Expression of esophageal cancer related gene 4 (ECRG4), a novel tumor suppressor gene, in esophageal cancer and its inhibitory effect on the tumor growth in vitro and in vivo

A potential role of human esophageal cancer-related gene-4 in cardiovascular homeostasis

Human esophageal cancer related gene-4 (ECRG-4) encodes a 148-aminoacid pre-pro-peptide that can be processed tissue-dependently into multiple small peptides possessing multiple functions distinct from, similar to, or opposite to the tumor suppressor function of the full-length Ecrg4. Ecrg-4 is covalently bound to the cell surface through its signal peptide, colocalized with the innate immunity complex (TLR4-CD14-MD2), and functions as a 'sentinel' molecule in the maintenance of epithelium and leukocyte homeostasis, meaning that the presence of Ecrg-4 on the cell surface signals the maintained homeostasis, whereas the loss of Ecrg-4 due to tissue injury activates pro-inflammatory and tissue proliferative responses, and the level of Ecrg-4 gradually returns to its pre-injury level upon wound healing. Interestingly, Ecrg-4 is also highly expressed in the heart and its conduction system, endothelial cells, and vascular smooth muscle cells. Accumulating evidence has shown that Ecrg-4 is involved in cardiac rate/rhythm control, the development of atrial fibrillation, doxorubicin-induced cardiotoxicity, the ischemic response of the heart and hypoxic response in the carotid body, the pathogenesis of atherosclerosis, and likely the endemic incidence of idiopathic dilated cardiomyopathy. These preliminary discoveries suggest that Ecrg-4 may function as a 'sentinel' molecule in cardiovascular system as well. Here, we briefly review the basic characteristics of ECRG-4 as a tumor suppressor gene and its regulatory functions on inflammation and apoptosis; summarize the discoveries about its distribution in cardiovascular system and involvement in the development of CVDs, and discuss its potential as a novel therapeutic target for the maintenance of cardiovascular system homeostasis.

Complex and pleiotropic signaling pathways regulated by the secreted protein augurin

The secreted protein augurin, the product of the tumor suppressor gene Ecrg4, has been identified as a peptide hormone in the human proteome in 2007. Since then, a number of studies have been carried out to highlight its structure and processing and its potential roles in physiopathology. Although augurin has been shown to be implicated in a variety of processes, ranging from tumorigenesis, inflammation and infection to neural stem cell proliferation, hypothalamo-pituitary adrenal axis regulation and osteoblast differentiation, the molecular mechanisms of its biological effects and the signaling pathways it regulates are still poorly characterized. Here we provide a comprehensive overview of augurin-dependent signal transduction pathways. Because of their secreted nature and the potential to be manipulated pharmacologically, augurin and its derived peptides represent attractive targets for diagnostic development and discovery of new therapeutic agents for the human diseases resulting from the deregulation of the signaling cascades they modulate. From this perspective, the characterization of the precise nature of augurin derived peptides and the identification of the receptor(s) on the cell surface conveying augurin signaling to downstream effectors are crucial to develop agonists and antagonists for this protein. Video abstract.

A potential link between aberrant expression of ECRG4 and atrial fibrillation

Esophageal cancer-related gene-4 (ECRG4), a 148-amino acid propertied and new tumor suppressor, is initially cloned from the normal esophageal epithelium. ECRG4 was found to be expressed not only in esophageal tissues but also in cardiomyocytes. Previous studies demonstrated that ECRG4 is constitutively expressed in esophageal epithelial cells, and its degree of downregulation is directly proportional to prognosis in patients with esophageal cancer. In the heart, ECRG4 shows greater expression in the atria than in the ventricles, which accounts for its heterogeneity. Downregulation of ECRG4 expression level correlates with esophageal cancer, as well as myocardial injuries and arrhythmias. As a result, this review summarizes the possible susceptibility gene, ECRG4 and its associated molecular mechanisms in cancer patients with atrial fibrillation and myocardial injury. The review begins by describing ECRG4's biological background, discusses its expression in the cardiovascular system, lists the clinical and animal research related to the downregulation of ECRG4 in atrial fibrillation, and focuses on its potential role in atrial fibrillation. Downregulation of ECRG4 may increase the risk of atrial fibrillation by affecting ion channels, MMPs expression and inflammatory response. We will then discuss how ECRG4 can be used in the treatment of tumors and arrhythmias, and provide a novel possible strategy to reduce the occurrence of perioperative cardiovascular adverse events in patients with tumors such as esophageal cancer and gastric cancer.

Loss of Ecrg4 improves calcium oxalate nephropathy

Kidney stone is one of the most frequent urinary tract diseases, affecting 10% of the population and displaying a high recurrence rate. Kidney stones are the result of salt supersaturation, including calcium and oxalate. We have previously identified Esophageal cancer-related gene 4 (Ecrg4) as being modulated by hypercalciuria. Ecrg4 was initially described as a tumor suppressor gene in the esophagus. Lately, it was shown to be involved as well in apoptosis, cell senescence, cell migration, inflammation and cell responsiveness to chemotherapy. To the best of our knowledge, nothing is known about ECRG4's function in the renal tissue and its relationship with calciuria. We hypothesized that the increased expression of Ecrg4 mRNA is triggered by hypercalciuria and might modulate intratubular calcium-oxalate precipitation. In this study, we have first (i) validated the increased Ecrg4 mRNA in several types of hypercalciuric mouse models, then (ii) described the Ecrg4 mRNA expression along the nephron and (iii) assessed ECRG4's putative role in calcium oxalate nephropathy. For this, Ecrg4 KO mice were challenged with a kidney stone-inducing diet, rich in calcium and oxalate precursor. Taken together, our study demonstrates that Ecrg4's expression is restricted mainly to the distal part of the nephron and that the Ecrg4 KO mice develop less signs of tubular obstruction and less calcium-oxalate deposits. This promotes Ecrg4 as a modulator of renal crystallization and may open the way to new therapeutic possibilities against calcium oxalate nephropathy.

ECRG4 acts as a tumor suppressor in nasopharyngeal carcinoma by suppressing the AKT/GSK3β/β-catenin signaling pathway

Nasopharyngeal carcinoma (NPC) is a malignant tumor with a poor prognosis. Studies have shown that esophageal carcinoma related gene 4 (ECRG4) is hypermethylated and significantly downregulated in NPC tissues. However, the role of ECRG4 in NPC, and in particular the underlying molecular mechanism, is largely unclear. In this study, using immunohistochemical staining of ECRG4 in NPC and normal specimens, we confirmed that ECRG4 was downregulated in human NPC tissues. In addition, various biological and molecular studies were carried out and the results showed that ECRG4 exerted anticancer effect in NPC, including inhibiting cell growth, migration, and invasion of NPC cells in vitro. Moreover, restoring ECRG4 expression suppressed the in vivo tumorigenesis of CNE2 cells. ECRG4 inhibited AKT/GSK3β/β-catenin signaling, as well as the downstream targets of β-catenin. LiCl treatment, which reduced GSK3β phosphorylation and upregulated β-catenin expression, restored the invasive ability of ECRG4-overexpressing NPC cells. Furthermore, we showed that the DNA methylation inhibitor 5-aza-dC reduced ECRG4 methylation and the invasive ability of negative control cells, but not that of ECRG4-overexpressing cells, suggesting that the inhibitory effect of 5-aza-dC depends on low expression of ECRG4. Collectively, our results demonstrated that ECRG4 downregulation contributed to NPC growth and invasion by activating AKT/GSK3β/β-catenin signaling pathway. ECRG4 could be a promising therapeutic target for the treatment of NPC.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10616-022-00520-8.

Pharmacological Modulation of Ubiquitin-Proteasome Pathways in Oncogenic Signaling

The ubiquitin-proteasome pathway (UPP) is involved in regulating several biological functions, including cell cycle control, apoptosis, DNA damage response, and apoptosis. It is widely known for its role in degrading abnormal protein substrates and maintaining physiological body functions via ubiquitinating enzymes (E1, E2, E3) and the proteasome. Therefore, aberrant expression in these enzymes results in an altered biological process, including transduction signaling for cell death and survival, resulting in cancer. In this review, an overview of profuse enzymes involved as a pro-oncogenic or progressive growth factor in tumors with their downstream signaling pathways has been discussed. A systematic literature review of PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was carried out to understand the nature of the extensive work done on modulation of ubiquitin-proteasome pathways in oncogenic signaling. Various in vitro, in vivo studies demonstrating the involvement of ubiquitin-proteasome systems in varied types of cancers and the downstream signaling pathways involved are also discussed in the current review. Several inhibitors of E1, E2, E3, deubiquitinase enzymes and proteasome have been applied for treating cancer. Some of these drugs have exhibited successful outcomes in in vivo studies on different cancer types, so clinical trials are going on for these inhibitors. This review mainly focuses on certain ubiquitin-proteasome enzymes involved in developing cancers and certain enzymes that can be targeted to treat cancer.

Dysregulation of ECRG4 is associated with malignant properties and of prognostic importance in human gastric cancer

BACKGROUND

We have previously characterized esophageal carcinoma-related gene 4 (ECRG4) as a novel tumor suppressor gene, which is frequently inactivated in nasopharyngeal carcinoma and breast cancer. Nevertheless, the expression status and prognostic significance of ECRG4 maintain elusive in human gastric cancer. Herein, we examined ECRG4 expression profile in gastric cancer and assessed its association with clinicopathological characteristics and patient survival.

METHODS

Online data mining, real-time RT-PCR and immunohistochemistry were employed to determined ECRG4 expression at transcriptional and protein levels in tumors vs. noncancerous tissues. Statistical analyses including the Kaplan-Meier survival analysis and the Cox hazard model were utilized to detect the impact on clinical outcome. Moreover, ECRG4 expression was silenced in gastric cancer SGC7901 cells, and cell proliferation, colony formation and invasion assays were carried out.

RESULTS

ECRG4 mRNA and protein levels were obviously downregulated in cancer tissues than noncancerous tissues. Statistical analyses demonstrated that low ECRG4 expression was found in 34.5% (58/168) of primary gastric cancer tissues, which was associated with higher histological grade (P= 0.018), lymph node metastasis (P= 0.011), invasive depth (P= 0.020), advanced tumor stage (P= 0.002) and poor overall survival (P< 0.001). Multivariate analysis showed ECRG4 expression is an independent prognostic predictor (P< 0.001). Silencing ECRG4 expression promoted gastric cancer cell growth and invasion. Western blot analysis revealed the anti-metastatic functions of ECRG4 by downregulating of E-cadherin and α-Catenin, as well as upregulating N-cadherin and Vimentin.

CONCLUSIONS

Our observations reveal that ECRG4 expression is involved in gastric cancer pathogenesis and progression, and may serve as a candidate prognostic biomarker for this disease.

Brain endothelial cells-derived extracellular vesicles overexpressing ECRG4 inhibit glioma proliferation through suppressing inflammation and angiogenesis

Esophageal cancer related gene-4 (ECRG4) has been shown to be a candidate tumor suppressor in many tumors, but its role in glioma remains poorly understood. This study aimed to explore whether extracellular vesicles (EVs) derived from brain endothelial cells which overexpressed ECRG4 have anti-tumor effect on gliomas in vivo and in vitro, as well as the possible mechanism. A constructed lentivirus expressing the ECRG4 gene was transfected into the hCMEC/D3 cell line. The EVs were isolated from the cells and characterized by Western blot with exosome markers of CD9, CD63, CD81, Alix. RT-PCR and Western blot were performed to verify ECRG4 expression. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and clone formation assays were applied to detect the proliferation of glioma cells incubated with EVs expressing the ECRG4 (ECRG4-exo). The level of inflammatory cytokines and angiogenesis related factors, including nuclear factor kappa-B (NF-κB), interleukin (IL)-1β, IL-6, IL-8, monocyte chemoattractant protein-1 (MCP-1), hypoxia-inducible factor 1-alpha (HIF-1α), vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 2 (VEGFR2) levels were detected by ELISA. The T98G cell xenograft mouse model was established and treated with ECRG4-EV. The tumor volume and weight were recorded. p38-MAPK, p-p38-MAPK proteins were determined by Western blot in tumor tissues. As a result, EVs can be internalized into U87MG and T98G cells. ECRG4-EV inhibited U87MG and T98G cell proliferation. ECRG4-EV also inhibited the expression of factors involved in inflammation and angiogenesis. In addition, ECRG4-EVs suppressed tumor growth and decreased the production of inflammatory cytokines through inactivation of p38-MAPK signal pathway. In conclusion, ECRG4-EVsuppresses glioma proliferation through modulating the inflammation and angiogenesis.

Aspirin enhances the therapeutic efficacy of cisplatin in oesophageal squamous cell carcinoma by inhibition of putative cancer stem cells

BACKGROUND

Cancer stem cells (CSCs) are related to the patient's prognosis, recurrence and therapy resistance in oesophageal squamous cell carcinoma (ESCC). Although increasing evidence suggests that aspirin (acetylsalicylic acid, ASA) could lower the incidence and improve the prognosis of ESCC, the mechanism(s) remains to be fully understood.

METHODS

We investigated the role of ASA in chemotherapy/chemoprevention in human ESCC cell lines and an N-nitrosomethylbenzylamine-induced rat ESCC carcinogenesis model. The effects of combined treatment with ASA/cisplatin on ESCC cell lines were examined in vitro and in vivo. Sphere-forming cells enriched with putative CSCs (pCSCs) were used to investigate the effect of ASA in CSCs. Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC-seq) was performed to determine the alterations in chromatin accessibility caused by ASA in ESCC cells.

RESULTS

ASA inhibits the CSC properties and enhances cisplatin treatment in human ESCC cells. ATAC-seq indicates that ASA treatment results in remarkable epigenetic alterations on chromatin in ESCC cells, especially their pCSCs, through the modification of histone acetylation levels. The epigenetic changes activate Bim expression and promote cell death in CSCs of ESCC. Furthermore, ASA prevents the carcinogenesis of NMBzA-induced ESCC in the rat model.

CONCLUSIONS

ASA could be a potential chemotherapeutic adjuvant and chemopreventive drug for ESCC treatment.

Biological Functions Driven by mRNAs Carried by Extracellular Vesicles in Cancer

Extracellular vesicles (EVs), including exosomes and microvesicles, are extracellular nanovesicles released by most cells. EVs play essential roles in intercellular communication via the transport of a large variety of lipids, proteins, and nucleic acids to recipient cells. Nucleic acids are the most commonly found molecules inside EVs, and due to their small size, microRNAs and other small RNAs are the most abundant nucleic acids. However, longer molecules, such as messenger RNAs (mRNAs), have also been found. mRNAs encapsulated within EVs have been shown to be transferred to recipient cells and translated into proteins, altering the behavior of the cells. Secretion of EVs is maintained not only through multiple normal physiological conditions but also during aberrant pathological conditions, including cancer. Recently, the mRNAs carried by EVs in cancer have attracted great interest due to their broad roles in tumor progression and microenvironmental remodeling. This review focuses on the biological functions driven by mRNAs carried in EVs in cancer, which include supporting tumor progression by activating cancer cell growth, migration, and invasion; inducing microenvironmental remodeling via hypoxia, angiogenesis, and immunosuppression; and promoting modulation of the microenvironment at distant sites for the generation of a premetastatic niche, collectively inducing metastasis. Furthermore, we describe the potential use of mRNAs carried by EVs as a noninvasive diagnostic tool and novel therapeutic approach.

Glioblastoma-initiating cell heterogeneity generated by the cell-of-origin, genetic/epigenetic mutation and microenvironment

Glioblastoma (GBM) and other malignant tumours consist of heterogeneous cancer cells, including GBM-initiating cells (GICs). This heterogeneity is likely to arise from the following: different sets of genetic mutations and epigenetic modifications, which GICs gain in the transformation process; differences in cells of origin, such as stem cells, precursor cells or differentiated cells; and the cancer microenvironment, in which GICs communicate with neural cells, endothelial cells and immune cells. Furthermore, considering that various types of GICs can be generated at different time points of the transformation process, GBM very likely consists of heterogeneous GICs and their progeny. Because cancer cell heterogeneity is responsible for therapy resistance, it is crucial to develop methods of reducing such heterogeneity. Here, I summarize how GIC heterogeneity is generated in the transformation process and present how cell heterogeneity in cancer can be addressed based on recent findings.

Aberrant DNA Methylation in Esophageal Squamous Cell Carcinoma: Biological and Clinical Implications

Almost all cancer cells possess multiple epigenetic abnormalities, which cooperate with genetic alterations to enable the acquisition of cancer hallmarks during tumorigenesis. As the most frequently found epigenetic change in human cancers, aberrant DNA methylation manifests at two major forms: global genomic DNA hypomethylation and locus-specific promoter region hypermethylation. It has been recognized as a critical contributor to esophageal squamous cell carcinoma (ESCC) malignant transformation. In ESCC, DNA methylation alterations affect genes involved in cell cycle regulation, DNA damage repair, and cancer-related signaling pathways. Aberrant DNA methylation patterns occur not only in ESCC tumors but also in precursor lesions. It adds another layer of complexity to the ESCC heterogeneity and may serve as early diagnostic, prognostic, and chemo-sensitive markers. Characterization of the DNA methylome in ESCC could help better understand its pathogenesis and develop improved therapies. We herein summarize the current research and knowledge about DNA methylation in ESCC and its clinical significance in diagnosis, prognosis, and treatment.

ECRG4 Represses Cell Proliferation and Invasiveness via NFIC/OGN/NF-κB Signaling Pathway in Bladder Cancer

Bladder cancer (BCa) is a malignant tumor in the urinary system with high cancer-related mortality worldwide. However, the molecular mechanisms of many genes dysregulated in BCa are still unclear. Herein, we showed that esophageal cancer-related gene-4 (ECRG4), which is downregulated in BCa tissues and cell lines, has a positive correlation with osteoglycin (OGN). Further functional experimental studies suggested that both ECRG4 and OGN inhibit cell proliferation, migration, and invasion in BCa cells. Moreover, ECRG4 acts as a tumor repressor and promotes the expression of OGN via the upregulation of nuclear factor 1 C-type (NFIC), which can bind to the promoter region of OGN and regulate its transcription. Bioinformatics analysis revealed that NFIC is downregulated in BCa tissues and has a positive correlation with ECRG4 or OGN. Esophageal cancer-related gene-4 could positively regulate the protein levels of NFIC in BCa cells. In addition, we demonstrated for the first time that ECRG4 inhibits the nuclear factor (NF)-κB signaling pathway via the upregulation of OGN in BCa cells. Overall, these findings provide evidence that both ECRG4 and OGN function as tumor repressors and that overexpression of ECRG4 inhibits the NF-κB signaling pathway by promoting NFIC/OGN signaling in BCa cells. Our results reveal the molecular regulatory mechanisms of the ECRG4-mediated repression of the NFIC/OGN/NF-κB signaling pathway in BCa and provide potential biomarkers or therapeutic targets for BCa.

Metformin suppresses the esophageal carcinogenesis in rats treated with NMBzA through inhibiting AMPK/mTOR signaling pathway

Metformin is a widely used antidiabetic drug for the management of type 2 diabetes mellitus. Recently, epidemiological studies demonstrate that metformin has anticancer effects on esophageal squamous cell carcinoma (ESCC) and other cancers. However, the effects and potential mechanisms of metformin on ESCC remain elusive. In this study, we used N-nitroso-N-methylbenzylamine (NMBzA), a special carcinogen for esophagi, to develop a rat ESCC model, in which the carcinogenesis progression of ESCC in rat was induced and promoted. We investigated the effects of metformin on carcinogenesis of ESCC in this model. Our results revealed that metformin significantly decreased the incidence and precancerous lesions of ESCC and inhibited proliferation and promoted apoptosis of esophageal epithelial cells in rat treated with NMBzA. Moreover, metformin also increased apoptosis and inhibited migration, colony formation and tumor sphere formation of human ESCC cells in vitro. Immunohistochemistry and western blotting showed that without interfering the metabolism of NMBzA, metformin inhibited the inflammation of esophagi via reducing the expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6). Treatment of metformin led to activation of AMP-activated protein kinase (AMPK) and attenuated signaling of the downstream molecules such as p-mTOR, p-p70S6K and cyclin D1 expression both in vivo and in vitro. Taken together, our study demonstrated that metformin suppressed the carcinogenesis of ESCC through inhibiting AMPK/mammalian target of the rapamycin (mTOR) signaling pathway, resulting in its chemopreventive effects on the carcinogenesis of ESCC.

ITIH5 and ECRG4 DNA Methylation Biomarker Test (EI-BLA) for Urine-Based Non-Invasive Detection of Bladder Cancer

Bladder cancer is one of the more common malignancies in humans and the most expensive tumor for treating in the Unites States (US) and Europe due to the need for lifelong surveillance. Non-invasive tests approved by the FDA have not been widely adopted in routine diagnosis so far. Therefore, we aimed to characterize the two putative tumor suppressor genes ECRG4 and ITIH5 as novel urinary DNA methylation biomarkers that are suitable for non-invasive detection of bladder cancer. While assessing the analytical performance, a spiking experiment was performed by determining the limit of RT112 tumor cell detection (range: 100-10,000 cells) in the urine of healthy donors in dependency of the processing protocols of the RWTH cBMB. Clinically, urine sediments of 474 patients were analyzed by using quantitative methylation-specific PCR (qMSP) and Methylation Sensitive Restriction Enzyme (MSRE) qPCR techniques. Overall, ECRG4-ITIH5 showed a sensitivity of 64% to 70% with a specificity ranging between 80% and 92%, i.e., discriminating healthy, benign lesions, and/or inflammatory diseases from bladder tumors. When comparing single biomarkers, ECRG4 achieved a sensitivity of 73%, which was increased by combination with the known biomarker candidate NID2 up to 76% at a specificity of 97%. Hence, ITIH5 and, in particular, ECRG4 might be promising candidates for further optimizing current bladder cancer biomarker panels and platforms.

Neurochemical regulation of the expression and function of glial fibrillary acidic protein in astrocytes

Glial fibrillary acidic protein (GFAP), a type III intermediate filament, is a marker of mature astrocytes. The expression of GFAP gene is regulated by many transcription factors (TFs), mainly Janus kinase-2/signal transducer and activator of transcription 3 cascade and nuclear factor κ-light-chain-enhancer of activated B cell signaling. GFAP expression is also modulated by protein kinase and other signaling molecules that are elicited by neuronal activity and hormones. Abnormal expression of GFAP proteins occurs in neuroinflammation, neurodegeneration, brain edema-eliciting diseases, traumatic brain injury, psychiatric disorders and others. GFAP, mainly in α-isoform, is the major component of cytoskeleton and the scaffold of astrocytes, which is essential for the maintenance of astrocytic structure and shape. GFAP also has highly morphological plasticity because of its quick changes in assembling and polymerizing states in response to environmental challenges. This plasticity and its corresponding cellular morphological changes endow astrocytes the functions of physical barrier between adjacent neurons and stabilizer of extracellular environment. Moreover, GFAP colocalizes and even molecularly associates with many functional molecules. This feature allows GFAP to function as a platform for direct interactions between different molecules. Last, GFAP involves transportation and localization of other functional proteins and thus serves as a protein transport guide in astrocytes. This guiding role of GFAP involves an elastic retraction and extension cytoskeletal network that couples with GFAP reassembling, transporting, and membrane protein recycling machinery. This paper reviews our current understanding of the expression and functions of GFAP as well as their regulation.

Potential functions of esophageal cancer-related gene-4 in the cardiovascular system

Esophageal cancer-related gene-4 (Ecrg4) is cloned from the normal epithelium of the esophagus. It is constitutively expressed in quiescent epithelial cells and downregulated during tumorigenesis, and Ecrg4 expression levels are inversely correlated with the malignant phenotype of tumor cells, validating that Ecrg4 is a real tumor suppressor gene. Unlike other tumor suppressor genes that usually encode membrane or intracellular proteins, Ecrg4 encodes a 148-amino acid pre-pro-peptide that is tethered on the cell surface in epithelial cells, specialized epithelial cells, and human leukocytes, where it can be processed tissue dependently into several small peptides upon cell activation. Ecrg4 is expressed in a wide variety of other cells/tissues, including cardiomyocytes and conduction system of the heart, the glomus cells of the carotid body, adrenal glands, choroid plexus, and leukocytes among others, where it exerts distinct functions, such as promoting/suppressing inflammation, inducing neuron senescence, stimulating the hypothalamus-pituitary-adrenal axis, maintaining the stemness of stem cells, participating in the rhythm and rate control of the heart, and possibly gauging the responsiveness of the cardiovascular system (CVS) to hypoxia, in addition to tumor suppression. Here, we briefly review the latest discoveries on Ecrg4 and its underlying molecular mechanisms as a tumor suppressor and focus on the emerging roles of Ecrg4 in the CVS.

Esophageal cancer related gene-4 inhibits the migration and proliferation of oral squamous cell carcinoma through BC200 lncRNA/MMP-9 and -13 signaling pathway

Esophageal cancer related gene-4 (ECRG4) inhibits the malignant phenotype of oral squamous cell carcinoma. However, the molecular mechanisms remain to be explored. Using the tongue carcinoma cell line, TCA8113 as a cell model, we showed that forced expression of ECRG4 down-regulated the expression of the BC200 long non-coding RNA (lncRNA) and matrix metalloproteinases (MMP-9 and MMP-13). Restoration of BC200 lncRNA rescued ECRG4-mediated down-regulation of MMP-9 and -13. Furthermore, over-expression of Ecrg4 inhibited cell proliferation and migration, which was abolished by forced expression of BC200 lncRNA in TCA8113 cells. Our results indicate that ECRG4 inhibits the malignant phenotype of TCA8113 cells most likely through suppression of BC200 lncRNA/MMPs signaling pathway, rationalizing that BC200 lncRNA may be a potential target for oral squamous cell carcinoma (OSCC) therapy.

Ecrg4 deficiency extends the replicative capacity of neural stem cells in a Foxg1-dependent manner

The self-renewal activity of neural stem cells (NSCs) has been suggested to decrease with aging, resulting in age-dependent declines in brain function, such as presbyopia and memory loss. The molecular mechanisms underlying decreases in NSC proliferation with age need to be elucidated in more detail to develop treatments that promote brain function. We have previously reported that the expression of esophageal cancer-related gene 4 (Ecrg4) was upregulated in aged NSCs, whereas its overexpression decreased NSC proliferation, suggesting a functional relationship between Ecrg4 and NSC aging. Using Ecrg4-deficient mice in which the Ecrg4 locus was replaced with the lacZ gene, we here show that Ecrg4 deficiency recovered the age-dependent decline in NSC proliferation and enhanced spatial learning and memory in the Morris water-maze paradigm. We demonstrate that the proliferation of Ecrg4-deficient NSCs was partly maintained by the increased expression of Foxg1. Collectively, these results determine Ecrg4 as a NSC aging factor.

Downregulation and DNA methylation of ECRG4 in gastric cancer

Background

Esophageal cancer-related gene 4 (ECRG4) is a novel candidate tumor suppressor gene. Our study investigated the expression and function of ECRG4 in gastric cancer and highlighted the role of DNA hypermethylation at the promoter in silencing the ECRG4 expression.

Methods

The GSE63089 data set was obtained from the Gene Expression Omnibus and analyzed for differentially expressed genes. Carcinoma and para-carcinoma tissues of 102 patients with gastric cancer were collected from January 2010 to July 2011. Immunohistochemistry, real-time polymerase chain reaction (PCR), and western blot analyses were performed to evaluate the expression of ECRG4. After measuring the change in the level of ECRG4 expression, CCK-8, Transwell, and flow cytometric cell cycle assays were performed. In addition, methylation-specific PCR was performed to detect the methylation state of ECRG4, and 5-aza-2′-deoxycytidine was used for demethylation of ECRG4. All statistical analyses were performed using the SPSS 17.0 software.

Results

We found that ECRG4 expression was downregulated in gastric cancer, and this was closely related to lymph node metastasis. After ECRG4 was silenced using a specific small interfering RNA, the BGC-823 cell line became highly aggressive and proliferative. In addition, we verified whether downregulation of ECRG4 was highly correlated with DNA methylation of the ECRG4 promoter and found that the demethylating agent 5-aza-2′-deoxycytidine could effectively enhance ECRG4 expression.

Conclusion

The aberrant expression of ECRG4 is associated with hypermethylation in the promoter region and plays an important role in the malignancy of gastric cancer. Therefore, ECRG4 may be a potential biomarker for molecular diagnosis of gastric cancer, and the use of 5-Aza-dC to reverse the hypermethylation of ECRG4 may be a new approach to the treatment of gastric cancer.

ECRG4: a new potential target in precision medicine

Given the rapid development in precision medicine, tremendous efforts have been devoted to discovering new biomarkers for disease diagnosis and treatment. Esophageal cancer-related gene-4 (ECRG4), which is initially known as a new candidate tumor suppressor gene, is emerging as a sentinel molecule for gauging tissue homeostasis. ECRG4 is unique in its cytokine-like functional pattern and epigenetically-regulated gene expression pattern. The gene can be released from the cell membrane upon activation and detected in liquid biopsy, thus offering considerable potential in precision medicine. This review provides an updated summary on the biology of ECRG4, with emphasis on its important roles in cancer diagnosis and therapy. The future perspectives of ECRG4 as a potential molecular marker in precision medicine are also discussed in detail.

Serum exosomes contain ECRG4 mRNA that suppresses tumor growth via inhibition of genes involved in inflammation, cell proliferation, and angiogenesis

Esophageal cancer related gene-4 (Ecrg4) has been shown to be a tumor suppressor in many organs. Exosomes are naturally secreted nanosized particles that carry signal molecules including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and messenger RNAs (mRNAs) among others. Upon internalization, exosomes unload their cargos that in turn modulate the biology of the recipient cells. Mounting evidence has shown that exosomal miRNAs are functional. However, reports that exosomes carry functional mRNAs remain scarce. We found that serum exosomes contain ECRG4 open reading frame. To simulate serum exosomal ECRG4, stable cell line expressing ECRG4 was created, from which exosomes were isolated and characterized, and the internalization and the resulting biological effects of exosomal ECRG4 were evaluated. Results showed that serum exosomes contain higher levels of ECRG4 mRNA in healthy individuals than their cancer counterparts. Exosomal ECRG4 can be internalized and unload the encapsulated ECRG4 into recipient cells, which subsequently suppressed cell proliferation in vitro, and inhibited tumor growth in a xenograft mouse model. Mechanistically, ECRG4-containing exosomes, when internalized, suppressed the expression of genes commonly implicated in inflammation, cell proliferation, and angiogenesis. Given that exosome is an ideal vehicle for therapeutics delivery and that ECRG4 is a tumor suppressor gene, the exosomal ECRG4 can be exploited as a formulation for cancer gene therapy.

A short synthetic peptide fragment of human C2ORF40 has therapeutic potential in breast cancer

C2ORF40 encodes a secreted protein which is cleaved to generate soluble peptides by proteolytic processing and this process is believed to be necessary for C2ORF40 to exert cell type specific biological activity. Here, we reported a short mimic peptide of human C2ORF40 acts potential therapeutic efficacy in human cancer cells in vitro and in vivo. We synthesized a short peptide of human C2ORF40, named C2ORF40 mimic peptide fragment and assessed its biological function on cancer cell growth, migration and tumorigenesis. Cell growth assay showed that C2ORF40 mimic peptide fragment significantly suppressed cell proliferation of breast and lung cancer cells. Moreover, C2ORF40 mimic peptide fragment significantly inhibited the migration and invasion of breast cancer cells. Furthermore, we showed that this peptide suppressed tumorigenesis in breast tumor xenograft model. Cell cycle assay indicated that the C2ORF40 mimic peptide fragment suppressed the growth of tumor cells through inducing mitotic phase arrest. In conclusion, our results firstly suggested that this short synthetic peptide of human C2ORF40 may be a candidate tumor therapeutic agent.

Ecrg4 peptide is the ligand of multiple scavenger receptors

Esophageal cancer-related gene 4 (Ecrg4) encodes a hormone-like peptide that is believed to be involved in a variety of physiological phenomena, including tumour suppression. Recent progress in the study of Ecrg4 has shown that Ecrg4 is a proinflammatory factor and induces the expression of several cytokines and chemokines in macrophages/microglia. However, the detailed molecular mechanisms of Ecrg4 signalling, especially the Ecrg4 receptors, remain poorly understood. Here, using retrovirus-mediated expression cloning, we identified lectin-like oxidised low-density lipoprotein receptor-1 (LOX-1) as a membrane protein that binds amino acid residues 71–132 of Ecrg4 (Ecrg4(71–132)). Moreover, in addition to LOX-1, several scavenger receptors, such as Scarf1, Cd36 and Stabilin-1, facilitated the efficient internalisation of Ecrg4(71–132) into cells. A broad competitive inhibitor of scavenger receptors, polyinosinic acid, reduced both the binding of Ecrg4(71–132) and the activation of NF-κB in microglia. This activation was dependent on MyD88, an adaptor protein that recruits signalling proteins to Toll-like receptors (TLRs), with the consequent induction of various immune responses. These data suggest that multiple scavenger receptors recognise Ecrg4(71–132) and transduce its signals, together with TLRs, in microglia.

Genome-wide pleiotropy analysis of neuropathological traits related to Alzheimer's disease

BACKGROUND

Simultaneous consideration of two neuropathological traits related to Alzheimer's disease (AD) has not been attempted in a genome-wide association study.

METHODS

We conducted genome-wide pleiotropy analyses using association summary statistics from the Beecham et al. study (PLoS Genet 10:e1004606, 2014) for AD-related neuropathological traits, including neuritic plaque (NP), neurofibrillary tangle (NFT), and cerebral amyloid angiopathy (CAA). Significant findings were further examined by expression quantitative trait locus and differentially expressed gene analyses in AD vs. control brains using gene expression data.

RESULTS

Genome-wide significant pleiotropic associations were observed for the joint model of NP and NFT (NP + NFT) with the single-nucleotide polymorphism (SNP) rs34487851 upstream of C2orf40 (alias ECRG4, P = 2.4 × 10^-8) and for the joint model of NFT and CAA (NFT + CAA) with the HDAC9 SNP rs79524815 (P = 1.1 × 10^-8). Gene-based testing revealed study-wide significant associations (P ≤ 2.0 × 10^-6) for the NFT + CAA outcome with adjacent genes TRAPPC12, TRAPPC12-AS1, and ADI1. Risk alleles of proxy SNPs for rs79524815 were associated with significantly lower expression of HDAC9 in the brain (P = 3.0 × 10^-3), and HDAC9 was significantly downregulated in subjects with AD compared with control subjects in the prefrontal (P = 7.9 × 10^-3) and visual (P = 5.6 × 10^-4) cortices.

CONCLUSIONS

Our findings suggest that pleiotropy analysis is a useful approach to identifying novel genetic associations with complex diseases and their endophenotypes. Functional studies are needed to determine whether ECRG4 or HDAC9 is plausible as a therapeutic target.

Counter regulation of ECRG4 gene expression by hypermethylation-dependent inhibition and the Sp1 transcription factor-dependent stimulation of the c2orf40 promoter

The human cytokine precursor ECRG4 has been associated with multiple physiological, developmental and pathophysiological processes involving cell proliferation, cell migration, innate immunity, inflammation, cancer progression and metastases. Although down-regulation of ECRG4 gene expression has been largely attributed to hypermethylation of CpG islands in the 5'untranslated region of the ECRG4 promoter, the mechanisms that underlie the dynamics of its regulation have never been systematically described. Here we show that the ECRG4 gene is widely expressed in human tissues and report that its core promoter lies between the -780 to +420 base pairs relative to the ATG start codon of the ECRG4 open reading frame. This sequence, which contains several CpG islands, also includes multiple overlapping Sp1 consensus binding sequences and a putative binding site for NF-kB activation. 5'RACE of mRNA derived from human leukocytes shows that ECRG4 transcription initiates from the guanidine at -11 from the initiation ATG of the ECRG4 open reading frame. While there is no canonical TATA- or CAAT-boxes proximal to this translational initiation site, there is a distal TATA-sequence in the 5'UTR. This region was identified as the sequence targeted by hypermethylation because in vitro methylation of plasmids encoding the ECRG4 promoter abolish promoter activity and the treatment of Jurkat cells (which naturally express ECRG4) with the methylation inhibitor 5-AzaC, increases endogenous ECRG4 expression. Because ChIP assays show that Sp1 binds the ECRG4 promoter, that forced Sp1 expression trans-activates the ECRG4 promoter and Sp1 inhibition with mithramycin inhibits ECRG4 expression, we conclude that the dynamic positive and negative regulatory elements controlling ECRG4 expression include a counter regulation between promoter methylation and Sp1 activation.

Functional evidence that the self-renewal gene NANOG regulates esophageal squamous cancer development

Cancer cell molecular mimicry of stem cells (SC) follows with enhanced proliferative and renewal capacities. In support, numerous mediators of SC self-renewal have been evinced to exhibit oncogenic potential. More and more researches showed that the embryonic stem cell self-renewal genes express in various cancer cells. In this study, we sought to test the tumorigenic functions of NANOG, particularly, in esophageal cancer (EC). Using quantitative RT-PCR and western blotting, we confirmed that EC cells highly express NANOG mRNA and protein. We then constructed a shRNA-mediated plasmid to knockdown of NANOG mRNA. We observed that NANOG deficiency in Eca109 cells decreased clone formation, cell proliferation, and showed G1 arrest. To further investigate the functions and mechanisms of NANOG in Eca109 cells, we detected the changes of multiple signaling molecules when NANOG deficiency. We foud that NANOG deficiency affected multiple genes, particularly, supressed drug-resistance via down-regulated ABCG2 in Eca109 cells, and caused G1 arrest by down-regulated cyclin D1 (CCND1) expression. The present loss-of-function work, establish the integral role for NANOG in Eca109 cell proliferation, drug resistance, and shed light on its mechanisms of action.

A Potential Role of Esophageal Cancer Related Gene-4 for Atrial Fibrillation

Epidemiological studies have shown a strong correlation between tumor and AF. However, the molecular link between tumor and AF remains unknown. ECRG4, a tumor suppressor gene that is expressed in the A-V node and in sporadic ventricular myocytes, inhibits tumorigenesis and monitors tissue homeostasis by functioning as a ‘sentinel’ molecule gauging inflammatory and cell proliferative responses. To explore the potential physiological function of Ecrg4 in heart, we evaluated its distribution in heart, analyzed its expression in patients with persistent AF and in a canine AF model, and dissected the molecular events downstream of Ecrg4. The results showed that the level of Ecrg4 expression is homogenously high in atria and the conduction systems and in sporadic ventricular myocytes. Importantly, the expression of Ecrg4 was significantly decreased in atrial appendages of AF patients than patients with SR. Moreover, in rapid pacing canine AF models, the expression of ECRG4 in atria was significantly decreased compared to that of the controls. Mechanistically, knockdown ECRG4 in atrial myocytes significantly shortened the APDs, inhibited the expression of Gja1, and activated pro-inflammatory cascades and genes involved in cardiac remodeling. These results suggest that Ecrg4 may play a critical role in the pathogenesis of AF.

Cell Cycle M-Phase Genes Are Highly Upregulated in Anaplastic Thyroid Carcinoma

BACKGROUND

Anaplastic thyroid carcinoma (ATC) accounts for only 3% of thyroid cancers, yet strikingly, it accounts for almost 40% of thyroid cancer deaths. Currently, no effective therapies exist. In an effort to identify ATC-specific therapeutic targets, we analyzed global gene expression data from multiple studies to identify ATC-specific dysregulated genes.

METHODS

The National Center for Biotechnology Information Gene Expression Omnibus database was searched for high-throughput gene expression microarray studies from human ATC tissue along with normal thyroid and/or papillary thyroid cancer (PTC) tissue. Gene expression levels in ATC were compared with normal thyroid or PTC using seven separate comparisons, and an ATC-specific gene set common in all seven comparisons was identified. We investigated these genes for their biological functions and pathways.

RESULTS

There were three studies meeting inclusion criteria, (including 32 ATC patients, 69 PTC, and 75 normal). There were 259 upregulated genes and 286 downregulated genes in ATC with at least two-fold change in all seven comparisons. Using a five-fold filter, 36 genes were upregulated in ATC, while 40 genes were downregulated. Of the 10 top globally upregulated genes in ATC, 4/10 (MMP1, ANLN, CEP55, and TFPI2) are known to play a role in ATC progression; however, 6/10 genes (TMEM158, CXCL5, E2F7, DLGAP5, MME, and ASPM) had not been specifically implicated in ATC. Similarly, 3/10 (SFTA3, LMO3, and C2orf40) of the most globally downregulated genes were novel in this context, while 7/10 genes (SLC26A7, TG, TSHR, DUOX2, CDH1, PDE8B, and FOXE1) have been previously identified in ATC. We experimentally validated a significant correlation for seven transcription factors (KLF16, SP3, ETV6, FOXC1, SP1, EGFR1, and MAFK) with the ATC-specific genes using microarray analysis of ATC cell lines. Ontology clustering of globally altered genes revealed that "mitotic cell cycle" is highly enriched in the globally upregulated gene set (44% of top upregulated genes, p-value <10^-30).

CONCLUSIONS

By focusing on globally altered genes, we have identified a set of consistently altered biological processes and pathways in ATC. Our data are consistent with an important role for M-phase cell cycle genes in ATC, and may provide direction for future studies to identify novel therapeutic targets for this disease.

Downregulated ECRG4 is correlated with lymph node metastasis and predicts poor outcome for nasopharyngeal carcinoma patients

OBJECTIVE

Esophageal cancer-related gene 4 (ECRG4) is a new candidate tumor suppressor gene. In this retrospective study, we evaluated ECRG4 protein expression in patients with nasopharyngeal carcinoma (NPC) under curative treatment and examined its association with pathological features and clinical outcomes as a possible biomarker for diagnosis and prognosis of NPC.

METHODS

We enrolled 122 patients with a first diagnosis between January 2001 and December 2003. Tumor tissue and control tissue from biopsies underwent immunohistochemical staining for ECRG4. ECRG4 expression was analyzed by clinicopathological variables. After Kaplan-Meier survival analysis, we used Cox proportional hazards regression to estimate the predictive effect of ECRG4 expression on overall survival.

RESULTS

ECRG4 protein level was lower in NPC than control tissue (P < 0.01). It was inversely related to node status (P < 0.001) and clinical stage (P = 0.027). ECRG4 expression was associated with overall survival, and downregulated ECRG4 expression was an independent prognostic factor of poor survival (hazard ratio = 0.677, 95 % confidence interval 0.463-0.989, P = 0.044).

CONCLUSIONS

A significant NPC patients showed downregulated ECRG4 expression, which is correlated with lymph node metastasis. The marker could be an independent prognostic factor for NPC patients. The precise function of ECRG4 in the progression of NPC, especially for lymphatic metastasis, deserves further investigation, which would bring a new target for personalized therapy.

Ecrg4 contributes to the anti-glioma immunosurveillance through type-I interferon signaling

Esophageal cancer-related gene 4 (Ecrg4), a hormone-like peptide, is thought to be a tumor suppressor, however, little is known about the mechanism of how Ecrg4 suppresses tumorigenesis. Here, we show that the ecrg4 null glioma-initiating cell (GIC) line, which was generated from neural stem cells of ecrg4 knockout (KO) mice, effectively formed tumors in the brains of immunocompetent mice, whereas the transplanted ecrg4 wild type-GIC line GIC(+/+) was frequently eliminated. This was caused by host immune system including adaptive T cell responses, since depletion of CD4⁺, CD8⁺, or NK cells by specific antibodies in vivo recovered tumorigenicity of GIC(+/+). We demonstrate that Ecrg4 fragments, amino acid residues 71-132 and 133-148, which are produced by the proteolitic cleavage, induced the expression of pro-inflammatory cytokines in microglia in vitro. Moreover, blockades of type-I interferon (IFN) signaling in vivo, either depleting IFN-α/β receptor 1 or using stat1 KO mice, abrogated the Ecrg4-dependent antitumor activity. Together, our findings indicate a major antitumor function of Ecrg4 in enhancing host immunity via type-I IFN signaling, and suggest its potential as a clinical candidate for cancer immunotherapy.

Soluble purified recombinant C2ORF40 protein inhibits tumor cell growth in vivo by decreasing telomerase activity in esophageal squamous cell carcinoma

The chromosome 2 open reading frame 40 (C2ORF40) gene is a candidate tumor suppressor gene for a variety of tumors. Previous results by the present authors revealed that the C2ORF40 protein is a secreted protein. However, the exact biological function of secreted C2ORF40 protein in carcinogenesis has not been thoroughly investigated. In the present study, the signal peptide sequence of the C2ORF40 cDNA was initially removed to produce secreted recombinant human C2ORF40 protein (rhC2ORF40). Soluble rhC2ORF40 was successfully expressed and purified, which was evaluated for the first time, to the best of our knowledge, for tumor-suppressing function in vivo in esophageal cancer. The present results revealed that soluble purified rhC2ORF40 was concentrated with a purity of >95%. Furthermore, rhC2ORF40 inhibited esophageal cancer cell growth in vivo in a dose-dependent manner compared with a control group (P<0.05). In addition, the present study demonstrated for the first time that rhC2ORF40 decreased telomerase activity using telomeric repeat amplification protocol-enzyme-linked immunosorbent assay (P<0.05), without affecting the expression levels of telomerase-component RNA (P>0.05), as shown with polymerase chain reaction. Overall, the present results demonstrated that soluble rhC2ORF40 inhibited tumor cell growth in vivo by decreasing telomerase activity in esophageal squamous cell carcinoma. Therefore, soluble rhC2ORF40 with a high purity and biological activity may be a potential biological therapy drug for esophageal cancer.

The detective, prognostic, and predictive value of DNA methylation in human esophageal squamous cell carcinoma

Esophageal cancer is one of the most common malignancies in the world. Squamous cell carcinoma accounts for approximately 90 % of esophageal cancer cases. Genetic and epigenetic changes have been found to accumulate during the development of various cancers, including esophageal squamous carcinoma (ESCC). Tobacco smoking and alcohol consumption are two major risk factors for ESCC, and both tobacco and alcohol were found to induce methylation changes in ESCC. Growing evidence demonstrates that aberrant epigenetic changes play important roles in the multiple-step processes of carcinogenesis and tumor progression. DNA methylation may occur in the key components of cancer-related signaling pathways. Aberrant DNA methylation affects genes involved in cell cycle, DNA damage repair, Wnt, TGF-β, and NF-κB signaling pathways, including P16, MGMT, SFRP2, DACH1, and ZNF382. Certain genes methylated in precursor lesions of the esophagus demonstrate that DNA methylation may serve as esophageal cancer early detection marker, such as methylation of HIN1, TFPI-2, DACH1, and SOX17. CHFR methylation is a late stage event in ESCC and is a sensitive marker for taxanes in human ESCC. FHIT methylation is associated with poor prognosis in ESCC. Aberrant DNA methylation changes may serve as diagnostic, prognostic, and chemo-sensitive markers. Characterization of the DNA methylome in ESCC will help to better understand its mechanisms and develop improved therapies.

Down-regulated ECRG4 expression in breast cancer and its correlation with tumor progression and poor prognosis--A short Report

BACKGROUND

Recently, we identified the esophageal carcinoma related gene 4 (ECRG4) as a novel candidate tumor suppressor gene and a promising therapeutic target in nasopharyngeal carcinoma (NPC). In addition, we found that reduced ECRG4 expression in NPC was associated with promoter hypermethylation. The aim of the current study was to assess the expression status of the ECRG4 protein in breast cancer and to clarify its clinicopathological significance and potential prognostic implications.

METHODS

Western blotting was used to examine ECRG4 protein levels in 20 paired breast cancer tissues and adjacent noncancerous tissues. In addition, we performed ECRG4 immunohistochemistry on 113 clinicopathologically well-characterized breast cancer samples and assessed putative associations between its expression and overall patient survival rates.

RESULTS

We found that ECRG4 protein expression was significantly reduced in the breast cancer tissues compared to the noncancerous tissues. Clinicopathological analyses revealed that loss of ECRG4 protein expression, observed in 41.6 % (47/113) of the primary breast cancer tissues tested, was significantly correlated with lymph node metastasis (P = 0.026), advanced tumor stage (P = 0.042) and unfavorable overall survival (P = 0.004). Additional multivariate analyses revealed that ECRG4 protein expression may serve as an independent prognostic factor for the prediction of patient survival (P = 0.033).

CONCLUSION

Our data suggest that loss of ECRG4 protein expression may be involved in tumor progression and may serve as a prognostic biomarker for breast cancer.

Downregulated ECRG4 is associated with poor prognosis in renal cell cancer and is regulated by promoter DNA methylation

Esophageal cancer-related gene 4 (ECRG4) has been proposed as a putative tumor suppressor gene in several tumors. However, the role and regulation of ECRG4 in the pathogenesis of human renal cancer remain largely unknown. Our current study revealed that expression of ECRG4 is downregulated in renal cell lines and renal cancer tissues. ECRG4 expression was significantly associated with histological grade of tumors (p < 0.001), primary tumor stage (p = 0.017), and distant metastasis (p = 0.017). Low expression of ECRG4 was an independent prognostic indicator for survival of renal cancer patients. Silencing of ECRG4 expression in renal cell lines was associated with its promoter methylation. Moreover, ectopic expression of ECRG4 markedly inhibited cell proliferation and invasion in renal cancer cell lines. These results indicated that ECRG4 is frequently silenced by the methylation of promoter in renal cell cancers. ECRG4 may be a tumor suppressor in renal cancer and serve as a prognostic marker.

A preliminary study of the effect of ECRG4 overexpression on the proliferation and apoptosis of human laryngeal cancer cells and the underlying mechanisms

Human esophageal cancer-related gene 4 (ECRG4) is a potential tumor suppressor gene isolated from human esophageal epithelial cells. Studies have shown that ECRG4 effectively inhibits the proliferation of tumor cells and induces apoptosis. However, the role of ECRG4 in laryngeal cancer has not yet been clearly defined. In this study, a human laryngeal cancer cell line stably overexpressing ECRG4 was established. The effect of ECRG4 on the proliferation and apoptosis of laryngeal cancer cells and the associated mechanisms were investigated. The Hep-2 human laryngeal carcinoma cell line exhibited a low basal level of ECRG4 expression and was selected for the present study. The eukaryotic expression plasmid pcDNA3.1-ECRG4 was constructed and introduced into Hep-2 cells by transfection reagents. Western blot analysis, reverse transcription-quantitative polymerase chain reaction and immunofluorescence staining confirmed high-level expression of ECRG4. The 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and colony formation assay showed that ECRG4 over-expression suppressed the proliferative capacity of laryngeal cancer cells in vitro. Cell cycle analysis showed that ECRG4 induced cell cycle arrest at the G0/G1 phase. Flow cytometric analysis and Hoechst staining demonstrated that overexpres-sion of ECRG4 significantly induced apoptosis. Western blot analysis confirmed that Bcl-2-associated X protein, cleaved-caspase-3 and cleaved-poly (ADP-ribose) polymerase were upregulated in the apoptotic process, whereas B-cell lymphoma 2 was downregulated. In conclusion, overexpression of ECRG4 inhibited laryngeal cancer cell proliferation and induced cancer cell apoptosis. Therefore, ECRG4 exhibits potential as an effective target in gene therapy for laryngeal cancer.

Soluble purified recombinant C2ORF40 protein inhibits esophageal cancer cell proliferation by inducing cell cycle G1 phase block

Chromosome 2 open reading frame 40 (C2ORF40) plays a significant role in numerous processes, including cell differentiation, senescence, apoptosis, inflammation and neuroendocrine hormone regulation. Moreover, C2ORF40 is a candidate tumor suppressor gene in a variety of tumors, and is closely associated with prognosis. Bioinformatics analysis has indicated that pro-C2ORF40 is a secreted protein with a signal peptide. Secreted C2ORF40 protein (sC2ORF40) exists in cancer cell medium. However, thus far, the exact biological function of sC2ORF40 in carcinogenesis has not been thoroughly researched. In the present study, the signal peptide sequence of the C2ORF40 complementary DNA was initially cut off to produce secreted recombinant human C2ORF40 protein (rhC2ORF40). The soluble rhC2ORF40 was expressed, purified and examined for tumor-suppressing function for the first time. The results revealed that the soluble purified rhC2ORF40 protein was concentrated with a purity of >95%. Furthermore, the rhC2ORF40 inhibited esophageal cancer cell proliferation in vitro (P<0.05) and caused cell cycle G₁ phase block, as determined by flow cytometric analysis (P<0.05). Overall, the soluble rhC2ORF40 protein with high purity and biological activity was obtained, which suppressed esophageal cancer cells proliferation by inducing cell cycle G₁ phase block in vitro. Therefore, the soluble rhC2ORF40 protein could be potential biological therapy drug for esophageal carcinoma.

ECRG4 expression in normal rat tissues: expression study and literature review

The Esophageal Cancer Related Gene 4 (ECRG4) is a highly conserved tumour suppressor gene encoding various peptides (augurin, CΔ16 augurin, ecilin, argilin, CΔ16 argilin) which can be processed and secreted. In the present work, we examined ECRG4 expression and location in a wide range of rat organs and reviewed the available literature. ECRG4 mRNA was identified in all examined tissues by quantitative PCR (qPCR). ECRG4 immunoreaction was mainly cytoplasmic, and was detected in heart and skeletal muscles, smooth muscle cells showing only weak reactions. In the digestive system, ECRG4 immunostaining was stronger in the esophageal epithelium, bases of gastric glands, hepatocytes and pancreatic acinar epithelium. In the lymphatic system, immunoreactive cells were detectable in the thymus cortex, lymph node medulla and splenic red pulp. In the central and peripheral nervous systems, different neuronal groups showed different reaction intensities. In the endocrine system, ECRG4 immunoreaction was detected in the hypothalamic paraventricular and supraoptic nuclei, hypophysis, thyroid and parathyroid glands, adrenal zona glomerularis and medulla and Leydig cells, as well as in follicular and luteal cells of the ovary. In the literature, ECRG4 has been reported to inhibit cell proliferation and increase apoptosis in various cell types. It is down-regulated, frequently due to hypermethylation, in esophageal, prostate, breast and colon cancers, together with glioma (oncosuppressor function), although it is up-regulated in papillary thyroid cancer (oncogenic role). ECRG4 expression is also higher in non-proliferating cells of the lymphatic system. In conclusion, our identification of ECRG4 in many structures suggests the involvement of ECRG4 in the tumorigenesis of other organs and also the need for further research. In addition, on the basis of the location of ECRG4 in neurons and endocrine cells and the fact that it can be secreted, its role as a neurotransmitter/neuromodulator and endocrine factor must be examined in depth in the future.

ECRG4 acts as a tumor suppressor and as a determinant of chemotherapy resistance in human nasopharyngeal carcinoma

BACKGROUND

Human nasopharyngeal carcinoma (NPC) is a malignant type of cancer with an increasing incidence. As yet, however, molecular biomarkers with a strong diagnostic impact and a major therapeutic promise have remained elusive. Here, we identified the esophageal carcinoma related gene 4 (ECRG4) as a novel candidate tumor suppressor gene and a promising therapeutic target for NPC.

METHODS

RT-PCR, Western blotting, methylation-specific PCR and bisulfite sequencing were performed to assess the expression and methylation status of the ECRG4 gene in primary NPC samples, NPC-derived cell lines and patient-derived peripheral blood samples. The NPC-derived cell line CNE1 was selected for treatment with a methylation inhibitor to restore ECRG4 expression. In addition, cell proliferation, invasion and colony formation assays were performed to assess the inhibitory effects of exogenous ECRG4 expression in CNE1 cells.

RESULTS

Down-regulated ECRG4 expression was found to occur in 82.5% (33/40) of the primary NPC biopsies tested. This down-regulation was significantly correlated with its tumor-specific promoter methylation status (72.5%, 29/40) and was also observed in the matching peripheral blood samples from the NPC patients (57.5%, 23/40). Pharmacologic demethylation through 5-aza-dC treatment led to gene reactivation in ECRG4 methylated and silenced NPC cell lines. Moreover, exogenous expression of ECRG4 in the CNE1 cell line strongly inhibited its growth and invasive capacities, as well as its enhanced chemosensitivity to cisplatin through autophagy induction.

CONCLUSION

Our data suggest that methylation-mediated suppression of the ECRG4 gene occurs frequently in NPC and that restoration of its expression may have therapeutic benefits.

Pulmonary preconditioning, injury, and inflammation modulate expression of the candidate tumor suppressor gene ECRG4 in lung

PURPOSE

The human c2orf40 gene encodes a candidate tumor suppressor called Esophageal Cancer-Related Gene-4 (ECRG4) that is a cytokine-like epigenetically-regulated protein that is characteristically downregulated in cancer, injury, inflammation, and infection. Here, we asked whether ECRG4 gene expression is detectable in lung epithelial cells and if its expression changes with inflammation, infection, and/or protective preconditioning.

MATERIALS AND METHODS

We used immunoblotting, PCR, and quantitative PCR to measure ECRG4 and either inhalation anesthesia preconditioning, lipopolysaccharide injection, or laparotomy to modulate lung inflammation.

RESULTS

Immunoblotting establishes the presence of the full-length 14 kDa ECRG4 peptide in mouse lung. Immunohistochemistry localizes ECRG4 to type l alveolar epithelial cells. Basal ECRG4 mRNA is greater than TNF-α, IL-1β, and IL-6 but following inflammatory lung injury, TNF-α, IL-1β, IL-6, and IL-10 are upregulated while ECRG4 gene expression is decreased. Similar findings are observed after an intravenous administration of lipopolysaccharide. In contrast, lung preconditioning with isoflurane anesthesia increases lung ECRG4 gene expression. Over-expression of ECRG4 in human lung epithelial cells in vitro decreases cell proliferation implying that a loss of ECRG4 in vivo would be permissive to cell growth.

CONCLUSIONS

This study supports the hypothesis that ECRG4 acts as a sentinel growth inhibitor in lung alveolar epithelial cells. Its downregulation by injury, infection, and inflammation and upregulation by preconditioning supports a role for ECRG4 in regulating the alveolar epithelium response to injury and inflammation. By extension, the findings support a functional consequence to its inhibition by promoter hypermethylation (i.e. lung cancer) and suggest potential benefits to its upregulation.

Esophageal cancer-related gene-4 (ECRG4) interactions with the innate immunity receptor complex

OBJECTIVE AND DESIGN

The human c2orf40 gene encodes a tumor suppressor gene called esophageal cancer-related gene-4 (ECRG4) with pro- and anti-inflammatory activities that depend on cell surface processing. Here, we investigated its physical and functional association with the innate immunity receptor complex.

METHODS

Interactions between ECRG4 and the innate immunity receptor complex were assessed by flow cytometry, immunohistochemistry, confocal microscopy, and co-immunoprecipitation. Phage display was used for ligand targeting to cells that overexpress the TLR4-MD2-CD14.

RESULTS

Immunoprecipitation and immunohistochemical studies demonstrate a physical interaction between ECRG4 and TLR4-MD2-CD14 on human granulocytes. Flow cytometry shows ECRG4 on the cell surface of a subset of CD14(+) and CD16(+) leukocytes. In a cohort of trauma patients, the C-terminal 16 amino acid domain of ECRG4 (ECRG4(133-148)) appears to be processed and shed, presumably at a thrombin-like consensus sequence. Phage targeting this putative ligand shows that this peptide sequence internalizes into cells through the TLR4/CD14/MD2 complex, but modulates inflammation through non-canonical, NFκB signal transduction.

CONCLUSIONS

ECRG4 is present on the surface of human monocytes and granulocytes. Its interaction with the human innate immunity receptor complex supports a role for cell surface activation of ECRG4 during inflammation and implicates this receptor in its mechanism of action.

Thrombin-processed Ecrg4 recruits myeloid cells and induces antitumorigenic inflammation

BACKGROUND

Extensive infiltration of brain tumors by microglia and macrophages is a hallmark of tumor progression, and yet the overall tumor microenvironment is characterized by an immunosuppressive phenotype. Here we identify esophageal cancer-related gene 4 (Ecrg4) as a novel thrombin-processed monocyte chemoattractant that recruits myeloid cells, promotes their activation, and leads to a blockade of tumor progression.

METHODS

Both xenograft glioma and syngeneic glioma models were used to measure orthotopic tumor progression and overall survival. Flow cytometry and immunohistochemical analyses were performed to assess myeloid cell localization, recruitment, and activation.

RESULTS

Ecrg4 promotes monocyte recruitment and activation of microglia in a T-/B-cell-independent mechanism, which leads to a reduction in glioma tumor burden and increased survival. Mutational analysis reveals that the biological activity of Ecrg4 is dependent on a thrombin-processing site at the C-terminus, inducing monocyte invasion in vivo and in vitro. Furthermore, tumor-induced myeloid cell recruitment is impaired in Ecrg4 knockout mice, leading to increased tumor burden and decreased survival.

CONCLUSIONS

Together, these results identify Ecrg4 as a paracrine factor that activates microglia and is chemotactic for monocytes, with potential as an antitumor therapeutic.

The tumor-promoting function of ECRG4 in papillary thyroid carcinoma and its related mechanism

This study aimed to explore the tumor-promoting function of esophageal cancer-related gene 4 (ECRG4) in the papillary thyroid cancer and its related mechanism. ECRG4 Messenger RNA (mRNA) and protein expression analysis in papillary thyroid cancer tissues was performed by quantitative real-time PCR (Q-RT-PCR), Western blot, and immunohistochemistry methods. Ten pairs of fresh samples from the papillary thyroid carcinoma patients were analyzed for ECRG4 promoter CpG island methylation status by bisulfite sequencing analysis. We also transfected ECRG4 into papillary thyroid cancer cell lines W3 and K1 with lentivirus and analyzed ECRG4 functions through evaluating the changes of the proliferation activity, the cell cycle, and the cell apoptosis rate of these transformed cells. We found that ECRG4 expression was upregulated in most papillary thyroid cancer samples (70.0%, 28 out of 40 papillary thyroid cancer samples) on the protein level, and the ECRG4 mRNA level was also enhanced in tumor tissues compared to their matched nontumor tissues. CpG islands around the ECRG4 promoter region were demethylated in the papillary thyroid cancer samples. At the same time, the upregulated expression of ECRG4 in papillary thyroid cancer cell lines W3 and K1 could promote both the proliferation activity and the cell cycle transition from the G1 phase into the G2 but could not affect the cell apoptosis rate. The expression of ECRG4 is frequently upregulated in a papillary thyroid carcinoma through the demethylation mechanism of CpG islands in the gene promoter region, and the ECRG4 has a tumor-promoting function through inducing the cell cycle transition from the G1 phase to the G2 in papillary thyroid carcinoma cells.

Esophageal cancer-related gene 4 at the interface of injury, inflammation, infection, and malignancy

In humans, esophageal cancer-related gene 4 (ECRG4) is encoded by four exons in the c2orf40 locus of chromosome 2. Translation of ECRG4 messenger ribonucleic acid produces a 148 amino acid-secreted 17 KDa protein that is then processed to 14, ten, eight, six, four, and two KDa peptides, depending on the cell in which the gene is expressed. As hypermethylation at the c2orf40 locus inhibits ECRG4 gene expression in many epithelial cancers, several investigators have speculated that ECRG4 is a candidate tumor suppressor. Indeed, overexpression of ECRG4 inhibits cell proliferation in vitro, but it also has a wide range of effects in vivo beyond its antitumor activity. ECRG4 overexpression affects apoptosis, senescence, cell migration, inflammation, injury, and infection responsiveness. ECRG4 activities also depend on its cellular localization, secretion, and post-translational processing. These cytokine/chemokine-like characteristics argue that ECRG4 is not a traditional candidate tumor suppressor gene, as originally predicted by its downregulation in cancer. We review how insights into the regulation of ECRG4 gene expression, knowledge of its primary structure, and the study of its emerging physiological functions come together to support a much more complex role for ECRG4 at the interface of inflammation, infection, and malignancy.

High mobility group box 1 release from cholangiocytes in patients with acute-on-chronic liver failure

High mobility group box chromosomal protein 1 (HMGB1) is an important proinflammatory molecule in a number of inflammatory disorders, but little is known about its role in acute-on-chronic liver failure (ACLF). To elucidate the role of HMGB1 in ACLF, the expression of HMGB1 in liver specimens from patients with ACLF was investigated. Immunohistochemical staining was performed to confirm the expression and subcellular localization of HMGB1 in liver specimens obtained from 13 patients with ACLF caused by hepatitis B virus (HBV) infection, 20 patients with chronic viral hepatitis B and 20 healthy controls. In addition, TFK-1 cells (human cholangiocarcinoma cell line) were stimulated with lipopolysaccharide (LPS) or tumor necrosis factor (TNF)-α. The extracellular level of HMGB1 in the culture medium was then determined by ELISA, and cell viability was also examined. In patients with ACLF caused by HBV infection, HMGB1 was found mainly in the cholangiocytes, and cytoplasmic translocation was observed in the cholangiocytes in the liver specimens. In the TFK-1 cell cultures, HMGB1 levels gradually increased from as early as 4 h after stimulation with LPS or TNF-α until the end of the stimulation. LPS and TNF-α actively induced the cytoplasmic translocation of the HMGB1 protein in TFK-1 cells. These data suggest that HMGB1 plays a critical role in the systemic inflammation associated with ACLF.

Expression of ECRG4 is associated with lower proliferative potential of esophageal cancer cells

We have shown that ECRG4 suppressed Fas-induced apoptosis in Jurkat cells. ECRG4 mRNA expression was ubiquitously detected in normal adult human tissues, suggesting that ECRG4 plays a major role in human tissues. ECRG4 mRNA expression was down-regulated in tumor cells. Expression of ECRG4 suppressed cell growth. We established an anti-ECRG4 monoclonal antibody. Our immunohistochemical analysis demonstrated that ECRG4-positive cells tended to be distributed in the region that was negative for Ki-67 in esophageal squamous cell carcinoma tissues. There was a significant inverse correlation between ECRG4 expression and Ki-67 labeling index in esophageal squamous cell carcinoma. This study provides the first functional evidence for an association of endogenous expression of ECRG4 with cell proliferation. ECRG4 is a candidate tumor suppressor gene that might be involved in the proliferation of esophageal squamous cell carcinoma.