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

Potential Application of Small Interfering RNA in Gastro-Intestinal Tumors

Despite the progress made in the diagnoses and therapy of gastrointestinal cancers, these diseases are still plagued by a high mortality. Thus, novel therapeutic approaches are urgently required. In this regard, small interfering RNA (siRNA), double-stranded RNA molecules able to specifically target the mRNA of pathological genes, have the potential to be of therapeutic value. To be effective in the human body, siRNAs need to be protected against degradation. Additionally, they need to target the tumor, leaving the normal tissue untouched in an effort to preserve organ function. To accomplish these tasks, siRNAs have been formulated with smart delivery systems such has polymers and lipids. While siRNA protection is not particularly difficult to achieve, their targeting of tumor cells remains problematic. Here, after introducing the general features of gastrointestinal cancers, we describe siRNA characteristics together with representative delivery systems developed for gastrointestinal cancers. Afterward, we present a selection of research papers employing siRNAs against upper- and lower- gastrointestinal cancers. For the liver, we also consider papers using siRNAs to combat liver cirrhosis, a relevant risk factor for liver cancer development. Finally, we present a brief description of clinical trials employing siRNAs for gastrointestinal cancers.

Metadherin (AEG-1/MTDH/LYRIC) expression: Significance in malignancy and crucial role in colorectal cancer

Metadherin (AEG-1/MTDH/LYRIC) is a 582-amino acid transmembrane protein, encoded by a gene located at chromosome 8q22, and distributed throughout the cytoplasm, peri-nuclear region, nucleus, and nucleolus as well as the endoplasmic reticulum (ER). It contains several structural and interacting domains through which it interacts with transcription factors such as nuclear factor-κB (NF-κB), promyelocytic leukemia zinc finger (PLZF), staphylococcal nuclease domain containing 1 (SND1) and lung homing domain (LHD). It is regulated by miRNAs and mediates its oncogenic function via activation of cell proliferation, survival, migration and metastasis, as well as, angiogenesis and chemoresistance via phosphatidylinositol-3-kinase/AKT (PI3K/AKT), NF-κB, mitogen-activated protein kinase (MAPK) and Wnt signaling pathways. In this chapter, metadherin is reviewed highlighting its role in mediating growth, metastasis and chemoresistance in colorectal cancer (CRC). Metadherin, as well as its variants, and antibodies are associated with CRC progression, poorer prognosis, decreased survival and advanced clinico-pathology. The potential of AEG-1/MTDH/LYRIC as a diagnostic and prognostic marker as well as a therapeutic target in CRC is explored.

Metadherin-mediated mechanisms in human malignancies

Metadherin (MTDH) has been recognized as a novel protein that is critical for the progression of multiple types of human malignancies. Studies have reported that MTDH enhances the metastatic potential of cancer cells by regulating multiple signaling pathways. miRNAs and various tumor-related proteins have been shown to interact with MTDH, making it a potential therapeutic target as well as a biomarker in human malignancies. MTDH plays a critical role in inflammation, angiogenesis, hypoxia, epithelial-mesenchymal transition and autophagy. In this review, we present the function and mechanisms of MTDH for cancer initiation and progression.

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

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

Multifunctional Role of Astrocyte Elevated Gene-1 (AEG-1) in Cancer: Focus on Drug Resistance

Simple Summary

Chemotherapy is a major mode of treatment for cancers. However, cancer cells adapt to survive in stressful conditions and in many cases, they are inherently resistant to chemotherapy. Additionally, after initial response to chemotherapy, the surviving cancer cells acquire new alterations making them chemoresistant. Genes that help adapt the cancer cells to cope with stress often contribute to chemoresistance and one such gene is Astrocyte elevated gene-1 (AEG-1). AEG-1 levels are increased in all cancers studied to date and AEG-1 contributes to the development of highly aggressive, metastatic cancers. In this review, we provide a comprehensive description of the mechanism by which AEG-1 augments tumor development with special focus on its ability to regulate chemoresistance. We also discuss potential ways to inhibit AEG-1 to overcome chemoresistance.

Abstract

Cancer development results from the acquisition of numerous genetic and epigenetic alterations in cancer cells themselves, as well as continuous changes in their microenvironment. The plasticity of cancer cells allows them to continuously adapt to selective pressures brought forth by exogenous environmental stresses, the internal milieu of the tumor and cancer treatment itself. Resistance to treatment, either inherent or acquired after the commencement of treatment, is a major obstacle an oncologist confronts in an endeavor to efficiently manage the disease. Resistance to chemotherapy, chemoresistance, is an important hallmark of aggressive cancers, and driver oncogene-induced signaling pathways and molecular abnormalities create the platform for chemoresistance. The oncogene Astrocyte elevated gene-1/Metadherin (AEG-1/MTDH) is overexpressed in a diverse array of cancers, and its overexpression promotes all the hallmarks of cancer, such as proliferation, invasion, metastasis, angiogenesis and chemoresistance. The present review provides a comprehensive description of the molecular mechanism by which AEG-1 promotes tumorigenesis, with a special emphasis on its ability to regulate chemoresistance.

The Scope of Astrocyte Elevated Gene-1/Metadherin (AEG-1/MTDH) in Cancer Clinicopathology: A Review

Since its initial cloning in 2002, a plethora of studies in a vast number of cancer indications, has strongly established AEG-1 as a bona fide oncogene. In all types of cancer cells, overexpression and knockdown studies have demonstrated that AEG-1 performs a seminal role in regulating proliferation, invasion, angiogenesis, metastasis and chemoresistance, the defining cancer hallmarks, by a variety of mechanisms, including protein-protein interactions activating diverse oncogenic pathways, RNA-binding promoting translation and regulation of inflammation, lipid metabolism and tumor microenvironment. These findings have been strongly buttressed by demonstration of increased tumorigenesis in tissue-specific AEG-1 transgenic mouse models, and profound resistance of multiple types of cancer development and progression in total and conditional AEG-1 knockout mouse models. Additionally, clinicopathologic correlations of AEG-1 expression in a diverse array of cancers establishing AEG-1 as an independent biomarker for highly aggressive, chemoresistance metastatic disease with poor prognosis have provided a solid foundation to the mechanistic and mouse model studies. In this review a comprehensive analysis of the current and up-to-date literature is provided to delineate the clinical significance of AEG-1 in cancer highlighting the commonality of the findings and the discrepancies and discussing the implications of these observations.

Therapeutic Targeting of Metadherin Suppresses Colorectal and Lung Cancer Progression and Metastasis

Colorectal and lung cancers account for one-third of all cancer-related deaths worldwide. Previous studies suggested that metadherin (MTDH) is involved in the development of colorectal and lung cancers. However, how MTDH regulates the pathogenesis of these cancers remains largely unknown. Using genetically modified mouse models of spontaneous colorectal and lung cancers, we found that MTDH promotes cancer progression by facilitating Wnt activation and by inducing cytotoxic T-cell exhaustion, respectively. Moreover, we developed locked nucleic acid-modified (LNA) MTDH antisense oligonucleotides (ASO) that effectively and specifically suppress MTDH expression in vitro and in vivo. Treatments with MTDH ASOs in mouse models significantly attenuated progression and metastasis of colorectal, lung, and breast cancers. Our study opens a new avenue for developing therapies against colorectal and lung cancers by targeting MTDH using LNA-modified ASO. SIGNIFICANCE: This study provides new insights into the mechanism of MTDH in promoting colorectal and lung cancers, as well as genetic and pharmacologic evidence supporting the development of MTDH-targeting therapeutics.

Long Noncoding RNA DLGAP1-AS1 Promotes the Aggressive Behavior of Gastric Cancer by Acting as a ceRNA for microRNA-628-5p and Raising Astrocyte Elevated Gene 1 Expression

Purpose

The long noncoding RNA DLGAP1 antisense RNA 1 (DLGAP1-AS1) plays well-defined roles in the malignant progression of hepatocellular carcinoma. The purpose of this study was to determine whether DLGAP1-AS1 affects the aggressive behavior of gastric cancer (GC).

Methods

DLGAP1-AS1 expression in GC tissue samples and cell lines was determined by reverse-transcription quantitative PCR. GC cell proliferation, apoptosis, migration, invasion, and tumor growth in vitro as well as in vivo were examined by the Cell Counting Kit-8 assay, flow-cytometric analysis, transwell migration and invasion assays, and xenograft model experiments, respectively.

Results

DLGAP1-AS1 was overexpressed in GC tissue samples and cell lines. Among patients with GC, the increased level of DLGAP1-AS1 correlated with tumor size, TNM stage, lymph node metastasis, distant metastasis, and shorter overall survival. The knockdown of DLGAP1-AS1 suppressed GC cell proliferation, migration, and invasion in vitro, as well as promoted cell apoptosis and hindered tumor growth in vivo. Mechanistically, DLGAP1-AS1 functioned as a competing endogenous RNA for microRNA-628-5p (miR-628-5p) in GC cells, thereby increasing the expression of the miR-628-5p target astrocyte elevated gene 1 (AEG-1). Functionally, the recovery of the miR-628-5p/AEG-1 axis output attenuated the effects of DLGAP1-AS1 knockdown in GC cells.

Conclusion

DLGAP1-AS1 is a pleiotropic oncogenic lncRNA in GC. DLGAP1-AS1 plays a pivotal part in the oncogenicity of GC in vitro and in vivo by regulating the miR-628-5p/AEG-1 axis. DLGAP1-AS1, miR-628-5p, and AEG-1 form a regulatory pathway to facilitate GC progression, suggesting this pathway as an effective target for the treatment of GC.

Role of serum Metadherin mRNA expression in the diagnosis and prediction of survival in patients with colorectal cancer

Early diagnosis and treatment of colorectal cancer (CRC) are important for improving patients' survival. Metadherin is an oncogene that plays a pivotal role in carcinogenesis and can be suggested as a cancer biomarker. This study aimed to elucidate the efficacy of serum Metadherin mRNA expression as a potential non-invasive biomarker for early diagnosis of CRC in relation to other screening markers as carcinoembryonic antigen (CEA), carbohydrate antigen 19.9 (CA19.9) and Fecal occult blood (FOB) and also to assess its relationship with the tumor stage and survival rate. A convenience series of 86 CRC cases (group I) were recruited with 78 subjects as controls (group II). Serum Metadherin mRNA expression level was determined using reverse transcription polymerase chain reaction (RT-PCR). Serum Metadherin mRNA expression level was significantly elevated in CRC cases when compared with controls (P < 0.001). For CRC diagnosis; Receiver operator characteristic (ROC) analyses revealed that the diagnostic accuracy of serum Metadherin mRNA (AUC = 0.976) was significantly higher than other routine CRC screening markers as CEA, CA19.9 and FOB. The combined accuracy of these markers (AUC = 0.741) was increased when used with serum Metadherin mRNA (AUC = 0.820). High serum Metadherin mRNA expression was associated with poorly differentiated histological grade, advanced tumor stage and lower survival rate. AUC of Metadherin was 0.820 for differentiating advanced versus early tumor stages. Serum Metadherin mRNA expression is a useful non-invasive biomarker for CRC. It can be used for screening and early diagnosis of CRC and can increase the efficacy of other routine CRC screening markers when it is estimated in CRC patients with them. It is also associated with advanced tumor stage and a lower survival rate.

The Effect of Metadherin on NF-κB Activation and Downstream Genes in Ovarian Cancer

Ovarian cancer (OC) is the most aggressive gynecological cancer. Even with the advances in detection and therapeutics, it still remains clinically challenging and there is a pressing need to identify novel therapeutic strategies. In searching for rational molecular targets, we identified metadherin (MTDH), a multifunctional gene associated with several tumor types but previously unrecognized in OC. In this study, we found the MTDH is overexpressed in OC tissues. Through in vitro assays with overexpression cells, we characterized the role of MTDH. We confirmed MTDH stable overexpression significantly increased the expression of TNF-α, IL-6, IL-8, IL-10, and IL-1β. Interestingly, NF-kappa-B (NF-κB) and MTDH were found in a feed-forward loop motif. Thus, our findings support the notion that the MTDH and NF-κB signaling network contributes to OC traits. MTDH represents a new OC-associated gene that can contribute to insights of OC biology and suggests other treatment strategies.

A 21‑gene Support Vector Machine classifier and a 10‑gene risk score system constructed for patients with gastric cancer

Gastric cancer (GC) ranks fifth in terms of incidence and third in terms of tumor mortality worldwide. The present study was designed to construct a Support Vector Machine (SVM) classifier and risk score system for GC. The GSE62254 (training set) and GSE26253 (validation set 2) datasets were downloaded from the Gene Expression Omnibus database. Furthermore, the gene expression profile of GC (validation set 1) was obtained from The Cancer Genome Atlas database. Differentially expressed genes (DEGs) between recurrent and non‑recurrent samples were determined using the limma package. The feature genes were selected using the Caret package, and an SVM classifier was built using the e1071 package. Using the penalized package, the optimal predictive genes for constructing a risk score system were screened. Finally, stratification analysis of clinical factors and pathway enrichment analysis were performed using Gene Set Enrichment Analysis. A total of 239 DEGs were identified in GSE62254, among which 114 DEGs were significantly associated with both recurrence‑free survival and overall survival. Subsequently, 21 feature genes were screened from the 114 DEGs, and an SVM classifier was built. A risk score system for survival prediction was constructed, following the selection of 10 optimal genes, including A‑kinase anchoring protein 12, angiopoietin‑like protein 1, cysteine‑rich sequence 1, myeloid/lymphoid or mixed‑lineage leukemia, translocated to chromosome 11, neuron navigator 3, neurobeachin, nephroblastoma overexpressed, pleiotrophin, tumor suppressor candidate 3 and zinc finger and SCAN domain containing 18. The stratification analysis revealed that pathological stage was an independent prognostic clinical factor in the high‑risk group. Additionally, eight significant pathways were associated with the 10‑gene signature. The SVM classifier and risk score system may be applied for classifying and predicting the prognosis of patients with GC, respectively.

AEG-1 promotes the growth of gastric cancer through the upregulation of eIF4E expression

Background: AEG-1 has been proven to be tumor enhancer in gastric cancer. However, its mechanism has not yet been fully clarified. Methods: Gain-of-function and loss-of-function experiments were conducted to determine the role of eIF4E in AEG-1-induced growth of gastric cancer cells and xenografts of a nude mouse model. Western blot analysis and SRB assay were used to determine the protein expression levels and survival cell numbers. Results: Silencing the expression of AEG-1 inhibited the growth of gastric cancer cells in parallel with a decreased eIF4E and cyclin D1 expression; however, the overexpression of AEG-1 promoted cell growth and increased eIF4E and cyclin D1 expression. Moreover, the overexpression of eIF4E partially reversed the AEG-1 silencing-induced reduction of cyclin D1 and the inhibition of cell growth. An eIF4E knockdown also partially reversed the AEG-1 overexpression-induced upregulation of cyclin D1 and cell growth. Notably, manipulating the expression of eIF4E did not affect the expression of AEG-1. Finally, the silencing of AEG-1 expression inhibited the growth of SGC-7901 xenografts in parallel with the downregulation of eIF4E and cyclin D1 expression in the nude mouse model. Conclusion: AEG-1 promoted the growth of gastric cancer through upregulation of eIF4E/cyclin D1 signaling pathway.

miR-30e-5p suppresses cell proliferation and migration in bladder cancer through regulating metadherin

Recent studies have suggested that miR-30e-5p is dysregulated in several human carcinomas; however, the mechanism of miR-30e-5p in bladder cancer (BCa) remains unknown. Here, we confirmed that the expression of miR-30e-5p was decreased in human BCa specimens and cell lines by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Upregulation of miR-30e-5p decreased the proliferation and migration in T24 and UM-UC-3 cells. Metadherin (MTDH) was a potential target for miR-30e-5p through bioinformatics analysis. Dual-luciferase assays were conducted to validate the interaction between miR-30e-5p and MTDH, which demonstrates that the relative luciferase activity was significantly downregulated after transfected miR-30e-5p mimic compared with control mimic in 293T cells. We also detected that whether silencing of MTDH by using small interfering(si)-MTDH matched effects caused by miR-30e-5p overexpression in BCa cells lines by Cell Counting Kit-8 (CCK-8), colony formation, and transwell assay, and we found the effects of silencing of MTDH same as miR-30e-5p overexpression. Furthermore, we verified that the restoration of MTDH in miR-30e-5p-overexpressed BCa cells rescued the inhibitory effects of miR-30e-5p. In conclusion, these results demonstrated that miR-30e-5p may inhibit BCa cells growth and invasiveness by targeting MTDH and may be a promising therapeutic agent for treating clinical BCa patients.

Metadherin Is a Prognostic Apoptosis Modulator in Mesothelioma Induced via NF-κB-Mediated Signaling

Therapies against malignant pleural mesothelioma (MPM) have yielded disappointing results, in part, because pathologic mechanisms remain obscure. In searching for rational molecular targets, we identified metadherin (MTDH), a multifunctional gene associated with several tumor types but previously unrecognized in MPM. Cox proportional hazards regression analysis delineated associations between higher MTDH expression and lower patient survival from three independent MPM cohorts (n = 349 patients). Through in vitro assays with overexpression and downregulation constructs in MPM cells, we characterized the role of MTDH. We confirmed in vivo the phenotype of altered MTDH expression in a murine xenograft model. Transcriptional regulators of MTDH were identified by chromatin immunoprecipitation. Overexpression of both MTDH mRNA (12-fold increased) and protein levels was observed in tumor tissues. MTDH stable overexpression significantly augmented proliferation, invasiveness, colony formation, chemoresistance, and an antiapoptosis phenotype, while its suppression showed opposite effects in MPM cells. Interestingly, NF-κB and c-Myc (in a feed-forward loop motif) contributed to modulating MTDH expression. Knockdown of MTDH expression profoundly retarded xenograft tumor growth. Thus, our findings support the notion that MTDH integrates upstream signals from certain transcription factors and mediates pathogenic interactions contributing to MPM traits. MTDH represents a new MPM-associated gene that can contribute to insights of MPM biology and, as such, suggest other treatment strategies.

Vinculin promotes gastric cancer proliferation and migration and predicts poor prognosis in patients with gastric cancer

Vinculin is a highly conserved protein involved in cell proliferation, migration, and adhesion. However, the effects of vinculin on gastric cancer (GC) remain unclear. Therefore, we aimed to explore the functional role of vinculin in GC, as well as its underlying mechanism. Expression of vinculin in patients with GC was analyzed by real-time polymerase chain reaction, Western blot analysis, and immunohistochemistry. Overall survival was evaluated by the Kaplan-Meier method with the log-rank test. The relationship between vinculin and clinicopathological characteristics of patients with GC was further identified. In addition, we assessed the expression of vinculin in GC cell lines. Besides, vinculin was suppressed or overexpressed by transfection with small interfering (si-vinculin) or pcDNA-vinculin and then cell viability, cell apoptosis, and/or migration was respectively examined by the 3-(4, 5-dimethylthiazole-2-yl)-2, 5-biphenyl tetrazolium bromide assay, flow cytometer, and scratch assay, respectively. Moreover, the cell cycle- and apoptosis-related proteins were detected by Western blot analysis. The expression of vinculin was significantly increased in the GC tissues and cells compared with the nontumor tissues or cells. Vinculin protein positive staining was mainly located in the cell membrane and cytoplasm. Moreover, vinculin was significantly associated with Tumor Node Metastasis (TNM) and poor differentiation. Patients with high vinculin levels had significantly worse overall survival than those with low levels. Suppression of vinculin significantly decreased cell viability and migration and promoted cell apoptosis. However, overexpression of vinculin statistically increased cell viability but had no effects on cell apoptosis. Vinculin promotes GC proliferation and migration and predicts poor prognosis in patients with GC.

MicroRNA-30a Mediates Cell Migration and Invasion by Targeting Metadherin in Colorectal Cancer

MicroRNAs play critical roles in the occurrence and progression in various cancers including colorectal cancer. Here, we found that microRNA-30a expression was significantly downregulated in colorectal cancer tissues compared to adjacent noncancerous tissues, and the suppression levels of microRNA-30a were significantly associated with tumor differentiation and lymph node metastasis. We also discovered that the expression level of microRNA-30a was inversely proportional to the invasive potential of several colorectal cancer cell lines. Moreover, overexpression of microRNA-30a in colorectal cancer cells inhibited activity of cell migration and invasion. Luciferase reporter assay confirmed metadherin could be a direct target of microRNA-30a, as the overexpression of microRNA-30a decreased metadherin expression at both the protein and messenger RNA levels. Furthermore, the knockdown of metadherin expression in SW620 significantly decreased cell metastasis and invasion. The upregulation of metadherin at the protein level negatively correlated with the expression of microRNA-30a in colorectal cancer tissues, and this upregulation could partially attenuate the effect induced by microRNA-30a. These findings indicate that microRNA-30a may act as a tumor suppressor in colorectal cancer and that microRNA-30a represses cell migration and invasion by decreasing metadherin, highlighting the therapeutic potential of microRNA-30a and metadherin in colorectal cancer treatment.

A Preliminary Study on Metadherin as a Potential Marker for Progression of Diffuse Large B Cell Lymphoma

AIMS

To determine if Metadherin (MTDH) expression levels are positively correlated with the clinical stage of diffuse large B-cell lymphoma (DLBCL) based on MTDH being highly expressed in other type of tumors including melanoma, malignant glioma, breast cancer, and hepatocellular carcinoma. In this study, we investigated the pathologic significance of MTDH and its potential in predicting DLBCL outcomes.

MATERIALS AND METHODS

Tissue samples from 50 patients with DLBCL and 22 patients with lymph node reactive hyperplasia were collected and evaluated using immunohistochemical staining, microscopy, and western blotting. The Kaplan-Meier method and Cox regression model were used for survival analysis of patients.

RESULTS

Our results show that the overexpression of the MTDH protein in tissues was observed in 66% of patients with DLBCL, whereas it was not overexpressed in the patients with reactive hyperplastic lymph nodes. While there was no correlation between MTDH overexpression with age, sex, presence of B symptoms, and lactate dehydrogenase (LDH) levels in patients with DLBCL, this parameter was positively correlated with clinical stages. Moreover, MTDH-negative patients had significantly better prognoses compared with the MTDH-positive patients.

CONCLUSION

Our preliminary study indicates that MTDH may play an important role in the development of DLBCL, and that MTDH overexpression is potentially associated with the clinical progression of DLBCL. In addition, high expression levels of MTDH in tissues was correlated with a poorer prognosis for patients with DLBCL. As such, MTDH may be a potential therapeutic target for specific therapy. However, research on a larger group of patients is needed to verify these preliminary results.

Astrocyte Elevated Gene 1 (AEG-1) Acts as a Promoter Gene in Clear Cell Renal Cell Carcinoma Cell Growth and Metastasis

Background

Clear cell renal cell carcinoma (ccRCC) is usually incurable once it progresses to metastatic stage. Hence, in-depth investigations to reveal the precise molecular mechanisms behind the metastasis of ccRCC are required to improve the therapeutic outcome of ccRCC.

Material/Methods

The level of astrocyte elevated gene 1 (AEG-1) in ccRCC tissues and cell lines was determined by quantitative real-time PCR (qRT-PCR) assay. The MTS, colony formation, wound-healing, and Transwell invasion assays were used to assess the role of AEG-1 in ccRCC cells growth, migration, and invasion in vitro, respectively. Xenograft model and lung metastasis models were constructed to analyze the functions of AEG-1 in ccRCC cells growth and metastasis in vivo.

Result

We found that AEG-1 was overexpressed in ccRCC and was associated with the progression of ccRCC. Knocked-down AEG-1 impaired the migration and invasion of ccRCC cells in vitro. Furthermore, under-expression of AEG-1 caused complete inhibition of ccRCC cells growth and metastasis in vivo. In contrast, overexpression of AEG-1 significantly increased the migration and invasion ability of ccRCC cells in vitro. Finally, we revealed that AEG-1 boosted the metastatic ability of ccRCC cells via regulating Notch homolog 1 (Notch1).

Conclusions

The AEG-1/Notch1 signaling axis plays a vital role in ccRCC cell growth and metastasis.

Efficient and tumor-specific knockdown of MTDH gene attenuates paclitaxel resistance of breast cancer cells both in vivo and in vitro

Background

Drug resistance of paclitaxel (TAX), the first-line chemotherapy drug for breast cancer, was reported to develop in 90% of patients with breast cancer, especially metastatic breast cancer. Investigating the mechanism of TAX resistance of breast cancer cells and developing the strategy improving its therapeutic efficiency are crucial to breast cancer cure.

Methods and Results

We here report an elegant nanoparticle (NP)-based technique that realizes efficient breast cancer treatment of TAX. Using lentiviral vector-mediated gene knockdown, we first demonstrated that TAX therapeutic efficiency was closely correlated with metadherin (MTDH) gene expression in breast cancer cell lines. This finding was also supported by efficacy of TAX treatment in breast cancer patients from our clinical studies. Specifically, TAX treatment became more effective when MTDH expression was decreased in MCF-7 cancer cells by the blocking nuclear factor-kappa B (NF-κB) pathway. Based on these findings, we subsequently synthesized a polymeric NP that could co-deliver MTDH-small interfering RNA (MTDH–siRNA) and TAX into the breast cancer tumors in tumor-bearing mice. The NPs were composed of a cationic copolymer, which wrapped TAX in the inside and adsorbed the negatively charged siRNA on their surface with high drug-loading efficiency and good stability.

Conclusions

NP-based co-delivery approach can effectively knock down the MTDH gene both in vitro and in vivo, which dramatically inhibits breast tumor growth, achieving effective TAX chemotherapy treatment without overt side effects. This study provides a potential therapeutic strategy for the treatment of a wide range of solid tumors highly expressing MTDH.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1042-7) contains supplementary material, which is available to authorized users.

Downregulation of microRNA-216b contributes to glioma cell growth and migration by promoting AEG-1-mediated signaling

Accumulating evidence indicates microRNA-216b (miR-216b) plays an important role in the development and progression of various cancers. However, little is known about the function of miR-216b in gliomas. In this study, we aimed to investigate the expression level and functional significance of miR-216b in gliomas. We found that miR-216b was significantly downregulated in glioma specimens and cell lines. Overexpression of miR-216b suppressed the growth and migration of glioma cells, while miR-216b inhibition showed the opposite effects. Astrocyte elevated gene-1 (AEG-1) was predicted as a potential target gene of miR-216b by bioinformatics analysis. A dual-luciferase reporter assay showed that miR-216b could directly target the 3'-untranslated region of AEG-1. RT-qPCR and western blot analysis showed that miR-216 negatively regulated AEG-1 expression in glioma cells. Correlation analysis revealed an inverse correlation between miR-216b and AEG-1 in clinical glioma specimens. miR-216b also regulated the activation of nuclear factor-κB and Wnt signaling in glioma cells. Moreover, restoration of AEG-1 expression partially reversed the inhibitory effect of miR-216b overexpression on glioma cell growth and migration. Overall, these results revealed a tumor suppressive role of miR-216b in glioma tumorigenesis, and identified AEG-1 as a target gene of miR-216b action. Our study suggests that miR-216b can be potentially targeted for the development of novel therapies for gliomas.

Pathway- and clinical-factor-based risk model predicts the prognosis of patients with gastric cancer

Gastric cancer (GC) has a high incidence and mortality rate. If discovered late, GC tends to have a poor prognosis. Improvements in the prognostic accuracy of GC through combined analysis of multiple relevant genes and clinical factors may solve this problem. In the present study, GSE62254 (including 300 GC tissues), obtained from the Gene Expression Omnibus database, was used as a training set, and the mRNA-sequencing data of GC (including 384 GC tissues) downloaded from the Cancer Genome Atlas database served as a validation set. Based on the t-test and Wilcoxon test, the significantly differentially expressed genes (DEGs) were obtained by screening the intersecting DEGs. The prognosis-associated genes and clinical factors were identified using Cox regression analysis in the R survival package. The optimal prognosis-associated pathways were examined using the Cox-proportional hazards (Cox-PH) model in the R penalized package. Finally, risk prediction models were constructed and validated using the Cox-PH model and the Kaplan-Meier method, respectively. There were a total of 382 significant DEGs, including 268 upregulated genes and 114 downregulated genes. A total of 50 prognosis-associated genes were identified, 16 optimal prognosis-associated pathways (including mitochondrial pathway and the tyrosine-protein kinase JAK-signal transducer and activator of transcription signaling pathway, which involve caspase 7, phosphoinositide-3-kinase regulatory subunit 3, peroxisome proliferator-activated receptor γ and collagen triple helix repeat containing 1) and four prognosis-associated clinical factors [including Pathologic_N, Pathologic_stage, mutL homolog 1 (MLH1) mutation and recurrence]. The pathway- and clinical-factor-based risk prediction model exhibited marked prognostic accuracy. The clinical-factor-based risk prediction model with improved P-values for prognosis prediction may be superior to the pathway-based risk prediction model in predicting the prognosis of GC patients.

Metadherin: An emerging key regulator of the malignant progression of multiple cancers

We and others recently identified the gene metadherin (MTDH) as a functional driver in multiple aspects of cancer progression. It is overexpressed in cancer cells originating from a variety of tissues, partially due to DNA amplification of the chromosomal 8q22 region where this gene resides. The rapidly accumulated data from MTDH studies of the past several years have documented its role in tumorigenesis, angiogenesis, cell proliferation, survival, anchorage-independent growth, metastasis and chemoresistance. In particular, it simultaneously helps the primary tumor cells to survive conventional chemotherapy and spread to distant organs, both of which are major contributors to cancer therapy failure and ultimately patient death. The efforts to elucidate the molecular mechanism of MTDH functions led to observations indicating its involvement in several prominent cancer-related signaling pathways including Ras, c-Myc, PI3K/AKT, NF-κB, Wnt/β-catenin, and more recently, microRNA machinery. Herein we will briefly summarize the studies that establish MTDH as a promising target for cancer therapeutics.

MicroRNA-197 inhibits gastric cancer progression by directly targeting metadherin

Gastric cancer is the fifth most frequent malignancy and the fourth most common cause of cancer‑associated mortality worldwide. MicroRNAs (miRNAs) are a group of small RNAs that regulate several cellular processes. In particular, a large number of miRNAs are involved in gastric cancer formation and progression. Thus, miRNAs may be considered as effective diagnostic biomarkers and therapeutic methods for gastric cancer. The aim of the current study was to detect miRNA (miR)‑197 expression in gastric cancer and to investigate its biological role and associated mechanism in gastric cancer. In the present study, miR‑197 expression was demonstrated to be considerably downregulated in gastric cancer tissues and cell lines. Its low expression level was associated with tumour size, invasive depth, tumour‑node‑metastasis staging and lymph node metastasis. High expression of miR‑197 inhibited tumour cell proliferation and invasion in vitro. Subsequently, metadherin (MTDH) was identified as a direct target gene of miR‑197 in gastric cancer, and this was confirmed by bioinformatics analysis, Dual‑luciferase reporter assay, reverse transcription quantitative polymerase chain reaction and western blot analysis. MTDH expression was upregulated in gastric cancer and was inversely correlated with miR‑197 expression levels. In addition, MTDH overexpression prevented the proliferation and inhibited invasion induced by miR‑197 overexpression. In addition, miR‑197 was demonstrated to regulate the phosphatase and tensin homolog (PTEN)/AKT signalling pathway in gastric cancer. The results of the present study suggested that miR‑197 serves a tumour‑suppressing role in human gastric carcinogenesis and progression by regulating the MTDH/PTEN/AKT signalling pathway. The miR‑197/MTDH axis may provide a novel effective therapeutic target for patients with gastric cancer.

AEG-1 mRNA expression in non-small cell lung cancer is associated with increased tumor angiogenesis

Astrocyte-elevated gene-1 (AEG-1) is implicated in the oncogenesis and angiogenesis of various types of human malignant disease. However, the angiogenesis roles of AEG-1 in non-small cell lung cancer (NSCLC) remain to be further elucidated. In the present study, the expression level of AEG-1 mRNA in seven human lung cell lines and 89 paired tissue samples (tumor tissues (TTs) and pair-matched normal adjacent tissues (PMNATs)) from NSCLC patients was detected by real-time PCR. Staining of vascular endothelial growth factor (VEGF) and intratumoral microvessel density (iMVD, labeled by CD105) were assessed by immunohistochemistry. Furthermore, cell migration and invasion were evaluated by wound healing assay and transwell assays. AEG-1 mRNA level was significantly higher in human lung cancer cells and TTs than that in human normal bronchial epithelial cell line 16HBE and PMNATs, respectively (P<0.001). Higher AEG-1 mRNA level in patients with NSCLC was correlated with clinical stages (P=0.028), differentiation (P=0.042), and lymph node metastasis (P=0.004). Moreover, Upregulated AEG-1 mRNA expression level was associated with higher tumor angiogenesis, reflected by the increase of VEGF expression and iMVD counting (P=0.021, P<0.001). However, 95D cell line transfected with AEG-1 siRNA oligos (siAEG-1) exhibited no significant decrease of cell invasion or migration capacities when compared with the control cells (P>0.05).These results suggested that AEG-1 may play important roles at the transcription level in malignant transformation and tumor angiogenesis in NSCLC, and anti-AEG-1 mRNA expression may be a novel potential strategy for anti-angiogenic therapy of NSCLC.

Post-trimodality expression levels of metadherin (MTDH) as a prognostic biomarker for esophageal adenocarcinoma patients

Resectable esophageal adenocarcinoma (EAC) patients often receive chemoradiation followed by surgery. However, most patients experience recurrences. Overexpression of MTDH, an oncoprotein with multiple functions, has been found to be associated with poor prognosis in breast cancer, glioblastoma, melanoma and various gastrointestinal malignancies, but not in EAC. We sought to establish its role in resistant EAC (post-treatment residual EAC). MTDH was assessed by immunohistochemistry in resected EAC, and results were correlated with clinical outcomes. MTDH expression was detectable in 72.5% (50/69) of patients, while expression levels were high (positive) in 50.7% (35/69). Of 69 patients analyzed, 25 had no relapse and 44 patients had a relapse (8 with local-regional and 36 with distant). The median follow-up duration was 3 years (0.4-11.6). The median overall survival was not associated with MTDH status (2.79 years for MTDH-negative and 3.60 years for MTDH-positive patients, p = 0.121). In addition, MTDH was not associated with either the type of relapse (local or distant), baseline clinical stage, tumor grade, presence of signet ring cells, surgical (yp) stage, percentage of residual EAC or presence of lymphovascular invasion. Our data reveal that MTDH is not a prognostic biomarker in resistant EAC after trimodality therapy.

AEG-1 induces gastric cancer metastasis by upregulation of eIF4E expression

Gastric cancer is the third leading cause of cancer-related deaths worldwide, and patients with lymph node, peritoneal and distant metastasis have a poor prognosis. Overexpression of Astrocyte-elevated gene-1 (AEG-1) has been reported to be correlated with the progression and metastasis of gastric cancer. However, its mechanisms are quite unclear. In this study, we found that elevated expression of AEG-1 was correlated with metastasis in human gastric cancer tissues. Moreover, gain- or loss-of-function of AEG-1, respectively, promoted or suppressed epithelial-mesenchymal transition (EMT), migration and invasion of gastric cancer cells. AEG-1 positively regulated eIF4E, MMP-9 and Twist expression. Manipulating eIF4E expression by transfection of overexpression constructs or siRNAs partially eliminated AEG-1-regulated EMT, cell migration and invasion. In addition, overexpression or knockdown of eIF4E promoted or suppressed EMT, cell migration and invasion in parallel with upregulation of MMP-9 and Twist expression, while manipulating eIF4E expression partially abrogated AEG-1-induced MMP-9 and Twist. Finally, silencing of AEG-1 expression not only inhibited tumour growth in parallel with downregulation of eIF4E, MMP-9 and Twist expression in a xenograft nude mouse model, but also suppressed lymph node and peritoneal metastasis of gastric cancer in an orthotopic nude mouse model. These findings suggest that AEG-1 promotes gastric cancer metastasis through upregulation of eIF4E-mediated MMP-9 and Twist, which provides new diagnostic markers and therapeutic targets for cancer metastasis.

The expressions of metadherin and LEF-1 in mucosa-associated lymphoid tissue lymphoma of ocular adnexal

AIM

To investigate the expressions of metadherin (astrocyte elevated gene-1, AEG-1) and lymphoid enhancer-binding factor-1 (LEF-1) in ocular adnexal mucosa-associated lymphoid tissue (MALT) lymphoma.

METHODS

The expressions of AEG-1 and LEF-1 were detected on specimens harvested from patients suffering from MALT lymphoma and lymphadenosis of ocular adnexal in Ophthalmology Department, Affiliated Hospital of Qingdao University from 2000 to 2015 by immunohistochemical and polymerase chain reaction (PCR) analysis.

RESULTS

AEG-1 and LEF-1 expressions in MALT lymphoma was respectively higher than that in lymphadenosis, both by immunohistochemical and PCR analysis (P<0.05). Diversity of AEG-1 and LEF-1 expressions in different Ann Arbor clinical stages showed a statistically significant result (P<0.05). A positive relevance between AEG-1 and LEF-1 was observed in MALT ocular adnexal lymphoma (r=0.435, P=0.016).

CONCLUSION

The over expressions of AEG-1 and LEF-1 at the level of protein and mRNA participates in the tumorigenesis of ocular adnexal MALT lymphoma. They should act as a new biological marker for pathological diagnosis in the future.

SU6668 modulates prostate cancer progression by downregulating MTDH/AKT signaling pathway

Prostate cancer is the second leading cause of cancer deaths among men in Western counties and has increased in incidence also in China in recent years. Although diagnosis modalities for primary prostate cancer have markedly improved, there are still no effective therapies for metastatic prostate cancer. SU6668 is an inhibitor of the tyrosine kinase activity of three angiogenic receptors VEGFR2, PDGFRβ and FGFR1. There is strong experimental evidence that SU6668 can induce growth inhibition of various primary tumors. However, the function and molecular mechanism of SU6668 in prostate cancer has not been fully elucidated. In the present study, we found that SU6668 inhibited the proliferation and invasion of prostate cancer cells. Functional studies also demonstrated that SU6668 inhibited epithelial-mesenchymal transition in DU145 and LNCap cells. After treatment with SU6668, MTDH protein, which has been reported to be significantly overexpressed in many human tumor tissues, was downregulated in DU145 and LNCap cells. siRNA-mediated silencing of MTDH in prostate cancer cells decreased their proliferation and invasive capabilities, suggesting that SU6668 may inhibit cell proliferation and invasion of prostate cancer cells partly through downstream targeting of MTDH. Mechanistic investigations showed that AKT signaling pathway was inhibited after SU6668 treatment in prostate cancer cells. Moreover, a combination of SU6668 and PI3K-AKT pathway inhibitor LY29004 resulted in increased inhibition of cell proliferation and invasion in DU145 cells. Taken together, our findings revealed that SU6668 suppressed prostate cancer progression by downregulating MTDH/AKT signaling pathway and identified a promising therapeutic strategy for prostate 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.

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 (r_s=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.

Astrocyte elevated gene-1 (AEG-1) and the A(E)Ging HIV/AIDS-HAND

Recent attempts to analyze human immunodeficiency virus (HIV)-1-induced gene expression changes in astrocytes uncovered a multifunctional oncogene, astrocyte elevated gene-1 (AEG-1). Our previous studies revealed that AEG-1 regulates reactive astrocytes proliferation, migration and inflammation, hallmarks of aging and CNS injury. Moreover, the involvement of AEG-1 in neurodegenerative disorders, such as Huntington's disease and migraine, and its induction in the aged brain suggest a plausible role in regulating overall CNS homeostasis and aging. Therefore, it is important to investigate AEG-1 specifically in aging-associated cognitive decline. In this study, we decipher the common mechanistic links in cancer, aging and HIV-1-associated neurocognitive disorders that likely contribute to AEG-1-based regulation of astrocyte responses and function. Despite AEG-1 incorporation into HIV-1 virions and its induction by HIV-1, tumor necrosis factor-α and interleukin-1β, the specific role(s) of AEG-1 in astrocyte-driven HIV-1 neuropathogenesis are incompletely defined. We propose that AEG-1 plays a central role in a multitude of cellular stress responses involving mitochondria, endoplasmic reticulum and the nucleolus. It is thus important to further investigate AEG-1-based cellular and molecular regulation in order to successfully develop better therapeutic approaches that target AEG-1 to combat cancer, HIV-1 and aging.

Astrocyte Elevated Gene-1 as a Novel Clinicopathological and Prognostic Biomarker for Gastrointestinal Cancers: A Meta-Analysis with 2999 Patients

BACKGROUND

There have been numerous articles as to whether the staining index (SI) of astrocyte elevated gene-1 (AEG-1) adversely affects clinical progression and prognosis of gastrointestinal cancers. Nevertheless, controversy still exists in terms of correlations between AEG-1 SI and clinicopathological parameters including survival data. Consequently, we conducted a comprehensive meta-analysis to confirm the role of AEG-1 in clinical outcomes of gastrointestinal carcinoma patients.

METHODS

We performed a comprehensive search in PubMed, ISI Web of Science, Cochrane Central Register of Controlled Trials, EMBASE, Science Direct, Wiley Online Library, China National Knowledge Infrastructure (CNKI), WanFang and Chinese VIP databases. STATA 12.0 (STATA Corp., College, TX) was used to analyze the data extracted from suitable studies and Newcastle-Ottawa Scale was applied to assess the quality of included articles.

RESULTS

The current meta-analysis included 2999 patients and our results suggested that strong associations emerged between AEG-1 SI and histological differentiation (OR = 2.129, 95%CI: 1.377-3.290, P = 0.001), tumor (T) classification (OR = 2.272, 95%CI: 1.147-4.502, P = 0.019), lymph node (N) classification (OR = 2.696, 95%CI: 2.178-3.337, P<0.001) and metastasis (M) classification (OR = 3.731, 95%CI: 2.167-6.426, P<0.001). Furthermore, high AEG-1 SI was significantly associated with poor overall survival (OS) (HR = 2.369, 95%CI: 2.005-2.800, P<0.001) and deteriorated disease-free survival (DFS) (HR = 1.538, 95%CI: 1.171-2.020, P = 0.002). For disease-specific survival (DSS) and relapse-free survival (RFS), no statistically significant results were observed (HR = 1.573, 95%CI: 0.761-3.250, P = 0.222; HR = 1.432, 95%CI: 0.108-19.085, P = 0.786). Subgroup analysis demonstrated that high AEG-1 SI was significantly related to poor prognosis in esophageal squamous cell carcinoma (ESCC) (HR = 1.715, 95%CI: 1.211-2.410, P = 0.002), gastric carcinoma (GC) (HR = 2.255, 95%CI: 1.547-3.288, P<0.001), colorectal carcinoma (CRC) (HR = 2.922, 95%CI: 1.921-4.444, P<0.001), gallbladder carcinoma (GBC) (HR = 3.047, 95%CI: 1.685-5.509, P<0.001), hepatocellular carcinoma (HCC) (HR = 2.245, 95%CI: 1.620-3.113, P<0.001), pancreatic adenocarcinoma (PAC) (HR = 2.408, 95%CI: 1.625-3.568, P<0.001).

CONCLUSIONS

The current meta-analysis indicated that high AEG-1 SI might be associated with tumor progression and poor survival status in patients with gastrointestinal cancer. AEG-1 might play a vital role in promoting tumor aggression and could serve as a potential target for molecular treatments. Further clinical trials are needed to validate whether AEG-1 SI provides valuable insights into improving treatment decisions.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

AEG-1 was associated with the progression of CSCC by promoting epithelial-mesenchymal transition via Wnt signaling pathway.

The expression of astrocyte elevated gene-1 in human non-small-cell lung cancer and its relationship with postoperative chemotherapy and radiotherapy

AIMS

To examine the expression of astrocyte elevated gene-1 (AEG-1) in non-small-cell lung cancer (NSCLC) and analyse the correlation between AEG-1 expression and the prognosis of the patients, particularly the relationship between AEG-1 expression and postoperative chemotherapy and radiotherapy.

METHODS

The expression of AEG-1 was analysed by immunohistochemistry in 225 primary NSCLC specimens and 42 adjacent normal lung tissue specimens. Statistical analyses were performed to evaluate the correlation between AEG-1 expression and the clinicopathological characteristics of the patients as well as the predictive value of AEG-1.

RESULTS

The expression of AEG-1 was associated with the pathological stage (P < 0.001) and lymph node status (P = 0.028). A multivariate analysis indicated that AEG-1 expression was an independent prognostic factor for both overall survival (OS) and disease-free survival (DFS). In the postoperative chemotherapy group, the OS (P = 0.014) and DFS (P = 0.009) in the low AEG-1 expression group were longer than the survival times in the high AEG-1 expression group. In the postoperative radiotherapy group, the local recurrence-free survival was significantly shorter in patients whose tumours showed high AEG-1 expression (P = 0.016).

CONCLUSIONS

AEG-1 expression could be a predictor for OS and DFS in NSCLC patients. Patients with low AEG-1 expression received the greatest benefit from both postoperative chemotherapy and radiotherapy.

Molecular Modification of Metadherin/MTDH Impacts the Sensitivity of Breast Cancer to Doxorubicin

BACKGROUND

Breast cancer is a leading cause of death in women and with an increasing worldwide incidence. Doxorubicin, as a first-line anthracycline-based drug is conventional used on breast cancer clinical chemotherapy. However, the drug resistances limited the curative effect of the doxorubicin therapy in breast cancer patients, but the molecular mechanism determinants of breast cancer resistance to doxorubicin chemotherapy are not fully understood. In order to explore the association between metadherin (MTDH) and doxorubicin sensitivity, the differential expressions of MTDH in breast cancer cell lines and the sensitivity to doxorubicin of breast cancer cell lines were investigated.

METHODS

The mRNA and protein expression of MTDH were determined by real-time PCR and Western blot in breast cancer cells such as MDA-MB-231, MCF-7, MDA-MB-435S, MCF-7/ADR cells. Once MTDH gene was knocked down by siRNA in MCF-7/ADR cells and overexpressed by MTDH plasmid transfection in MDA-MB-231 cells, the cell growth and therapeutic sensitivity of doxorubicin were evaluated using MTT and the Cell cycle assay and apoptosis rate was determined by flow cytometry.

RESULTS

MCF-7/ADR cells revealed highly expressed MTDH and MDA-MB-231 cells had the lowest expression of MTDH. After MTDH gene was knocked down, the cell proliferation was inhibited, and the inhibitory rate of cell growth and apoptosis rate were enhanced, and the cell cycle arrest during the G0/G1 phase in the presence of doxorubicin treatment. On the other hand, the opposite results were observed in MDA-MB-231 cells with overexpressed MTDH gene.

CONCLUSION

MTDH gene plays a promoting role in the proliferation of breast cancer cells and its high expression may be associated with doxorubicin sensitivity of breast cancer.

Astrocyte elevated gene-1 overexpression in hepatocellular carcinoma: an independent prognostic factor

PURPOSE

Astrocyte elevated gene-1 (AEG-1) plays important roles in tumorigenesis such as proliferation, invasion, metastasis, angiogenesis, and chemoresistance. We examined the expression of AEG-1 in patients with hepatocellular carcinoma (HCC).

METHODS

Eighty-five samples were collected from patients with HCC who underwent surgery and were histopathologically confirmed to have HCC. Two independent pathologists, experienced in evaluating immunohistochemistry and blinded to the clinical outcomes of the patients, reviewed all samples. They determined AEG-1 expression semiquantitatively by assessing the percentage of positively stained immunoreactive cells and staining intensity. Clinicopathological data were analyzed in association with prognosis.

RESULTS

The association was estimated by univariate and multivariate analyses with Cox regression. Tumor size (hazard ratio [HR], 2.285; 95% confidence interval [CI], 1.175-4.447; P = 0.015), microvascular invasion (HR, 6.754; 95% CI, 1.631-27.965; P = 0.008), and AEG-1 expression (HR, 4.756; 95% CI, 1.697-13.329; P = 0.003) were independent prognostic factors for overall survival. Those for disease-free survival rate were tumor size (HR, 2.245; 95% CI, 1.282-3.933; P = 0.005) and AEG-1 expression (HR, 1.916; 95% CI, 1.035-3.545; P = 0.038). The cumulative 5-year survival and recurrence rates were 89.2% and 50.0% in the low-expressing group and 24.5% and 82.4% in the high-expressing group, respectively.

CONCLUSION

The results suggest that AEG-1 overexpression could serve as a valuable prognostic marker in patients with HCC.

Metadherin contributes to the pathogenesis of chronic lymphocytic leukemia partially through Wnt/β-catenin pathway

Metadherin (MTDH) is involved in aberrant proliferation, migration, and chemoresistance of tumor cells. It has been demonstrated that it can promote tumor growth by modulation multiple oncogenic signaling pathways. However, MTDH expression, significance, and related mechanism in chronic lymphocytic leukemia (CLL) are still unclear. The objective of this study was to investigate the expression of MTDH in CLL and the involvement of Wnt/β-catenin signaling pathway in MTDH effects. Overexpression of MTDH mRNAs was seen in CLL samples. MTDH expression was associated with Rai stage classification of CLL, and altered levels of β2-MG and lactate dehydrogenase in serum samples from patients. Overexpression of MTDH protein was seen in 87 % of CLL samples. Specific siRNAs inhibited MEC-1 cell growth and enhanced cell apoptosis (P < 0.05). Inhibition of MTDH expression resulted in decreased expression levels of lymphoid enhancer-binding factor 1 (LEF-1), and its downstream target genes c-myc and cyclin D1. And there was a strong correlation between MTDH and LEF-1 protein expression in 14 patients with CLL. The results demonstrate that MTDH is specifically expressed in B cell of CLL and exert a preservative role through activation of Wnt signaling pathway. Our findings indicated that MTDH may be a potential therapeutic target of CLL.

Overexpression of astrocyte-elevated gene-1 is associated with ovarian cancer development and progression

It has previously been reported that astrocyte‑elevated gene‑1 (AEG‑1) has a critical role in the regulation of tumor development, and/or progression. However, the functional significance of AEG‑1 in human ovarian cancer remains unclear. The present study conducted an immunohistochemical analysis of ovarian tissues, and the association between AEG‑1 protein expression, clinicopathological features and outcomes were investigated. The gain or loss of AEG‑1 function was also examined, through exogenous overexpression or knockdown of expression by small interfering RNA, in ovarian cancer cells. Normal ovarian tissue exhibited very little or no AEG‑1 immunoreactivity, whereas high expression levels of AEG‑1 were detected in 12.7% of cystadenomas, 30.0% of borderline tumors, and 71.2% of ovarian carcinomas, respectively, as determined by immunohistochemistry. Statistical analyses demonstrated a significant correlation of AEG‑1 expression with differentiation (P=0.001), lymph node metastasis (P=0.008) and clinical staging (P=0.002). In addition, the overall survival time of patients with higher AEG‑1 expression levels was markedly shorter, as compared with patients with lower expression levels of AEG‑1 (P=0.001). Multivariate analysis indicated that AEG‑1 expression was an independent prognostic indicator of the survival of patients with ovarian cancer. Furthermore, exogenous overexpression of AEG‑1 in ovarian cancer cells was shown to significantly enhance cell proliferation, adhesion and invasion. Conversely, silencing AEG‑1 expression caused an inhibition of cell growth, adhesion and invasion. The results of the present study indicate that AEG‑1 is a valuable biomarker for the prediction of ovarian cancer prognosis, and AEG‑1 inhibition may be a potential therapeutic strategy for ovarian cancer treatment.

MicroRNA-542-3p suppresses cell growth of gastric cancer cells via targeting oncogene astrocyte-elevated gene-1

MicroRNAs (miRNAs) have been suggested to play critical roles in tumorigenesis as well as in the development of therapies for the treatment of cancers. However, the tumor-associated miRNAs in gastric cancers remain poorly understood. Here, we report on miR-542-3p in gastric cancers, which has been widely studied in other cancers as a tumor suppressor. Real-time quantitative PCR analysis demonstrated that miR-542-3p was significantly down-regulated in gastric cancer tissues (p < 0.0001) and cell lines (p < 0.001). Overexpression of miR-542-3p significantly inhibited cell growth of gastric cancer cells both in vitro (p < 0.01) and in vivo (p < 0.01). Notably, overexpression of miR-542-3p apparently reduced the protein expression of astrocyte-elevated gene-1 (AEG-1) (p < 0.01). The dual-luciferase reporter assay validated that miR-542-3p directly bound the 3'-untranslated region (UTR) of AEG-1, which could be abolished by mutation of the predicted miR-542-3p binding site. Furthermore, overexpression of miR-542-3p markedly inhibited the activation of oncogenic signaling pathways including the Akt, β-catenin and nuclear factor-κB pathways. Additionally, overexpression of AEG-1 without the 3'-UTR partially reversed the cell growth arrest induced by miR-542-3p overexpression in gastric cancer cells (p < 0.05). Taken together, these data suggest that miR-542-3p might function as a tumor suppressor in gastric cancer, potentially by targeting the oncogene AEG-1, implying a potential role for miR-542-3p in the development of therapeutic methods for gastric cancer.

High expression of astrocyte elevated gene-1 is associated with clinical staging, metastasis, and unfavorable prognosis in gastric carcinoma

More and more evidence has demonstrated that astrocyte elevated gene-1 (AEG-1) is tightly associated with progression, metastasis, and unfavorable prognosis in many malignancies. However, the potential biological role of AEG-1 in gastric carcinoma (GC) has not been thoroughly delineated. In the current study, we found that AEG-1 mRNA and protein levels in GC tissues were significantly higher than those in normal gastric mucosa (P < 0.05). Simultaneously, statistical analysis displayed a significant correlation of high AEG-1 mRNA and protein expressions with differentiation status, TNM staging, invasive depth, and lymph node metastasis (P < 0.05). Most importantly, expressions of AEG-1 mRNA and protein in high clinical staging and metastatic GC tissues were dramatically higher than those in low clinical staging and non-metastatic GC tissues (P < 0.05). Stepwise investigation confirmed that the survival time of the patients with high AEG-1 level was shorter than those with low AEG-1 level or negative AEG-1 staining. Taken altogether, our data presented herein suggest that AEG-1 may be a novel predictor for metastasis and prognosis of the patients with GC.

Low expression of SOCS-1 and SOCS-3 is a poor prognostic indicator for gastric cancer patients

BACKGROUND AND OBJECTIVES

Inflammation plays an important role in gastric cancer (GC) development and progression. Suppressor of cytokine signaling (SOCS)-1 and SOCS-3 negatively regulate proinflammatory cytokine signaling; however, their prognostic significance in GC remains unknown. We evaluated the clinicopathological correlation and prognostic significance of SOCS-1 and SOCS-3 in GC.

METHODS

SOCS-1 and SOCS-3 mRNA levels were analyzed in 80 paired gastric tumor and adjacent normal mucosal tissues using a microarray dataset from the Gene Expression Omnibus. Univariate and multivariate analyses were performed to investigate the prognostic impact of SOCS-1 and SOCS-3 immunohistochemical expression on overall survival (OS) and relapse-free survival (RFS) in 186 consecutive GC patients who underwent curative surgery.

RESULTS

SOCS-1 and SOCS-3 mRNA expression levels were lower in gastric tumor tissues than in matched normal mucosa. OS and RFS were significantly longer in the high SOCS-1 and SOCS-3 expression groups than in their corresponding low expression groups (p < 0.05). High simultaneous SOCS-1 and SOCS-3 expression were associated with longer OS compared with low simultaneous SOCS-1 and SOCS-3 expression (68.8 vs. 22.2 months; p < 0.001). SOCS-1 [hazards ratio (HR) 0.54, 95 % confidence interval (CI) 0.33-0.87, p = 0.011] and SOCS-3 (HR 0.46, 95 % CI 0.26-0.80, p = 0.006) were independent prognostic factors for OS. Only SOCS-1 (HR 0.20, 95 % CI 0.11-0.38, p = 0.006) was an independent prognostic factor for RFS.

CONCLUSION

Low SOCS-1 and SOCS-3 expression are poor prognostic indicators in GC. GC patients with low SOCS-1 and SOCS-3 expression need close follow-up.

Uncontrolled inflammation induced by AEG-1 promotes gastric cancer and poor prognosis

Gastric cancer is one of the most common causes of cancer-related death worldwide. Helicobacter pylori infection plays an important role in the development and progression of gastric cancer. The expression of astrocyte-elevated gene-1 (AEG-1) is increased in gastric cancer tissues, thereby contributing to the inflammatory response. We investigated whether and how AEG-1 regulated proinflammatory signaling in gastric cancer cells. We used human gastric cancer cell lines and athymic nude mice to investigate the role of AEG-1 in the regulation of the TLR4/nuclear factor-κB (NF-κB) signaling pathway and cancer invasion and compared the expression of AEG-1 and related proteins in 93 patients with gastric cancer by immunohistochemistry. In human gastric cancer cells, both AEG-1 and TLR4 could be induced by lipopolysaccharide (LPS) stimulation. AEG-1 was upregulated via LPS-TLR4 signaling and in turn promoted nuclear translocation of the NF-κB p65 subunit. At the same time, AEG-1 overexpression decreased the levels of suppressor of cytokine signaling (SOCS) protein SOCS-1, a negative regulator of the TLR4 pathway. Furthermore, nude mice engrafted with AEG-1/TLR4-expressing cells demonstrated larger tumor volumes than control animals. In patients with gastric cancer, the expression of AEG-1 correlated with that of TLR4, SOCS-1, and NF-κB and was higher in tumors compared with noncancerous adjacent tissues. Overall survival in patients with gastric cancer with simultaneous expression of AEG-1 and TLR4 was poor. Our results demonstrate that AEG-1 can promote gastric cancer progression by a positive feedback TLR4/NF-κB signaling-related mechanism, thus providing new mechanistic explanation for the role of inflammation in cancer progression.

Metadherin expression and lung relapse in patients with colorectal carcinoma

Colorectal cancer (CRC) is the third most common malignant disease in men and the second in women worldwide. CRC relapse occurs mostly in liver and lungs, decreasing the 5-year survival to 6 %. Metadherin (MTDH) is overexpressed in several types of cancer, has been implicated in proliferation, invasion, metastasis, angiogenesis, and chemoresistance, and is a factor of poor prognosis in CRC. In this work we addressed the prognostic significance of MTDH expression in CRC progression to the lungs. We found that MTDH gene was more frequently amplified (copy number >1.8) in patients with CRC and relapse to the lung, when compared to patients without lung metastases (17.4 vs 100 %; p < 0.001). We observed a correlation between MTDH gene copy number and MTDH expression by IHC (p = 0.0001). Next we also analyzed MTDH expression by IHC in samples from 85 patients diagnosed with CRC, stage II or III, M0, with at least 3 years of follow-up. Kaplan-Meier survival analysis showed that lung relapse-free survival (HR 5.29, 95 % CI 1.90-14.77, p = 0.0004), liver relapse-free survival (HR 8.59, 95 % CI 0.99-74.18, p = 0.003), relapse-free survival (HR 4.85, 95 % CI 1.88-12.45, p = 0.0003) and overall survival (HR 3.75, 95 % CI 1.15-12.18, p = 0.018) were significantly lower in the group with high MTDH expression. Multivariate analysis showed that high MTDH expression was an independent factor for all outcomes. This study demonstrates that high MTDH expression is a biomarker of relapse in CRC, including lung-specific relapse. Determination of MTDH expression in primary CRC may be useful in the earlier detection of lung metastases in patients with high expression and increased risk.

Progress of cancer research on astrocyte elevated gene-1/Metadherin (Review)

Tumor development is initiated by an accumulation of numerous genetic and epigenetic alterations that promote tumor initiation, invasion and metastasis. Astrocyte elevated gene-1 [AEG-1; also known as Metadherin (MTDH) and Lysine-rich CEACAM1 co-isolated (LYRIC)] has emerged in recent years as a potentially crucial mediator of tumor malignancy, and a key converging point of a complex network of oncogenic signaling pathways. AEG-1/MTDH has a multifunctional role in tumor development that has been found to be involved in the following signaling cascades: i) The Ha-Ras and PI3K/Akt pathways; ii) the nuclear factor-κB signaling pathway; iii) the ERK/mitogen-activated protein kinase and Wnt/β-catenin pathways; and iv) the Aurora-A kinase signaling pathway. Studies have established that AEG-1/MTDH is crucial in tumor progression, including transformation, the evasion of apoptosis, invasion, angiogenesis and metastasis. In addition, recent clinical studies have convincingly associated AEG-1/MTDH with tumor progression and poor prognosis in a number of cancer types, including hepatocellular, esophageal squamous cell, gallbladder and renal cell carcinomas, breast, non-small cell lung, prostate, gastric and colorectal cancers, and glioma, melanoma, neuroblastoma and osteosarcoma. AEG-1/MTDH may be used as a biomarker to identify subgroups of patients who require more intensive treatments and who are likely to benefit from AEG-1/MTDH-targeted therapies. The therapeutic targeting of AEG-1/MTDH may simultaneously block metastasis, suppress tumor growth and enhance the efficacy of chemotherapeutic treatments.