Astrocyte Elevated Gene-1 Expression Research Articles

Circular RNA PVT1 Promotes Breast Cancer Progression via miR-30b-5p/AEG-1 Axis

Background: Circular RNA PVT1 (circPVT1) is involved in malignant tumorigenesis. However, the function of circPVT1 in breast cancer (BC) has not been investigated. The purpose of this research is to explore the mechanisms of circPVT1 in breast cancer from different perspectives. Methods: In this study, the expressions of circPVT1 and microRNA-30b-5p (miR-30b-5p) were analyzed by quantitative real-time polymerase chain reaction (q-PCR). The Kaplan-Meier was adopted to compare disease free survival (DFS) and overall survival (OS). CircPVT1 was depleted with special si-RNA, Cell Counting Kit-8 (CCK-8) to evaluate the cell viability and transwell assays to examine invasion ability. Astrocyte elevated gene 1 (AEG-1) protein level was measured by western blot. The competitive endogenous functions among circPVT1, miR-30b-5p and AEG-1 were verified by bioinformatics analysis and luciferase assay. Results: In this study, it was found that the circPVT1 was significantly elevated in BC tissues and cell lines compared to the control group. The Kaplan-Meier results indicated that higher circPVT1 expression had a worse prognosis than the low circPVT1 expression group in DFS (χ2 = 7.174, p = 0.007) and OS (χ2 = 3.946, p = 0.047). CircPVT1 regulated the BC cell viability, migration, and invasion ability. Besides, miR-30b-5p was found as a molecular target of circPVT1, and AEG-1 was identified as a target of miR-30b-5p. The suppression of circPVT1 promoted the expression of miR-30b-5p and inhibited AEG-1 expression. Moreover, simultaneous inhibition of miR-30b-5p expression in the circPVT1 knockout group could reverse the inhibition of AEG-1. Conclusions: Our results indicate circPVT1 regulates AEG-1 expression by binding to miR-30b-5p in breast cancer cells. CircPVT1 promoted AEG-1 expression by inhibiting miR-30b-5p in order to enhance the BC cell viability, migration, and invasion. Our results reveal a new molecular therapy target for breast cancer.

Interaction and binding mechanism of anticancer echinacoside phenylethanoid glycoside against hepatocellular carcinoma with subdomains of human serum albumin

A phenylethanoid glycoside known as echinacoside has demonstrated promising anticancer properties against numerous cancer cell types. However, its pharmacokinetics or anticancer mechanism has remained unclear. Herein, the interaction of the echinacoside with human serum albumin (HSA) was explored by intrinsic/extrinsic fluorescence spectroscopy, circular dichroism (CD) spectroscopy as well as molecular docking simulation. Also, the anticancer effects and possible mechanism of action of the echinacoside against hepatocellular carcinoma (HCC) cells, MHCC-97-H with high tumorgenicity and metastasis, were assessed by cell viability, flow cytometry, qRT-PCR, and western blot assays. The results showed a static quenching mechanism in the formation of echinacoside-HSA complex, one binding site on HSA for echinacoside, contribution of hydrophobic interactions (PHE157, GLU188 and PRO447), and slight conformational changes of HSA in the complex form. Cellular assays disclosed that treatment with echinacoside concentration-dependently mitigated the proliferation of MHCC97-H cells in vitro with an IC50 concentration of around 30 µM. Also, echinacoside triggered apoptosis through the regulation of caspase-3 at mRNA and protein levels. Moreover, echinacoside reduced the expression of astrocyte elevated gene-1 (AEG-1)and N-cadherin, while enhancing the expression of E-cadherin, as the main hallmarks of epithelial–mesenchymal transition (EMT) in tumorigenicity and metastasis. Therefore, these data indicated that echinacoside with a promising binding affinity with HSA in a mimicking physiological condition may inhibit the proliferation and metastatic activity of MHCC97-H cells mediated by manipulation of the AEG-1/EMT pathway.

Inhibition of Granule Cell Dispersion and Seizure Development by Astrocyte Elevated Gene-1 in a Mouse Model of Temporal Lobe Epilepsy.

Although granule cell dispersion (GCD) in the hippocampus is known to be an important feature associated with epileptic seizures in temporal lobe epilepsy (TLE), the endogenous molecules that regulate GCD are largely unknown. In the present study, we have examined whether there is any change in AEG-1 expression in the hippocampus of a kainic acid (KA)-induced mouse model of TLE. In addition, we have investigated whether the modulation of astrocyte elevated gene-1 (AEG-1) expression in the dentate gyrus (DG) by intracranial injection of adeno-associated virus 1 (AAV1) influences pathological phenotypes such as GCD formation and seizure susceptibility in a KA-treated mouse. We have identified that the protein expression of AEG-1 is upregulated in the DG of a KA-induced mouse model of TLE. We further demonstrated that AEG-1 upregulation by AAV1 delivery in the DG-induced anticonvulsant activities such as the delay of seizure onset and inhibition of spontaneous recurrent seizures (SRS) through GCD suppression in the mouse model of TLE, while the inhibition of AEG-1 expression increased susceptibility to seizures. The present observations suggest that AEG-1 is a potent regulator of GCD formation and seizure development associated with TLE, and the significant induction of AEG-1 in the DG may have therapeutic potential against epilepsy.

HIV-1 gp120 amplifies astrocyte elevated gene-1 activity to compromise the integrity of the outer blood-retinal barrier.

This study aims to investigate the functions and mechanistic pathways of Astrocyte Elevated Gene-1 (AEG-1) in the disruption of the blood-retinal barrier (BRB) caused by the HIV-1 envelope glycoprotein gp120. We utilized ARPE-19 cells challenged with gp120 as our model system. Several analytical techniques were employed to decipher the intricate interactions at play. These included PCR, Western blot, and immunofluorescence assays for the molecular characterization, and transendothelial electrical resistance (TEER) measurements to evaluate barrier integrity. We observed that AEG-1 expression was elevated, whereas the expression levels of tight junction proteins ZO-1, Occludin, and Claudin5 were downregulated in gp120-challenged cells. TEER measurements corroborated these findings, indicating barrier dysfunction. Additional mechanistic studies revealed that the activation of NFκB and MMP2/9 pathways mediated the AEG-1-induced barrier destabilization. Through the use of lentiviral vectors, we engineered cell lines with modulated AEG-1 expression levels. Silencing AEG-1 alleviated gp120-induced downregulation of tight junction proteins and barrier impairment while concurrently inhibiting the NFκB and MMP2/9 pathways. Conversely, overexpression of AEG-1 exacerbated these pathological changes, further compromising the integrity of the BRB. Gp120 upregulates the expression of AEG-1 and activates the NFκB and MMP2/9 pathways. This in turn leads to the downregulation of tight junction proteins, resulting in the disruption of barrier function.

Using the metabolite alterations monitoring the AEG-1 expression level and cell biological behaviour of U251 cell in vitro.

Astrocyte elevated gene-1 (AEG-1) is an important oncogene that overexpresses in gliomas and plays a vital role in their occurrence and progression. However, few reports have shown which biomarkers could reflect the level of AEG-1 expression in vivo so far. In recent years, intracellular metabolites monitored by proton magnetic resonance spectroscopy (1H MRS) as non-invasive imaging biomarkers have been applied to the precise diagnosis and therapy feedback of gliomas. Therefore, understanding the correlation between 1H MRS metabolites and AEG-1 gene expression in U251 cells may help to identify relevant biomarkers. This study constructed three monoclonal AEG-1-knockout U251 cell lines using the clustered regularly interspaced short palindromic repeat (CRISPR) /Cas9 technique and evaluated the biological behaviors and metabolite ratios of these cell lines. With the decline in AEG-1 expression, the apoptosis rate of the AEG-1-knockout cell lines increased. At the same time, the metastatic capacities decreased, and the relative contents of total choline (tCho) and lactate (Lac) were also reduced. In conclusion, deviations in AEG-1 expression influence the apoptosis rate and metastasis capacity of U251 cells, which the 1H MRS metabolite ratio could monitor. The tCho/creatinine(Cr) and Lac/Cr ratios positively correlated with the AEG-1 expression and malignant cell behavior. This study may provide potential biomarkers for accurate preoperative diagnosis and future AEG-1-targeting treatment evaluation of gliomas in vivo.

ELK3 Targeting AEG1 Promotes Migration and Invasion of Ovarian Cancer Cells under Hypoxia.

Ovarian cancer (OC) is one of the most common tumors in female reproductive organs with a five-year survival rate of less than 45%. Metastasis is a crucial contributor to OC development. ETS transcription factor (ELK3), as a transcriptional factor, have been involved in multiple tumor development. However, its role in OC remains elusive. In this study, we observed high expression of ELK3 and AEG1 in human OC tissues. OVCAR-3 and SKOV3 cells were treated with hypoxia to mimic tumor microenvironment in vivo. We found that the expression of ELK3 was significantly increased in cells under hypoxia compared with normoxia. ELK3 knockdown inhibited cell migration and invasion abilities under hypoxia. Moreover, ELK3 knockdown decreased β-catenin expression and inhibited the activation of Wnt/β-catenin pathway in SKOV3 cells under hypoxia. Astrocyte-elevated gene-1 (AEG1) has been reported to promote OC progression. Our results showed that the mRNA level of AEG1 was decreased when ELK3 knockdown under hypoxia. Dural luciferase assay confirmed that ELK3 bound to gene AEG1 promoter (-2005-+15) and enhanced its transcriptional activity under hypoxia. Overexpression of AEG1 increased the migration and invasion abilities of SKOV3 cell with ELK3 knockdown. In the absence of ELK3, the activation of β-catenin was recovered by AEG1 overexpression. To sum up, we conclude that ELK3 promotes AEG1 expression by binding to its promoter. ELK3 could promote migration and invasion of OC cells by targeting AEG1, which provides a potential basis for therapeutic approaches to OC.

Transcriptome analysis in an AEG‑1‑deficient neuronal HT22 cell line.

Astrocyte elevated gene-1 (AEG-1) is a key regulatory factor of progression in multiple types of tumor and neurodegenerative disease development. AEG-1 is associated with glutamate excitotoxicity due to its reported function of repressing excitatory amino acid transporter 2 expression in astrocytes. Although the function of AEG-1 has been demonstrated in neurological disorders, such as Alzheimer's disease and amyotrophic lateral sclerosis, the underlying mechanism of neuronal AEG-1 function remains unclear. The aim of the present study was to clarify the function and related mechanism of AEG-1 in neurons. A stable AEG-1-deficient HT22 neuronal cell line was constructed using CRISPR/Cas9 gene-editing technology. Reverse transcription-quantitative PCR and western blotting were carried out to analyze the knockdown efficiency of AEG-1-deficient HT22 cell line. RNA Sanger sequencing analysis was performed in AEG-1-deficient HT22 cells and wild-type HT22 cells without knockout (KO). Results from RNA sequencing revealed that AEG-1 modulated neuronal morphology and development by regulating the expression of numerous genes, such as ubiquitin C, C-X-C motif chemokine ligand 1, MMP9, Notch1, neuropilin 1 and ephrin type-A receptor 4. In addition, AEG-1 deficiency impacted several signaling pathways by mediating cell survival differentiation, apoptosis, and migration; this included the TNF-α pathway, the NF-κB pathway, the MAPK signaling pathway, the Notch signaling pathway and Axon guidance. Downregulation in cellular ion homeostasis, including ion channel function and neurotransmitter release, were observed after knocking out AEG-1 expression. Collectively, the present study provides insights into AEG-1-dependent gene regulation and signaling pathway transduction in neurons. The results of the present study may be applied for improving the understanding of AEG-1-associated central nervous system diseases.

The Role of Astrocyte Elevated Gene-1 (AEG-1), a Novel Multifunctional Protein, in Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a prominent dose-limiting side effect of chemotherapy treatment, often resulting in the discontinuation of treatment for cancer patients. Taxanes, such as Paclitaxel, are a class of chemotherapeutics associated with high prevalence of CIPN development in patients. Taxanes are known to activate peripheral macrophages, generating a neurotoxic inflammatory response that contributes to the development and maintenance of neuropathy. Astrocyte Elevated Gene-1 (AEG-1) is a multifunctional protein that operates in a variety of intracellular signaling pathways. It has been shown to regulate macrophage activation and mediate cellular inflammation through direct interaction with NFκB, a transcriptional regulator of proinflammatory cytokine (PIC) expression. Our goal is to investigate if AEG-1 contributes to the development and maintenance of Paclitaxel-Induced Peripheral Neuropathy (PIPN) and associated neuroinflammation in dorsal root ganglia (DRG). Twelve- to 24-week old AEG-1 global knockout (KO) and wildtype (WT) male and female mice on C57BL/6J background were used in a model of CIPN produced by administration of four 8 mg/kg, i.p. injections of paclitaxel. Mechanical hypersensitivity and cold sensitivity were assessed via Von Frey filaments and acetone test, respectively. mRNA expression was quantified via qRT-PCR. Plasma level concentrations of paclitaxel were assessed via mass spectrometry. AEG-1 KO mice displayed protection from paclitaxel-induced mechanical hypersensitivity and cold sensitivity, unlike their WT counterparts. Paclitaxel increased the expression of AEG-1 and multiple PIC (TNFα, IL1-β, IL-6) in the DRGs of male WT mice. However, these cytokine levels were unchanged in paclitaxel treated AEG-1 KO male mice. Plasma concentration levels of paclitaxel did not differ between AEG-1 KO or WT mice at any time following drug administration. Our data suggest that AEG-1 plays a significant role in the development and maintenance of paclitaxel-induced mechanical and cold hypersensitivity. And that the expression of AEG-1 mediates paclitaxel-induced neuroinflammation in the DRGs. Grant support from 1R01CA221260-01.

Downregulation of Astrocyte Elevated Gene-1 Expression Combined with All-Trans Retinoic Acid Inhibits Development of Vasculogenic Mimicry and Angiogenesis in Glioma.

This study aimed to investigate the effects of downregulating astrocyte elevated gene-1 (AEG-1) expression combined with all-trans retinoic acid (ATRA) on vasculogenic mimicry (VM) formation and angiogenesis in glioma. U87 glioma cells were transfected with AEG-1 shRNA lentiviral vectors (U87-siAEG-1) and incubated in a medium containing 20 µmol/L ATRA. Matrigel-based tube formation assay was performed to evaluate VM formation, and the cell counting kit-8 (CCK-8) assay was used to analyze the proliferation of glioma cells in vitro. Reverse transcription-quantitative polymerase chain reaction and Western blot analysis were used to investigate the mRNA and protein expression of related genes, respectively. Glioma xenograft models were generated via subcutaneous implantation of glioma cells in nude mice. Tumor-bearing mice received an intraperitoneal injection of ATRA (10 mg/kg per day). Immunohistochemistry was used to evaluate the expression of related genes and the microvessel density (MVD) in glioma xenograft models. CD34/periodic acid-Schiff double staining was performed to detect VM channels in vivo. The volume and weight of tumors were measured, and a tumor growth curve was drawn to evaluate tumor growth. A combination of ATRA intervention and downregulation of AEG-1 expression significantly inhibited the proliferation of glioma cells in vitro and glioma VM formation in vitro and in vivo. It also significantly decreased MVD and inhibited tumor growth. Further, the expression levels of matrix metalloproteinase (MMP)-2, MMP-9, vascular endothelial-cadherin (VE-cadherin), and vascular endothelial growth factor (VEGF) in glioma significantly decreased in vivo and in vivo. Hence, a combinatorial approach might be effective in treating glioma through regulating MMP-2, MMP-9, VEGF, and VE-cadherin expression.

Circulating mRNA Expression of Astrocyte-Elevated Gene-1 Associated with Treatment Response and Survival in Non-Small Cell Lung Cancer Patients Treated with Pemetrexed

Background: Astrocyte-elevated gene-1 (AEG-1) functions as an oncogene and regulates angiogenesis in non-small cell lung cancer (NSCLC). In this prospective study, we assessed the values of plasma AEG-1 mRNA expression by liquid biopsy associated with tumour response and survival in NSCLC patients treated with pemetrexed. Methods: Patients diagnosed with advanced NSCLC were enrolled to be treated with pemetrexed combined with platinum as first-line chemotherapy. All patients underwent blood sampling before any cancer treatment (C0) and at first response evaluation after two cycles (C2) of treatments. Response to chemotherapy and survival were assessed. Plasma mRNA was extracted from peripheral blood mononuclear cell (PBMC) and quantification of RNA was performed by real-time PCR. Results: A total of 50 patients with advanced NSCLC were included and 13 of 50 patients combined with bevacizumab. In patient groups of stable disease (SD) (n = 13) and progressive disease (PD) (n = 10), the plasma mRNA of AEG-1, thymidylate synthase (TS), and CK19 were elevated significantly at C2 compared to patients in treatment response group (PR, n = 27) (PR vs. SD or PD, AEG-1: 1.22 ± 0.80 vs. 4.51 ± 15.45, p = 0.043). NSCLC patients who had elevated AEG-1 (AEG-1 ≥ 2) after two cycles of chemotherapy had shorter PFS and OS (high AEG-1 vs. low AEG-1, median, PFS: 5.5 vs. 11.9 months, p = 0.021; OS: 25.9 vs. 40.8 months, p = 0.019, respectively). In a Cox regression analysis, increased plasma mRNA expression of AEG-1indicated poor prognosis in survival. Conclusions: Circulating mRNA concentration of AEG-1 could be a predictive and prognostic biomarker in NSCLC patients treated with pemetrexed. Increased expression of AEG-1 contributed to the chemoresistance and caused lung cancer progression.

Expression of astrocyte-elevated gene-1 indicates prognostic value of fluoropyrimidine-based adjuvant chemotherapy in resectable stage III colorectal cancer.

It is unclear which prognostic factor such as pathological features and gene mutation are majorly relevant for stage III disease and whether they aid in determining patients who will be benefit from postoperative adjuvant chemotherapy. The expression of astrocyte-elevated gene-1 (AEG-1), thymidylate synthase (TS), excision repair cross-complementation group 1 (ERCC1), epidermal growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF) was examined to investigate their role in adjuvant chemotherapy for patients with resectable stage III colorectal cancer (CRC). A significant positive correlation was observed between AEG-1, TS, ERCC1, EGFR, and VEGF gene expression levels in CRC cell lines, and low AEG-1 and TS expression were highly sensitive to 5-fluorouracil treatment. Our results showed that AEG-1 expression was high in T4 and caused CRC recurrence or metastasis. Patients with T4, high AEG-1, TS and VEGF expression had a significantly short disease-free survival and overall survival. In multivariate Cox regression analysis, high AEG-1 expression could be an independent prognostic factor indicating poor survival in patients with resectable stage III CRC treated with adjuvant chemotherapy. In conclusion, AEG-1 expression and tumor grade are potential prognostic factors for recurrence and survival in patients with stage III CRC receiving adjuvant fluoropyrimidine-based chemotherapy.

AEG-1 silencing attenuates M2-polarization of glioma-associated microglia/macrophages and sensitizes glioma cells to temozolomide

Glioma is the most frequent primary malignancy in the brain; temozolomide (TMZ) is the first-line chemotherapeutic agent used to combat this tumor. We showed here that astrocyte elevated gene-1 (AEG-1) was overexpressed in glioma tissues and associated with a worse subtype and a poor prognosis. CCK-8 proliferation assays and clone formation experiments presented that AEG-1 knockdown sensitizes glioma cells to TMZ. The γH2AX foci formation assays indicated that AEG-1 silencing promotes TMZ-induced DNA damage in glioma cells. Glioma-associated microglia/macrophages (GAMs), the largest subpopulation infiltrating glioma, play important roles in the tumor microenvironment. Bioinformatics analyses and functional studies demonstrated that AEG-1 silencing decreased M2-polarization of HMC3 microglia and the secretion of tumor supportive cytokines IL-6 and TGF-β1. The expression of AEG-1 was positively associated with M2 markers in glioma tissues varified by IHC staining. Based on the results of Affymetrix microarray and GSEA analyses, Western blot and Co-Immunoprecipitation assays were conducted to show that AEG-1 activates Wnt/β-catenin signaling by directly interacting with GSK-3β. The co-localization of AEG-1 and GSK-3β in the cytoplasm of glioma cells was detected through immunofluorescence staining. This study raises the possibility that targeting AEG-1 might improve the efficiency of chemotherapy and reduce immunosuppressive M2 GAMs in glioma.

Emerging Role and Clinicopathological Significance of AEG-1 in Different Cancer Types: A Concise Review.

Tumor breakthrough is driven by genetic or epigenetic variations which assist in initiation, migration, invasion and metastasis of tumors. Astrocyte elevated gene-1 (AEG-1) protein has risen recently as the crucial factor in malignancies and plays a potential role in diverse complex oncogenic signaling cascades. AEG-1 has multiple roles in tumor growth and development and is found to be involved in various signaling pathways of: (i) Ha-ras and PI3K/AKT; (ii) the NF-κB; (iii) the ERK or mitogen-activated protein kinase and Wnt or β-catenin and (iv) the Aurora-A kinase. Recent studies have confirmed that in all the hallmarks of cancers, AEG-1 plays a key functionality including progression, transformation, sustained angiogenesis, evading apoptosis, and invasion and metastasis. Clinical studies have supported that AEG-1 is actively intricated in tumor growth and progression which includes esophageal squamous cell, gastric, colorectal, hepatocellular, gallbladder, breast, prostate and non-small cell lung cancers, as well as renal cell carcinomas, melanoma, glioma, neuroblastoma and osteosarcoma. Existing studies have reported that AEG-1 expression has been induced by Ha-ras through intrication of PI3K/AKT signaling. Conversely, AEG-1 also activates PI3K/AKT pathway and modulates the defined subset of downstream target proteins via crosstalk between the PI3K/AKT/mTOR and Hedgehog signaling cascade which further plays a crucial role in metastasis. Thus, AEG-1 may be employed as a biomarker to discern the patients of those who are likely to get aid from AEG-1-targeted medication. AEG-1 may play as an effective target to repress tumor development, occlude metastasis, and magnify the effectiveness of treatments. In this review, we focus on the molecular mechanism of AEG-1 in the process of carcinogenesis and its involvement in regulation of crosstalk between the PI3K/AKT/mTOR and Hedgehog signaling. We also highlight the multifaceted functions, expression, clinicopathological significance and molecular inhibitors of AEG-1 in various cancer types.

Identification of Nucleolin as a Novel AEG-1-Interacting Protein in Breast Cancer via Interactome Profiling.

Simple SummaryBreast cancer is one of the most common cancers affecting women today. Astrocyte Elevated Gene-1 (AEG-1) is elevated in breast cancer patients and is associated with metastasis and poor prognosis. However, the mechanisms by which AEG-1 promotes breast cancer are not fully understood. This report focuses on a novel AEG-1 interacting protein, nucleolin (NCL), which we identified via mass spectrometry-based interactome profiling. We found NCL to be important for the oncogenic function of AEG-1 in breast cancer. Further, c-Met was identified as a novel mediator of the oncogenic function of the AEG-1-NCL complex. Collectively, our study suggests that targeting the AEG-1-NCL protein complex could be an effective therapeutic approach for the treatment of some breast cancers.Breast cancer is one of the most common malignant diseases worldwide. Astrocyte elevated gene-1 (AEG-1) is upregulated in breast cancer and regulates breast cancer cell proliferation and invasion. However, the molecular mechanisms by which AEG-1 promotes breast cancer have yet to be fully elucidated. In order to delineate the function of AEG-1 in breast cancer development, we mapped the AEG-1 interactome via affinity purification followed by LC-MS/MS. We identified nucleolin (NCL) as a novel AEG-1 interacting protein, and co-immunoprecipitation experiments validated the interaction between AEG-1 and NCL in breast cancer cells. The silencing of NCL markedly reduced not only migration/invasion, but also the proliferation induced by the ectopic expression of AEG-1. Further, we found that the ectopic expression of AEG-1 induced the tyrosine phosphorylation of c-Met, and NCL knockdown markedly reduced this AEG-1 mediated phosphorylation. Taken together, our report identifies NCL as a novel mediator of the oncogenic function of AEG-1, and suggests that c-Met could be associated with the oncogenic function of the AEG-1-NCL complex in the context of breast cancer.

In silico analysis and prediction of transcription factors of the proteins interacting with astrocyte elevated gene-1

Multifunctional in nature, the protein Astrocyte Elevated Gene-1 (AEG-1) controls several cancers through protein-protein interactions. Although, specific physiological processes and molecular functions linked with AEG-1 interactors remain unclear. In our present study, we procured the data of AEG-1 interacting proteins and evaluated their biological functions, associated pathways, and interaction networks using bioinformatic tools. A total of 112 proteins experimentally detected to interact with AEG-1 were collected from various public databases. DAVID 6.8 Online tool was utilized to identify the molecular functions, biological processes, cellular components that aid in understanding the physiological function of AEG-1 and its interactors in several cell types. With the help of integrated network analysis of AEG-1 interactors using Cytoscape 3.8.0 software, cross-talk between various proteins, and associated pathways were revealed. Additionally, the Enrichr online tool was used for performing enrichment of transcription factors of AEG-1 interactors’ which further revealed a closely associated self-regulated interaction network of a variety of transcription factors that shape the expression of AEG-1 interacting proteins. As a whole, the study calls for better understanding and elucidation of the pathways and biological roles of both AEG-1 and its interactor proteins that might enable their application as biomarkers and therapeutic targets in various diseases in the very near future.

Astrocyte elevated gene-1 (AEG-1): A key driver of hepatocellular carcinoma (HCC).

An array of human cancers, including hepatocellular carcinoma (HCC), overexpress the oncogene Astrocyte elevated gene-1 (AEG-1). It is now firmly established that AEG-1 is a key driver of carcinogenesis, and enhanced expression of AEG-1 is a marker of poor prognosis in cancer patients. In-depth studies have revealed that AEG-1 positively regulates different hallmarks of HCC progression including growth and proliferation, angiogenesis, invasion, migration, metastasis and resistance to therapeutic intervention. By interacting with a plethora of proteins as well as mRNAs, AEG-1 regulates gene expression at transcriptional, post-transcriptional, and translational levels, and modulates numerous pro-tumorigenic and tumor-suppressive signal transduction pathways. Even though extensive research over the last two decades using various in vitro and in vivo models has established the pivotal role of AEG-1 in HCC, effective targeting of AEG-1 as a therapeutic intervention for HCC is yet to be achieved in the clinic. Targeted delivery of AEG-1 small interfering ribonucleic acid (siRNA) has demonstrated desired therapeutic effects in mouse models of HCC. Peptidomimetic inhibitors based on protein-protein interaction studies has also been developed recently. Continuous unraveling of novel mechanisms in the regulation of HCC by AEG-1 will generate valuable knowledge facilitating development of specific AEG-1 inhibitory strategies. The present review describes the current status of AEG-1 in HCC gleaned from patient-focused and bench-top studies as well as transgenic and knockout mouse models. We also address the challenges that need to be overcome and discuss future perspectives on this exciting molecule to transform it from bench to bedside.

Downregulation of astrocyte elevated gene-1 expression inhibits the development of vasculogenic mimicry in gliomas.

Vasculogenic mimicry (VM) contributes to the resistance of anti-angiogenic therapies in glioma. Certain genes, including MMP-2 and VEGF may be associated with the development of VM. Astrocyte elevated gene-1 (AEG-1) is considered to be an oncogene that promotes autophagy, invasion, metastasis, angiogenesis and drug resistance; however, the association between AEG-1 and VM formation is still unknown. The present study investigated the effects of AEG-1 downregulation on VM formation in the U87 glioma cell line in vitro and in xenograft models of glioma, and the potential underlying mechanisms of action. In the present study, U87 glioma cells were infected with the AEG-1 short hairpin RNA lentivirus. A Matrigel-based tube formation assay was performed to evaluate VM formation in vitro. Reverse transcription-quantitative PCR and western blot analysis were conducted to investigate the mRNA and protein expression levels of MMP-2 and VEGF. Glioma xenograft models were generated through the intracerebral implantation of U87 glioma cells into nude rats; CD34/Periodic Acid-Schiff double-staining was performed to detect VM channels in vivo. Following AEG-1 downregulation in U87 cells, the development of VM was significantly decreased in vitro and in vivo. In addition, the expression levels of MMP-2 and VEGF in glioma cells were decreased compared with the control group. These results suggested that downregulation of AEG-1 expression could significantly inhibit the development of VM in gliomas, both in vitro and in vivo, and may be partially related to the regulation of VEGF and MMP-2 expression.

Astrocyte elevated gene-1 serves as a target of miR542 to promote glioblastoma proliferation and invasion.

Background:Epithelial to mesenchymal transition (EMT) is strongly linked with tumor invasion and metastasis, which performs a vital role in carcinogenesis and cancer progression. Emerging evidence suggests that microRNAs (miRNAs) expression are closely associated to EMT by regulating targeted genes. MiR542 has been found to be involved in the EMT program and bound up with various cancers. However, the functions of miR542 and its underlying mechanism in glioblastoma multiforme (GBM) remain largely unknown. In the current study, we investigated the effect of astrocyte elevated gene-1 (AEG-1) on U251 cells aggressiveness, proliferation, apoptosis, and cell cycle.Methods:The screening of targeted miRNAs was performed, as well as the functional roles and mechanisms of miR542 were explored.Results:MiR542 was selected as the target because of the most significantly differential expression and this high level of expression negatively correlated with cell migration and proliferation, which suggested that miR542 could be a novel tumor suppressor. Moreover, we confirmed that AEG-1 was a direct targeted gene of miR542 by luciferase activity assay, reverse transcription-polymerase chain reaction, and immunoblotting analysis. Furthermore, miR542 suppressed the expression of AEG-1, which upgraded the level of E-cadherin and degraded Vimentin expression contributing to retraining EMT.Conclusion:The in vitro findings demonstrated that miR542 inhibited the migration and proliferation of U251 cells and suppressed EMT through targeting AEG-1, indicating that miR542 may be a potential anti-cancer target for GBM.

Abstract 353: Expression of astrocyte-elevated gene-1 is associated with prognostic value of adjuvant chemotherapy in resectable stage III colorectal cancer

Abstract Background: Administration of postoperative adjuvant chemotherapy has reduced the risk of tumor recurrence and improved survival for patients with resected colorectal cancer (CRC). Regarding the prognostic factors, including pathologic features and gene mutation have major relevance for stage III disease, it is not well known whether they might help select patients who would fare favorably when received adjuvant chemotherapy. OBJECTIVE: Expression of astrocyte-elevated gene-1 (AEG-1), thymidylate synthase (TS), excision repair cross-complementation group 1 (ERCC1), epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF) were needed to investigate the role involved in adjuvant combination therapy for patients with resectable stage III colon cancer. Methods: AEG-1, TS, ERCC1, EGFR and VEGF were investigated by CRC cell lines and intra-tumor immunohistochemistry stain. Furthermore, this study collected 29 patients with stage III colorectal cancer who underwent surgical resection from 2011 to 2016 and received postoperative adjuvant chemotherapy. The culmination of clinical data registration included surgical procedures, tumor size, number of lymph node metastases, and types of chemotherapy drugs. Result: A significant positive correlation between AEG-1, TS, ERCC1, EGFR, and VEGF gene expression levels were revealed in CRC cell lines. Cell lines with lower AEG-1 and TS expression had higher sensitivity to 5-FU treatment. In clinical studies, we found that higher AEG-1 expression was noted in T4 and also caused CRC recurrence or metastasis. Patients with T4 and stage IIIC CRC had a significantly shorter DFS (T4 v.s. T1-3, DFS, months, median: 4.1 ± 1.2 v.s. non-reach [NR], p < 0.001; IIIC v.s. IIIA or IIIB, DFS, months, median: 10.6 ± 5.3 v.s. NR, p = 0.037; respectively). Patients with higher AEG-1 and TS expression had a shorter DFS (AEG-1, high v.s. low, months, median: 12.8 ± 2.4 v.s. NR, p = 0.003; TS, high v.s. low, months, median: 13.8 ± 2.3 v.s. NR, p = 0.012; respectively). In multivariate Cox Regression analysis, advanced tumor invasion (T4) and high AEG-1 expression could be an independent prognostic factor to cause poor survival in resectable stage III CRC patients treated with adjuvant chemotherapy. Conclusion: Expressions of AEG-1 and tumor grade as a candidate prognostic factor of recurrence in stage III colorectal cancer patients receiving adjuvant fluoropyrimidine-based chemotherapy. A prospective cohort study should be guaranteed to validate these factors to be predictive markers of adjuvant chemotherapy benefit for stage III CRC. Citation Format: Chung-Yu Chen, Peng-Sheng Lai, Ying-Yin Chen, Long-Wei Lin. Expression of astrocyte-elevated gene-1 is associated with prognostic value of adjuvant chemotherapy in resectable stage III colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 353.

AEG-1 promotes angiogenesis and may be a novel treatment target for tongue squamous cell carcinoma.

The study explored the potential function of astrocyte elevated gene-1 (AEG-1) on angiogenesis in tongue squamous cell carcinoma (TSCC) in TSCC cell lines. The different degrees of angiogenesis were detected in TSCC cell lines expressing different levels of AEG-1 by chick chorioallantoic membrane (CAM) experimental model. Next, we established xenografts of different TSCC cell lines with different expression levels of AEG-1 in nude mice and conducted immunohistochemistry to evaluate the expression of the angiogenesis-associated factor, that is, vascular endothelial growth receptor factor 2 (VEGFR-2) and microvessel density (MVD). Vascular endothelial growth factor (VEGF) was detected by ELISA. CAM assay showed that the number of vessels was significantly reduced in AEG-1-down um1 cell line (p<.05), whereas the number was significantly increased in AEG-1-over um2 cell line (p<.05). Moreover, up-regulated AEG-1 expression level was associated with higher tumor angiogenesis, which was reflected by augmented expression levels of VEGF (p<.01), VEGFR-2 (p<.05), and MVD counting (p<.01). This study demonstrated that AEG-1 can promote tumor angiogenesis in TSCC and inhibition of tumor angiogenesis by repressing the expression of AEG-1 may be a novel potential treatment approach for TSCC.