Expression of estrogen receptor-related receptor isoforms and clinical significance in endometrial adenocarcinoma

Primary health care team faultlines and team performance: the mediating role of knowledge sharing

Family doctor teams, serving as health gatekeepers, are extensively advocated in China. Their composition, comprising a heterogeneous mix of professionals, contributes to a more comprehensive service, but also poses challenges. Consequently, scholarly interest has arisen in comprehending how these compositions, known as faultlines, influence team dynamics and outcomes. However, there is a lack of comprehensive exploration into how faultlines influence team members' communication processes and knowledge sharing. This study aims to provide insights into the associations between faultlines in primary care teams and team performance, specifically exploring how knowledge sharing may mediate these effects, with the goal of revealing key insights to optimize contracted family doctor services. Survey data from 291 family doctor teams in China was utilized to test hypotheses, revealing a negative association between (social-category and information-based) faultlines and knowledge sharing. Team knowledge sharing acts as a mediator in the relationship between these faultlines and team performance. Our findings advance faultlines theory and emphasize the mediating role of knowledge sharing in elucidating the interplay between faultlines and team performance. These insights are crucial for fostering collaboration, managing faultlines, and enhancing healthcare team performance.

An integrated approach of network pharmacology, molecular docking, and experimental verification uncovers kaempferol as the effective modulator of HSD17B1 for treatment of endometrial cancer

BACKGROUND

Endometrial cancer (EC) is one of the most common gynecological malignancies globally, and the development of innovative, effective drugs against EC remains a key issue. Phytoestrogen kaempferol exhibits anti-cancer effects, but the action mechanisms are still unclear.

METHOD

MTT assays, colony-forming assays, flow cytometry, scratch healing, and transwell assays were used to evaluate the proliferation, apoptosis, cell cycle, migration, and invasion of both ER-subtype EC cells. Xenograft experiments were used to assess the effects of kaempferol inhibition on tumor growth. Next-generation RNA sequencing was used to compare the gene expression levels in vehicle-treated versus kaempferol-treated Ishikawa and HEC-1-A cells. A network pharmacology and molecular docking technique were applied to identify the anti-cancer mechanism of kaempferol, including the building of target-pathway network. GO analysis and KEGG pathway enrichment analysis were used to identify cancer-related targets. Finally, the study validated the mRNA and protein expression using real-time quantitative PCR, western blotting, and immunohistochemical analysis.

RESULTS

Kaempferol was found to suppress the proliferation, promote apoptosis, and limit the tumor-forming, scratch healing, invasion, and migration capacities of EC cells. Kaempferol inhibited tumor growth and promotes apoptosis in a human endometrial cancer xenograft mouse model. No significant toxicity of kaempferol was found in human monocytes and normal cell lines at non-cytotoxic concentrations. No adverse effects or significant changes in body weight or organ coefficients were observed in 3-7 weeks' kaempferol-treated animals. The RNA sequencing, network pharmacology, and molecular docking approaches identified the overall survival-related differentially expressed gene HSD17B1. Interestingly, kaempferol upregulated HSD17B1 expression and sensitivity in ER-negative EC cells. Kaempferol differentially regulated PPARG expression in EC cells of different ER subtypes, independent of its effect on ESR1. HSD17B1 and HSD17B1-associated genes, such as ESR1, ESRRA, PPARG, AKT1, and AKR1C1\2\3, were involved in several estrogen metabolism pathways, such as steroid binding, 17-beta-hydroxysteroid dehydrogenase (NADP+) activity, steroid hormone biosynthesis, and regulation of hormone levels. The molecular basis of the effects of kaempferol treatment was evaluated.

CONCLUSIONS

Kaempferol is a novel therapeutic candidate for EC via HSD17B1-related estrogen metabolism pathways. These results provide new insights into the efficiency of the medical translation of phytoestrogens.

Role of HIF-1α/ERRα in Enhancing Cancer Cell Metabolism and Promoting Resistance of Endometrial Cancer Cells to Pyroptosis

Oxygen is critical to energy metabolism, and tumors are often characterized by a hypoxic microenvironment. Owing to the high metabolic energy demand of malignant tumor cells, their survival is promoted by metabolic reprogramming in the hypoxic microenvironment, which can confer tumor cell resistance to pyroptosis. Pyroptosis resistance can inhibit anti-tumor immunity and promote the development of malignant tumors. Hypoxia inducible factor-1α (HIF-1α) is a key regulator of metabolic reprogramming in tumor cells, and estrogen-related receptor α (ERRα) plays a key role in regulating cellular energy metabolism. Therefore, the close interaction between HIF-1α and ERRα influences the metabolic and functional changes in cancer cells. In this review, we summarize the reprogramming of tumor metabolism involving HIF-1α/ERRα. We review our understanding of the role of HIF-1α/ERRα in promoting tumor growth adaptation and pyroptosis resistance, emphasize its key role in energy homeostasis, and explore the regulation of HIF-1α/ERRα in preventing and/or treating endometrial carcinoma patients. This review provides a new perspective for the study of the molecular mechanisms of metabolic changes in tumor progression.

Immunohistochemical Analysis of PGC-1α and ERRα Expression Reveals Their Clinical Significance in Human Ovarian Cancer

Purpose

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and estrogen-related receptor alpha (ERRα) play a vital role in various human cancers. The purpose of this study was to investigate whether the PGC-1α/ERRα axis could serve as an effective prognostic marker in ovarian cancer (OC).

Patients and Methods

We investigated the expression of both PGC-1α and ERRα in 42 ovarian cancer and 31 noncancerous ovarian samples by immunohistochemistry (IHC). The relationship between the expression of PGC-1α and ERRα in OC and the clinical characteristics of patients was evaluated. In addition, data from the Human Protein Atlas (HPA) database were collected to validate the prognostic significance of PGC-1α and ERRα mRNA expression in OC.

Results

PGC-1α and ERRα showed notably higher expression in OC tissues than in noncancerous tissues (P=0.0059, P=0.002). Moreover, in patients with OC, high ERRα and PGC-1α/ERRα expression significantly correlated with tumor differentiation (P=0.027; P=0.04), lymph node status (P=0.023; P=0.021), CA125 (P=0.036; P=0.021), and HE4 (P=0.021; P=0.05), while high PGC-1α expression was only significantly associated with tumor differentiation (P=0.029). The combined analysis of high PGC-1α and ERRα expression revealed a tendency towards poor cancer-specific survival (P=0.1276).

Conclusion

PGC-1α and ERRα are overexpressed in OC and might be significant prognostic factors for this cancer.

Novel endocrine therapeutic strategy in endometrial carcinoma targeting estrogen-related receptor α by XCT790 and siRNA

Purpose

To explore the targeted therapy of estrogen-related receptor α (ERRα) in endometrial cancer (EC) cells and its potential mechanisms.

Methods

The mRNA and protein expression levels of ERRα and estrogen receptor α (ERα) were detected by qPCR and Western blotting in RL-952, AN3-CA, HEC-1A, and HEC-1B EC cell lines. After treatment with the ERRα-specific antagonist XCT790 or infection with lentivirus-mediated small interfering RNA (siRNA) targeting the ERRα (siRNA-ERRα), cell proliferation and apoptosis were evaluated by MTS assay and flow cytometry. After treatment with siRNA-ERRα, the expression profiles of transcription factors (TFs) were analyzed by protein/DNA arrays in EC cells.

Results

The relative mRNA levels of ERRa in RL-952 (1±0.0831) and AN3-CA (1.162±0.0325) were significantly higher than those in HEC-1A (0.3081±0.0339) and HEC-1B (0.1119±0.0091) (P<0.05), and similar results were observed for ERRα protein levels. A higher ratio of ERa/ERRa was observed in ERα-positive RL-952 (10-fold) and ANC-3A (8.5-fold) cells, whereas a lower ratio was observed in ERα-negative HEC-1A (3.75-fold) and HEC-1B cells (0-fold). Both – exogenous XCT790 and endogenous siRNA-ERRα – can decrease the expression of ERRα, thereby inhibiting proliferation but promoting apoptosis in both ERα-positive and -negative EC cells. The XCT790 presented higher proliferation-inhibition and apoptosis rates in the ERα-positive than ERα-negative cells, whereas the siRNA-ERRα exhibited higher proliferation-inhibition and apoptosis rates in the ERα-negative than in ERα-positive cells. In total, 3 upregulated and 17 downregulated TFs were screened out by knocked-down expression of ERRα in all EC cells. Among them, the upregulated TFs organic cation transporter 3/4(Oct3/4), hepatic nuclear factor 4 (HNF4), HNF4 and chicken ovalbumin upstream TF (COUP-TF) as well as downregulated transcription factor EB (TFEB) were found to be statistically significant (P<0.05).

Conclusion

Targeting ERRα provides a promising novel endocrine therapeutic strategy.

Estrogen related receptor alpha triggers the migration and invasion of endometrial cancer cells via up regulation of TGFB1

Estrogenic signals have been suggested to be important for the tumorigenesis and progression of endometrial cancer (EC) cells. Our present data showed that estrogen related receptor alpha (ERRα), while not ERRβ or ERRγ, was significantly elevated in EC cells and tissues when compared to their controls. Targeted inhibition of ERRα by siRNA or its inverse agonist XCT-790 can suppress the migration and invasion of EC cells. Both si-ERRα and XCT-790 decreased the expression of transforming growth factor-beta (TGF-β). ERRα can directly bind with the promoter of TGFB1 and then increase its transcription. Further, ERRα was involved in the positive self-feedback loop of TGF-β in EC cells. Targeted inhibition of ERRα/TGF-β can synergistically suppress the in vitro invasion of EC cells. Collectively, our data suggested that ERRα can trigger the cell migration and invasion via increasing the positive self-feedback regulation of TGF-β.

High expression of estrogen-related receptor α is significantly associated with poor prognosis in patients with colorectal cancer

Colorectal cancer (CRC) is one of the most common types of malignancy with high morbidity and mortality rates worldwide. This biologically heterogeneous disease results in diverse therapeutic responses, thus, novel prognostic biomarkers are required to improve CRC treatment. Estrogen-related receptor α (ERRα) is a nuclear orphan receptor, which is associated with estrogen receptor α. The present study aimed to investigate the expression of ERRα in patients with CRC, and explore the association between ERRα expression and clinicopathological factors, local recurrence and prognosis. In the present study, ERRα expression was detected in 15 fresh CRC tissues using quantitative real-time polymerase chain reaction (RT-qPCR) and in 128 paraffin-embedded CRC tissues using immunohistochemistry. The associations between ERRα expression and prognosis of CRC patients were evaluated by univariate, and multivariate (Cox proportional hazards model) analysis. RT-qPCR demonstrated that the mRNA expression of ERRα in CRC tissues was significantly higher compared with that in matched normal tissues. Immunohistochemistry revealed that ERRα high expression was detected in the nuclei of cancer cells from 39.1% (50/128) of CRC tissues. ERRα expression based on immunohistochemical staining was significantly associated with tumor differentiation, tumor invasion, lymph node status and Dukes stage (all P<0.05). Furthermore, patients with high ERRα expression were significantly associated with an increased risk of recurrence and poor prognosis, compared with patients with low ERRα expression. ERRα expression was identified as an independent prognostic factor for patients with CRC. In conclusion, ERRα serves important roles in the progression of CRC and is a potential prognostic factor for patients with CRC.

The discovery of novel, potent ERR-alpha inverse agonists for the treatment of triple negative breast cancer

The estrogen-related receptor α (ERRα) is an orphan receptor and a novel target for solid tumor therapy, conceivably through effects on the regulation of tumor cell energy metabolism associated with energy stress within solid tumor micro environments. Here we describe the discovery of novel potent inverse agonists of ERRα. In vitro, compound 11 potently inhibits ERRα's transcriptional activity by preventing endogenous PGC-1α and ERRα binding and suppresses the proliferation of different human cancer cell lines and the migration of breast cancer cells (MDA-MB-231). In vivo, compound 11 demonstrates a strong inhibitory effect on the growth of human breast cancer xenografts (MDA-MB-231) and the tumor growth is inhibited by 40.9% after treating with compound 11 (30 mg/kg). The binding mode shows that compound 11 interacts with the binding pocket of ERRα through hydrogen interactions with the residue Gly397 and hydrophobic interactions with the hydrophobic residues. All these results suggest that compound 11 represents a novel potent ERRα inverse agonist and is promising in the discovery of antitumor compounds for the treatment of triple negative breast cancer.

Anti-tumor effect of estrogen-related receptor alpha knockdown on uterine endometrial cancer

Estrogen-related receptor (ERR)α presents structural similarities with estrogen receptor (ER)α. However, it is an orphan receptor not binding to naturally occurring estrogens. This study was designed to investigate the role of ERRα in endometrial cancer progression. Immunohistochemistry analysis on 50 specimens from patients with endometrial cancer showed that ERRα was expressed in all examined tissues and the elevated expression levels of ERRα were associated with advanced clinical stages and serous histological type (p < 0.01 for each). ERRα knockdown with siRNA suppressed angiogenesis via VEGF and cell proliferation in vitro (p < 0.01). Cell cycle and apoptosis assays using flow cytometry and western blot revealed that ERRα knockdown induced cell cycle arrest during the mitotic phase followed by apoptosis initiated by caspase-3. Additionally, ERRα knockdown sensitized cells to paclitaxel. A significant reduction of tumor growth and angiogenesis was also observed in ERRα knockdown xenografts (p < 0.01). These findings indicate that ERRα may serve as a novel molecular target for the treatment of endometrial cancer.

Research progress on the reproductive and non-reproductive endocrine tumors by estrogen-related receptors

Oncologists have traditionally considered that tumorigenesis are closely related to classical nuclear estrogen receptors (ERs), such as estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), through the ligands binding and target gene transcription induction. Estrogen-related receptors (ERRs) have similar structures with ERs, which are also gradually thought to be relevant to reproductive endocrine tumor diseases, even non-reproductive endocrine tumors. In this review, different subtypes of ERRs and their structures firstly will be introduced, then the expression patterns in gynecological oncology (i.e., breast cancer, endometrial cancer, and ovarian cancer), male genitourinary system malignancy especially prostatic cancer along with other non-reproductive endocrine tumors (i.e., lung cancer, colorectal cancer, and liver cancer) will be described, and simultaneously the role of tumorigenesis related to ERRs will be discussed. Therefore, the review is benefit to explore the way of tumor prevention and treatment.

Messenger RNA profile analysis deciphers new Esrrb responsive genes in prostate cancer cells

Background

Orphan nuclear receptor estrogen related receptor β (Esrrb or ERRβ) is well known in stem cells and early embryonic development. However, little is known about its function in cancer.

Method

We investigated the mRNA profile alterations induced by Esrrb expression and its synthetic ligand DY131 in human prostate cancer DU145 cells via RNA-Seq analysis.

Results

We distinguished 67 mRNAs differentially expressed by Esrrb alone. Although DY131 alone did not change any gene, treatment of DY131 in the presence of Esrrb altered 1161 mRNAs. These observations indicated Esrrb had both ligand-independent and ligand-dependent activity. When Esrrb was expressed, DY131 treatment further regulated 15 Esrrb-altered mRNAs. DY131 acted as an antagonist for 11 of 15 mRNAs (wdr52, f13a1, pxdn, spns2, loc100506599, tagln, loc441454, tkel1, sema3f, zcwpw2, sdc2) and as an agonist for 4 of the 15 mRNAs (rarres3, oasl, padi2, ddx60). Gene ontology analyses showed altered genes are related to transcription and translation regulation, cell proliferation and apoptosis regulation, and cellular metabolism.

Conclusion

Our results characterized mRNA profiles in DU145 prostate cancer cells driven by Esrrb expression and Esrrb ligand DY131, and provided multiple markers to characterize Esrrb’s function in Esrrb research.

Electronic supplementary material

The online version of this article (doi:10.1186/s12867-015-0049-1) contains supplementary material, which is available to authorized users.

PGE2 modulates the transcriptional activity of ERRa in prostate stromal cells

The regulation of the transcriptional activity of the estrogen receptor-related receptor a (ERRa) has not yet been clearly documented. Aromatase is a direct target gene of ERRa, and we previously reported that prostaglandin E2 (PGE2) increased the expression of ERRa in the prostate stromal cell line WPMY-1, which ultimately promoted estradiol production by enhancing aromatase gene transcription. Here, we show that PGE2 also affects aromatase expression by regulating ERRa transcriptional activity in prostate stromal cells. When the cells were cultured in serum-free medium, the expression of aromatase was not proportional to the ERRa protein level, if no other stimulation occurred, indicating the absence of a factor that activates ERRa. PGE2 could upregulate aromatase and ERRa response element (ERRE)-reporter expression and also enhance ERRa phosphorylation and nuclear localization. PGE2 functions through the PGE2 receptors (EP) 2 and EP4, which couple to adenylate cyclase. The activation of adenylate cyclase with Forskolin mimicked the PGE2-mediated enhancement of extracellular signal-regulated kinase (ERK) phosphorylation and ERRa target gene expression. Experiments using specific signaling pathway inhibitors showed that both phosphatidylinositol 3-kinase (PI3K) and ERK are involved in ERRa activation, and the PI3K inhibitor was shown to abolish ERK activation. Our results suggest that PGE2 is a modulator of ERRa transcriptional activity. Furthermore, PGE2 activates the EP2/EP4-cAMP-PI3K-ERK signaling pathway, which enhanced ERRa transcriptional potentiality by increasing ERRa phosphorylation and nuclear translocation, subsequently promoting the expression of its target genes, such as aromatase.

ERRα augments HIF-1 signalling by directly interacting with HIF-1α in normoxic and hypoxic prostate cancer cells

Adaptation of cancer cells to a hypoxic microenvironment is important for their facilitated malignant growth and advanced development. One major mechanism mediating the hypoxic response involves up-regulation of hypoxia-inducible factor 1 (HIF-1) expression, which controls reprogramming of energy metabolism and angiogenesis. Oestrogen-related receptor-α (ERRα) is a pivotal regulator of cellular energy metabolism and many biosynthetic pathways, and has also been proposed to be an important factor promoting the Warburg effect in advanced cancer. We and others have previously shown that ERRα expression is increased in prostate cancer and is also a prognostic marker. Here we show that ERRα is oncogenic in prostate cancer and also a key hypoxic growth regulator. ERRα-over-expressing prostate cancer cells were more resistant to hypoxia and showed enhanced HIF-1α protein expression and HIF-1 signalling. These effects could also be observed in ERRα-over-expressing cells grown under normoxia, suggesting that ERRα could function to pre-adapt cancer cells to meet hypoxia stress. Immunoprecipitation and FRET assays indicated that ERRα could physically interact with HIF-1α via its AF-2 domain. A ubiquitination assay showed that this ERRα-HIF-1α interaction could inhibit ubiquitination of HIF-1α and thus reduce its degradation. Such ERRα-HIF-1α interaction could be attenuated by XCT790, an ERRα-specific inverse agonist, resulting in reduced HIF-1α levels. In summary, we show that ERRα can promote the hypoxic growth adaptation of prostate cancer cells via a protective interaction with HIF-1α, suggesting ERRα as a potential therapeutic target for cancer treatment.

The PGC-1/ERR signaling axis in cancer

Proliferating cells need to produce a large amount of energy and, at the same time, need to maintain a constant supply of biosynthetic precursors of macromolecules that are used as building blocks for generating new cells. Indeed, many cancer cells undergo a switch from mitochondrial to glycolytic metabolism and display a truncated tricarboxylic acid cycle to match these specific metabolic requirements of proliferation. Understanding the mechanisms by which cancer cells reprogram various metabolic pathways to satisfy their unique bioenergetic requirements has become an active field of research. Concomitantly, it has emerged that members of a family of orphan nuclear receptors known as the estrogen-related receptors (ERRs), working in concert with members of the PPARγ coactivator (PGC)-1 family, act as central transcriptional regulators of metabolic gene networks involved in maintaining energy homeostasis in normal cells. Recent studies have suggested that the PGC-1/ERR transcriptional axis is also important in the metabolic reprogramming of cancer cells. This review focuses on the functional integration of the PGC-1/ERR axis with known oncogenes and the observation that modulation of the activity of this axis can have both pro- and anti-proliferative properties.

Control of the human osteopontin promoter by ERRα in colorectal cancer

Colorectal cancer is the second leading cause of death from cancer. Osteopontin (OPN) is a component of tumor extracellular matrix identified as a key marker of cancer progression. The estrogen-related receptor α (ERRα) has been implicated in endocrine-related cancer development and progression, possibly through modulation of cellular energy metabolism. Previous reports that ERRα regulates OPN expression in bone prompted us to investigate whether ERRα controls OPN expression in human colorectal cancer. Using a tissue microarray containing 83 tumor-normal tissue pairs of colorectal cancer samples, we found that tumor epithelial cells displayed higher staining for ERRα than normal mucosa, in correlation with elevated OPN expression. In addition, knocking down endogenous ERRα led to reduced OPN expression in HT29 colon cancer cells. Promoter analysis, inhibition of ERRα activity, and expression and mutation of potential ERRα response elements in the proximal promoter of human OPN showed that ERRα and its obligate co-activator, peroxisome proliferator-activated receptor γ co-activator-1 α, positively control human OPN promoter activity. Furthermore, chromatin immunoprecipitation experiments confirmed in vivo occupancy of the OPN promoter by ERRα in HT29 cells, suggesting that OPN is a direct target of ERRα in colorectal cancer. These findings suggest an additional mechanism by which ERRα participates in the development and progression of colorectal cancer, further supporting the relevance of targeting ERRα with antagonists as anticancer agents.

Estrogen-related receptor-γ regulates estrogen receptor-α responsiveness in uterine endometrial cancer

OBJECTIVE

Estrogen-related receptors (ERRs) are orphan nuclear receptors that modulate the estrogen receptor (ER)-mediated pathway and play roles in the regulation of breast and prostate cancer cell growth. However, the significance of the localization and the function of ERRs in uterine endometrial cancer remain unclear. We aimed to measure the expression of ERRγ and determine its association with the ER-mediated pathway in human endometrial cancer.

METHODS

Proliferation, luciferase, and quantitative polymerase chain reaction assays were performed in ERα-positive (Ishikawa) and ERα-negative (HEC1A) endometrial cancer cell lines. The association between ERRγ and ERα expressions was determined by immunohistochemical analysis in uterine endometrial cancer tissues.

RESULTS

Estrogen-induced estrogen response element transcriptional activity was repressed by ERRγ in ERα-positive cells but was stimulated by ERRγ in ERα-negative cells. The stable overexpression of ERRγ regulated the in vitro cell growth in the ERα-positive and ERα-negative endometrial cancer cell lines. A selective ERRγ agonist, DY131, inhibited the growth of the ERα-positive endometrial cancer cells but promoted that of the ERα-negative cancer cells. Furthermore, we found that ERRγ is expressed in the nuclei of human uterine endometrial cancer tissues. Estrogen-related receptor γ was not associated with pathological parameters such as the International Federation of Gynecology and Obstetrics stage and histological type. The uterine endometrial cancer tissues with ERRγ-positive/ERα-negative status may have a significantly poor prognosis.

CONCLUSIONS

The relationship between ERRγ and ERα status could be a predictive marker for the treatment of uterine endometrial cancer, which provides an impetus for the identification of ligands for nuclear orphan receptor ERRγ.

Molecular mining of GGAA tagged transcripts and their expression in water buffalo Bubalus bubalis

Repeat sequences are involved in regulation of gene expression both at the transcriptional and translational level. In the mammalian genomes, tri- and tetranucleotide repeats like ATA, AATA, GGAA and GAAA have been associated with diseases. In silico analysis of (GGAA)5 distribution across the species showed maximum number of this repeat in the mouse transcriptome compared to that in other species. Following this, we conducted minisatellite associated sequence amplification (MASA) to explore the buffalo's transcriptome using cDNA from different tissues and an oligo based on (GGAA)5 repeats. MASA uncovered twenty six mRNA transcripts showing homology to known genes in the database. qPCR studies showed the highest expression of twelve transcripts in the spleen. A transcript, pLRC107 with its partial sequence of 203 nucleotides showed sequence variation at several positions in spleen as compared to other four tissues examined. Transcript pLRC100 was found to represent the partial coding sequence of Bos taurus HECT {(homologous to E6-associated protein (UBE3A) carboxyl-terminus domain) and RCC1 (CHC1)-like domain (RLD) 1}, mRNA. We ascertained full length coding sequence of HECT gene and localized the same on buffalo chromosome 10 employing FISH. This gene was found to be conserved across the species. Another gene LRP8 uncovered in the process showed copy number variation between buffalo males (4-9) and females (34-54). The MASA approach enabled us to identify several genes in Bubalus bubalis without screening an entire cDNA library. The highest expression of 12 mRNA transcripts in spleen suggests their likely involvement with immuno transaction. A comprehensive knowledge of the repeat tagged transcriptomes is envisaged to help in understanding their significance in genome organization and evolution forming rich basis of functional and comparative genomics.

Dual function of ERRα in breast cancer and bone metastasis formation: implication of VEGF and osteoprotegerin

Bone metastasis is a complication occurring in up to 70% of advanced breast cancer patients. The estrogen receptor-related receptor alpha (ERRα) has been implicated in breast cancer and bone development, prompting us to examine whether ERRα may function in promoting the osteolytic growth of breast cancer cells in bone. In a mouse xenograft model of metastatic human breast cancer, overexpression of wild-type ERRα reduced metastasis, whereas overexpression of a dominant negative mutant promoted metastasis. Osteoclasts were directly affected and ERRα upregulated the osteoclastogenesis inhibitor, osteoprotegerin (OPG), providing a direct mechanistic basis for understanding how ERRα reduced breast cancer cell growth in bone. In contrast, ERRα overexpression increased breast cancer cell growth in the mammary gland. ERRα-overexpressing primary tumors were highly vascularized, consistent with an observed upregulation of angiogenic growth factor, the VEGF. In support of these findings, we documented that elevated expression of ERRα mRNA in breast carcinomas was associated with high expression of OPG and VEGF and with disease progression. In conclusion, our results show that ERRα plays a dual role in breast cancer progression in promoting the local growth of tumor cells, but decreasing metastatic growth of osteolytic lesions in bone.

The genomic relationship between primary breast carcinomas and their nodal metastases

We screened the whole tumor genome to identify DNA copy number gains and losses that discriminate between primary breast carcinomas (MP) and their nodal metastases (ML). Six candidate genes were confirmed by quantitative PCR to have differentially distributed copy number changes. Three of the genes (ERRγ, DDX6, and TIAM1) were more commonly amplified in nodal metastases. Principal component analysis revealed that MP-ML pairs varied markedly in their genomic divergence. The latter was larger in PR-negative tumors. Nodal metastases may form early or late in the development of breast carcinomas and PR-negative tumors may metastasize earlier or are genomically less stable.

Involvement of estrogen receptor-related receptors in human ovarian endometriosis

OBJECTIVE

To determine whether decreased estrogen receptor alpha (ER-α) expression in endometriotic lesions could be balanced by an increased expression of estrogen receptor-related receptors (ERRs). To evaluate whether ERR-α expression is influenced by hormonal change in fertile and menopausal women.

DESIGN

Prospective controlled study.

SETTING

University Hospital, Department of Gynecology.

PATIENT(S)

Twenty-five women: 20 women of reproductive age with (n = 10) and without (control; n = 10) endometriosis and 5 menopausal women.

INTERVENTION(S)

Real-time polymerase chain reaction (qPCR). Immunohistochemistry.

MAIN OUTCOME MEASURE(S)

The ER and ERR expression levels were studied by reverse transcriptase-qPCR, ELISA, and immunohistochemistry using endometriotic and normal endometrial tissues. The ERR-α protein distribution was performed by immunohistochemistry in fertile and menopausal women.

RESULT(S)

Increased levels of ER-β were associated with ER-α, ERR-α, and ERR-γ reductions in ectopic tissue but not in eutopic and normal endometria. Similar levels of ERR-β were found in women with and without endometriosis. The ERR-α expression was similar in proliferative and secretory endometrial samples, whereas a down-regulation of this receptor was found in atrophic tissue.

CONCLUSION(S)

Our data confirm the up-regulation of ER-β as the principal receptor involved in the progression of human endometriosis. In addition, we found that ERR-α seems to be unresponsive to hormonal changes during the menstrual cycle.

Exercise and PGC-1α-independent synchronization of type I muscle metabolism and vasculature by ERRγ

How type I skeletal muscle inherently maintains high oxidative and vascular capacity in the absence of exercise is unclear. We show that nuclear receptor ERRγ is highly expressed in type I muscle and, when transgenically expressed in anaerobic type II muscles (ERRGO mice), dually induces metabolic and vascular transformation in the absence of exercise. ERRGO mice show increased expression of genes promoting fat metabolism, mitochondrial respiration, and type I fiber specification. Muscles in ERRGO mice also display an activated angiogenic program marked by myofibrillar induction and secretion of proangiogenic factors, neovascularization, and a 100% increase in running endurance. Surprisingly, the induction of type I muscle properties by ERRγ does not involve PGC-1α. Instead, ERRγ genetically activates the energy sensor AMPK in mediating the metabovascular changes in ERRGO mice. Therefore, ERRγ represents a previously unrecognized determinant that specifies intrinsic vascular and oxidative metabolic features that distinguish type I from type II muscle.

Estrogen-related receptor gamma promotes mesenchymal-to-epithelial transition and suppresses breast tumor growth

Estrogen-related receptors (ERR), ERR alpha (ERRα) and ERR gamma (ERRγ), are orphan nuclear receptors implicated in breast cancer that function similarly in the regulation of oxidative metabolism genes. Paradoxically, in clinical studies, high levels of ERRα are associated with poor outcomes whereas high levels of ERRγ are associated with a favorable course. Recent studies suggest that ERRα may indeed promote breast tumor growth. The roles of ERRγ in breast cancer progression and how ERRα and ERRγ may differentially affect cancer growth are unclear. In mammary carcinoma cells that do not express endogenous ERRγ, we found that ectopic expression of ERRγ enhanced oxidative metabolism in vitro and inhibited the growth of tumor xenografts in vivo. In contrast, ectopic expression of the ERRα coactivator PGC-1α enhanced oxidative metabolism but did not affect tumor growth. Notably, ERRγ activated expression of a genetic program characteristic of mesenchymal-to-epithelial transition (MET). This program was apparent by changes in cellular morphology, upregulation of epithelial cell markers, downregulation of mesenchymal markers, and decreased cellular invasiveness. We determined that this program was also associated with upregulation of E-cadherin, which is activated directly by ERRγ. In contrast, PGC-1α activated only a subset of genes characteristic of the MET program and, unlike ERRγ, did not upregulate E-cadherin. In conclusion, these results show that ERRγ induces E-cadherin, promotes MET, and suppresses breast cancer growth. Our findings suggest that ERRγ agonists may have applications in the treatment of breast cancer.

Expression profile of mammalian microRNAs in endometrioid adenocarcinoma

MicroRNAs (miRNAs) are small noncoding RNAs of 19-24 nucleotides in length and involved in gene expression regulation. They are associated with cell proliferation, differentiation, apoptosis, and carcinogenesis. The specific expression profiles of miRNAs have been found in many human cancers, but there are few studies on endometrioid adenocarcinoma. We found the miRNA expression profile in 10 pairs of endometrioid adenocarcinoma and adjacent nontumorous endometrium using human miRNA microarray. Seventeen miRNAs exhibited higher expression and six miRNAs exhibited lower expression in endometrioid adenocarcinoma samples than those in the nontumorous samples in the microarray. Of those, the miR-205, miR-449, and miR-429 were greatly enriched; in contrast the miR-204, miR-99b, and miR-193b were greatly downregulated in adenocarcinoma tissues. The expressions of these six miRNAs were validated using real time reverse transcription-PCR. This information may provide the candidate miRNA genome for further confirming the role of miRNAs in carcinogenesis of endometrioid adenocarcinoma and potentially serving as a diagnostic or therapeutic tool in endometrioid adenocarcinoma.

Estrogen receptor related beta is expressed in human endometrium throughout the normal menstrual cycle

BACKGROUND

Estrogen receptor related beta (ERRbeta, ESRRB/NR3B2) is an orphan receptor that shares significant sequence homology with estrogen receptors ERalpha and ERbeta. ERR family members are reported to exhibit constitutive transcriptional activity; however, little is known about the biological function of ERRbeta. In an attempt to delineate its role, we examined expression of ERRbeta in normal human endometrium, a tissue that undergoes cyclic remodelling under the influence of estrogen and progesterone.

METHODS

Well-characterized endometrial tissue (n = 31), including full-thickness biopsies, was obtained from women with regular menstrual cycles. RT-PCR was used to measure mRNA encoding ERRbeta, the peroxisome proliferator activated receptor gamma coactivators (PGC)-1alpha and beta and to determine whether ERRbeta splice variant mRNAs were expressed. ERRbeta was immunolocalized using both single and double antibody immunohistochemistry.

RESULTS

Total ERRbeta mRNA appeared higher in proliferative phase samples but results did not reach significance. Transcripts corresponding to the long- and short-splice variants of ERRbeta as well as PGC1alpha and beta were detected but ERRbetaDelta10 was absent. ERRbeta protein was localized to cell nuclei within multiple endometrial cell types including the glands, stroma, endothelium and immune cells, including uterine natural killer (uNK) cells and macrophages. Fluorescent immunohistochemistry revealed that some cells co-expressed ERRbeta and ERalpha or ERbeta, for example, endothelial and uNK cells were ERRbeta+/ERbeta+.

CONCLUSIONS

ERRbeta mRNA and protein are expressed in healthy human endometrium. Further studies are warranted to characterize the functional impact of ERRbeta on endometrial biology.

Estrogen induces estrogen-related receptor alpha gene expression and chromatin structural changes in estrogen receptor (ER)-positive and ER-negative breast cancer cells

Estrogen-related receptor alpha (ERRalpha), a member of the nuclear receptor superfamily, is closely related to the estrogen receptors (ERalpha and ERbeta). The ERRalpha gene is estrogen-responsive in several mouse tissues and cell lines, and a multiple hormone-response element (MHRE) in the promoter is an important regulatory region for estrogen-induced ERRalpha gene expression. ERRalpha was recently shown to be a negative prognostic factor for breast cancer survival, with its expression being highest in cancer cells lacking functional ERalpha. The contribution of ERRalpha in breast cancer progression remains unknown but may have important clinical implications. In this study, we investigated ERRalpha gene expression and chromatin structural changes under the influence of 17beta-estradiol in both ER-positive MCF-7 and ER-negative SKBR3 breast cancer cells. We mapped the nucleosome positions of the ERRalpha promoter around the MHRE region and found that the MHRE resides within a single nucleosome. Local chromatin structure of the MHRE exhibited increased restriction enzyme hypersensitivity and enhanced histone H3 and H4 acetylation upon estrogen treatment. Interestingly, estrogen-induced chromatin structural changes could be repressed by estrogen antagonist ICI 182 780 in MCF-7 cells yet were enhanced in SKBR3 cells. We demonstrated, using chromatin immunoprecipitation assays, that 17beta-estradiol induces ERRalpha gene expression in MCF-7 cells through active recruitment of co-activators and release of co-repressors when ERRalpha and AP1 bind and ERalpha is tethered to the MHRE. We also found that this estrogen effect requires the MAPK signaling pathway in both cell lines.

The NR3B subgroup: an ovERRview

Members of the NR3B group of the nuclear receptor superfamily, known as the estrogen-related receptors (ERRs), were the first orphan receptors to be identified two decades ago. Despite the fact that a natural ligand has yet to be associated with the ERRs, considerable knowledge about their mode of action and biological functions has emerged through extensive biochemical, genetic and functional genomics studies. This review describes our current understanding of how the ERRs work as transcription factors and as such, how they control diverse developmental and physiological programs.