Involvement of estrogen-related receptors in transcriptional response to hypoxia and growth of solid tumors

Estrogen-related receptor alpha promotes thyroid tumor cell survival via a tumor subtype-specific regulation of target gene networks

Mortalin (encoded by HSPA9) is a mitochondrial chaperone often overexpressed in cancer through as-yet-unknown mechanisms. By searching different RNA-sequencing datasets, we found that ESRRA is a transcription factor highly correlated with HSPA9 in thyroid cancer, especially in follicular, but not C cell-originated, tumors. Consistent with this correlation, ESRRA depletion decreased mortalin expression only in follicular thyroid tumor cells. Further, ESRRA expression and activity were relatively high in thyroid tumors with oncocytic characteristics, wherein ESRRA and mortalin exhibited relatively high functional overlap. Mechanistically, ESRRA directly regulated HSPA9 transcription through a novel ESRRA-responsive element located upstream of the HSPA9 promoter. Physiologically, ESRRA depletion suppressed thyroid tumor cell survival via caspase-dependent apoptosis, which ectopic mortalin expression substantially abrogated. ESRRA depletion also effectively suppressed tumor growth and mortalin expression in the xenografts of oncocytic or ESRRA-overexpressing human thyroid tumor cells in mice. Notably, our Bioinformatics analyses of patient data revealed two ESRRA target gene clusters that contrast oncocytic-like and anaplastic features of follicular thyroid tumors. These findings suggest that ESRRA is a tumor-specific regulator of mortalin expression, the ESRRA-mortalin axis has higher significance in tumors with oncocytic characteristics, and ESRRA target gene networks can refine molecular classification of thyroid cancer.

Therapeutic Strategies for RB1-Deficient Cancers: Intersecting Gene Regulation and Targeted Therapy

The retinoblastoma (RB) transcriptional corepressor 1 (RB1) is a critical tumor suppressor gene, governing diverse cellular processes implicated in cancer biology. Dysregulation or deletion in RB1 contributes to the development and progression of various cancers, making it a prime target for therapeutic intervention. RB1's canonical function in cell cycle control and DNA repair mechanisms underscores its significance in restraining aberrant cell growth and maintaining genomic stability. Understanding the complex interplay between RB1 and cellular pathways is beneficial to fully elucidate its tumor-suppressive role across different cancer types and for therapeutic development. As a result, investigating vulnerabilities arising from RB1 deletion-associated mechanisms offers promising avenues for targeted therapy. Recently, several findings highlighted multiple methods as a promising strategy for combating tumor growth driven by RB1 loss, offering potential clinical benefits in various cancer types. This review summarizes the multifaceted role of RB1 in cancer biology and its implications for targeted therapy.

ERRα: unraveling its role as a key player in cell migration

Cell migration is essential throughout the life of multicellular organisms, and largely depends on the spatial and temporal regulation of cytoskeletal dynamics, cell adhesion and signal transduction. Interestingly, Estrogen-related receptor alpha (ERRα) has been identified as a major regulator of cell migration in both physiological and pathological conditions. ERRα is an orphan member of the nuclear hormone receptor superfamily of transcription factors and displays many biological functions. ERRα is a global regulator of energy metabolism, and it is also highly involved in bone homeostasis, development, differentiation, immunity and cancer progression. Importantly, in some instances, the regulation of these biological processes relies on the ability to orchestrate cell movements. Therefore, this review describes how ERRα-mediated cell migration contributes not only to tissue homeostasis but also to tumorigenesis and metastasis, and highlights the molecular and cellular mechanisms by which ERRα finely controls the cell migratory potential.

Estrogen receptor-related receptor γ uppresses hypoxia-induced angiogenesis by regulating VEGFA in endometrial cancer

OBJECTIVE

Estrogen receptor-related receptor γ (ERRγ), is implicated in cancer cell proliferation and metastasis. The function of ERRγ in tumor angiogenesis, however, is to be revealed. This study was designed to elaborate the regulatory effect of ERRγ on angiogenesis in endometrial cancer (EC).

METHODS

Immunohistochemistry (IHC) was adopted to determine the protein expression of ERRγ, VEGFA, CD31 and hypoxia-inducible factor-1 (HIF-1) in tumor tissues. HEC-1A cells stably expressing ERRγ were established bytransfection, and then an endothelial cell tube formation assay was performed. CCK-8 assay was employed for cell viability, and wound healing assay for cell migration ability. Besides, western blot, ELISA and qRT-PCR were used to examine the VEGFA expression. After hypoxia treatment of ERRγ overexpressing HEC-1A cells, the ERRγ expression and VEGFA expression were determined by western blot. Finally, EC xenografts in nude mice were constructed by subcutaneous injection of ERRγ stably expressing HEC-1A cells and control HEC-1A cells.

RESULTS

IHC results revealed a negative correlation between the expression of ERRγ and VEGFA in EC tissues. ERRγ overexpression significantly decreased the level of HIF-1 in tumor tissue of nude mice. ERRγ overexpression down-regulated inhibited angiogenesis capability and inhibited the proliferation and migration of HEC-1A cells. Furthermore, ERRγ expression was suppressed under the condition of hypoxia while restoration of ERRγ partially inhibited hypoxia-induced VEGFA expression in HEC-1A cells.

CONCLUSIONS

ERRγ is an angiogenesis suppressor and involved in hypoxia-induced VEGFA expression in EC. Hence, ERRγ might be a promising antiangiogenic target for human EC.

ERRα promotes glycolytic metabolism and targets the NLRP3/caspase-1/GSDMD pathway to regulate pyroptosis in endometrial cancer

BACKGROUND

Tumor cells can resist chemotherapy-induced pyroptosis through glycolytic reprogramming. Estrogen-related receptor alpha (ERRα) is a central regulator of cellular energy metabolism associated with poor cancer prognosis. Herein, we refine the oncogenic role of ERRα in the pyroptosis pathway and glycolytic metabolism.

METHODS

The interaction between ERRα and HIF-1α was verified using co-immunoprecipitation. The transcriptional binding sites of ERRα and NLRP3 were confirmed using dual-luciferase reporter assay and cleavage under targets and tagmentation (CUT&Tag). Flow cytometry, transmission electron microscopy, scanning electron microscopy, cell mito stress test, and extracellular acidification rate analysis were performed to investigate the effects of ERRα on the pyroptosis pathway and glycolytic metabolism. The results of these experiments were further confirmed in endometrial cancer (EC)-derived organoids and nude mice. In addition, the expression of ERRα-related pyroptosis genes was analyzed using The Cancer Genome Atlas and Gene Expression Omnibus database.

RESULTS

Triggered by a hypoxic microenvironment, highly expressed ERRα could bind to the promoter of NLRP3 and inhibit caspase-1/GSDMD signaling, which reduced inflammasome activation and increased pyroptosis resistance, thereby resulting in the resistance of cancer cells to cisplatin. Moreover, ERRα activated glycolytic rate-limiting enzyme to bridge glycolytic metabolism and pyroptosis in EC. This phenomenon was further confirmed in EC-derived organoids and nude mice. CUT & Tag sequencing and The Cancer Genome Atlas database analysis showed that ERRα participated in glycolysis and programmed cell death, which resulted in EC progression.

CONCLUSIONS

ERRα inhibits pyroptosis in an NLRP3-dependent manner and induces glycolytic metabolism, resulting in cisplatin resistance in EC cells.

Metabolic regulation of forkhead box P3 alternative splicing isoforms and their impact on health and disease

Forkhead Box P3 (FOXP3) is crucial for the development and suppressive function of human regulatory T cells (Tregs). There are two predominant FOXP3 splicing isoforms in healthy humans, the full-length isoform and the isoform lacking exon 2, with different functions and regulation mechanisms. FOXP3 splicing isoforms show distinct abilities in the cofactor interaction and the nuclear translocation, resulting in different effects on the differentiation, cytokine secretion, suppressive function, linage stability, and environmental adaptation of Tregs. The balance of FOXP3 splicing isoforms is related to autoimmune diseases, inflammatory diseases, and cancers. In response to environmental challenges, FOXP3 transcription and splicing can be finely regulated by T cell antigen receptor stimulation, glycolysis, fatty acid oxidation, and reactive oxygen species, with various signaling pathways involved. Strategies targeting energy metabolism and FOXP3 splicing isoforms in Tregs may provide potential new approaches for the treatment of autoimmune diseases, inflammatory diseases, and cancers. In this review, we summarize recent discoveries about the FOXP3 splicing isoforms and address the metabolic regulation and specific functions of FOXP3 splicing isoforms in Tregs.

The Role of the Estrogen-Related Receptor Alpha (ERRa) in Hypoxia and Its Implications for Cancer Metabolism

Under low oxygen conditions (hypoxia), cells activate survival mechanisms including metabolic changes and angiogenesis, which are regulated by HIF-1. The estrogen-related receptor alpha (ERRα) is a transcription factor with important roles in the regulation of cellular metabolism that is overexpressed in hypoxia, suggesting that it plays a role in cell survival in this condition. This review enumerates and analyses the recent evidence that points to the role of ERRα as a regulator of hypoxic genes, both in cooperation with HIF-1 and through HIF-1- independent mechanisms, in invertebrate and vertebrate models and in physiological and pathological scenarios. ERRα's functions during hypoxia include two mechanisms: (1) direct ERRα/HIF-1 interaction, which enhances HIF-1's transcriptional activity; and (2) transcriptional activation by ERRα of genes that are classical HIF-1 targets, such as VEGF or glycolytic enzymes. ERRα is thus gaining recognition for its prominent role in the hypoxia response, both in the presence and absence of HIF-1. In some models, ERRα prepares cells for hypoxia, with important clinical/therapeutic implications.

Multifaceted Transcriptional Network of Estrogen-Related Receptor Alpha in Health and Disease

Estrogen-related receptors (ERRα, β and γ in mammals) are orphan members of the nuclear receptor superfamily acting as transcription factors. ERRs are expressed in several cell types and they display various functions in normal and pathological contexts. Amongst others, they are notably involved in bone homeostasis, energy metabolism and cancer progression. In contrast to other nuclear receptors, the activities of the ERRs are apparently not controlled by a natural ligand but they rely on other means such as the availability of transcriptional co-regulators. Here we focus on ERRα and review the variety of co-regulators that have been identified by various means for this receptor and their reported target genes. ERRα cooperates with distinct co-regulators to control the expression of distinct sets of target genes. This exemplifies the combinatorial specificity of transcriptional regulation that induces discrete cellular phenotypes depending on the selected coregulator. We finally propose an integrated view of the ERRα transcriptional network.

Non-genetic stratification reveals epigenetic heterogeneity and identifies vulnerabilities of glycolysis addiction in lung adenocarcinoma subtype

Lung adenocarcinoma (LUAD) exhibits high heterogeneity and is well known for its high genetic variation. Recently, the understanding of non-genetic variation provides a new perspective to study the heterogeneity of LUAD. Little is known about whether super-enhancers (SEs) may be primarily responsible for the inter-tumor heterogeneity of LUAD. We used super-enhancer RNA (seRNA) levels of a large-scale clinical well-annotated LUAD cohort to stratify patients into three clusters with different prognosis and other malignant characteristics. Mechanistically, estrogen-related receptor alpha (ERRα) in cluster 3-like cell lines acts as a cofactor of BRD4 to assist SE-promoter loops to activate glycolysis-related target gene expression, thereby promoting glycolysis and malignant progression, which confers a therapeutic vulnerability to glycolytic inhibitors. Our study identified three groups of patients according to seRNA levels, among which patients in cluster 3 have the worst prognosis and vulnerability of glycolysis dependency. We also proposed a 3-TF index model to stratify patients with glycolysis-addicted tumors according to tumor SE stratification.

ERRα coordinates actin and focal adhesion dynamics

Cell migration depends on the dynamic organisation of the actin cytoskeleton and assembly and disassembly of focal adhesions (FAs). However, the precise mechanisms coordinating these processes remain poorly understood. We previously identified the oestrogen-related receptor α (ERRα) as a major regulator of cell migration. Here, we show that loss of ERRα leads to abnormal accumulation of actin filaments that is associated with an increased level of inactive form of the actin-depolymerising factor cofilin. We further show that ERRα depletion decreases cell adhesion and results in defective FA formation and turnover. Interestingly, specific inhibition of the RhoA-ROCK-LIMK-cofilin pathway rescues the actin polymerisation defects resulting from ERRα silencing, but not cell adhesion. Instead, we found that MAP4K4 is a direct target of ERRα and down-regulation of its activity rescues cell adhesion and FA formation in the ERRα-depleted cells. Altogether, our results highlight a crucial role of ERRα in coordinating the dynamic of actin network and FAs through the independent regulation of the RhoA and MAP4K4 pathways.

RB1 loss triggers dependence on ESRRG in retinoblastoma

Retinoblastoma (Rb) is a deadly childhood eye cancer that is classically initiated by inactivation of the RB1 tumor suppressor. Clinical management continues to rely on nonspecific chemotherapeutic agents that are associated with treatment resistance and toxicity. Here, we analyzed 103 whole exomes, 20 whole transcriptomes, 5 single-cell transcriptomes, and 4 whole genomes from primary Rb tumors to identify previously unknown Rb dependencies. Several recurrent genomic aberrations implicate estrogen-related receptor gamma (ESRRG) in Rb pathogenesis. RB1 directly interacts with and inhibits ESRRG, and RB1 loss uncouples ESRRG from negative regulation. ESRRG regulates genes involved in retinogenesis and oxygen metabolism in Rb cells. ESRRG is preferentially expressed in hypoxic Rb cells in vivo. Depletion or inhibition of ESRRG causes marked Rb cell death, which is exacerbated in hypoxia. These findings reveal a previously unidentified dependency of Rb cells on ESRRG, and they implicate ESRRG as a potential therapeutic vulnerability in Rb.

Emerging Roles of COX7RP and Mitochondrial Oxidative Phosphorylation in Breast Cancer

Metabolic alterations are critical events in cancers, which often contribute to tumor pathophysiology. While aerobic glycolysis is a known characteristic of cancer-related metabolism, recent studies have shed light on mitochondria-related metabolic pathways in cancer biology, including oxidative phosphorylation (OXPHOS), amino acid and lipid metabolism, nucleic acid metabolism, and redox regulation. Breast cancer is the most common cancer in women; thus, elucidation of breast cancer-related metabolic alteration will help to develop cancer drugs for many patients. We here aim to define the contribution of mitochondrial metabolism to breast cancer biology. The relevance of OXPHOS in breast cancer has been recently defined by the discovery of COX7RP, which promotes mitochondrial respiratory supercomplex assembly and glutamine metabolism: the latter is also shown to promote nucleic acid and fatty acid biosynthesis as well as ROS defense regulation. In this context, the estrogen-related receptor (ERR) family nuclear receptors and collaborating coactivators peroxisome proliferator-activated receptor-γ coactivator-1 (PGC-1) are essential transcriptional regulators for both energy production and cancer-related metabolism. Summarizing recent findings of mitochondrial metabolism in breast cancer, this review will aim to provide a clue for the development of alternative clinical management by modulating the activities of responsible molecules involved in disease-specific metabolic alterations.

Thermoneutral Regulation and Acute Injury: Implications for Acute Kidney Injury

Acute kidney injury (AKI) has demonstrated sex differences as illustrated in clinical and preclinical studies. In most cases, females show a significant resistance to AKI as manifested by renal indicators of injury, and thus much of the literature is derived from studies exclusively in males. Thermoneutral housing alters sex differences in acute injury of the liver, but has not been studied in the kidney. Thermoneutrality, the ambient temperature at which additional energy is not needed to maintain core body temperature, is regulated by mechanisms residing in mitochondria. Importantly, mitochondrial function plays an important role in induction and recovery of AKI. Mechanisms that regulate thermoneutrality include uncoupling proteins (UCPs) and one of its upstream regulators peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α). PGC-1α has been extensively studied in AKI in males. UCP-2, a UCP expressed in the kidney, has been minimally studied in AKI in males. Expression of other UCPs in the kidney has not been well defined. No studies of either PGC-1α or UCPs have interrogated for a sex difference nor have they been investigated at thermoneutrality in the kidney. In this brief review, pathways of importance in thermoneutrality are described and related to pathways of importance in modulating susceptibility to AKI. Clarity in the understanding of the impact of thermoneutrality on AKI in altering susceptibility in females may expand our understanding of the critical role of mitochondrial function in this setting. Unique utilization of mitochondrial-based molecular pathways in females may then inform potential therapies.

Hypoxia as a physiological cue and pathological stress for coral larvae

Ocean deoxygenation events are intensifying worldwide and can rapidly drive adult corals into a state of metabolic crisis and bleaching-induced mortality, but whether coral larvae are subject to similar stress remains untested. We experimentally exposed apo-symbiotic coral larvae of Acropora selago to deoxygenation stress with subsequent reoxygenation aligned to their night-day light cycle, and followed their gene expression using RNA-Seq. After 12 h of deoxygenation stress (~2 mg O₂ /L), coral planulae demonstrated a low expression of HIF-targeted hypoxia response genes concomitant with a significantly high expression of PHD2 (a promoter of HIFα proteasomal degradation), similar to corresponding adult corals. Despite exhibiting a consistent swimming phenotype compared to control samples, the differential gene expression observed in planulae exposed to deoxygenation-reoxygenation suggests a disruption of pathways involved in developmental regulation, mitochondrial activity, lipid metabolism, and O₂ -sensitive epigenetic regulators. Importantly, we found that treated larvae exhibited a disruption in the expression of conserved HIF-targeted developmental regulators, for example, Homeobox (HOX) genes, corroborating how changes in external oxygen levels can affect animal development. We discuss how the observed deoxygenation responses may be indicative of a possible acclimation response or alternatively may imply negative latent impacts for coral larval fitness.

The role of estrogen and progesterone receptors in the rotator cuff disease: a retrospective cohort study

Background

Rotator cuff (RC) tears represent a common cause of shoulder pain and dysfunction in adults. The disease affects primarily women and occurs mainly in the postmenopausal period.

This study aimed to investigate immunohistochemically the presence of estrogen receptor-alpha (ER-⍺), estrogen receptor-beta (ER-β) and progesterone receptor (PR) in the supraspinatus tendon of patients with RC tendinopathy, searching for gender differences of expression. A secondary aim was to evaluate potential links between their expression and the typical histopathological findings of the ailment.

Methods

Biopsies of the supraspinatus tendon were collected intraoperatively from 15 postmenopausal women and 9 men undergoing RC surgery. Specimens were stained with Haematoxylin/Eosin, Masson-Goldner Trichrome, Alcian Blu and immunohistochemical stainings for ER-⍺, ER-β and PR were performed. Tendon alterations were evaluated with the Bonar histopathological scale. Statistical tests used in this study were the Spearman correlation coefficient and the Mann-Whitney U test.

Results

In the supraspinatus tendon, cells expressed ER-⍺ (p = 0.043), ER-β (p = 0.048) and PR (p = 0.004) with statistically significant differences related to age and sex of patients. Immunoreactivity was seen in the nuclei of tenocytes and vascular cells. Postmenopausal women’s samples showed a markedly higher expression of these receptors compared to their male counterpart. There was a positive correlation between the expression of ER-⍺ and ER-β (r = 0.59; p = 0.02) and between ER-β and PR (r = 0.72; p = 0.002) in women’s samples. Furthermore, in postmenopausal women the PR expression decreased with age (r = − 0.56; p = 0.027). Only in women, the ER-β expression positively correlated with the total Bonar histopathological score (p = 0.019) and the ER-β vascular expression positively correlated with ground substance alterations (p = 0.029).

Conclusions

These results reveal that ERs and PR are present in the supraspinatus tendon of patients with RC tears, suggesting a role of sex hormones in the pathogenesis of the disease.

HIF-1-Independent Mechanisms Regulating Metabolic Adaptation in Hypoxic Cancer Cells

In solid tumours, cancer cells exist within hypoxic microenvironments, and their metabolic adaptation to this hypoxia is driven by HIF-1 transcription factor, which is overexpressed in a broad range of human cancers. HIF inhibitors are under pre-clinical investigation and clinical trials, but there is evidence that hypoxic cancer cells can adapt metabolically to HIF-1 inhibition, which would provide a potential route for drug resistance. Here, we review accumulating evidence of such adaptions in carbohydrate and creatine metabolism and other HIF-1-independent mechanisms that might allow cancers to survive hypoxia despite anti-HIF-1 therapy. These include pathways in glucose, glutamine, and lipid metabolism; epigenetic mechanisms; post-translational protein modifications; spatial reorganization of enzymes; signalling pathways such as Myc, PI3K-Akt, 2-hyxdroxyglutarate and AMP-activated protein kinase (AMPK); and activation of the HIF-2 pathway. All of these should be investigated in future work on hypoxia bypass mechanisms in anti-HIF-1 cancer therapy. In principle, agents targeted toward HIF-1β rather than HIF-1α might be advantageous, as both HIF-1 and HIF-2 require HIF-1β for activation. However, HIF-1β is also the aryl hydrocarbon nuclear transporter (ARNT), which has functions in many tissues, so off-target effects should be expected. In general, cancer therapy by HIF inhibition will need careful attention to potential resistance mechanisms.

miR-137/ERRα axis mediates chemoresistance of nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is the most common malignant tumor of the head and neck region and is characterized by an increased risk of developing chemoresistance after treatment. The present study demonstrated that estrogen-related receptor α (ERRα) was upregulated in cisplatin- and fluorouracil-resistant NPC cells. In addition, ERRα knockdown or treatment of cells with the ERRα inverse agonist XCT-790 attenuated the chemoresistance of NPC cells. Mechanistically, the increased expression of ERRα in chemoresistant cells was associated with enhanced mRNA stability. Bioinformatics analysis for screening microRNAs (miRs) regulating the expression of ERRα revealed that miR-137 was downregulated in chemoresistant NPC cells. Additionally, transfection of cells with miR-137 mimics reduced ERRα mRNA stability and increased the chemosensitivity of NPC cells. Furthermore, ERRα knockdown reduced glucose consumption, and lactate and ATP production rates in chemoresistant cells. The aforementioned findings suggested that the miR-137/ERRα-mediated metabolic programming could be involved in the chemoresistance of NPC cells.

Estrogen-related receptor α is involved in angiogenesis and skeletal muscle revascularization in hindlimb ischemia

Skeletal muscle ischemia is a major consequence of peripheral arterial disease (PAD) or critical limb ischemia (CLI). Although therapeutic options for resolving muscle ischemia in PAD/CLI are limited, the issue is compounded by poor understanding of the mechanisms driving muscle vascularization. We found that nuclear receptor estrogen-related receptor alpha (ERRα) expression is induced in murine skeletal muscle by hindlimb ischemia (HLI), and in cultured myotubes by hypoxia, suggesting a potential role for ERRα in ischemic response. To test this, we generated skeletal muscle-specific ERRα transgenic (TG) mice. In these mice, ERRα drives myofiber type switch from glycolytic type IIB to oxidative type IIA/IIX myofibers, which are typically associated with more vascular supply in muscle. Indeed, RNA sequencing and functional enrichment analysis of TG muscle revealed that "paracrine angiogenesis" is the top-ranked transcriptional program activated by ERRα in the skeletal muscle. Immunohistochemistry and angiography showed that ERRα overexpression increases baseline capillarity, arterioles and non-leaky blood vessel formation in the skeletal muscles. Moreover, ERRα overexpression facilitates ischemic neo-angiogenesis and perfusion recovery in hindlimb musculature of mice subjected to HLI. Therefore, ERRα is a hypoxia inducible nuclear receptor that is involved in skeletal muscle angiogenesis and could be potentially targeted for treating PAD/CLI.

Transcriptional Regulation of ROS Homeostasis by the ERR Subfamily of Nuclear Receptors

Reactive oxygen species (ROS) such as superoxide anion (O₂^•-) and hydrogen peroxide (H₂O₂) are generated endogenously by processes such as mitochondrial oxidative phosphorylation, or they may arise from exogenous sources like bacterial invasion. ROS can be beneficial (oxidative eustress) as signaling molecules but also harmful (oxidative distress) to cells when ROS levels become unregulated in response to physiological, pathological or pharmacological insults. Indeed, abnormal ROS levels have been shown to contribute to the etiology of a wide variety of diseases. Transcriptional control of metabolic genes is a crucial mechanism to coordinate ROS homeostasis. Therefore, a better understanding of how ROS metabolism is regulated by specific transcription factors can contribute to uncovering new therapeutic strategies. A large body of work has positioned the estrogen-related receptors (ERRs), transcription factors belonging to the nuclear receptor superfamily, as not only master regulators of cellular energy metabolism but, most recently, of ROS metabolism. Herein, we will review the role played by the ERRs as transcriptional regulators of ROS generation and antioxidant mechanisms and also as ROS sensors. We will assess how the control of ROS homeostasis by the ERRs can be linked to physiology and disease and the possible contribution of manipulating ERR activity in redox medicine.

Polymorphisms in genes involved in breast cancer among Iranian patients

This review gives a summary of the important genetic polymorphisms in breast cancer with a focus on people in Iran. Several single nucleotide polymorphisms were considered as breast cancer susceptibility polymorphisms within genes (STK15, ERRs, ESR1, p53, SEP15, AURKA, SHBG, SRC, FAS, VEGF, XRCC1, GST, NFκB1, XPC, XRCC3, sirtuin-3, NKG2D). Cytosine-adenine repeat (IGF-I), rs3877899, G-2548A, GGC (eRF3a/GSPT1), IVS2nt-124A/G have shown an increased risk of breast cancers and a decreased risk has been observed in 4G/5G (PAI-1), rs6505162, tri-nucleotide (GCG TGFBR1). We observed that the signaling pathways and antioxidant related genes are the main molecular processes associated with breast cancer progression. Further studies on types of polymorphisms in breast cancer could validate the prognostic value of biomarkers.

Polymorphisms and alterations in gene expression associated with rotator cuff tear and healing following surgical repair: a systematic review

BACKGROUND

Rotator cuff tears (RCTs) are a common cause of shoulder disability, yet both conservative and surgical treatment strategies can lead to poor results in some patient populations. Enhanced understanding of the genetic processes associated with RCTs can assist in the development of more effective management options and help predict individual responses to surgical treatment. This systematic review analyzes the current literature on the genetic footprint associated with RCTs and interprets these findings to enhance the current understanding of RCT pathogenesis, potential treatment regimens, and prognostic biomarkers of outcomes after surgical repair.

METHODS

A systematic search of the Embase, PubMed, and Web of Science electronic databases was performed. Medical Subject Headings (MeSH) and Emtree index terms were formulated from the concept terms "rotator cuff tear," "genetics," and "human," and synonyms of these concepts were applied to the Web of Science search. Articles were screened against predefined inclusion and exclusion criteria. Eligible studies compared gene expression patterns and genetic polymorphisms between cases (with RCTs) and controls (without RCTs). Quality assessment was performed with studies being rated as high, moderate, or poor quality. A modified best-evidence synthesis was applied, and studies were determined to be of strong, moderate, or limited evidence.

RESULTS

The search identified 259 articles. Of these studies, 26 were eligible for review. Two studies were considered poor quality; 15 studies, moderate quality; and 9 studies, high quality. Analysis of these articles found that RCTs were associated with alterations in genes that code for the extracellular matrix, cell apoptosis, immune and inflammatory responses, and growth factor pathways. In particular, there was strong evidence of a significant association between RCTs and the genes MMP3, TNC, and ESRRB. Strong evidence of an association between BMP5 upregulation and successful healing after surgical repair was also found.

CONCLUSION

This review provides strong evidence of an genetic association with RCTs. The genotype and gene expression patterns detailed within this review can assist in deciphering the biological mechanisms resulting in RCTs, as well as predicting an individual's response to surgical repair. Future research could investigate whether manipulating these genes-or their associated signaling pathways-could assist in RCT healing and whether genetic biomarkers could be used clinically to predict patient outcomes after surgical repair of RCTs.

Identification of Compounds That Inhibit Estrogen-Related Receptor Alpha Signaling Using High-Throughput Screening Assays

The nuclear receptor, estrogen-related receptor alpha (ERRα; NR3B1), plays a pivotal role in energy homeostasis. Its expression fluctuates with the demands of energy production in various tissues. When paired with the peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), the PGC/ERR pathway regulates a host of genes that participate in metabolic signaling networks and in mitochondrial oxidative respiration. Unregulated overexpression of ERRα is found in many cancer cells, implicating a role in cancer progression and other metabolism-related diseases. Using high throughput screening assays, we screened the Tox21 10K compound library in stably transfected HEK293 cells containing either the ERRα-reporter or the reporter plus PGC-1α expression plasmid. We identified two groups of antagonists that were potent inhibitors of ERRα activity and/or the PGC/ERR pathway: nine antineoplastic agents and thirteen pesticides. Results were confirmed using gene expression studies. These findings suggest a novel mechanism of action on bioenergetics for five of the nine antineoplastic drugs. Nine of the thirteen pesticides, which have not been investigated previously for ERRα disrupting activity, were classified as such. In conclusion, we demonstrated that high-throughput screening assays can be used to reveal new biological properties of therapeutic and environmental chemicals, broadening our understanding of their modes of action.

Key regulator of cellular metabolism, estrogen-related receptor α, a new therapeutic target in endocrine-related gynecological tumor

The estrogen-related receptor α (ERRα), is an orphan transcription factor. Recently, many studies have reported its regulatory mechanisms and transcriptional targets after identification. Therefore, it may be eligible to join the rank of other nuclear receptors that control almost all aspects of cell metabolism. Cellular metabolism reprogramming plays a key role in fueling malignant change. The purpose of this review was to demonstrate that the ERRα plays an important role in the association between gynecological endocrine-related tumors and energy metabolism. Furthermore, regulation of ERRα may represent a promising strategy to induce cellular metabolic vulnerability of cancer from different origins. Thus, a comprehensive understanding of current treatment strategies may be achieved.

The estrogen-related receptors in metabolism and cancer: newer insights

The eukaryotic nuclear receptors (NRs) super-family of transcriptional factors include the estrogen-related receptors (ERRs) that have diverse roles in control of cellular energy balance, general metabolism, growth and development, immunity etc. Mouse knock-out models of specific ERR isoforms (ERRα, ERRβ and ERRγ) exhibit defects in several phenotypic traits. Newer findings indicate important roles of ERRs in the regulation of brown adipocyte tissue mitochondrial oxidative functions as well as metabolic control in association with hypoxia-inducible factors during cellular hypoxic state. Genes involved in cardiac metabolism is also influenced by ERRα and ERRγ in association with the co-activators PGC-1α and PGC-1β. On the other hand, ERRs have crucial involvement at the interface of metabolism and diseases such as cancer. Recent findings have implicated ERRα in the progression of tumor and malignancy of the breast, prostate, colon, endometrium etc. In this article, new insights into the regulatory role of ERRs in metabolism and cancer shall be reviewed.

Cholesterol as an Endogenous ERRα Agonist: A New Perspective to Cancer Treatment

The estrogen-related receptors (ERRs) are important members of nuclear receptors which contain three isoforms (α, β, and γ). ERRα is the best-characterized isoform expressed mainly in high-energy demanding tissues where it preferentially works in association with the peroxisome proliferator-activated receptor-γ co-activator 1α (PGC-1α) and PGC-1β. ERRα together with its cofactors modulates cellular metabolism, supports the growth of rapidly dividing cells, directs metabolic programs required for cell differentiation and maintains cellular energy homeostasis in differentiated cells. In cancer cells, the functional association between ERRα and PGC-1s is further influenced by oncogenic signals and induces metabolic programs favoring cell growth and proliferation as well as tumor progression. Recently, cholesterol has been identified as a natural ERRα ligand using a combined biochemical strategy. This new finding highlighted some important physiological aspects related to the use of cholesterol-lowering drugs such as statins and bisphosphonates. Even more meaningful is the link between increased cholesterol levels and certain cancer phenotypes characterized by an overexpressed ERRα such as mammary, prostatic, and colorectal cancers, where the metabolic adaptation affects many cancer processes. Moreover, high-energy demanding cancer-related processes are strictly related to the cross-talk between tumor cells and some key players of tumor microenvironment, such as tumor-associated macrophage that fuels cancer progression. Some evidence suggests that high cholesterol content and ERRα activity favor the inflammatory environment by the production of different cytokines. In this review, starting from the most recent observations on the physiological role of the new signaling activated by the natural ligand of ERRα, we propose a new hypothesis on the suitability to control cholesterol levels as a chance in modulating ERRα activity in those tumors in which its expression and activity are increased.

LSD1 binds to HPV16 E7 and promotes the epithelial-mesenchymal transition in cervical cancer by demethylating histones at the Vimentin promoter

Lysine-specific demethylase 1 (LSD1), which specifically demethylates histone H3 lysine 4 (H3K4) and lysine 9 (H3K9), is dysregulated in several cancers. We found that ectopic expression of LSD1 in cervical cancer cells promoted invasion and metastasis in vitro and in vivo, reduced the expression of the epithelial marker E-cadherin, and induced the expression of the mesenchymal marker, Vimentin. By contrast, LSD1 knockdown had the opposite effect and attenuated the HPV16 E7-induced epithelial-mesenchymal transition (EMT). We proposed a novel mechanism, whereby LSD1 is recruited to the Vimentin promoter and demethylates H3K4me1 and H3K4me2. Notably, HPV16 E7 enhanced the expression of LSD1, formed a complex with LSD1, and suppressed LSD1 demethylase activity by hindering the recruitment of LSD1 to the Vimentin promoter. Thus, LSD1 is a primary and positive regulator of the HPV16 E7-induced EMT and an attractive therapeutic target for alleviating HPV16 E7-induced EMT and tumor metastasis.

HIF-1α inhibition by diethylstilbestrol and its polyacetal conjugate in hypoxic prostate tumour cells: insights from NMR metabolomics

In this study, we have employed ¹H NMR metabolomics to assess the metabolic responses of PC3 prostate tumour cells to hypoxia and to pharmacological HIF-1α inhibition by DES or its polyacetal conjugate tert-DES. Oxygen deprivation prompted a number of changes in intracellular composition and metabolic activity, mainly reflecting upregulated glycolysis, amino acid catabolism and other compensatory mechanisms used by hypoxic cells to deal with oxidative imbalance and energy deficit. Cell treatment with a non-cytotoxic concentration of DES, under hypoxia, triggered significant changes in 17 metabolites. Among these, lactate, phosphocreatine and reduced glutathione, whose levels showed opposite variations in hypoxic and drug-treated cells, emerged as possible markers of DES-induced HIF-1α inhibition. Furthermore, the free drug had a much higher impact on the cellular metabolome than tert-DES, particularly concerning polyamine and pyrimidine biosynthetic pathways, known to be tightly involved in cell proliferation and growth. This is likely due to the different cell pharmacokinetics observed between free and conjugated DES. Overall, this study has revealed a number of unanticipated metabolic changes that inform on DES and tert-DES direct cellular effects, providing further insight into their mode of action at the biochemical level.

Estrogen-related receptor α participates transforming growth factor-β (TGF-β) induced epithelial-mesenchymal transition of osteosarcoma cells

Osteosarcoma patients often exhibit pulmonary metastasis, which results in high patient mortality. Understanding the mechanisms of advanced metastasis in osteosarcoma cell is important for the targeted treatment and drug development. Our present study revealed that transforming growth factor-β (TGF-β) treatment can significantly promote the in vitro migration and invasion of human osteosarcoma MG-63 and HOS cells. The loss of epithelial characteristics E-cadherin (E-Cad) and up regulation of mesenchymal markers Vimentin (Vim) suggested TGF-β induced epithelial-mesenchymal transition (EMT) of osteosarcoma cells. TGF-β treatment obviously increased the expression of Snail, a key EMT-related transcription factor, in both MG-63 and HOS cells. Silencing of Snail markedly attenuated TGF-β induced down regulation of E-cad and up regulation of Vim. TGF-β treatment also significantly increased the expression and nuclear translocation of estrogen-related receptors α (ERRα), while had no obvious effect on the expression of ERα, ERβ, or ERRγ. Knock down of ERRα or its inhibitor XCT-790 significantly attenuated TFG-β induced EMT and transcription of Snail in osteosarcoma cells. Collectively, our present study revealed that TGF-β treatment can trigger the EMT of osteosarcoma cells via ERRα/Snail pathways. Our data suggested that ERRα/Snail pathways might be potential therapeutic targets of metastasis of osteosarcoma cells.

ERRα negatively regulates type I interferon induction by inhibiting TBK1-IRF3 interaction

Estrogen-related receptor α (ERRα) is a member of the nuclear receptor superfamily controlling energy homeostasis; however, its precise role in regulating antiviral innate immunity remains to be clarified. Here, we showed that ERRα deficiency conferred resistance to viral infection both in vivo and in vitro. Mechanistically, ERRα inhibited the production of type-I interferon (IFN-I) and the expression of multiple interferon-stimulated genes (ISGs). Furthermore, we found that viral infection induced TBK1-dependent ERRα stabilization, which in turn associated with TBK1 and IRF3 to impede the formation of TBK1-IRF3, IRF3 phosphorylation, IRF3 dimerization, and the DNA binding affinity of IRF3. The effect of ERRα on IFN-I production was independent of its transcriptional activity and PCG-1α. Notably, ERRα chemical inhibitor XCT790 has broad antiviral potency. This work not only identifies ERRα as a critical negative regulator of antiviral signaling, but also provides a potential target for future antiviral therapy.

Hybrid Cellular Metabolism Coordinated by Zic3 and Esrrb Synergistically Enhances Induction of Naive Pluripotency

Naive pluripotent stem cells (PSCs) utilize both glycolysis and oxidative phosphorylation (OXPHOS) to satisfy their metabolic demands. However, it is unclear how somatic cells acquire this hybrid energy metabolism during reprogramming toward naive pluripotency. Here, we show that when transduced with Oct4, Sox2, and Klf4 (OSK) into murine fibroblasts, Zic3 and Esrrb synergistically enhance the reprogramming efficiency by regulating cellular metabolic pathways. These two transcription factors (TFs) cooperatively activate glycolytic metabolism independently of hypoxia inducible factors (HIFs). In contrast, the regulatory modes of the TFs on OXPHOS are antagonistic: Zic3 represses OXPHOS, whereas Esrrb activates it. Therefore, when introduced with Zic3, Esrrb restores OXPHOS activity, which is essential for efficient reprogramming. In addition, Esrrb-mediated OXPHOS activation is critical for the conversion of primed PSCs into the naive state. Our study suggests that the combinatorial function of TFs achieves an appropriate balance of metabolic pathways to induce naive PSCs.

CURRENT CONCEPTS ON THE GENETIC FACTORS IN ROTATOR CUFF PATHOLOGY AND FUTURE IMPLICATIONS FOR SPORTS PHYSICAL THERAPISTS

CONTEXT

Recent advances within the field of genetics are currently changing many of the methodologies in which medicine is practiced. These advances are also beginning to influence the manner in which physical therapy services are rendered. Rotator cuff pathology is one of the most common diagnoses treated by the sports physical therapist. The purpose of this commentary is to educate sports physical therapists on the recent advances regarding how genetics influences rotator cuff pathology, including rotator cuff tears, and provide a perspective on how this information will likely influence post-operative shoulder rehabilitation in the near future.

EVIDENCE ACQUISITION

A comprehensive review of the literature was completed using the Medline database along with individual searches of relevant physical therapy, surgical, cell biology, and sports medicine journals. Search terms included: shoulder, rotator cuff pathology, genetics, apoptosis, and physical therapy. Search results were compiled and evaluated; relevant primary studies and review articles were gathered; the results from this comprehensive review are summarized here.

STUDY DESIGN

Clinical Commentary, Review of the Literature.

RESULTS

Recent advances within the understanding of rotator cuff pathology have further elucidated the cellular and molecular mechanisms associated with rotator cuff tears. There appears to be a hypoxic-induced apoptotic cellular pathway that contributes to rotator cuff tears. Activation of specific proteins termed matrix metalloproteinases appear to be involved in not only primary rotator cuff tears, but also may influence the re-tear rate after surgical intervention. Further advancements in the understanding of the cellular mechanisms contributing to rotator cuff tears and postoperative techniques to help prevent re-tears, may soon influence the methodology in which physical therapy services are provided to patients sustaining a rotator cuff injury.

CONCLUSIONS

At this time continued research is required to more fully develop a comprehensive understanding of the role of genetic variables both within primary rotator cuff tears and their influences on post-operative rehabilitation from rotator cuff repair surgery.

LEVEL OF EVIDENCE

Level 5.

Emerging functional roles of nuclear receptors in breast cancer

Nuclear receptors (NRs) have been targets of intensive drug development for decades due to their roles as key regulators of multiple developmental, physiological and disease processes. In breast cancer, expression of the estrogen and progesterone receptor remains clinically important in predicting prognosis and determining therapeutic strategies. More recently, there is growing evidence supporting the involvement of multiple nuclear receptors other than the estrogen and progesterone receptors, in the regulation of various processes important to the initiation and progression of breast cancer. We review new insights into the mechanisms of action of NRs made possible by recent advances in genomic technologies and focus on the emerging functional roles of NRs in breast cancer biology, including their involvement in circadian regulation, metabolic reprogramming and breast cancer migration and metastasis.

The obesity-related pathology and Th17 cells

Chronic inflammation associated with obesity plays a major role in the development of metabolic diseases, cancer, and autoimmune diseases. Among Th subsets, Th17 cells are involved in the pathogenesis of autoimmune disorders such as psoriasis, rheumatoid arthritis, inflammatory bowel disease, steroid-resistant asthma, and multiple sclerosis. Accumulating data suggest that reciprocal interactions between the metabolic systems and immune system play pivotal roles in the pathogenesis of obesity-associated diseases. We herein outline the developing principles in the control of T cell differentiation and function via their cellular metabolism. Also discussed are recent findings that changes in the intracellular metabolism, including fatty acid metabolism, affect the Th17 cell function in obese individuals. Finally, we will also highlight the unique molecular mechanism involved in the activation of retinoid-related orphan receptor-gamma-t (RORγt) by intracellular metabolism and discuss a new therapeutic approach for treating autoimmune disorders through the inhibition of RORγt.

A compendium of proteins that interact with HIF-1α

Hypoxia-inducible factor 1 (HIF-1) is the founding member of a family of transcription factors that function as master regulators of oxygen homeostasis. HIF-1 is composed of an O₂-regulated HIF-1α subunit and a constitutively expressed HIF-1β subunit. This review provides a compendium of proteins that interact with the HIF-1α subunit, many of which regulate HIF-1 activity in either an O₂-dependent or O₂-independent manner.

NPAS1-ARNT and NPAS3-ARNT crystal structures implicate the bHLH-PAS family as multi-ligand binding transcription factors

The neuronal PAS domain proteins NPAS1 and NPAS3 are members of the basic helix-loop-helix-PER-ARNT-SIM (bHLH-PAS) family, and their genetic deficiencies are linked to a variety of human psychiatric disorders including schizophrenia, autism spectrum disorders and bipolar disease. NPAS1 and NPAS3 must each heterodimerize with the aryl hydrocarbon receptor nuclear translocator (ARNT), to form functional transcription complexes capable of DNA binding and gene regulation. Here we examined the crystal structures of multi-domain NPAS1-ARNT and NPAS3-ARNT-DNA complexes, discovering each to contain four putative ligand-binding pockets. Through expanded architectural comparisons between these complexes and HIF-1α-ARNT, HIF-2α-ARNT and CLOCK-BMAL1, we show the wider mammalian bHLH-PAS family is capable of multi-ligand-binding and presents as an ideal class of transcription factors for direct targeting by small-molecule drugs.

DOI:http://dx.doi.org/10.7554/eLife.18790.001

Transcription factors are proteins that can bind to DNA to regulate the activity of genes. One family of transcription factors in mammals is known as the bHLH-PAS family, which consists of sixteen members including NPAS1 and NPAS3. These two proteins are both found in nerve cells, and genetic mutations that affect NPAS1 or NPAS3 have been linked to psychiatric conditions in humans. Therefore, researchers would like to discover new drugs that can bind to these proteins and control their activities in nerve cells. Understanding the three-dimensional structure of a protein can aid the discovery of small molecules that can bind to these proteins and act as drugs. Proteins in the bHLH-PAS family have to form pairs in order to bind to DNA: NPAS1 and NPAS3 both interact with another bHLH-PAS protein called ARNT, but it is not clear exactly how this works.

In 2015, a team of researchers described the shapes that ARNT adopts when it forms pairs with two other bHLH-PAS proteins that are important for sensing when oxygen levels drop in cells. Here, Wu et al. – including many of the researchers involved in the earlier work – have used a technique called X-ray crystallography to determine the three-dimensional shapes of NPAS1 when it is bound to ARNT, and NPAS3 when it is bound to both ARNT and DNA. The experiments show that each of these structures contains four distinct pockets that certain small molecules might be able to bind to. The NPAS1 and NPAS3 structures are similar to each other and to the previously discovered bHLH-PAS structures involved in oxygen sensing.

Further analysis of other bHLH-PAS proteins suggests that all the members of this protein family are likely to be able to bind to small molecules and should therefore be considered as potential drug targets. The next step following on from this work is to identify small molecules that bind to bHLH-PAS proteins, which will help to reveal the genes that are regulated by this family. In the future, these small molecules may have the potential to be developed into new drugs to treat psychiatric conditions and other diseases in humans.

DOI:http://dx.doi.org/10.7554/eLife.18790.002

Characterization of a selective inverse agonist for estrogen related receptor α as a potential agent for breast cancer

The estrogen-related receptor α (ERRα) is an orphan nuclear receptor that plays a primary role in the regulation of cellular energy homeostasis and osteogenesis. It is reported that ERRα is widely expressed in a range of tissues and accumulating evidence has supported that the high expression of ERRα correlates with poor prognosis of various human malignancies, including breast, endometrium, colon, prostate and ovary cancers. Herein is described the discovery of a novel selective inverse agonist (HSP1604) of ERRα, but not of ERRβ and ERRγ, as determined using transient transfection luciferase reporter assay and a time-resolved fluorescence resonance energy transfer (TR-FRET) co-activator assay. HSP1604 potently inhibits ERRα transcriptional activity with IC50=1.47±0.17μM in cell-based luciferase reporter assay and also decreases the protein level of ERRα and the mRNA levels of its downstream target genes such as pyruvate dehydrogenase kinase 4 (PDK4), pS2 and osteopontin. HSP1604 has also suppressed the proliferation of different human cancer cell lines and the migration of breast cancer cells with high expression of ERRα. Representative in vivo results show that HSP1604 suppresses the growth of human breast cancer xenograft in nude mice as doses at 30mg/kg or 100mg/kg administered every other day during 28-day period. HSP1604 thus has the potential both as a new agent to inhibit the growth of tumors and as a chemical probe of ERRα biology.

The PLA2R1-JAK2 pathway upregulates ERRα and its mitochondrial program to exert tumor-suppressive action

Little is known about the biological role of the phospholipase A2 receptor (PLA2R1) transmembrane protein. In recent years, PLA2R1 has been shown to have an important role in regulating tumor-suppressive responses via JAK2 activation, but the underlying mechanisms are largely undeciphered. In this study, we observed that PLA2R1 increases the mitochondrial content, judged by increased levels of numerous mitochondrial proteins, of the mitochondrial structural component cardiolipin, of the mitochondrial DNA content, and of the mitochondrial DNA replication and transcription factor TFAM. This effect of PLA2R1 relies on a transcriptional program controlled by the estrogen-related receptor alpha1 (ERRα) mitochondrial master regulator. Expression of ERRα and of its nucleus-encoded mitochondrial targets is upregulated upon PLA2R1 ectopic expression, and this effect is mediated by JAK2. Conversely, downregulation of PLA2R1 decreases the level of ERRα and of its nucleus-encoded mitochondrial targets. Finally, blocking the ERRα-controlled mitochondrial program largely inhibits the PLA2R1-induced tumor-suppressive response. Together, our data document ERRα and its mitochondrial program as downstream effectors of the PLA2R1-JAK2 pathway leading to oncosuppression.

The emerging roles of orphan nuclear receptors in prostate cancer

Orphan nuclear receptors are members of the nuclear receptor (NR) superfamily and are so named because their endogenous physiological ligands are either unknown or may not exist. Because of their important regulatory roles in many key physiological processes, dysregulation of signalings controlled by these receptors is associated with many diseases including cancer. Over years, studies of orphan NRs have become an area of great interest because their specific physiological and pathological roles have not been well-defined, and some of them are promising drug targets for diseases. The recently identified synthetic small molecule ligands, acting as agonists or antagonists, to these orphan NRs not only help to understand better their functional roles but also highlight that the signalings mediated by these ligand-independent NRs in diseases could be therapeutically intervened. This review is a summary of the recent advances in elucidating the emerging functional roles of orphan NRs in cancers, especially prostate cancer. In particular, some orphan NRs, RORγ, TR2, TR4, COUP-IFII, ERRα, DAX1 and SHP, exhibit crosstalk or interference with androgen receptor (AR) signaling in either normal or malignant prostatic cells, highlighting their involvement in prostate cancer progression as androgen and AR signaling pathway play critical roles in this process. We also propose that a better understanding of the mechanism of actions of these orphan NRs in prostate gland or prostate cancer could help to evaluate their potential value as therapeutic targets for prostate 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.

Identification of a genetic variant associated with rotator cuff repair healing

BACKGROUND

A familial and genetic predisposition for the development of rotator cuff tearing has been identified. The purpose of this study was to determine if a familial predisposition exists for healing after rotator cuff repair and if the reported significant association with a single-nucleotide polymorphism (SNP) in the ESRRB gene is present in patients who fail to heal.

MATERIALS AND METHODS

The study recruited 72 patients undergoing arthroscopic rotator cuff repair for a full-thickness posterosuperior tear. Magnetic resonance imaging studies were performed at a minimum of 1 year postoperatively (average, 2.6 years). Healing failures were classified as lateral or medial. Self-reported family history of rotator cuff tearing data and genome-wide genotypes were available. Characteristics of cases with and without a family history of rotator cuff tearing were compared, and a comparison of the frequency of SNP 1758384 (in ESRRB) was performed between patients who healed and those who failed to heal.

RESULTS

Of the rotator cuff repairs, 42% failed to heal; 42% of patients reported a family history of rotator cuff tear. Multivariate regression analysis showed a significant association between familiality and overall healing failure (medial and lateral failures) (P = .036) and lateral failures independently (P = .006). An increased risk for the presence of a rare allele for SNP rs17583842 was present in lateral failures compared with those that healed (P = .005).

CONCLUSIONS

Individuals with a family history of rotator cuff tearing were more likely to have repair failures. Significant association of a SNP variant in the ESRRB gene was also observed with lateral failure.

Inverse agonist of estrogen-related receptor α suppresses the growth of triple negative breast cancer cells through ROS generation and interaction with multiple cell signaling pathways

There is an urgent clinical need for targeted therapy approaches for triple-negative breast cancer (TNBC) patients. Increasing evidences suggested that the expression of estrogen-related receptor alpha (ERRα) was correlate with unfavorable clinical outcomes of breast cancer patients. We here show that inhibition of ERRα by its inverse agonist XCT-790 can suppress the proliferation, decrease G2/M phases, and induce mitochondrial-related apoptosis of TNBC cells. XCT-790 elevates the proteins related to endoplasmic reticulum (ER) stress such as ATF4/6, XBT-1 and CHOP. It also increases the expression of growth inhibition related proteins such as p53 and p21. Further, XCT-790 can increase the generation of reactive oxygen species (ROS) in TNBC cells mainly through inhibition of SOD1/2. While ROS scavenger NAC abolishes XCT-790 induced ER-stress and growth arrest. XCT-790 treatment can rapidly activate the signal molecules including ERK1/2, p38-MAPK, JNK, Akt, p65, and IκBα, while NAC attenuates effects of XCT-790 induced phosphorylation of ERK1/2, p38-MAPK and Akt. Further, the inhibitors of ERK1/2, JNK, Akt, and NF-κB attenuate XCT-790 induced ROS generation. These data suggest that AKT/ROS and ERK/ROS positive feedback loops, NF-κB/ROS, and ROS/p38-MAPK, are activated in XCT-790 treated TNBC cells. In vivo experiments show that XCT-790 significantly suppresses the growth of MDA-MB-231 xenograft tumors, which is associated with up regulation of p53, p21, ER-stress related proteins while down regulation of bcl-2. The present discovery makes XCT-790 a promising candidate drug and lays the foundation for future development of ERRα-based therapies for TNBC patients.

There and back again: The journey of the estrogen-related receptors in the cancer realm

The identification of two genes encoding polypeptides with structural features common with the estrogen receptor more than a quarter century ago, referred to as the estrogen-related receptors (ERRs), subsequently led to the discovery of several previously unrecognized hormone responsive systems through the application of reverse endocrinology. Paradoxically, the natural ligand(s) associated with members of the ERR subfamily remains to be identified. While initial studies on the mode of action and physiological functions of the ERRs focused on interaction with estrogen signalling in breast cancer, subsequent work showed that the ERRs are ubiquitous master regulators of cellular energy metabolism. This review aims to demonstrate that the ERRs occupy a central node at the interface of cancer and metabolism, and that modulation of their activity may represent a worthwhile strategy to induce metabolic vulnerability in tumors of various origins and thus achieve a more comprehensive response to current therapies.

Genome-wide association study for rotator cuff tears identifies two significant single-nucleotide polymorphisms

BACKGROUND

The precise etiology of rotator cuff disease is unknown, but prior evidence suggests a role for genetic factors. Limited data exist identifying specific genes associated with rotator cuff tearing. The purpose of this study was to identify specific genes or genetic variants associated with rotator cuff tearing by a genome-wide association study with an independent set of rotator cuff tear cases.

MATERIALS AND METHODS

A set of 311 full-thickness rotator cuff tear cases genotyped on the Illumina 5M single-nucleotide polymorphism (SNP) platform were used in a genome-wide association study with 2641 genetically matched white population controls available from the Illumina iControls database. Tests of association were performed with GEMMA software at 257,558 SNPs that compose the intersection of Illumina SNP platforms and that passed general quality control metrics. SNPs were considered significant if P < 1.94 × 10(-7) (Bonferroni correction: 0.05/257,558).

RESULTS

Tests of association revealed 2 significantly associated SNPs, one occurring in SAP30BP (rs820218; P = 3.8E-9) on chromosome 17q25 and another occurring in SASH1 (rs12527089; P = 1.9E-7) on chromosome 6q24.

CONCLUSIONS

This study represents the first attempt to identify genetic factors influencing rotator cuff tearing by a genome-wide association study using a dense/complete set of SNPs. Two SNPs were significantly associated with rotator cuff tearing, residing in SAP30BP on chromosome 17 and SASH1 on chromosome 6. Both genes are associated with the cellular process of apoptosis. Identification of potential genes or genetic variants associated with rotator cuff tearing may help in identifying individuals at risk for the development of rotator cuff tearing.

Targeting Tumor Metabolism for Cancer Treatment: Is Pyruvate Dehydrogenase Kinases (PDKs) a Viable Anticancer Target?

Cancer remains a lethal threat to global lives. Development of novel anticancer therapeutics is still a challenge to scientists in the field of biomedicine. In cancer cells, the metabolic features are significantly different from those of normal ones, which are hallmarks of several malignancies. Recent studies brought atypical cellular metabolism, such as aerobic glycolysis or the Warburg effect, into the scientific limelight. Targeting these altered metabolic pathways in cancer cells presents a promising therapeutic strategy. Pyruvate dehydrogenase kinases (PDKs), key enzymes in the pathway of glucose metabolism, could inactivate the pyruvate dehydrogenase complex (PDC) by phosphorylating it and preserving the substrates pyruvate, lactate and alanine for gluconeogenesis. Overexpression of PDKs could block the oxidative decarboxylation of pyruvate to satisfy high oxygen demand in cancer cells, while inhibition of PDKs could upregulate the activity of PDC and rectify the balance between the demand and supply of oxygen, which could lead to cancer cell death. Thus, inhibitors targeting PDKs represent a promising strategy for cancer treatment by acting on glycolytic tumors while showing minimal side effects on the oxidative healthy organs. This review considers the role of PDKs as regulator of PDC that catalyzes the oxidative decarboxylation of pyruvate in mitochondrion. It is concluded that PDKs are solid therapeutic targets. Inhibition of PDKs could be an attractive therapeutic approach for the development of anti-cancer drugs.

Mitochondrial retrograde signaling regulates neuronal function

Mitochondria are key regulators of cellular homeostasis, and mitochondrial dysfunction is strongly linked to neurodegenerative diseases, including Alzheimer's and Parkinson's. Mitochondria communicate their bioenergetic status to the cell via mitochondrial retrograde signaling. To investigate the role of mitochondrial retrograde signaling in neurons, we induced mitochondrial dysfunction in the Drosophila nervous system. Neuronal mitochondrial dysfunction causes reduced viability, defects in neuronal function, decreased redox potential, and reduced numbers of presynaptic mitochondria and active zones. We find that neuronal mitochondrial dysfunction stimulates a retrograde signaling response that controls the expression of several hundred nuclear genes. We show that the Drosophila hypoxia inducible factor alpha (HIFα) ortholog Similar (Sima) regulates the expression of several of these retrograde genes, suggesting that Sima mediates mitochondrial retrograde signaling. Remarkably, knockdown of Sima restores neuronal function without affecting the primary mitochondrial defect, demonstrating that mitochondrial retrograde signaling is partly responsible for neuronal dysfunction. Sima knockdown also restores function in a Drosophila model of the mitochondrial disease Leigh syndrome and in a Drosophila model of familial Parkinson's disease. Thus, mitochondrial retrograde signaling regulates neuronal activity and can be manipulated to enhance neuronal function, despite mitochondrial impairment.

Inhibition of ERRα suppresses epithelial mesenchymal transition of triple negative breast cancer cells by directly targeting fibronectin

Triple-negative breast cancer (TNBC) patients have poor prognosis due to the aggressive metastatic behaviors. Our study reveals that expression of estrogen related receptor α (ERRα) is significantly (p < 0.01) positively associated with high grade tumors and lymph node metastasis, while negatively correlated with overall survival (OS), in 138 TNBC patients. Targeted inhibition of ERRα by its inverse agonist XCT-790 or si-RNA obviously inhibits in vitro motility of TNBC cells. While over expression of ERRα triggers the invasion and migration of TNBC cells. Further, si-ERRα and XCT-790 inhibit the epithelial mesenchymal transition (EMT) of TNBC cells with increasing the expression of E-cadherin and decreasing fibronectin (FN) and vimentin. While XCT-790 has no effect on the expression of EMT related transcription factors such as Snail or Slug. Further, inhibitors of MAPK, PI3K/Akt, NF-κB signal molecules, which are activated by XCT-790, can not attenuate the suppression effects of XCT-790 on EMT. Alternatively, luciferase reporter gene assays and ChIP analysis indicate that ERRα can directly bind with FN promoter at ERR response element-3 (ERRE-1), ERRE-3, and ERRE-4, while XCT-790 reduces this bond. In vivo data show that ERRα expression is significantly (p < 0.05) correlated with FN in clinical TNBC patients. In MDA-MB-231 tumor xenograft models, XCT-790 decreases the expression of FN, inhibits the growth and lung metastasis, and suppresses the EMT. Our results demonstrate that ERRα functions as a metastasis stimulator and its targeted inhibition may be a new therapeutic strategy for TNBC treatment.

Differential network analysis reveals dysfunctional regulatory networks in gastric carcinogenesis

Gastric Carcinoma is one of the most common cancers in the world. A large number of differentially expressed genes have been identified as being associated with gastric cancer progression, however, little is known about the underlying regulatory mechanisms. To address this problem, we developed a differential networking approach that is characterized by including a nascent methodology, differential coexpression analysis (DCEA), and two novel quantitative methods for differential regulation analysis. We first applied DCEA to a gene expression dataset of gastric normal mucosa, adenoma and carcinoma samples to identify gene interconnection changes during cancer progression, based on which we inferred normal, adenoma, and carcinoma-specific gene regulation networks by using linear regression model. It was observed that cancer genes and drug targets were enriched in each network. To investigate the dynamic changes of gene regulation during carcinogenesis, we then designed two quantitative methods to prioritize differentially regulated genes (DRGs) and gene pairs or links (DRLs) between adjacent stages. It was found that known cancer genes and drug targets are significantly higher ranked. The top 4% normal vs. adenoma DRGs (36 genes) and top 6% adenoma vs. carcinoma DRGs (56 genes) proved to be worthy of further investigation to explore their association with gastric cancer. Out of the 16 DRGs involved in two top-10 DRG lists of normal vs. adenoma and adenoma vs. carcinoma comparisons, 15 have been reported to be gastric cancer or cancer related. Based on our inferred differential networking information and known signaling pathways, we generated testable hypotheses on the roles of GATA6, ESRRG and their signaling pathways in gastric carcinogenesis. Compared with established approaches which build genome-scale GRNs, or sub-networks around differentially expressed genes, the present one proved to be better at enriching cancer genes and drug targets, and prioritizing disease-related genes on the dataset we considered. We propose this extendable differential networking framework as a promising way to gain insights into gene regulatory mechanisms underlying cancer progression and other phenotypic changes.

Differential regulation of HIF-1α and HIF-2α in neuroblastoma: Estrogen-related receptor alpha (ERRα) regulates HIF2A transcription and correlates to poor outcome

Hypoxia-inducible factors (HIFs) are differentially regulated in tumor cells. While the current paradigm supports post-translational regulation of the HIF-α subunits, we recently showed that hypoxic HIF-2α is also transcriptionally regulated via insulin-like growth factor (IGF)-II in the childhood tumor neuroblastoma. Here, we demonstrate that transcriptional regulation of HIF-2α seems to be restricted to neural cell-derived tumors, while HIF-1α is canonically regulated at the post-translational level uniformly across different tumor forms. Enhanced expression of HIF2A mRNA at hypoxia is due to de novo transcription rather than increased mRNA stability, and chemical stabilization of the HIF-α proteins at oxygen-rich conditions unexpectedly leads to increased HIF2A transcription. The enhanced HIF2A levels do not seem to be dependent on active HIF-1. Using a transcriptome array approach, we identified members of the Peroxisome proliferator-activated receptor gamma coactivator (PGC)/Estrogen-related receptor (ERR) complex families as potential regulators of HIF2A. Knockdown or inhibition of one of the members, ERRα, leads to decreased expression of HIF2A, and high expression of the ERRα gene ESRRA correlates with poor overall and progression-free survival in a clinical neuroblastoma material consisting of 88 tumors. Thus, targeting of ERRα and pathways regulating transcriptional HIF-2α are promising therapeutic avenues in neuroblastoma.

Significant association of full-thickness rotator cuff tears and estrogen-related receptor-β (ESRRB)

BACKGROUND

The precise etiology of rotator cuff disease is unknown, but prior evidence suggests a role for genetic factors. Variants of estrogen-related receptor-β (ESRRB) have been previously associated with rotator cuff disease. The purpose of the present study was to confirm the association between multiple candidate genes, including ESRRB, and rotator cuff disease in an independent set of patients with rotator cuff tear.

MATERIALS AND METHODS

The Illumina 5M (Illumina Inc, San Diego, CA, USA) single nucleotide polymorphism (SNP) platform was used to genotype 175 patients with rotator cuff tear. Genotypes were used to select a set of 2595 genetically matched Caucasian controls available from the Illumina iControls database. Tests of association were performed with Genome-wide Efficient Mixed Model Association (GEMMA) software at 69 SNPs that fell within 20 kb of 6 candidate genes (DEFB1, DENND2C, ESRRB, FGF3, FGF10, and FGFR1).

RESULTS

Tests of association revealed 1 significantly associated SNP occurring in ESRRB (rs17583842; P = 4.4E-4). Another SNP within ESRRB (rs7157192) had a nominal P value of 7.8E-3. FastPHASE software estimated 2 frequent haplotypes among 54 individuals who carried both risk alleles at these 2 SNPs. The first haplotype had a frequency of 13.9% (n = 15) in risk-allele carriers and only 2.2% in controls (odds ratio, 6.9; 95% confidence interval, 3.9-2.2). The second haplotype had a frequency of 12.9% in risk-allele carriers and only 2.7% in controls (odds ratio, 5.3; 95% confidence interval, 3.0-9.5).

CONCLUSIONS

The significant association and the presence of high-risk haplotypes identified in the ESRRB gene confirm the association of variants in ESRRB and rotator cuff disease.