance in Mice

Aerobic exercise promotes skeletal muscle insulin sensitivity by enhancing glucose uptake and storage and by increasing mitochondrial oxidative capacity. Exercise-responsive transcriptional pathways that regulate metabolism represent potential therapeutic targets to combat insulin resistance. The ERRα nuclear receptor regulates mitochondrial oxidative metabolism and is required for the skeletal muscle metabolic response to exercise. In the current study investigated whether ERRα expression is sufficient to drive exercise-induced adaptations in muscle. We generated conditional ERRα transgenic mice that overexpress human ERRα in a tetracycline-inducible and skeletal muscle-specific manner (ERRαMOEiHSA). Dox-induced ERRαMOEiHSA (versus non-induced) mice exhibited reddening in glycolytic muscles, a characteristic of oxidative muscle. Mitochondrial content was increased in these muscles, based on mtDNA quantitation and citrate synthase activity. Consistently, ERRα-overexpressing muscles had higher O2 consumption rates and increased glycogen content. To determine if these metabolic changes altered exercise capacity, run performance was assessed in untrained mice. Dox-induced ERRαMOEiHSA mice tested at constant speed (endurance test) or at increasing speeds (aerobic test) ran longer compared to controls. Post-run blood glucose levels were higher in both testing paradigms, which may be due to greater reliance on β-oxidation and higher basal glycogen stores in ERRα-expressing muscles. Using ChIP and reporters assays we showed that ERRα directly activates gene encoding the catalytic (Ppp1ca) and regulatory subunits (Ppp1r3c) of protein phosphatase 1, involved in hormonal and contractile-activity control of glycogen metabolism. Collectively, these results demonstrate that short-term ERRα activation promotes muscle metabolic adaptations and exercise performance similar to exercise training. Disclosure J. Li: None. A. Hamilton: None. J.M. Huss: None. Funding American Diabetes Association (1-18-IBS-103 to J.M.H.)

Estrogen-related receptor alpha induces epithelial-mesenchymal transition through cancer-stromal interactions in endometrial cancer

Estrogen-related receptor alpha (ERRα), which shares structural similarities with estrogen receptors, is associated with tumor progression in endometrial cancer, but little is known about the detailed underlying mechanism. We investigated whether ERRα, in cooperation with peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), could participate in epithelial-mesenchymal transition (EMT) in endometrial cancer through cancer-stromal interactions. Two endometrial cancer cell lines, Ishikawa and HEC-1A, transfected with ERRα/PGC-1α expression plasmids or silenced for ERRα expression, were co-cultured with telomerase-transformed human endometrial stromal cells (T-HESCs). We found that EMT-associated factors including vimentin, Snail, and zinc finger E-box binding homeobox 1 were upregulated in cancer cells overexpressing ERRα/PGC-1α and that transforming growth factor-beta (TGF-β) was induced in T-HESCs in the same conditions. In contrast, ERRα knockdown suppressed EMT-associated factors in cancer cells and TGF-β in T-HESCs. ERRα/PGC-1α overexpression increased the expression of EMT-associated factors after TGF-β exposure; however, it decreased E-cadherin at protein level. ERRα knockdown suppressed EMT-associated factors in the presence of TGF-β, whereas E-cadherin remained unchanged. Matrigel invasion assays revealed that ERRα knockdown attenuated the stimulation of migration and invasion by TGF-β. These findings suggest that ERRα is a potential target for inhibiting TGF-β-induced EMT through cancer-stromal interactions in endometrial cancer.

The enhanced expression of estrogen‐related receptor α in human bladder cancer tissues and the effects of estrogen‐related receptor α knockdown on bladder cancer cells

Estrogen-related receptor α (ERRα) belongs to the superfamily of nuclear orphan receptors. However, the role of ERRα in bladder cancer remains unknown. This study examined the expression of ERRα in bladder cancer tissues and explored the molecular mechanisms of ERRα in bladder cancer progression. The expression of ERRα in bladder cancer tissues from 61 patients was determined by immunohistochemistry. We performed quantitative real-time polymerase chain reaction assay to detect the gene expression levels and carried out Western blot assay to measure protein levels. In vitro functional assays, including colony formation, Cell Counting Kit-8, Transwell invasion, and migration assays, were performed to detect bladder cancer cell growth, proliferation, invasion, and migration, respectively. Flow cytometry was used to determine the cell apoptotic rate of bladder cancer cells. Among the 61 detected bladder cancer tissues, 39 bladder cancer tissues showed positive ERRα immunoreactivity. Higher ERRα immunoreactivity score was significantly associated with TNM stage, tumor grade, distant metastasis, and poor survival in patients with bladder cancer. Univariate and multivariate analyses showed that ERRα immunoreactivity was an independent prognostic factor for overall survival in patients with bladder cancer. ERRα was found to be upregulated in bladder cancer cell lines, and knockdown of ERRα suppressed bladder cancer cell growth, proliferation, invasion, and migration; promoted bladder cancer cell apoptosis; and inhibited the epithelial-mesenchymal transition of bladder cancer cells. On the other hand, bladder cancer cell proliferation, invasion, and migration were significantly enhanced after cells were transfected with an ERRα-overexpressing vector. In vivo tumor growth and metastasis assays showed that ERRα knockdown resulted in remarkable inhibition of tumor growth and tumor metastasis in nude mice. Collectively, our results suggest that the enhanced expression of ERRα may play a key role in the development and progression of bladder cancer and ERRα may serve as an important prognostic factor for bladder cancer.

ERRα as a Bridge Between Transcription and Function: Role in Liver Metabolism and Disease.

As transcriptional factors, nuclear receptors (NRs) function as major regulators of gene expression. In particular, dysregulation of NR activity has been shown to significantly alter metabolic homeostasis in various contexts leading to metabolic disorders and cancers. The orphan estrogen-related receptor (ERR) subfamily of NRs, comprised of ERRα, ERRβ, and ERRγ, for which a natural ligand has yet to be identified, are known as central regulators of energy metabolism. If AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) can be viewed as sensors of the metabolic needs of a cell and responding acutely via post-translational control of proteins, then the ERRs can be regarded as downstream effectors of metabolism via transcriptional regulation of genes for a long-term and sustained adaptive response. In this review, we will focus on recent findings centered on the transcriptional roles played by ERRα in hepatocytes. Modulation of ERRα activity in both in vitro and in vivo models via genetic or pharmacological manipulation coupled with chromatin-immunoprecipitation (ChIP)-on-chip and ChIP-sequencing (ChIP-seq) studies have been fundamental in delineating the direct roles of ERRα in the control of hepatic gene expression. These studies have identified crucial roles for ERRα in lipid and carbohydrate metabolism as well as in mitochondrial function under both physiological and pathological conditions. The regulation of ERRα expression and activity via ligand-independent modes of action including coregulator binding, post-translational modifications (PTMs) and control of protein stability will be discussed in the context that may serve as valuable tools to modulate ERRα function as new therapeutic avenues for the treatment of hepatic metabolic dysfunction and related diseases.

Antitumor effect of XCT790, an ERRα inverse agonist, on ERα-negative endometrial cancer cells.

The estrogen-related receptor (ERR) α is structurally similar to classical estrogen receptors (ERs), but is considered to be an orphan nuclear receptor. We previously found that ERRα regulates uterine endometrial cancer progression. Here, we investigated the efficacy of XCT790, a selective inverse agonist of ERRα, on endometrial cancer cells in vitro and in vivo. HEC-1A and KLE, ERα-negative endometrial cancer cells exhibiting high ERRα expression levels, and HEC-1A cell-derived xenograft model mice were treated with XCT790. Transcriptional activity and cell proliferation were examined using luciferase, WST-8 and colony formation assays, respectively. Cell cycle progression was evaluated using flow cytometry, immunofluorescence cytochemistry and Western blotting. Apoptosis was evaluated using a caspase-3/7 activity assay. We found that XCT790 significantly inhibited ERRα-induced in vitro transcriptional activity, including that of the vascular endothelial growth factor (VEGF) gene, in a concentration-dependent manner (p < 0.05). We also found that XCT790 suppressed colony formation and cell proliferation in a concentration and time-dependent manner (p < 0.01) without cytotoxicity, and induced apoptosis (p < 0.01). XCT790 was found to cause cell cycle arrest at the mitotic phase. Akt and mTOR phosphorylation was found to be inhibited by XCT790, but PI3K levels were not found to be significantly affected. Combination therapy of XCT790 with paclitaxel elicited a synergistic inhibitory effect. Additionally, we found that XCT790 significantly inhibited in vivo tumor growth and angiogenesis, and induced apoptosis without a reduction in body weight, in xenograft models (p < 0.01). From our data we conclude that XCT790 has an anti-tumor effect on endometrial cancer cells in vitro and in vivo. As such, it may serve as a novel therapeutic agent for endometrial cancer.

Estrogen-related receptor-α mediates puromycin aminonucleoside-induced mesangial cell apoptosis and inflammatory injury.

Glomerular diseases are the leading cause of chronic kidney disease, and mesangial cells (MCs) have been demonstrated to be involved in the pathogenesis. Puromycin aminonucleoside (PAN) is a nephrotoxic drug that induces glomerular injury with elusive mechanisms. The present study was undertaken to investigate the role of PAN in MC apoptosis, as well as the underlying mechanism. Here we found that PAN induced MC apoptosis accompanied by declined cell viability and enhanced inflammatory response. The apoptosis was further evidenced by increments of apoptosis regulator BAX (BAX) and caspase-3 expression. In line with the apoptotic response in MCs following PAN treatment, we also found a remarkable induction of estrogen-related receptor-α (ERRα), an orphan nuclear receptor, at both mRNA and protein levels. Interestingly, ERRα silencing by an siRNA approach resulted in an attenuation of the apoptosis and inflammatory response caused by PAN. More importantly, overexpression of ERRα in MCs significantly triggered MC apoptosis in line with increased BAX and caspase-3 expression. In PAN-treated MCs, ERRα overexpression further aggravated PAN-induced apoptosis. In agreement with the in vitro study, we also observed increased ERRα expression in line with enhanced apoptotic response in renal cortex from PAN-treated rats. These data suggest a detrimental effect of ERRα on PAN-induced MC apoptosis and inflammatory response, which could help us to better understand the pathogenic mechanism of MC injury in PAN nephropathy.