Astrocyte-elevated gene-1 overexpression is associated with poor prognosis in gastric cancer

AEG-1 expression is an independent prognostic factor in rectal cancer patients with preoperative radiotherapy: a study in a Swedish clinical trial

Background:

Preoperative radiotherapy (RT) is widely used to downstage rectal tumours, but the rate of recurrence varies significantly. Therefore, new biomarkers are needed for better treatment and prognosis. It has been shown that astrocyte elevated gene-1 (AEG-1) is a key mediator of migration, invasion, and treatment resistance. Our aim was to analyse the AEG-1 expression in relation to RT in rectal cancer patients and to test its radiosensitising properties.

Methods:

The AEG-1 expression was examined by immunohistochemistry in 158 patients from the Swedish clinical trial of RT. Furthermore, we inhibited the AEG-1 expression by siRNA in five colon cancer cell lines and measured the survival after irradiation by colony-forming assay.

Results:

The AEG-1 expression was increased in the primary tumours compared with the normal mucosa independently of the RT (P<0.01). High AEG-1 expression in the primary tumour of the patients treated with RT correlated independently with higher risk of distant recurrence (P=0.009) and worse disease-free survival (P=0.007). Downregulation of AEG-1 revealed a decreased survival after radiation in radioresistant colon cancer cell lines.

Conclusions:

The AEG-1 expression was independently related to distant recurrence and disease-free survival in rectal cancer patients with RT and could therefore be a marker to discriminate patients for distant relapse.

Metadherin, p50, and p65 expression in epithelial ovarian neoplasms: an immunohistochemical study

NF-κB signaling promotes cancer progression in a large number of malignancies. Metadherin, a coactivator of the NF-κB transcription complex, was recently identified to regulate different signaling pathways that are closely related to cancer. We assessed the immunohistochemical expression of p50, p65, and metadherin in 30 ovarian carcinomas, 15 borderline ovarian tumours, and 31 benign ovarian cystadenomas. Ovarian carcinomas exhibited significantly higher expression of all 3 markers compared to benign ovarian tumours. Borderline ovarian tumours demonstrated significantly higher expression for all 3 markers compared to benign cystadenomas. Ovarian carcinomas demonstrated significantly higher expression of p50 and metadherin compared to borderline ovarian tumours, whereas no significant difference was noted in p65 expression between ovarian carcinomas and borderline ovarian tumours. There was a strong correlation with the expression levels of p50, p65, and metadherin, whereas no correlation was observed with either grade or stage. Strong p50, p65, and metadherin expression was associated with a high probability to distinguish ovarian carcinomas over borderline and benign ovarian tumours, as well as borderline ovarian tumours over benign ovarian neoplasms. A gradual increase in the expression of these molecules is noted when moving across the spectrum of ovarian carcinogenesis, from borderline ovarian tumours to epithelial carcinomas.

AEG-1 is associated with tumor progression in nonmuscle-invasive bladder cancer

Astrocyte elevated gene-1 (AEG-1), a novel oncoprotein, has been implicated in oncogenesis and cancer progression in various types of human cancers. Here, immunohistochemistry was used to detect AEG-1 expression in nonmuscle-invasive bladder cancer (NMIBC), and these data were examined for correlation with clinicopathological parameters, and prognosis. Immunohistochemical analysis revealed that AEG-1 expression was significantly higher in bladder cancer tissues than that in normal tissues. High expression of AEG-1 was found in 45 % of bladder cancers and significantly associated with tumor grade (P = 0.002) and progression (P = 0.028). The Kaplan-Meier survival analysis demonstrated that AEG-1 expression was significantly associated with shorter progression-free survival (P = 0.0011). Multivariate analysis further demonstrated that AEG-1 was an independent prognostic factor for patients with BC. AEG-1 protein may contribute to the malignant progression of bladder cancer, and present as a novel marker to predict the progression of NMIBC.

Non-coding RNAs and gastric cancer

Non-coding RNAs (ncRNAs) play key roles in development, proliferation, differentiation and apoptosis. Altered ncRNA expression is associated with gastric cancer occurrence, invasion, and metastasis. Moreover, aberrant expression of microRNAs (miRNAs) is significantly related to gastric cancer tumor stage, size, differentiation and metastasis. MiRNAs interrupt cellular signaling pathways, inhibit the activity of tumor suppressor genes, and affect the cell cycle in gastric cancer cells. Some miRNAs, including miR-21, miR-106a and miR-421, could be potential markers for the diagnosis of gastric cancer. Long non-coding RNAs (lncRNAs), a new research hotspot among cancer-associated ncRNAs, play important roles in epigenetic, transcriptional and post-transcriptional regulation. Several gastric cancer-associated lncRNAs, such as CCAT1, GACAT1, H19, and SUMO1P3, have been explored. In addition, Piwi-interacting RNAs, another type of small ncRNA that is recognized by gastroenterologists, are involved in gastric carcinogenesis, and piR-651/823 represents an efficient diagnostic biomarker of gastric cancer that can be detected in the blood and gastric juice. Small interfering RNAs also function in post-transcriptional regulation in gastric cancer and might be useful in gastric cancer treatment.

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.

Astrocyte elevated gene-1 overexpression in histologically favorable Wilms tumor is related to poor prognosis

OBJECTIVE

Astrocyte elevated gene-1 (AEG-1) is associated with tumorigenesis and progression in various types of human cancers. However, the status of AEG-1 expression and its significance in Wilms tumor are still unclear. In this study, we investigated the expression of AEG-1 and evaluated its clinical and prognostic significance in favorable-histology Wilms tumor (FHWT).

MATERIALS AND METHODS

Immunohistochemistry was performed to examine AEG-1 protein expression in paraffin-embedded tissues from 38 FHWT patients. All patients underwent radical nephrectomy from January 2003 to June 2008 with subsequent therapy according to National Wilms Tumor Study Group protocols. Statistical analyses were performed to evaluate the association between AEG-1 expression and clinical parameters.

RESULTS

We found high AEG-1 expression in 17 of 38 (44.7%) patients. AEG-1 expression was significantly correlated with clinical stage (p = 0.019) and status of recurrence (p = 0.023). Importantly, patients with high AEG-1 expression had a shorter disease-free survival and overall survival compared with those with low AEG-1 expression (p = 0.011 and p = 0.013).

CONCLUSION

AEG-1 expression is associated with FHWT outcome in this study, and AEG-1 may represent a novel and valuable predictor for prognostic evaluation of FHWT patients.

AEG-1/MTDH/LYRIC: clinical significance

"Gain-of-function" and "loss-of-function" studies in human cancer cells and analysis of a transgenic mouse model have convincingly established that AEG-1/MTDH/LYRIC performs a seminal role in regulating proliferation, invasion, angiogenesis, metastasis, and chemoresistance, the salient defining hallmarks of cancer. These observations are strongly buttressed by clinicopathologic correlations of AEG-1/MTDH/LYRIC expression in a diverse array of cancers distinguishing AEG-1/MTDH/LYRIC as an independent biomarker for highly aggressive metastatic disease with poor prognosis. AEG-1/MTDH/LYRIC has been shown to be a marker predicting response to chemotherapy, and serum anti-AEG-1/MTDH/LYRIC antibody titer also serves as a predictor of advanced stages of aggressive cancer. However, inconsistent findings have been reported regarding the localization of AEG-1/MTDH/LYRIC protein in the nucleus or cytoplasm of cancer cells and the utility of nuclear or cytoplasmic AEG-1/MTDH/LYRIC to predict the course and prognosis of disease. This chapter provides a comprehensive analysis of the existing literature to emphasize the common and conflicting findings relative to the clinical significance of AEG-1/MTDH/LYRIC in cancer.

The role of AEG-1/MTDH/LYRIC in the pathogenesis of central nervous system disease

Astrocyte-elevated gene-1 (AEG-1/MTDH/LYRIC) is a potent oncogene that regulates key cellular processes underlying disease of the central nervous system (CNS). From its involvement in human immunodeficiency virus (HIV)-1 infection to its role in neurodegenerative disease and malignant brain tumors, AEG-1/MTDH/LYRIC facilitates cellular survival and proliferation through the control of a multitude of molecular signaling cascades. AEG-1/MTDH/LYRIC induction by HIV-1 and TNF highlights its importance in viral infection, and its incorporation into viral vesicles supports its potential role in active viral replication. Overexpression of AEG-1/MTDH/LYRIC in the brains of Huntington's disease patients suggests its function in neurodegenerative disease, and its association with genetic polymorphisms in large genome-wide association studies of migraine patients suggests a possible role in the pathogenesis of migraine headaches. In the field of cancer, AEG-1/MTDH/LYRIC promotes angiogenesis, migration, invasion, and enhanced tumor metabolism through key oncogenic signaling cascades. In response to external stress cues and cellular mechanisms to inhibit further growth, AEG-1/MTDH/LYRIC activates pathways that bypass cell checkpoints and potentiates signals to enhance survival and tumorigenesis. As an oncogene that promotes aberrant cellular processes within the CNS, AEG-1/MTDH/LYRIC represents an important therapeutic target for the treatment of neurological disease.

AEG-1/MTDH/LYRIC, the beginning: initial cloning, structure, expression profile, and regulation of expression

Since its initial identification as a HIV-1-inducible gene in 2002, astrocyte elevated gene-1 (AEG-1), subsequently cloned as metadherin (MTDH) and lysine-rich CEACAM1 coisolated (LYRIC), has emerged over the past 10 years as an important oncogene providing a valuable prognostic marker in patients with various cancers. Recent studies demonstrate that AEG-1/MTDH/LYRIC is a pleiotropic protein that can localize in the cell membrane, cytoplasm, endoplasmic reticulum (ER), nucleus, and nucleolus, and contributes to diverse signaling pathways such as PI3K-AKT, NF-κB, MAPK, and Wnt. In addition to tumorigenesis, this multifunctional protein is implicated in various physiological and pathological processes including development, neurodegeneration, and inflammation. The present review focuses on the discovery of AEG-1/MTDH/LYRIC and conceptualizes areas of future direction for this intriguing gene. We begin by describing how AEG-1, MTDH, and LYRIC were initially identified by different research groups and then discuss AEG-1 structure, functions, localization, and evolution. We conclude with a discussion of the expression profile of AEG-1/MTDH/LYRIC in the context of cancer, neurological disorders, inflammation, and embryogenesis, and discuss how AEG-1/MTDH/LYRIC is regulated. This introductory discussion of AEG-1/MTDH/LYRIC will serve as the basis for the detailed discussions in other chapters of the unique properties of this intriguing molecule.

AEG-1/MTDH/LYRIC: signaling pathways, downstream genes, interacting proteins, and regulation of tumor angiogenesis

Astrocyte elevated gene-1 (AEG-1), also known as metadherin (MTDH) and lysine-rich CEACAM1 coisolated (LYRIC), was initially cloned in 2002. AEG-1/MTDH/LYRIC has emerged as an important oncogene that is overexpressed in multiple types of human cancer. Expanded research on AEG-1/MTDH/LYRIC has established a functional role of this molecule in several crucial aspects of tumor progression, including transformation, proliferation, cell survival, evasion of apoptosis, migration and invasion, metastasis, angiogenesis, and chemoresistance. The multifunctional role of AEG-1/MTDH/LYRIC in tumor development and progression is associated with a number of signaling cascades, and recent studies identified several important interacting partners of AEG-1/MTDH/LYRIC in regulating cancer promotion and other biological functions. This review evaluates the current literature on AEG-1/MTDH/LYRIC function relative to signaling changes, interacting partners, and angiogenesis and highlights new perspectives of this molecule, indicating its potential as a significant target for the clinical treatment of various cancers and other diseases.

In vitro regulation of hepatocellular carcinoma cell viability, apoptosis, invasion, and AEG-1 expression by LY294002

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world, and is characterized by advanced clinical stages at diagnosis and very poor prognosis.

SUBJECTS AND METHODS

This study investigated the effects of PI3K inhibitor, LY294002, on suppression of astrocyte elevated gene-1 (AEG-1) and regulation of HCC cell viability, apoptosis, and invasion in vitro. Cell lines derived from normal liver and HCC were treated with LY294002 and evaluated by RT-PCR, western blot, cell viability, migration, and invasion assays.

RESULTS

The data showed that AEG-1 mRNA and protein were overexpressed in HCC cells, compared to the normal liver cells. LY294002 treatment of HCC cells significantly reduced tumor cell viability, but promoted apoptosis. Tumor cell migration and invasion assays showed that LY294002 treatment also decreased the capacity of HCC cell migration and invasion. Molecularly, LY294002 treatment down-regulated AEG-1 expression, AKT and GSK3β phosphorylation, and expression of cyclinD1, CDK4, VEGF and Bcl2, but up-regulated Bax and c-Myc expression.

CONCLUSION

The data from this study demonstrated usefulness of LY294002 for effective control of HCC. Future studies should investigate the effects of LY294002 on HCC cells in vivo before initiating clinical trials in HCC patients.

Huaier polysaccharides suppresses hepatocarcinoma MHCC97-H cell metastasis via inactivation of EMT and AEG-1 pathway

We have recently reported that astrocyte elevated gene-1 (AEG-1) might be an epithelial-mesenchymal transition (EMT) associated biomarker in human hepatocellular carcinoma (HCC), and play an important role in the progression of hepatocellular carcinoma. To extend our study, we examined here the anti-invasive and metastatic effects of Huaier polysaccharide (HP) on human HCC cell line MHCC97-H and explored its possible mechanism of action. Treatment with HP dose-dependently inhibited the proliferation, adhesion, migration and invasion of MHCC97-H cells in vitro. This was achieved not only by reducing the expression of AEG-1 and N-cadherin, but also by enhancing E-cadherin expression. Therefore, these data suggested that HP can inhibit the growth and metastatic potential of MHCC97-H cells through modulation of the AEG-1/EMT pathway.

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

Background

Astrocyte 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.

Method

In 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.

Results

The 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).

Conclusions

Our 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.

Metadherin regulates metastasis of squamous cell carcinoma of the head and neck via AKT signalling pathway-mediated epithelial-mesenchymal transition

Our recent study suggested that metadherin (MTDH) is overexpressed in laryngeal squamous cell carcinoma. Here, we further investigated its role in promoting metastasis of squamous cell carcinoma of the head and neck (SCCHN). An immunohistochemistry analysis demonstrated that MTDH is elevated and positively correlated with metastasis in 189 primary SCCHN tissues. In vitro experiments demonstrated that MTDH overexpression enhanced the migratory and invasive ability of SCCHN cells. Moreover, MTDH induced epithelial-mesenchymal transition (EMT) by both regulating morphological changes and mediating the expression of the biomolecular makers E-cadherin and vimentin. In addition, MTDH mediated AKT activation, and all of the above effects were nearly completely blocked by the inhibition of AKT. Our results suggested that MTDH might promote the metastasis of SCCHN through AKT signalling pathway mediated-EMT.

AEG-1 is a target of perifosine and is over-expressed in gastric dysplasia and cancers

BACKGROUND

Perifosine, an alkylphospholipid, is an Akt inhibitor which inhibits the growth of diverse cancer cells. We have reported its inhibitory effects on the growth of gastric cancer cells recently, but its molecular mechanisms are still largely unknown.

AIMS

The purpose of this study was to investigate the effect and regulatory mechanism of perifosine in gastric cancer.

METHODS

Cell viability was determined by sulforhodamine B assay after transiently transfected with AEG-1 specific siRNAs. qRT-PCR and western blot assay were used to determine the mRNA expression and proteins levels of cell signaling molecules examined. Immunohistochemistry was used to detect the AEG-1 expression in 87 gastric carcinomas, 60 dysplasia, and 47 normal gastric mucosa.

RESULTS

Perifosine decreased AEG-1 gene expression along with inhibition of Akt/GSK3β/C-MYC signaling pathway. Knockdown of AEG-1 using siRNA led to significant down-regulation of cyclin D1 expression at both mRNA level and protein level, and inhibited the growth of gastric cancer cells. AEG-1 expression was elevated in gastric dysplasia and cancer tissues compared to normal gastric mucosa (P < 0.01). AEG-1 over-expression correlated with diffuse type of gastric cancer and advanced tumor stages.

CONCLUSIONS

Perifosine inhibits the growth of gastric cancer cells possibly through inhibition of the Akt/GSK3β/C-MYC signaling pathway-mediated down-regulation of AEG-1 that subsequently down-regulated cyclin D1. AEG-1 may play an important role in the carcinogenesis and progression of gastric cancer and could be a therapeutic target of perifosine.

Overexpression of astrocyte-elevated gene-1 is associated with cervical carcinoma progression and angiogenesis

Astrocyte-elevated gene-1 (AEG-1) is implicated in the oncogenesis and angiogenesis of various types of human cancers. However, the biological roles of AEG-1 in cervical carcinoma remain to be further elucidated. In the present study, we demonstrated that the expression of AEG-1 was markedly upregulated in the cervical carcinoma cell lines HeLa, CaSki and SiHa, as well as in 8 paired primary cervical carcinoma tissue (CCT) specimens at both the transcriptional and translational levels when compared with normal cervical epithelial cells (NCECs). Furthermore, immunohistochemical (IHC) analysis demonstrated that 180 of 200 (90%) archived CCT specimens exhibited positive staining for AEG-1, and statistical analysis revealed that the upregulation of AEG-1 was significantly correlated with the clinical staging of the patients (P=0.034), including T (P=0.019), N (P=0.038) and M classification (P=0.018) as well as tumor differentiation (P=0.043). Furthermore, loss‑ and gain‑of‑function results showed that knockdown of AEG-1 expression by specific shRNA not only inhibited SiHa cell proliferation and invasive ability, but also significantly decreased the expression of the angiogenesis-related genes HIF-1α, Tie2, VEGF and TEM1/CD248. Moreover, an increased vascular formation ability was observed in human umbilical vein endothelial cells (HUVECs) co-cultured with conditioned medium both from SiHa cells and NCECs transfected with ectopic AEG-1. In conclusion, these results suggest that elevated expression of AEG-1 plays an important role in the aggressiveness and angiogenesis of cervical carcinoma and that AEG‑1 represents a novel and valuable predictive factor for the prognostic evaluation of cervical carcinoma patients.

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.

Increased expression of metadherin protein predicts worse disease-free and overall survival in laryngeal squamous cell carcinoma

Metadherin (MTDH) is involved in tumourigenesis and cancer progression in multiple human malignancies. However, the MTDH protein has rarely been reported in laryngeal squamous cell carcinoma (LSCC). The expression pattern of the MTDH protein in 176 primary archival LSCC and 27 corresponding adjacent noncarcinoma specimens was detected by immunohistochemistry and further correlated with clinicopathological parameters. The results demonstrated that 161 (91.48%) primary LSCC samples stained positive for MTDH; however, staining was barely detectable in all adjacent noncarcinoma samples. Moreover, the expression of the MTDH protein was significantly associated with the primary tumour site (p = 0.021), T classification (p = 0.002), clinical stage (I + II/III + IV; p < 0.001), lymph node metastasis (p < 0.001) and postoperational recurrence (p < 0.001). Kaplan-Meier analysis revealed that MTDH expression was significantly associated with worse disease-free survival (DFS) and overall survival (OS) rates in patients with LSCC (both p < 0.001). When lymph node metastasis and MTDH expression were considered together, patients with lymph node metastasis and high MTDH expression had both poorer DFS and OS rates than others (both p < 0.001). Finally, multivariate analysis demonstrated that MTDH expression was an independent prognostic factor for both DFS and OS rates in patients with LSCC. Strong MTDH expression was negatively correlated with a canonical epithelial-mesenchymal transition molecule E-cadherin (p < 0.001) and positively associated with proangiogenic protein vascular endothelial growth factor (p < 0.001). MTDH overexpression was tightly associated with more aggressive tumour behaviour and a poor prognosis, indicating that MTDH is a valuable molecular biomarker for LSCC progression.

Establishment and characterization of MTDH knockdown by artificial MicroRNA interference - functions as a potential tumor suppressor in breast cancer

BACKGROUND

Considerable evidence suggests that metadherin (MTDH) is a potentially crucial mediator of tumor malignancy and an important therapeutic target for simultaneously enhancing chemotherapy efficacy and reducing metastasis risk. Inhibition of MTDH expression by RNA interference has been shown in several previous research, but silencing MTDH expression by microRNA (miRNA) interference in breast cancer has not been established. In the present study, we investigated the role of MTDH-miRNA in down-regulation of proliferation, motility and migration of breast carcinoma cells.

METHODS

Expression vectors of recombinant plasmids expressing artificial MTDH miRNA were constructed and transfected to knockdown MTDH expression in MDA-MB-231 breast cancer cells. Expression of MTDH mRNA and protein was detected by RT-PCR and Western blot, respectively. MTT assays were conducted to determine proliferation, and wound healing assays and transwell migration experiments for cell motility and migration.

RESULTS

Transfection of recombinant a plasmid of pcDNA-MTDH-miR-4 significantly suppressed the MTDH mRNA and protein levels more than 69% in MDA-MB-231 breast cancer cells. This knockdown significantly inhibited proliferation, motility and migration as compared with controls.

CONCLUSIONS

MTDH-miRNA may play an important role in down- regulating proliferation, motility and migration in breast cancer cells, and should be considered as a potential small molecule inhibitor therapeutic targeting strategy for the future.

AEG-1 expression characteristics in human non-small cell lung cancer and its relationship with apoptosis

Expression of astrocyte-elevated gene-1 (AEG-1), a novel oncoprotein, has been shown to promote cell growth and inhibit apoptosis, but the underlying molecular mechanisms and its functional significance in non-small cell lung cancer (NSCLC) remain to be elucidated. In the present study, statistical analysis displayed a significant correlation of AEG-1 expression with clinical staging (P = 0.048), differentiation (P = 0.019) and lymph node metastasis (P = 0.032). Simultaneously, the overall survival time in patients with higher AEG-1 expression was obviously shorter than that in patients with lower expression of AEG-1 (P < 0.001). Furthermore, we found that AEG-1 could inhibit apoptotic cell death in L-78 cells, as assessed by MTT, TUNEL and flow cytometry assay. After treating L-78 cells with AEG-1 siRNA, caspase-3 protein was significantly up-regulated and Bcl-2 protein was markedly decreased in L-78 cells, which was verified by the immunohistochemistry results about AEG-1, caspase-3 and Bcl-2. Furthermore, PI3K p110 protein and phosphorylated Akt were also largely attenuated by the treatment of AEG-1 siRNA. In conclusion, our results indicated that AEG-1 played a crucial role in the carcinogenesis of NSCLC and could inhibit apoptosis via activating cell survival signaling (enhancing the level of anti-apoptotic protein Bcl-2 and the activation of PI3K/Akt pathway).

The MTDH (-470G>A) polymorphism is associated with ovarian cancer susceptibility

MTDH (metadherin), an important oncogene that is widely overexpressed in various cancers, is a potential biomarker of tumor malignancy. Variants in MTDH have been associated with susceptibility to breast cancer. However, no studies assessing MTDH gene polymorphisms and their potential relationship to ovarian cancer susceptibility have been reported. Thus, we investigated the association of MTDH (-470G>A) polymorphism with ovarian cancer development in 145 ovarian cancer patients and 254 matched control subjects, using sequence analysis. We found that the MTDH (-470G>A) polymorphism was statistically correlated with ovarian cancer risk (under the additive genetic model, GG vs. GA vs AA, P = 0.042). Compared with genotypes containing the G allele (GG and GA), the AA genotype may decrease the risk of ovarian cancer (P = 0.0198, OR = 0.33, 95% CI [0.12∼0.78]). Compared with the G allele, the A allele is protective against ovarian cancer risk (P = 0.01756, OR = 0.66, 95% CI [0.46∼0.93]). Furthermore, a statistically significant association between the GG and GA+AA genotypes and the clinical stage was observed (P = 0.038). These data suggest that MTDH (-470G>A) could be a useful molecular marker for assessing ovarian cancer risk and for predicting ovarian cancer patient prognosis.

Expression of AEG-1 in human T-cell lymphoma enhances the risk of progression

The aim of this study was to examine the expression and role of astrocyte elevated gene-1 (AEG-1) in biological processes of T-cell non-Hodgkin's lymphoma (T-NHL). AEG-1 expression in T-NHL patients was characterized with immunohistochemistry. The expression of AEG-1, survivin, Bcl-2 and Bax in Jurkat and Hut-78 cells was detected by real-time PCR and western blotting. Cell proliferation, cell cycle and apoptosis were measured by MTT and flow cytometry. MMP-2/-9 activity was detected by gelatin zymography. Of the studied tumors, 104 (80.62%) exhibited cytoplasmic AEG-1 immunostaining. AEG-1-siRNA in Jurkat and Hut-78 cells suppressed cell proliferation and induced cell apoptosis, inhibited survivin and Bcl-2/Bax protein expression as well as MMP-2/-9 activity. Downregulation of AEG-1 using siRNA could provide a potential approach for gene therapy against T-NHL, and the antitumor effects may be associated with inhibition of survivin and Bcl-2/Bax protein expression and MMP-2/-9 activity.

Metadherin contributes to the pathogenesis of diffuse large B-cell lymphoma

Background

Metadherin (MTDH) has been demonstrated as a potentially crucial mediator of various types of human malignancies. However, the expression and role of MTDH in diffuse large-B-cell lymphoma (DLBCL) have not been reported yet. This study aimed to illuminate the role of MTDH in the pathogenesis of DLBCL.

Methodology/Principal Findings

A remarkable elevation of MTDH on mRNA level was detected in DLBCL tissues by quantitative polymerase chain reaction (PCR). Using Western-blot analysis we found that the expression of MTDH protein was significantly upregulated in DLBCL cell lines and DLBCL tissues compared with peripheral blood mononuclear cells (PBMCs) from healthy samples and tissues from patients of reactive hyperplasia of lymph node. The results showed high expression of MTDH in 23 of 30 (76.67%) DLBCL tissues by using immunohistochemical analysis and the over expression of MTDH was strongly correlated to the clinical staging of patients with DLBCL (P<0.05). Furthermore, the finding suggested that the increase of MTDH in DLBCL cells could distinctly enhance cell proliferation and inhibit cell apoptosis; meanwhile, inhibition of MTDH expression by specific siRNA clearly enhanced LY8 cell apoptosis. Upregulation of MTDH elevated the protein level of total β-catenin and translocation of β-catenin to the nucleus directly or indirectly. Knockdown of MTDH decreased the level of total, cytoplasmic β-catenin and reduced nuclear accumulation of β-catenin protein. This indicated that the function of MTDH on the development of DLBCL was mediated through regulation of Wnt/β-catenin signaling pathway.

Conclusions/Significance

Our results suggest that MTDH contributes to the pathogenesis of DLBCL mediated by activation of Wnt/β-catenin pathway. This novel study may contribute to further investigation on the useful biomarkers and potential therapeutic target in the DLBCL patients.

Expression of AEG-1 mRNA and protein in colorectal cancer patients and colon cancer cell lines

BACKGROUND

Astrocyte elevated gene 1 (AEG-1), an important oncogene, has been shown to be overexpressed in several types of cancers. In colorectal cancer (CRC), the protein level of AEG-1 is up-regulated in tumour tissue compared to normal mucosa, showing prognostic significance. Since little is known about the transcriptional level of AEG-1 expression and its biological pathway in CRC the aim of the present study was to examine the relationship of AEG-1 mRNA expression, the protein level and clinicopathological variables as well as its biology pathway in CRC.

MATERIAL AND METHODS

The mRNA expression of AEG-1 was analysed by qPCR in fresh frozen patient samples including 156 primary tumours, along with the corresponding normal mucosa, and in five colon cancer cell lines, SW480, SW620, KM12C, KM12SM and KM12L4a. AEG-1 protein expression was investigated by immunohistochemistry in paraffin-embedded materials from 74 distant normal mucosa, 107 adjacent mucosa, 158 primary tumour, 35 lymph node metastasis and 9 liver metastasis samples. In addition, the AEG-1 protein expression was elucidated in the cell lines by Western blot.

RESULTS

The lymph node metastatic cell line SW620 had a significantly higher AEG-1 mRNA (0.27 ± 0.02) expression compared to the primary tumour cell line SW480 (0.17 ± 0.04, p = 0.026). AEG-1 expression at the mRNA level and/or the protein level was significantly up-regulated gradually from normal mucosa to primary CRC, and then to lymph node metastasis and finally to liver metastasis (p < 0.05). There were significant associations of AEG-1 mRNA expression with tumour location (p = 0.047), as well as mRNA and protein expression with the tumour stage (p < 0.03). Furthermore AEG-1 protein expression was positively related to biological variables including NF-κB, p73, Rad50 and apoptosis (p < 0.05).

CONCLUSION

AEG-1 is up-regulated, at the mRNA and the protein level, during CRC development and aggressiveness, and is related to tumour location and stage. It may play its role in CRC through the NF-κB signaling pathway.

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

AIMS

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.

METHODS AND RESULTS

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).

CONCLUSION

Our findings indicate that tumour AEG-1 overexpression is associated with poor prognosis and cisplatin resistance in advanced serous ovarian cancer.

Astrocyte elevated gene-1 (AEG-1) is a marker for aggressive salivary gland carcinoma

BACKGROUND

Astrocyte elevated gene-1 (AEG-1) is associated with tumorigenesis and progression in diverse human cancers. The present study was aimed to investigate the clinical and prognostic significance of AEG-1 in salivary gland carcinomas (SGC).

METHODS

Real-time PCR and western blot analyses were employed to examine AEG-1 expression in two normal salivary gland tissues, eight SGC tissues of various clinical stages, and five pairs of primary SGC and adjacent salivary gland tissues from the same patient. Immunohistochemistry (IHC) was performed to examine AEG-1 protein expression in paraffin-embedded tissues from 141 SGC patients. Statistical analyses was applies to evaluate the diagnostic value and associations of AEG-1 expression with clinical parameters.

RESULTS

AEG-1 expression was evidently up-regulated in SGC tissues compared with that in the normal salivary gland tissues and in matched adjacent salivary gland tissues. AEG-1 protein level was positively correlated with clinical stage (P < 0.001), T classification (P = 0.008), N classification (P = 0.008) and M classifications (P = 0.006). Patients with higher AEG-1 expression had shorter overall survival time, whereas those with lower tumor AEG-1 expression had longer survival time.

CONCLUSIONS

Our results suggest that AEG-1 expression is associated with SGC progression and may represent a novel and valuable predictor for prognostic evaluation of SGC patients.

MicroRNA-375 targets AEG-1 in hepatocellular carcinoma and suppresses liver cancer cell growth in vitro and in vivo

MicroRNAs (miRNAs) are believed to have fundamental roles in tumorigenesis and have great potential for the diagnosis and treatment of cancer. However, the roles of miRNAs in hepatocellular carcinogenesis are still not fully elucidated. We investigated the aberrantly expressed miRNAs involved in hepatoma by comparison of miRNA expression profiles in cancerous hepatocytes with normal primary human hepatocytes, and 37 dysregulated miRNAs were screened out by twofold change with a significant difference (P<0.05). Clustering analysis based on 13 miRNAs with changes over 15-folds showed that the miRNA expression patterns between the cancerous and normal hepatocytes were clearly different. Among the 13 miRNAs, we found that miR-375 was significantly downregulated in hepatocellular carcinoma (HCC) tissues and cell lines. Overexpression of miR-375 in liver cancer cells decreased cell proliferation, clonogenicity, migration/invasion and also induced G1 arrest and apoptosis. To unveil the molecular mechanism of miR-375-mediated phenotype in hepatoma cells described above, we examined the putative targets using bioinformatics tools and found that astrocyte elevated gene-1 (AEG-1) was a potential target of miR-375. Then we demonstrated that miR-375 bound directly to the 3'-untranslated region of AEG-1 and inhibited the expression of AEG-1. TaqMan quantitative reverse transcriptase-PCR and western blot analysis showed that miR-375 expression was inversely correlated with AEG-1 expression in HCC tissues. Knockdown of AEG-1 by RNAi in HCC cells, similar to miR-375 overexpression, suppressed tumor properties. Ectopic expression of AEG-1, conversely, could partially reverse the antitumor effects of miR-375. In a mouse model, therapeutic administration of cholesterol-conjugated 2'-O-methyl-modified miR-375 mimics (Chol-miR-375) could significantly suppress the growth of hepatoma xenografts in nude mice. In conclusion, our findings indicate that miR-375 targets AEG-1 in HCC and suppresses liver cancer cell growth in vitro and in vivo, and highlight the therapeutic potential of miR-375 in HCC treatment.

Astrocyte elevated gene 1: biological functions and molecular mechanism in cancer and beyond

Since its discovery, nearly one decade of research on astrocyte elevated gene 1 (AEG-1) has witnessed expanding knowledge of this molecule, ranging from its role in cancer biology to molecular mechanisms underlying the biological functions. As a multifunctional oncoprotein, AEG-1 has been shown to overexpress in multiple types of human cancer, and the elevation of AEG-1 in tumor cells leads to enhanced phenotypes characteristic of malignant aggressiveness, including increased abilities to proliferate robustly, to invade surrounding tissues, to migrate, to induce neovascularization, and to enhance chemoresistance. The multifunctional role of AEG-1 in tumor development and progression has been found to be associated with several signaling cascades, namely, 1) activation of NF-kappa B, partially through direct interaction with p65; 2) PI3K/AKT signaling triggered by AEG-1 indirectly; 3) enhancement of the transcriptional activity of beta-catenin by indirect activation of MAPK and induction of LEF1; 4) regulation of mi/siRNA-mediated gene silencing by interacting with SND1; and 5) promotion of protective autophagy; in addition to possibly unknown mechanisms. Elevated AEG-1 expression is seen in nearly all tumor types, and in most cases AEG-1 positively correlates with tumor progression and poorer patient survival. Taken together, AEG-1 might represent a potential prognostic biomarker and therapeutic target.

Significance of dysregulated metadherin and microRNA-375 in head and neck cancer

PURPOSE

Despite recent improvements in local control of head and neck cancers (HNC), distant metastasis remains a major cause of death. Hence, further understanding of HNC biology, and in particular, the genes/pathways driving metastasis is essential to improve outcome.

EXPERIMENTAL DESIGN

Quantitative reverse transcriptase PCR (qRT-PCR) was used to measure the expression of miR-375 and metadherin (MTDH) in HNC patient samples. Targets of miR-375 were confirmed using qRT-PCR, Western blot analysis, and luciferase assays. Phenotypic effects of miR-375 reexpression and MTDH knockdown were assessed using viability (MTS), clonogenic survival, cell migration/invasion, as well as in vivo tumor formation assays. The prognostic significance of miR-375 or MTDH in nasopharyngeal carcinoma (NPC) was determined by comparing low versus high expression groups.

RESULTS

MiR-375 expression was significantly reduced (P = 0.01), and conversely, MTDH was significantly increased (P = 0.0001) in NPC samples. qRT-PCR, Western blots, and luciferase assays corroborated MTDH as a target of miR-375. Reexpression of miR-375 and siRNA knockdown of MTDH both decreased cell viability and clonogenic survival, cell migration/invasion, as well as in vivo tumor formation. NPC patients whose tumors expressed high levels of MTDH experienced significantly lower survival and, in particular, higher distant relapse rates (5-year distant relapse rates: 26% vs. 5%; P = 0.005).

CONCLUSIONS

Dysregulation of miR-375 and MTDH may represent an important oncogenic pathway driving human HNC progression, particularly distant metastases, which is now emerging as a major cause of death for HNC patients. Hence, targeting this pathway could potentially be a novel therapeutic strategy by which HNC patient outcome could be improved.

Astrocyte elevated gene-1 (AEG-1): A multifunctional regulator of normal and abnormal physiology

Since its initial identification and cloning in 2002, Astrocyte Elevated Gene-1 (AEG-1), also known as metadherin (MTDH), 3D3 and LYsine-RIch CEACAM1 co-isolated (LYRIC), has emerged as an important oncogene that is overexpressed in all cancers analyzed so far. Examination of a large cohort of patient samples representing diverse cancer indications has revealed progressive increase in AEG-1 expression with stages and grades of the disease and an inverse relationship between AEG-1 expression level and patient prognosis. AEG-1 functions as a bona fide oncogene by promoting transformation. In addition, it plays a significant role in invasion, metastasis, angiogenesis and chemoresistance, all important hallmarks of an aggressive cancer. AEG-1 is also implicated in diverse physiological and pathological processes, such as development, inflammation, neurodegeneration, migraine and Huntington's disease. AEG-1 is a highly basic protein with a transmembrane domain and multiple nuclear localization signals and it is present in the cell membrane, cytoplasm, nucleus, nucleolus and endoplasmic reticulum. In each location, AEG-1 interacts with specific proteins thereby modulating diverse intracellular processes the combination of which contributes to its pleiotrophic properties. The present review provides a snapshot of the current literature along with future perspectives on this unique molecule.

Astrocyte elevated gene-1 (AEG-1): A multifunctional regulator of normal and abnormal physiology

Since its initial identification and cloning in 2002, Astrocyte Elevated Gene-1 (AEG-1), also known as metadherin (MTDH), 3D3 and LYsine-RIch CEACAM1 co-isolated (LYRIC), has emerged as an important oncogene that is overexpressed in all cancers analyzed so far. Examination of a large cohort of patient samples representing diverse cancer indications has revealed progressive increase in AEG-1 expression with stages and grades of the disease and an inverse relationship between AEG-1 expression level and patient prognosis. AEG-1 functions as a bona fide oncogene by promoting transformation. In addition, it plays a significant role in invasion, metastasis, angiogenesis and chemoresistance, all important hallmarks of an aggressive cancer. AEG-1 is also implicated in diverse physiological and pathological processes, such as development, inflammation, neurodegeneration, migraine and Huntington's disease. AEG-1 is a highly basic protein with a transmembrane domain and multiple nuclear localization signals and it is present in the cell membrane, cytoplasm, nucleus, nucleolus and endoplasmic reticulum. In each location, AEG-1 interacts with specific proteins thereby modulating diverse intracellular processes the combination of which contributes to its pleiotrophic properties. The present review provides a snapshot of the current literature along with future perspectives on this unique molecule.