Astrocyte Elevated Gene-1 Expression Level Research Articles

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.

Expression patterns of AEG-1 in the normal brain.

Astrocyte elevated gene-1 (AEG-1) is a well-known oncogene implicated in various types of human cancers, including brain tumors. Recently, AEG-1 has also been reported to play pivotal roles in glioma-associated neurodegeneration and neurodegenerative diseases like Parkinson's disease and amyotrophic lateral sclerosis. However, the normal physiological functions and expression patterns of AEG-1 in the brain are not well understood. In this study, we investigated the expression patterns of AEG-1 in the normal mouse brain and found that AEG-1 is widely expressed in neurons and neuronal precursor cells, but little in glial cells. We observed differential expression levels of AEG-1 in various brain regions, and its expression was mainly localized in the cell body of neurons rather than the nucleus. Additionally, AEG-1 was expressed in the cytoplasm of Purkinje cells in both the mouse and human cerebellum, suggesting its potential role in this brain region. These findings suggest that AEG-1 may have important functions in normal brain physiology and warrant further investigation. Our results may also shed light on the differential expression patterns of AEG-1 in normal and pathological brains, providing insights into its roles in various neurological disorders.

Overexpression of microRNA-124-5p sensitizes non-small cell lung cancer cells to treatment with 5-fluorouracil via AEG-1 regulation.

Chemotherapeutic resistance represents a major obstacle for the treatment of patients with non-small cell lung cancer (NSCLC); however, the associated molecular mechanisms underpinning the development of resistance remain poorly characterized. In the current study, 5-fluorouracil (5-FU)-resistant A549 cells (A549/5-FU) were generated from A549 cells. Reverse transcription-quantitative PCR and western blotting were used to detect microRNA(miR)-124-5p and astrocyte elevated gene 1 (AEG-1) expression levels in cells and tumor tissues. In addition, the cytotoxic effect of 5-FU on the cells was determined using the Cell Counting Kit-8 assay, and the Dual-luciferase reporter assay was used to validate AEG-1 as a target gene of miR-124-5p. Transfection with a miR-124-5p mimic enhanced inhibition of cell viability induced by 5-FU in A549/5-FU cells, whereas miR-124-5p inhibitor transfection partially reversed 5-FU-induced cell viability inhibition in A549 and H1299 cells. A decrease in miR-124-5p expression level was observed in A549/5-FU cells compared with the parental A549 cells. Furthermore, AEG-1 was predicted as a target gene of miR-124-5p, and its expression was increased in A549/5-FU cells compared with A549 cells. Additionally, the upregulation of miR-124-5p was associated with lower expression levels of AEG-1 in A549/5-FU cells, compared with parental A549 cells. Moreover, the Dual-luciferase reporter assay confirmed the ability of miR-124-5p to bind directly to the 3'-untranslated region of AEG-1 mRNA. Notably, the overexpression of AEG-1 reversed the ability of the miR-124-5p mimic to increase the sensitivity of A549/5-FU cells to 5-FU treatment. Additionally, a significant negative correlation between miR-124-5p expression and AEG-1 mRNA levels was detected in 40 pairs of NSCLC tissues and their corresponding adjacent paracancerous tissues. The results of the present study indicated that miR-124-5p may regulate the chemotherapeutic sensitivity of NSCLC cells, and may therefore represent a promising biomarker or therapeutic target for patients with NSCLC.

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.

Astrocyte-elevated gene-1 confers resistance to pemetrexed in non-small cell lung cancer by upregulating thymidylate synthase expression.

Previous studies have suggested that astrocyte-elevated gene-1 (AEG-1) contributes to the mechanisms of resistance to various chemotherapeutics. In this study, we investigated whether AEG-1 expression level correlated with that of thymidylate synthase (TS), as higher TS expression is known to be associated with the resistance to pemetrexed chemotherapy in patients with advanced lung adenocarcinoma. Using pemetrexed-resistant lung adenocarcinoma PC-9 cell line, we demonstrated that transfection of AEG-1 siRNA lowered TS expression and decreased pemetrexed IC50 value. In contrast, overexpression of AEG-1 was associated with increased expression of TS and higher pemetrexed IC50 value. Immunohistochemical staining of clinical biopsy samples showed that patients with lower AEG-1 expression had longer overall survival time. Moreover, analysis of repeated biopsy samples revealed that an increase in the TS level from baseline to disease progression was significantly associated with the elevation of AEG-1 expression. In conclusion, our data demonstrated that TS expression might be regulated by AEG-1 and that increased expression of these proteins contributes to lung cancer disease progression and may be associated with the development of resistance to pemetrexed.

Astrocyte Elevated Gene 1 Interacts with Acetyltransferase p300 and c-Jun To Promote Tumor Aggressiveness.

Astrocyte elevated gene 1 (AEG-1) is an oncoprotein that strongly promotes the development and progression of cancers. However, the detailed underlying mechanisms through which AEG-1 enhances tumor development and progression remain to be determined. In this study, we identified c-Jun and p300 to be novel interacting partners of AEG-1 in gliomas. AEG-1 promoted c-Jun transcriptional activity by interacting with the c-Jun/p300 complex and inducing c-Jun acetylation. Furthermore, the AEG-1/c-Jun/p300 complex was found to bind the promoter of c-Jun downstream targeted genes, consequently establishing an acetylated chromatin state that favors transcriptional activation. Importantly, AEG-1/p300-mediated c-Jun acetylation resulted in the development of a more aggressive malignant phenotype in gliomas through a drastic increase in glioma cell proliferation and angiogenesis in vitro and in vivo Consistently, the AEG-1 expression levels in clinical glioma specimens correlated with the status of c-Jun activation. Taken together, our results suggest that AEG-1 mediates a novel epigenetic mechanism that enhances c-Jun transcriptional activity to induce glioma progression and that AEG-1 might be a novel, potential target for the treatment of gliomas.

High BIM mRNA levels are associated with longer survival in advanced gastric cancer

Chemotherapy drugs, including 5-fluorouracil (5-FU), oxaliplatin and docetaxel, are commonly used in the treatment of gastric cancer (GC). Apoptosis-relevant genes may be associated with drug resistance. In the present study, the messenger RNA (mRNA) expression levels of B-cell lymphoma 2 interacting mediator of cell death (BIM), astrocyte elevated gene-1 (AEG-1) and AXL receptor tyrosine kinase (AXL) were investigated in 131 advanced GC samples, and the expression levels of these genes were correlated with patients' overall survival (OS). All 131 patients received first-line FOLFOX combination chemotherapy with folinic acid and 5-FU, in which 56 patients were further treated with second-line docetaxel-based chemotherapy. A correlation between the mRNA expression levels of BIM and AEG-1 was observed (rs=0.30; P=0.002). There was no association between the mRNA expression levels of any of the individual genes analyzed and OS in patients only receiving first-line FOLFOX chemotherapy. In a subgroup of patients receiving docetaxel-based second-line chemotherapy, those with high or intermediate levels of BIM exhibited a median OS of 18.2 months [95% confidence interval (CI), 12.8-23.6], compared with 9.6 months (95% CI, 8.9-10.3) in patients with low BIM levels (P=0.008). However, there was no correlation between the mRNA expression levels of AEG-1 or AXL and OS. The risk of mortality was higher in patients with low BIM mRNA levels than in those with high or intermediate BIM mRNA levels (hazard ratio, 2.61; 95% CI, 1.21-5.62; P=0.010). Therefore, BIM may be considered as a biomarker to identify whether patients could benefit from docetaxel-based second-line chemotherapy in GC.

MicroRNA-1297 inhibits prostate cancer cell proliferation and invasion by targeting the AEG-1/Wnt signaling pathway

MicroRNAs (miRNAs) have been known to be implicated in tumorigenic programs. miR-1297 has been reported to be dysregulated and involved in cancer progression in many types of human cancers. However, the expression level and the role of miR-1297 in prostate cancer remain unclear. Herein, we aimed to investigate the potential role and molecular mechanism of miR-1297 in prostate cancer progression. We found that miR-1297 was significantly downregulated in human prostate cancer specimens as well as in several prostate cancer cell lines. In addition, functional experiments demonstrated that overexpression of miR-1297 remarkably inhibited prostate cancer cell proliferation and invasion whereas miR-1297 suppression significantly promoted prostate cancer cell proliferation and invasion. Bioinformatics analysis showed that the Astrocyte elevated gene-1 (AEG-1), a well-known oncogene, is a predicted target of miR-1297. Dual-luciferase reporter assay showed that miR-1297 was able to directly target the 3’-untranslated region of AEG-1. In addition, RT-qPCR and Western blot analysis showed that miR-1297 regulated the mRNA and protein expression levels of AEG-1. We also showed that miR-1297 was able to regulate the Wnt signaling pathway. Moreover, rescue assays indicated that AEG-1 contributed to miR-1297-endowed effects on cell proliferation and invasion as well as Wnt signaling pathway. Taken together, these findings suggest that miR-1297 inhibits prostate cancer proliferation and invasion by targeting AEG-1, thereby providing novel insight into understanding the pathogenesis of prostate cancer. Thus, miR-1297 may be a novel potential therapeutic candidate to treat prostate cancer.

High expression of astrocyte elevated gene-1 (AEG-1) is associated with progression of cervical intraepithelial neoplasia and unfavorable prognosis in cervical cancer

BackgroundAstrocyte elevated gene-1(AEG-1) plays an important role in the development and progression of certain types of human cancers. However, the expression dynamics of AEG-1 in cervical cancer and its clinical/prognostic significance are unclear.MethodIn present study, the methods of tissue microarrays (TMA) and immunohistochemistry (IHC) were utilized to investigate AEG-1 expression in cervical intraepithelial neoplasia (CIN) and cervical cancer. Receiver operating characteristic (ROC) curve analysis, χ2 test, Kaplan-Meier plots, and multivariate Cox regression analysis were used to analyze the data.ResultsThe expression level of AEG-1 was increased from CIN I to CIN III. High expression of AEG-1 could be observed in 61.1% (55/90) of cervical cancer. Moreover, high expression of AEG-1 correlated with tumor size and lymph node metastasis (all P <0.05). More importantly, high expression of AEG-1 was closely associated with cervical cancer patient shortened survival time as evidenced by univariate and multivariate analysis (P <0.05).ConclusionsOur data suggest for the first time that high expression of AEG-1 is associated significantly with progression of cervical cancer. AEG-1 overexpression, as examined by IHC, has the potential to be used as an immunomarker to predict prognosis of cervical cancer patients.

Astrocyte elevated gene-1 is a novel biomarker of epithelial–mesenchymal transition and progression of hepatocellular carcinoma in two China regions

Astrocyte elevated gene-1 (AEG-1) is involved in important biological processes including cell invasion, metastasis, and carcinogenesis. However, its clinical significance has remained largely unknown in hepatocellular carcinoma. Here, specimens from 144 patients with hepatocellular carcinomas in Beijing and Heilongjiang regions were investigated by immunohistochemical staining for AEG-1, vimentin, and E-cadherin expressions. A clinicopathological study revealed that AEG-1 expression level in tumor cells was significantly correlated with TNM stage (P = 0.001) and Edmonson grade (P < 0.0001). In addition, AEG-1, vimentin, and E-cadherin (epithelial-mesenchymal transition (EMT) biomarker) expressions were correlated with each other. These findings suggest that AEG-1 may be an epithelial-mesenchymal transition-associated biomarker in human hepatocellular carcinoma and play important roles in the progression of hepatocellular carcinoma. In addition, the AEG-1 gene is a potential target for elimination of hepatocellular carcinoma in the future.

Ursolic acid inhibits epithelial–mesenchymal transition by suppressing the expression of astrocyte-elevated gene-1 in human nonsmall cell lung cancer A549 cells

Lung cancer is one of the most death-related cancers worldwide. Ursolic acid (UA), a pentacyclic triterpene acid, has a wide range of anticancer functions such as proapoptosis, antiangiogenesis, and antimetastasis. This study was carried out to explore the inhibition mechanism of UA on metastasis of lung cancer A549 cells. First, we found that UA inhibited the metastasis of lung cancer cells in a concentration-dependent manner through an adhesion assay, a cell wound healing assay, and a transwell migration assay in vitro. In addition, after treatment with UA, the A549 cells showed decreased expression of astrocyte-elevated gene-1 (AEG-1) accompanied by upregulation of E-cadherin and downregulation of N-cadherin and vimentin, which have been reported to characterize the epithelial-mesenchymal transition (EMT). Further results also confirmed that the expression of vimentin was decreased by the siRNA technique to directly knock down AEG-1 expression, indicating that AEG-1 was involved in UA-mediated EMT inhibition. Furthermore, our results showed that UA suppressed the expression level of AEG-1 by repressing nuclear factor-κB signaling. Altogether, UA inhibited the EMT by suppressing the expression of AEG-1, correlating with inhibition of nuclear factor-κB in A549 cells. These findings suggested that UA was a potent anti-lung cancer agent, and it may be able to prevent invasion and metastasis of lung cancer cells.

Abstract 5437: Astrocyte Elevated Gene-1 (AEG-1) interacts with retinoid X receptor (RXR) and abrogates its function.

Abstract The oncogene Astrocyte Elevated Gene-1 (AEG-1), also known as Metadherin (MTDH), is overexpressed in a diverse array of cancers, including hepatocellular carcinoma (HCC), and plays an important role in promoting tumor development and progression. Protein-protein interaction predominantly mediates the tumor promoting effects of AEG-1. We now describe screening of a human liver cDNA library by yeast two hybrid assay resulting in identification of Retinoid X Receptor (RXR) as an AEG-1-interacting protein. Site-directed mutagenesis assays identified an LXXLL motif in the N-terminus of AEG-1 mediating interaction with RXR. We employed human HCC cell lines stably overexpressing AEG-1 or with knockdown of AEG-1 and mouse hepatocytes isolated from a transgenic mouse with hepatocyte-specific expression of AEG-1 (Alb/AEG-1) and from AEG-1 knockout (AEG-1 KO) mouse for our studies. Luciferase reporter assays in these cells demonstrate that AEG-1 profoundly inhibits RXR-mediated transcriptional regulation of its heterodimer partner, such as Retinoic Acid Receptor (RAR), Thyroid Hormone Receptor (TR), Liver X Receptor (LXR) and Peroxisome Proliferator-Activated Receptor (PPAR), in the presence or absence of their corresponding ligands. In this study, we focus on retinoic acid (RA) and thyroid hormone (T3) function. AEG-1 markedly inhibits expression of RA- and T3-induced genes. Overexpressed AEG-1 in cancer cells and in transgenic hepatocytes accumulates in the cytoplasm and inhibits RXR function by trapping RXR in the cytoplasm precluding its nuclear translocation. Additionally, AEG-1 induces phosphorylation of RXR, via ERK and p38 MAPK pathways. Phosphorylated RXR has low transcriptional activity, functions as dominant negative inhibitor of RXR and might facilitate hepatocarcinogenesis by AEG-1. Indeed, chromatin immunoprecipitation (ChIP) assay using RA-target genes, RARB and HOXA1, shows decreased DNA binding of RXR, even upon ligand-treatment. Overexpression of AEG-1 significantly protects human HCC cells, mouse hepatocytes and human promyelocytic leukemia cells from the killing effects of retinoic acid and its synthetic analogs. By inhibiting the expression of T3-regulated gene type I deiodinase (DIO1), AEG-1 abrogates peripheral conversion of inactive T4 to active T3 which is reflected by significantly low T3 level in the circulation of Alb/AEG-1 mice compared to WT mice. Since AEG-1 is upregulated in a wide-variety of cancers it might play an important role in regulating a diverse array of RXR-dependent signaling pathways that are critical for regulating the oncogenic process. Synthetic retinoids are being evaluated as chemopreventive agents for HCC as well as a therapeutic modality for PML. AEG-1 expression level might determine the sensitivity of the patients to these retinoids. Additionally AEG-1 might play a key role in ‘low T3 syndrome’ associated with cancer. Citation Format: Jyoti Srivastava, Chadia L. Robertson, Rachel Gredler, Ayesha Siddiq, Devaraja Rajasekaran, Prasanna K. Santhekadur, Paul B. Fisher, Devanand Sarkar. Astrocyte Elevated Gene-1 (AEG-1) interacts with retinoid X receptor (RXR) and abrogates its function. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5437. doi:10.1158/1538-7445.AM2013-5437

Expression and clinical significance of astrocyte elevated gene-1 and vascular endothelial growth factor in cholangiocarcinoma

Objective To investigate the expression and clinical significance of astrocyte elevated gene-1 (AEG-1) and vascular endothelial growth factor (VEGF) in cholangiocarcinoma.Methods The expression levels of AEG-1 and VEGF in bile duct neoplasms were detected by using immunohistochemistry,including 112 cases of malignant tumors and 29 cases of benign tissues.Results The positive expression rate of AEG-1 and VEGF was respectively 71.4％ and 70.5％ in malignant tumors,higher than 0％ in benign tissues (P ＜0.01).The positive expression rate of AEG-1 was positively associated with histological classification (well-differentiated 45.5％,moderately differentiated 64.9％,and poorly differentiated 86.8％),clinical stage (stage Ⅰ-Ⅱ 61.8％,stage Ⅲ-Ⅳ a 91.7％) and lymph node metastasis (positive lymph node metastasis 61.8％,and negative lymph node metastasis 91.7％) (P ＜ 0.05),but not with ages and pathologic types (P ＞ 0.05).Conclusion Overexpression of AEG-1 and VEGF in cholangiocarcinoma suggests poor prognosis.They can be used as detection indexes to evaluate prognosis. Key words: Cholangiocarcinoma; Astrocyte elevated gene-1; Vascular endothelial growth factor

AEG-1 is associated with clinical outcome in neuroblastoma patients

Astrocyte elevated gene 1 (AEG-1), a novel gene that was cloned in 2002, has emerged in recent years as a potentially crucial mediator of tumor malignancy and aberrant elevation of AEG-1 expression frequently occurs in several human cancers, including breast cancer, prostate cancer, gastric cancer. However, whether AEG-1 deregulation also occurs in neuroblastoma remains unclear. In previous study we reported that AEG-1 was over expressed in neuroblastoma cell lines and knockdown of AEG-1 inhibits proliferation and enhancing chemo-sensitivity to cisplatin or doxorubicin in neuroblastoma cells. In this study, we investigated the expression of AEG-1 and evaluate its prognostic significance by correlating AEG-1 expression levels with clinic pathologic features and survival in 32 archived neuroblastoma patients We found that positive AEG-1 immunoreactivities were present in all neuroblastoma cases, 75% showed high expression of AEG-1. And high expression of AEG-1 was commonly seen in vascular endothelial cells and glandula in neuroblastoma samples. AEG-1 expression was strongly correlated with age at diagnosis (P=0.012), clinical stage (P=0.030) and tumor histology stage (P=0.041). However, our analyses did not show significant associations between AEG-1 expression and other clinical features including gender and primary tumor site. Importantly, our data presented in this report provide, for the first time, evidence that elevated expression of AEG-1 protein is correlated with poor prognosis and reduced survival of patients with neuroblastoma (P= 0.031). Overall, the data support the notion that AEG-1 might be used as a biomarker for neuroblastoma patients.

Astrocyte elevated gene‐1 interacts with β‐catenin and increases migration and invasion of colorectal carcinoma

To investigate the astrocyte elevated gene-1 (AEG-1) expression and its relationship with the clinicopathological features of colorectal carcinoma (CRC) and β-catenin signaling pathway. Real-time PCR, Western blot, immunohistochemistry, and immunofluorescence staining were performed to detect AEG-1 expression in CRC cell lines, 8 pairs of fresh CRC and adjacent nontumor tissues (ANT), 120 pairs of paraffin-embedded CRC specimens and ANT tissues, and 60 samples of lymph node metastatic CRC tissues. Scratch wound assay and transwell matrix penetration assay were performed to determine migration and invasion of SW480 cell lines with stable AEG-1 overexpression or SW620 cell lines with AEG-1 knockdown. AEG-1 expression was upregulated in CRC cell lines and tissues compared with ANT. Furthermore, AEG-1 expression level significantly correlated with UICC stage, and the N classification. AEG-1 overexpression significantly enhanced migration and invasion of SW480 cell lines. However, AEG-1 knockdown suppressed migration and invasion of SW620 cell lines. Meanwhile, there was a positive correlation between AEG-1 high expression and β-catenin nuclear expression in CRC. AEG-1 overexpression increased nuclear β-catenin accumulation in CRC cell lines. AEG-1 knockdown decreased nuclear β-catenin accumulation in CRC cell lines. Moreover, we firstly found that AEG-1 interacted with β-catenin in SW480 cell lines. Our results for the first time showed that AEG-1 interacted with β-catenin in CRC cells and AEG-1 expression was closely associated with progression of CRC. AEG-1 might be a potential therapeutic target in CRC.

Elevated expression of astrocyte elevated gene‐1 (AEG‐1) is correlated with cisplatin‐based chemoresistance and shortened outcome in patients with stages III–IV serous ovarian carcinoma

To correlate astrocyte elevated gene-1 (AEG-1) expression with the clinicopathological features and outcome of patients with stages III-IV ovarian serous carcinoma, and to clinically assess the involvement of AEG-1 in acquired cisplatin resistance. The frequency and intensity of immunohistochemical AEG-1 expression increased in a step-wise fashion from normal to chemosensitive to chemoresistant tissues. These observations were confirmed by Western blot analysis. AEG-1 expression level was correlated with lymph nodal metastasis, histological differentiation, residual tumour size and response to primary chemotherapy. Five-year progression-free survival (PFS) and overall survival (OS) rates were lower in the high-expression group than that in the low-expression group. AEG-1 overexpression was an independent but poor prognostic factor in the OS and PFS of these patients, as determined by multivariate Cox regression analysis. Multivariate logistic regression analysis revealed that the presence of cisplatin-based chemoresistance was significantly associated with expression level of AEG-1 and the degree of residual disease (P = 0.0001 and P = 0.0027, respectively). Our findings indicate that tumour AEG-1 overexpression is associated with poor prognosis and cisplatin resistance in advanced serous ovarian cancer.

Expression of Astrocyte Elevated Gene-1

To assess the expression of astrocyte elevated gene-1 (AEG-1) in different endometrial specimens and to investigate its relationship with clinicopathological features and its impact on patient outcome. By Western blot analysis, we investigated AEG-1 expression in paired endometrial tissues and adjacent nontumor tissues of the same patients (n = 4). Immunohistochemistry analysis was used to determine the expression levels of AEG-1 protein in 35 normal endometrium, 40 atypical endometrial hyperplasia, and 174 endometrial cancers. The correlation between AEG-1 expression and various clinicopathological characteristics of endometrial cancer patients was analyzed. Western blot analysis showed that AEG-1 expression levels were up-regulated in all 4 human primary endometrial cancer tissues compared with their matched adjacent noncancerous tissues. The frequent and strong expression of AEG-1 was gradually elevated in normal endometrial tissue, atypical hyperplasia, and endometrial cancers (P < 0.001). Although AEG-1 staining mainly emerged in the cytoplasm, a nuclear distribution was observed in both invasive and advanced endometrial cancer cells. The Ki67 (a proliferation marker) was frequently expressed in the high AEG-1-expressed area, whereas areas with low AEG-1 levels showed weak Ki67 expression. Astrocyte elevated gene-1 overexpression was positively correlated with the International Federation of Gynecology and Obstetrics stage, depth of myometrial invasion, lymph node metastasis, lymph vascular space invasion, and recurrence but not with age or histological type. Patients with high AEG-1 expression had significantly poor overall survival and disease-free survival compared with patients with AEG-1 low expression (both P < 0.001). Multivariate Cox proportional hazards regression demonstrated that high AEG-1 expression was an independent prognostic factor for both the overall survival and disease-free survival of patients with endometrial cancer (P = 0.002 and P = 0.004, respectively). Astrocyte elevated gene-1 overexpression may be associated with carcinogenesis and tumor progression in endometrial cancer. Moreover, it may be a new prognostic marker or a target for improving the treatment efficiency of patients with endometrial cancer.

Prognostic significance of AEG-1 expression in colorectal carcinoma

Astrocyte elevated gene-1 (AEG-1), as an HIV-1 or TNF-alpha-inducible transcript, is associated with various aspects of tumor malignancy. However, relatively little knowledge is available related to the role of AEG-1 in colorectal carcinoma. By immunohistochemical and western blot analysis, we investigated AEG-1 expression in normal mucosa, adenomas, and carcinomas of colorectum. By statistical analysis, we determined its relationship with clinicopathological parameters and overall survival in colorectal carcinoma. We found that AEG-1 expression levels were gradually elevated in normal tissues, low-grade adenoma, high-grade adenoma, and colorectal carcinoma, respectively. Though AEG-1 staining mainly emerged in the cytoplasm, we observed that nuclear staining of AEG-1 tends to become more common in lesions from patients with more advanced disease stages. Furthermore, there was a similar trend for Ki67 expression (as a proliferative index) from normal mucous to adenoma and carcinoma. Statistical analysis revealed that AEG-1 expression was markedly correlated with the UICC stage (P < 0.001), T classification (P = 0.002), N classification (P = 0.015), M classification (P = 0.010), Ki67 expression (P = 0.012), and histological differentiation (P = 0.037) in the colorectal cancer patients. Besides, those patients with high AEG-1 levels had shorter survival time (P < 0.001). High AEG-1 expression correlates with poor overall survival in the colorectal carcinoma patients. In addition, AEG-1 expression in colorectal carcinoma may be associated with tumor progression, indicating that AEG-1 may be a potential preventive and chemotherapeutic target in the patients.

Astrocyte Elevated Gene-1 Upregulates Matrix Metalloproteinase-9 and Induces Human Glioma Invasion

The poor prognosis of malignant gliomas is largely attributed to their highly invasive nature. The molecular mechanism underlying the invasiveness of glioma cells, however, remains to be elucidated. The present study found that astrocyte elevated gene-1 (AEG-1) was upregulated in human glioma cell lines and glioma tissues compared with normal astrocytes and brain tissues. AEG-1 was found to be upregulated in 265 of 296 (89.5%) glioma sections, and the AEG-1 expression level significantly correlated with clinicopathologic stages of gliomas. Ectopic expression or short hairpin RNA silencing of AEG-1 significantly enhanced or inhibited, respectively, the invasive ability of glioma cells. At the molecular level, we showed that upregulated AEG-1 in glioma cells interacted with matrix metalloproteinase-9 (MMP-9) promoter and transactivated MMP-9 expression, whereas knockdown of AEG-1 expression reduced the level of MMP-9. Two regions in MMP-9 promoter were found to be involved in the interaction with AEG-1. Suppression of endogenous MMP-9 abrogated the effects of AEG-1 on invasiveness. Consistent with these observations, immunostaining analysis revealed a significant correlation between the expressions of AEG-1 and MMP-9 in a cohort of clinical glioma samples. Moreover, intracranial xenografts of glioma cells engineered to express AEG-1 were highly invasive compared with the parental cells and expressed high level of MMP-9. Collectively, these findings provide evidence that AEG-1 contributes to glioma progression by enhancing MMP-9 transcription and, hence, tumor cell invasiveness, and underscore the importance of AEG-1 in glioma development and progression.