Knockdown Of Astrocyte Elevated Gene-1 Research Articles

Astrocytic AEG-1 regulates expression of TREK-1 under acute hypoxia.

TREK-1 (TWIK-related K+ channel), a member of the two-pore domain K+ (K2P) channel family, is highly expressed in astrocytes, where it plays a key role in glutamate release and passive conductance. In addition, TREK-1 is induced to protect neurons under pathological conditions such as hypoxia. However, the upstream regulation of TREK-1 remains poorly understood. In this study, we found that AEG-1 (astrocyte elevated gene-1) regulates the expression of astrocytic TREK-1 under hypoxic conditions. Upregulation of AEG-1 increased expression of TREK-1 in astrocytes, and knockdown of AEG-1 dramatically decreased the mRNA and protein levels of TREK-1, which were restored by expression of shRNA-insensitive AEG-1. In addition, expression of TREK-1 was not regulated in the absence of AEG-1, even when HIF1α was present. Together, these results suggest that AEG-1 acts as a major upstream regulator of TREK-1 channels in astrocytes under hypoxia. SIGNIFICANCE OF THE STUDY: Previous studies have reported that hypoxia increases the expression of astrocytic TREK-1 and that increased TREK-1 expression protects neuronal cells from apoptosis. However, its cellular mechanism is not clear. In this study we first showed that AEG-1 is a major mediator of hypoxic-regulated TREK-1 expression in normal astrocytes independently of HIF-1α.

Lipopolysaccharide-induced expression of astrocyte elevated gene-1 promotes degeneration and inflammation of chondrocytes via activation of nuclear factor-κB signaling

Osteoarthritis is an inflammatory disease characterized by joint degeneration and inflammation. Astrocyte elevated gene-1 (AEG-1) has been suggested as a novel inflammation-related factor in the pathological processes of various inflammatory diseases. To date, little is known about the role of AEG-1 in osteoarthritis. The aim of the present study was to explore the potential role of AEG-1 in the regulation of lipopolysaccharide-induced apoptosis and inflammation of chondrocytes. The results showed that AEG-1 expression was significantly upregulated in chondrocytes following exposure to lipopolysaccharide. Knockdown of AEG-1 increased the survival and decreased the expression of matrix metalloproteinases in chondrocytes treated with lipopolysaccharide. Moreover, silencing of AEG-1 restricted the lipopolysaccharide-induced production of proinflammatory cytokines. In contrast, AEG-1 overexpression caused opposite effects. Notably, we found that AEG-1 inhibition blocked the lipopolysaccharide-induced activation of nuclear factor-κB signaling through impeding the nuclear translocation of nuclear factor-κB p65 subunit. Additionally, inhibition of nuclear factor-κB partially reversed the AEG-1-mediated promotion of lipopolysaccharide-induced inflammatory injury in chondrocytes. In conclusion, our results demonstrate that inhibition of AEG-1 expression attenuates lipopolysaccharide-induced degeneration and inflammation of chondrocytes through suppressing the activation of nuclear factor-κB signaling. This work therefore highlights a potential role of AEG-1 in the pathogenesis of osteoarthritis, and indicates its potential as a therapeutic target.

Astrocyte elevated gene-1 induces autophagy in diabetic cardiomyopathy through upregulation of KLF4.

Astrocyte elevated gene-1 (AEG-1), also known as metadherin, 3D3, and lysine-rich carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) coisolated, has emerged as an important oncogene that is overexpressed in a variety of cancers. Previous studies revealed that AEG-1 is also involved in multiple physiological and pathological processes, such as development, inflammation, neurodegeneration, migraine, and Huntington's disease. However, the function of AEG-1 in diabetic cardiomyopathy (DCM) has not been reported yet. Therefore, we conducted this study to characterize the potential role and mechanism of AEG-1 in DCM rats. DCM was induced by injections of streptozocin (STZ) in Wistar rats. Rats were randomized to be injected with lentivirus carrying AEG-1 small interfering RNA. Haemodynamic changes of Wistar rats, assessment of cardiac weight index, and the expression of AEG-1 and KLF4 were detected and compared among these three groups. The expressions of AEG-1 and KLF4 in the STZ group were significantly elevated in cardiac tissues compared with the control group. Knockdown of AEG-1 significantly increased the values of left ventricular ejection fraction, ±dp/dt max , repressed autophagy, as well as upregulated the expression of KLF4. Knockdown of AEG-1 suppresses autophagy in DCM by downregulating the expression of KLF4. This study provide first-notion evidence for the potential value of AEG-1 as a therapeutic target for the treatment of the patients with DCM.

Silencing of Astrocyte elevated gene-1 (AEG-1) inhibits proliferation, migration, and invasiveness, and promotes apoptosis in pancreatic cancer cells.

To investigate the role of Astrocyte elevated gene-1 (AEG-1) in the development and progress of pancreatic cancer, short hairpin RNA (shRNA) was inserted into the RNA interference vector to knock-down the endogenous AEG-1 in two pancreatic cancer cell lines: AsPC-1 and PANC-1. Our results showed that silencing of AEG-1 suppressed the proliferation, colony formation ability, and cell stemness of AsPC-1 and PANC-1 cells, and inhibited their G1-to-S phase transition. Results from apoptosis assay showed that knock-down of AEG-1 led to cell apoptosis. The expression of anti-apoptotic Bcl-2 was downregulated and that of the pro-apoptotic Bax and cleaved caspase-3 was upregulated in AEG-1-silenced pancreatic cancer cells. Further, the capability of AEG-1-silenced cells to migrate and to invade through the Matrigel-coated membrane was weaker, and the expression of matrix metallopeptidase 2 (MMP-2) and MMP-9 were decreased. Moreover, the AKT-β-catenin signaling pathway was inhibited in the cells with knock-down of AEG-1. In addition, the growth of xenograft tumors formed by AsPC-1 and PANC-1 cells was suppressed by AEG-1 shRNA. In conclusion, our study demonstrates that pancreatic cancer cells require AEG-1 to maintain their survival and metastasis, suggesting AEG-1 as a potential target for the treatment of pancreatic cancers.

Effects of lentivirus-mediated knockdown of astrocyte elevated gene-1 on the biological behavior of uveal melanoma

Objective To investigate the effects of lentivirus-mediated knockdown of astrocyte elevated gene-1 (AEG-1) on the biological behavior of uveal melanoma(UM). Methods MUM-2B and MUM-2C cell lines with different invasiveness and metastasis potential were cultured.Based on AEG-1 sequence that designed the effective (RNA interference) RNAi target sequence and the RNAi negative control scramble sequence, and then performed the preparation of the lentiviral vector and viral packaging.In these two kinds of cell lines, the cells infected by AEG-1-RNAi lentivirus were used as lentiviral infection group, the cells of the RNAi negative control of the blank lentivirus infected cells were used as negative control group, and the cells without any processing were used as normal control group.Real-time PCR and Western blot were used to detect the change of AEG-1 transcription and protein expression levels in these two kinds of cell lines' groups, as well as by MTT method, Annexin V-APC method, cell invasion assay, and Transwell cell migration assay that to investigate the effect of lentivirus transfection induced knockdown of AEG-1 on the biological behavior of human UM cell lines. Results The successful preparation of RNAi lentivirus vector and its viral package were transfected to MUM-2B, MUM-2C cell lines of logarithmic growth phase, respectively.The relative expressions of AEG-1 mRNA in normal control groups, negative control groups and lentiviral infection groups were statistically significant (F=130.02, P 0.05). Western blot showed that no significant changes were found in the AEG-1 proteins expression levels between normal control groups and negative control groups in the two kinds of cell lines (F=146.17, P<0.01; F=156.79, P<0.01). The expression levels of AEG-1 protein in the lentiviral infection groups were significantly lower than that in negative control groups (all at P<0.01). The proliferation of both cells lines in lentiviral infection groups were significantly lower than that in negative control groups from the second day to the fifth day, the differences were statistically significant (t=5.78, 30.68, 23.99, 29.40, all at P<0.01; t=7.88, 7.09, 5.56, 6.60, all at P<0.01). In both cell lines, the apoptosis rate of lentiviral infection groups were significantly higher than those in the negative control groups, the differences were statistically significant (t=54.34, P<0.01; t=11.68, P<0.01). In both cell lines, the multiple of invasions in lentiviral infection groups were significantly lower than those in negative control groups, and the differences were statistically significant (t=16.04, P<0.01; t=13.98, P<0.01); In both cell lines, the multiple of transfer in lentiviral infection groups were significantly lower than those in negative control groups, and the differences were statistically significant (t=12.04, P<0.01; t=22.43, P<0.01). Conclusions Lentivirus transfection inducing knockdown of AEG-1 inhibits the transcription and protein expression level of AEG-1 in the melanoma cells, which changes the biological behaviors of UM, like slowing down cell proliferation, promoting apoptosis, and reducing the abilities of cells' invasion and metastasis. Key words: Uveal melanoma; Astrocyte elevated gene-1; Lentiviral vector; Cell proliferation; Apoptosis; Invasion; Metastasis

Nanoscale polysaccharide derivative as an AEG-1 siRNA carrier for effective osteosarcoma therapy.

BackgroundNanomedicine, which is the application of nanotechnology in medicine to make medical diagnosis and treatment more accurate, has great potential for precision medicine. Despite some improvements in nanomedicine, the lack of efficient and low-toxic vectors remains a major obstacle.ObjectiveThe aim of this study was to prepare an efficient and low-toxic vector which could deliver astrocyte elevated gene-1 (AEG-1) small interfering RNA (siRNA; siAEG-1) into osteosarcoma cells effectively and silence the targeted gene both in vitro and in vivo.Materials and methodsWe prepared a novel polysaccharide derivative by click conjugation of azidized chitosan with propargyl focal point poly (L-lysine) dendrons (PLLD) and subsequent coupling with folic acid (FA; Cs-g-PLLD-FA). We confirmed the complexation of siAEG-1and Cs-g-PLLD or Cs-g-PLLD-FA by gel retardation assay. We examined the cell cytotoxicity, cell uptake, cell proliferation and invasion abilities of Cs-g-PLLD-FA/siAEG-1 in osteosarcoma cells. In osteosarcoma 143B cells tumor-bearing mice models, we established the therapeutic efficacy and safety of Cs-g-PLLD-FA/siAEG-1.ResultsCs-g-PLLD-FA could completely encapsulate siAEG-1 and showed low cytotoxicity in osteosarcoma cells and tumour-bearing mice. The Cs-g-PLLD-FA/siAEG-1 nanocomplexes were capable of transferring siAEG-1 into osteosarcoma cells efficiently, and the knockdown of AEG-1 resulted in the inhibition of tumour cell proliferation and invasion. In addition, caudal vein injecting of Cs-g-PLLD-FA/siAEG-1 complexes inhibited tumor growth and lung metastasis in tumor-bearing mice by silencing AEG-1 and regulating MMP-2/9.ConclusionIn summary, Cs-g-PLLD-FA nanoparticles are a promising system for the effective delivery of AEG-1 siRNA for treating osteosarcoma.

AEG-1 associates with metastasis in papillary thyroid cancer through upregulation of MMP2/9.

Astrocyte elevated gene-1 (AEG-1), known as an oncogene, is overexpressed in various cancers and implicated in tumor progression and metastasis. However, its functional significance and underlying molecular mechanisms in thyroid cancer remain to be elucidated. In the present study, we detected the potential function of AEG-1 in papillary thyroid cancer (PTC). We also investigated the relation between AEG-1 and matrix metalloproteases (MMP)2 and 9 through immunohistochemistry, western blotting, real-time PCR, immunofluorescence staining, zymography and co-immunoprecipitation (Co-IP). We found that overexpression of AEG-1 in PTC was positively correlated with lymph node metastasis and MMP2/9 expression. Knockdown of AEG-1 reduced the capacity of migration and invasion through downregulation of MMP2/9 in thyroid cancer cells. Furthermore, we firstly found that AEG-1 interacted with MMP9 in thyroid cancer cells. AEG-1 was associated with the activation of the nuclear factor κB (NF-κB) signaling pathways in thyroid cancer cells. Overall, our results for the first time showed that AEG-1 interacted with MMP9 in thyroid cancer cells and AEG-1 expression was closely associated with progression and metastasis of papillary thyroid cancer. AEG-1 might be a potential therapeutic target in papillary thyroid cancer.

Knockdown of astrocyte elevated gene-1 inhibited cell growth and induced apoptosis and suppressed invasion in ovarian cancer cells

Emerging evidence has demonstrated that AEG-1 (astrocyte elevated gene-1) plays a pivotal oncogenic role in tumorigenesis. However, the molecular mechanism by which AEG-1 exerts its oncogenic function is elusive in ovarian cancer. To explore the role and molecular insight on AEG-1-mediated tumorigenesis in ovarian cancer, multiple approaches are performed including MTT assay, flow cytometry for apoptosis and cell cycle assay, gene transfection, real-time RT-PCR, Western blotting, and Transwell assay. Our MTT assay showed that knockdown of AEG-1 by its siRNA significantly inhibited cell growth in ovarian cancer cells. Moreover, AEG-1 siRNA treatment induced G0/G1 cell cycle arrest and triggered cell apoptosis in ovarian cancer cells. Notably, inhibition of AEG-1 suppressed cell migration and invasion in ovarian cancer cells. Intriguingly, we identified that knockdown of AEG-1 remarkably inhibited the activation of Akt pathway. Our results also validated that knockdown of AEG-1 inhibited the expression of MMP-2 and VEGF, which could lead to inhibition of cell migration and invasion. These data suggest that AEG-1 could be a potential therapeutic target for the treatment of ovarian cancer.

Clinical significance and effect of AEG-1 on the proliferation, invasion, and migration of NSCLC: a study based on immunohistochemistry, TCGA, bioinformatics, in vitro and in vivo verification.

BackgroundAstrocyte elevated gene-1 (AEG-1) is related to the tumorigenesis and deterioration of different cancers, including non-small cell lung cancer (NSCLC). However, the effect of AEG-1 in NSCLC remains unclear. In this study, we aimed to investigate the clinical significance and effect of AEG-1 on biological function of NSCLC.ResultsAEG-1 was significantly overexpressed in NSCLC tissues and closely correlated to the deterioration of NSCLC based on tissue microarray, TCGA database and meta-analysis. After knock-down of AEG-1, the proliferation, migration and invasion of NSCLC cells were all inhibited, and the tumorigenic and angiogenic ability of NSCLC cells were weakened. Furthermore, the AEG-1 co-expressed genes were significantly related to AMPK signaling pathway based on bioinformatics approaches.Materials and MethodsA tissue microarray, the Cancer Genome Atlas (TCGA) database, as well as a meta-analysis were performed to analyze the relationship between AEG-1 and the clinicopathological parameters of NSCLC. Furthermore, immunocytochemistry, Western blot analysis, scratch assay, colony formation assay, Transwell migration and invasion assay and the chick embryo chorioallantoic membrane (CAM) model were conducted to explore the effect of AEG-1 on NSCLC in vitro and in vivo. Additionally, bioinformatics analyses were carried out to assess the potential pathways and networks of the co-expressed genes of AEG-1.ConclusionsAEG-1 is positively activated in the tumorigenesis and deterioration of NSCLC. We hypothesize that AEG-1 could play an important role in NSCLC via AMPK signaling pathway. Inhibiting the expression of AEG-1 is expected to become a novel method in the therapeutic strategies of NSCLC.

AEG-1 promotes mesenchymal transition through the activation of Rho GTPases in human glioblastoma cells.

Despite growing evidence indicating that astrocyte elevated gene-1(AEG-1) plays pivotal roles in tumor progression in various types of human cancers including brain tumors; to date, its role in the regulation of mesenchymal transition is not clear in glioblastoma. In the present study, we investigated the contribution of AEG-1 to stress fiber formation and then the acquisition of mesenchymal characteristics of glioblastoma cells. Gain- and loss-of-function studies in normal immortalized primary human fetal astrocytes(IM-PHFAs) and glioblastoma cells revealed that overexpression of AEG-1 increased expression of mesenchymal markers including N-cadherin and two mesenchymal transition‑inducing transcription factors ZEB1 and Slug but decreased epithelial markers E-cadherin and ZO-1. In addition, knockdown of AEG-1 suppressed invasive ability and migration of glioblastoma cells. Overexpression of AEG-1 also induced stress fiber formation and activated the Rho GTPase signaling pathways in glioblastoma cells. Consistently, treatment with an RhoA inhibitor decreased AEG-1-mediated stress fiber formation in glioblastoma cells. Collectively, our findings suggest that AEG-1 promotes mesenchymal transition in glioblastoma through the regulation of the Rho signaling pathway, resulting in tumor invasion, a primary characteristic of malignant brain tumors.

Abstract 2944: Expression of AEG-1 associated with c-Myc and PI3K activation in regulation of TS and chemoresistance of pemetrexed in non-small cell lung cancer

Abstract Purpose: Expression of astrocyte-elevated gene-1 (AEG-1), a novel oncoprotein, is elevated in multiple cancers. Thymidylate synthase (TS) is an important enzyme in purine synthesis and DNA replication. In this study, we investigated the AEG-1 expression characteristics in non-small cell lung cancer (NSCLC) to determine whether its expression is correlated with TS regulation of NSCLC. Materials and Methods: A549, H157, CL1-0, CL1-5, PC9, H1975, H520 and H292 human lung cancer cell-lines were cultured in medium with RPMI1640 + 10% FBS. Immunohistochemical stain and Western blot of AEG-1 and TS were studied in all cell-lines. The primary antibodies used were anti-AEG-1 (1:1,000; chicken polyclonal), anti-actin (1:1,000; rabbit polyclonal; Santa Cruz), and anti-TS (1:1,000; mouse monoclonal; Abcam). Total RNA was extracted using a Qiagen mRNA easy mini kit (Qiagen). Real-time PCR was performed using ABI 7900 fast real-time PCR system to detect expression of AEG-1 and TS. Cell viability was determined by standard MTS assays to recognize IC50 of Pemetrexed in lung cancer cell-lines. Transfection of siRNA for AEG-1 was carried out to knock down AEG-1. AEG-1 pcDNA (Life technologies, CA, USA) were used to quantitatively examine AEG-1 activity. Expressive change of AEG-1associated with TS and signaling pathways were analyzed by Western blot and PCR. Results: TS and AEG-1 in H157, Cl1-0, CL1-5, H520 and H292 were higher detected by IHC stain, Western blot and RT-PCR mRNA level. The expression of TS was positive correlated with AEG-1 in lung cancer cell-lines. The IC50 values of Pemetrexed for cells were lower in the lung cancer cell-lines with lower TS gene expression. After knockdown of AEG-1 by siRNA in Pemetrexed-resistance PC-9 and A549 cell-lines, the expression of TS decreased associated with decreasing change IC50 of Pemetrexed. In contrast, transfection with AEG-1 pcDNA in PC-9 and A549 cell-lines overexpressed AEG-1 gene, TS level also enhanced associated with increasing change IC50 of Pemetrexed. AEG-1 expression can also activate the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway that augments binding of c-Myc thereby regulating AEG-1 transcription. Conclusions: Our data indicated a significant correlation between TS and AEG-1 gene expression in NSCLC cell-lines. TS expression might be regulated by AEG-1 through activation of PI3K/AKT and c-Myc signaling pathways associated with development of chemoresistance to pemetrexed in NSCLC treatment Citation Format: Chung-Yu Chen, Ying-Yin Chen, Kuan-Yu Chen, Jin-Yuan Shih, Yih-Leong Change, Chong-Jen Yu, Pan-Chyr Yang. Expression of AEG-1 associated with c-Myc and PI3K activation in regulation of TS and chemoresistance of pemetrexed in non-small cell lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2944.

Lentivirus-Mediated Knockdown of Astrocyte Elevated Gene-1 Inhibits Growth and Induces Apoptosis through MAPK Pathways in Human Retinoblastoma Cells.

PurposeTo explore expression and function of astrocyte elevated gene-1 (AEG-1) in human retinoblastoma (RB).MethodsThe expression of AEG-1 in histological sections of human RBs and in RB cell lines was examined using immunohistochemical staining and RT-PCR and Western blotting respectively. We knocked down AEG-1 gene levels by AEG-1-siRNA lentivirus transfection of human RB cell lines SO-RB50 and Y79, and using an MTT assay, we assessed the role of AEG-1 on RB cell proliferation. The biological significance of lentivirus transfection induced AEG-1 down-regulation was examined by assessing the apoptosis rate in the transfected RB cells by Annexin V-APC staining and flow cytometry. We additionally measured the expression of Bcl-2, Bax, cleaved-caspase-3 and caspase-3, and the phosphorylation and non-phosphorylation alternation of MAPKs.ResultsAEG-1 expression was detected to be strongly positive in the histological slides of 35 out of 54 (65%) patients with RB. AEG-1 expression increased significantly (P<0.05) with tumor stage. In the RB cell lines SO-RB50, Y79 and WERI-RB1 as compared with retinal pigment epithelium cells, expression of AEG-1 mRNA and AEG-1 protein was significantly higher. In AEG-1-siRNA lentivirus transfected cell cultures as compared with negative control lentivirus transfected cell cultures, levels of AEG-1 mRNA and of AEG-1 protein (P<0.05) and cell growth rates (P<0.01) were significantly lower, and apoptosis rate (P<0.001), Bax/Bcl-2 ratio and cleaved-caspase-3 protein level were significantly increased. The P-ERK/ERK ratio was significantly decreased in the AEG-1-siRNA lentivirus transfected cell lines.ConclusionsExpression of AEG-1 was associated with RB, in histological slides of patients and in cell culture experiments. Lentivirus transfection induced knockdown of AEG-1 had a tumor suppressive effect, potentially by tumor cell apoptosis induction through inhibition of ERK.

Knockdown of Astrocyte Elevated Gene-1 Inhibits Activation of Hepatic Stellate Cells.

Astrocyte elevated gene-1 (AEG-1) is a positive regulator of tumorigenesis and a valuable prognostic marker of a diverse array of cancers, including liver cancer; however, the relationship between AEG-1 and hepatic fibrogenesis is not known. The objective of this study was to explore the expression of AEG-1 during hepatic fibrogenesis and determine how AEG-1 regulates the profibrogenic phenotype of hepatic stellate cells (HSCs). The levels of AEG-1 were monitored in the fibrotic livers and transforming growth factor-β (TGF-β)- or lipopolysaccharide (LPS)-stimulated HSCs. The expression of AEG-1 was knocked down by lentivirus-mediated short hairpin RNA in HSCs, and collagen expression, proliferation assays, apoptosis induction studies, and migration assays were simultaneously conducted in vitro. AEG-1 expression was increased in the fibrotic livers. At the cellular level, TGF-β or LPS stimulation, which caused HSC activation, induced AEG-1 expression in HSC-T6 and primary rat HSCs (P<0.05). Knockdown of AEG-1 inhibited collagen I and α-smooth muscle actin expression (P<0.05), reduced cell proliferation (P<0.05) and motility (P<0.05), and induced cell apoptosis (P<0.05) in HSCs. This antifibrotic effect caused by lack of AEG-1 was associated with the inactivation of PI3K/Akt and the mitogen-activated protein kinase pathway. Knockdown of AEG-1 suppressed the activation of HSCs by modulating the phenotype and inducing apoptosis. AEG-1 might be a potential target in treatment of hepatic fibrosis.

The key role of astrocyte elevated gene-1 in CCR6-induced EMT in cervical cancer.

In recent years, astrocyte elevated gene-1 (AEG-1) has been recommended as an important mediator that is involved in the epithelial-to-mesenchymal transition (EMT) process. However, the mechanisms underlying the chemokine (C-C motif) ligand 20 (CCL20)/chemokine (C-C motif) receptor 6 (CCR6)-AEG-1 pathway-mediated EMT in cervical cancer (CC) have not been well featured till now. We used immunohistochemistry and immunoblotting to assess the expression of AEG-1 in 94 cervical cancer tissues and cells. Subsequently, cervical cancer SiHa cells were treated with si-AEG-1 and then subjected to in vitro assays. We observed that AEG-1 proteins were highly expressed in cervical cancer tissues and closely correlated with International Federation of Gynecology and Obstetrics (FIGO) stage and metastasis. Importantly, we validated the expression of AEG-1, p-Erk1/2, p-Akt, vimentin, N-cadherin, and matrix metalloproteinase 2 (MMP2) increased in SiHa with CCL20 treatment in a concentration-dependent manner. When cells were treated with si-AEG-1, the expression of p-Erk1/2, p-Akt, vimentin, N-cadherin, and MMP2 was also downregulated. Using the cell cycle assay, the knockdown of AEG-1 inhibited the entry of G1 into S phase. In conclusion, AEG-1 mediates CCL20/CCR6-induced EMT development via both Erk1/2 and Akt signaling pathway in cervical cancer, which indicates that CCL20/CCR6-AEG-1-EMT pathway could be suggested as a useful target to affect the progression of cervical cancer.

Astrocyte elevated gene-1 regulates CCL3/CCR5-induced epithelial-to-mesenchymal transition via Erk1/2 and Akt signaling in cardiac myxoma.

In recent years, astrocyte elevated gene-1 (AEG-1) has been reported as a key mediator that is involved in the epithelial-to-mesenchymal transition (EMT) process. However, the mechanisms underlying CCL3/CCR5-AEG-1 pathway-mediated EMT in cardiac myxoma (CM) has not been well featured till now. We used immnohistochemistry and immunoblotting to assess the expression of CCR5 and AEG-1 in 30cases of CM tissues and cells. Subsequently, cultured CMcells were treated with si-AEG-1 or si-CCR5 and then subjected to invitro assays. We observed that CCR5 and AEG-1 proteins were highly expressed in CM tissues (73.3 and 76.7%, respectively) and closely correlated with tumor size (>5cm). Importantly, we validated the expression of AEG-1, p-Erk1/2, p-Akt, vimentin, N-cadherin and MMP2 increased in the CM cell with CCL3 treatment in a time-andconcentration-dependent manner. When CM cells were treated with si-CCR5, the expression of AEG-1, p-Erk1/2, p-Akt, vimentin, N-cadherin and MMP2 was downregulated. In addition, when CM cells were treated with si-AEG-1, the expression of p-Erk1/2, p-Akt, vimentin, N-cadherin and MMP2 was also downregulated. Using the cell cycle and proliferation assay, the knockdown of AEG-1 inhibited the entry of G1 into Sphase and the proliferation capacity of CMcells. In conclusion, AEG-1 mediates CCL3/CCR5-induced EMT development via both Erk1/2 and Akt signaling pathway in CM patients, which indicates CCL3/CCR5-AEG-1-EMT pathway could be suggested as a useful target to affect the progression of CM.

Astrocyte Elevated Gene-1 (AEG-1) Contributes to Non-thyroidal Illness Syndrome (NTIS) Associated with Hepatocellular Carcinoma (HCC)

Non-thyroidal illness syndrome (NTIS), characterized by low serum 3,5,3'-triiodothyronine (T3) with normal l-thyroxine (T4) levels, is associated with malignancy. Decreased activity of type I 5'-deiodinase (DIO1), which converts T4 to T3, contributes to NTIS. T3 binds to thyroid hormone receptor, which heterodimerizes with retinoid X receptor (RXR) and regulates transcription of target genes, such as DIO1. NF-κB activation by inflammatory cytokines inhibits DIO1 expression. The oncogene astrocyte elevated gene-1 (AEG-1) inhibits RXR-dependent transcription and activates NF-κB. Here, we interrogated the role of AEG-1 in NTIS in the context of hepatocellular carcinoma (HCC). T3-mediated gene regulation was analyzed in human HCC cells, with overexpression or knockdown of AEG-1, and primary hepatocytes from AEG-1 transgenic (Alb/AEG-1) and AEG-1 knock-out (AEG-1KO) mice. Serum T3 and T4 levels were checked in Alb/AEG-1 mice and human HCC patients. AEG-1 and DIO1 levels in human HCC samples were analyzed by immunohistochemistry. AEG-1 inhibited T3-mediated gene regulation in human HCC cells and mouse hepatocytes. AEG-1 overexpression repressed and AEG-1 knockdown induced DIO1 expression. An inverse correlation was observed between AEG-1 and DIO1 levels in human HCC patients. Low T3 with normal T4 was observed in the sera of HCC patients and Alb/AEG-1 mice. Inhibition of co-activator recruitment to RXR and activation of NF-κB were identified to play a role in AEG-1-mediated down-regulation of DIO1. AEG-1 thus might play a role in NTIS associated with HCC and other cancers.

Astrocyte elevated gene-1 promotes progression of cervical squamous cell carcinoma by inducing epithelial-mesenchymal transition via Wnt signaling.

The aim of this study was to investigate the association of astrocyte elevated gene-1 (AEG-1) with epithelial-mesenchymal transition of cervical squamous cell carcinoma (CSCC) and the underlying mechanisms. The expression of proteins was determined by immunohistochemistry in tissues. Overexpression and knockdown of AEG-1 in SiHa cells were achieved by stable AEG-1 gene transfection (SiHa-AEG-1+) and AEG-1-siRNA (SiHa-AEG-1-), respectively. The cellular levels of messenger RNA and proteins were assessed with reverse transcription polymerase chain reaction and Western blotting, respectively. The cell invasion capacity was assessed by the chamber invasion assay. AEG-1 was overexpressed in clinical CSCC and associated with lymph node metastasis, parametrial involvement, stromal invasion, and vascular invasion. A high level of vimentin and a low level of E-cadherin were also detected in the cancer tissues. AEG-1 expression was positively correlated with vimentin expression and negatively with E-cadherin expression in CSCC tissues. In addition, high level of AEG-1 was related to unfavorable prognosis of CSCC. On a cellular level, overexpression of AEG-1 was found to lead to an up-regulation of vimentin and a down-regulation of E-cadherin on messenger RNA and protein level in SiHa cells, whereas AEG-1 knockdown led to a contrary result. Meanwhile, the nuclear levels of NF-κB p65 and β-catenin were also increased in SiHa-AEG-1+, whereas their nuclear levels were decreased in SiHa-AEG-1-. Inhibition of Wnt signaling significantly reduced vimentin level and enhanced E-cadherin level in SiHa-AEG+, but inhibition of NF-κB signaling did not. SiHa-AEG-1+ and SiHa-AEG- showed an enhanced and a decreased invasive capacity, respectively. The enhanced invasiveness of SiHa-AEG-1+ was weakened by inhibition of Wnt signaling. AEG-1 was associated with the progression of CSCC by promoting epithelial-mesenchymal transition via Wnt signaling pathway.

RNA interference-mediated knockdown of astrocyte elevated gene-1 inhibits growth, induces apoptosis, and increases the chemosensitivity to 5-fluorouracil in renal cancer Caki-1 cells.

Astrocyte elevated gene-1 (AEG-1) is a recently discovered oncogene that has been reported to be highly expressed in various types of malignant tumors, including renal cell carcinoma. However, the precise role of AEG-1 in renal cancer cell proliferation and apoptosis has not been clarified. In this study, we transfected the renal cancer cell line Caki-1 with a plasmid expressing AEG-1 short hairpin RNA (shRNA) and obtained cell colonies with stable knockdown of AEG-1. We found that AEG-1 down-regulation inhibited cell proliferation and colony formation and arrested cell cycle progression at the sub-G1 and G0/G1 phase. Western blot analysis indicated that the expression of proliferating cell nuclear antigen (PCNA), cyclin D1 and cyclin E were significantly reduced following AEG-1 down-regulation. In addition, AEG-1 knockdown led to the appearance of apoptotic bodies in renal cancer cells, and the ratio of apoptotic cells significantly increased. Expression of the anti-apoptotic factor Bcl-2 was dramatically reduced, whereas the pro-apoptotic factors Bax, caspase-3 and poly (ADP-ribose) polymerase (PARP) were significantly activated. Finally, AEG-1 knockdown in Caki-1 cells remarkably suppressed cell proliferation and enhanced cell apoptosis in response to 5-fluorouracil (5-FU) treatment, suggesting that AEG-1 inhibition sensitizes Caki-1 cells to 5-FU. Taken together, our data suggest that AEG-1 plays an important role in renal cancer formation and development and may be a potential target for future gene therapy for renal cell carcinoma.

Expression of astrocyte elevated gene-1 (AEG-1) in human meningiomas and its roles in cell proliferation and survival.

Astrocyte elevated gene-1 (AEG-1) has recently been proposed to be involved in tumor development, invasion, and metastasis in several human cancers. However, the functional importance of AEG-1 expression in human meningioma has not been determined. We investigate the level of AEG-1 expression by quantitative reverse transcription PCR, immunohistochemistry analysis, and western blotting in various human meningioma tissues and cells. To determine the suppressive effect of AEG-1 on meningioma progression, we inhibited AEG-1 expression using small interfering RNA and examined cell proliferation, apoptosis, colony formation and tumorigenicity in a mouse xenograft model. AEG-1 expression was frequently elevated at both mRNA and protein levels in meningioma tumor tissues and in meningioma-derived cells as well. This elevation was more commonly observed in high-grade tumors than in benign ones. The knockdown of AEG-1 led to a decrease in overall cell proliferation, as well as anchorage-independent growth of malignant meningioma. In addition, apoptotic cell death occurred in AEG-1 depleted meningioma cells through p-Akt and Bcl-2 suppression. Furthermore, a mouse xenograft meningioma model showed that inhibition of AEG-1 expression significantly decreased tumor growth. Altogether, these data show that the elevation of AEG-1 contributes to the malignant progression of meningiomas, suggesting that AEG-1 could be a novel therapeutic target against human meningiomas.

Astrocyte elevated gene-1 activates MMP9 to increase invasiveness of colorectal cancer

The molecular mechanism underlying the invasiveness of colorectal cancer (CRC) cells remains largely unknown. Here, we found that astrocyte elevated gene-1 (AEG-1) was significantly upregulated in CRC tissues, compared with the adjacent normal tissues from human patients. Ectopic expression of AEG-1 enhanced the invasive ability of CRC cells, while small interfering RNA (siRNA)-induced knockdown of AEG-1 inhibited the invasive ability of CRC cells. Transcription, protein levels, and secretion of matrix metalloproteinase 9 (MMP9), all increased by AEG-1 overexpression in CRC cells, and all decreased by AEG-1 inhibition. Suppression of endogenous MMP9 abrogated the effects of AEG-1 on invasiveness, without affecting AEG-1 levels. Taken together, these findings suggest that AEG-1 contributes to CRC invasiveness and metastasis by enhancing MMP9 activity. Thus, AEG-1 appears to be a novel therapeutic target for preventing the metastasis of CRC.