Overexpression of metadherin/MTDH is associated with an aggressive phenotype and a poor prognosis in invasive breast cancer

Role of glutaminyl-peptide cyclotransferase in breast cancer doxorubicin sensitivity

Doxorubicin (DOX) is one of the most effective and widely used chemotherapeutic drugs. However, DOX resistance is a critical risk problem for breast cancer treatment. Previous studies have demonstrated that metadherin (MTDH) involves in DOX resistance in breast cancer, but the exact mechanism remains unclear. In this study, we found that glutaminyl-peptide cyclotransferase (QPCT) was a MTDH DOX resistance-related downstream gene in breast cancer. Elevated expression of QPCT was found in the GEPIA database, breast cancer tissue, and breast cancer cells. Clinical data showed that QPCT expression was positively associated with poor prognosis in DOX-treated patients. Overexpression of QPCT could promote the proliferation, invasion and migration, and reduce DOX sensitivity in MCF-7 and MDA-MB-231 cells. Mechanistically, MTDH positively regulates the expressions of NF-κB (p65) and QPCT, and NF-κB (p65) directly regulates the expression of QPCT. Therefore, MTDH/NF-κB (p65)/QPCT signal axis was proposed. Collectively, our findings delineate the mechanism by which the MTDH/NF-κB (p65) axis regulate QPCT signaling and suggest that this complex may play an essential role in breast cancer progression and affect DOX sensitivity.

Comprehensive pan‑cancer analysis of MTDH for human tumor prognosis and as an immunological biomarker including breast and kidney cancer

Metadherin (MTDH), initially discovered in primary astrocytes of the human fetus through rapid subtraction hybridization and labeled as astrocyte elevated gene-1, represents a widely recognized oncogene present in multiple types of cancers. However, the role of MTDH in different types of cancer remains unclear. To address this, a comprehensive analysis of MTDH across various types of cancers was conducted by utilizing multiple databases such as The Cancer Genome Atlas. The present analysis discovered that MTDH exhibits differential expression in different types of cancer and is associated with important factors including tumor mutational burden and microsatellite instability. These findings highlighted the significance of MTDH in the tumor microenvironment and its involvement in the development of immune cells in specific cancers. Furthermore, the results of the present study indicated that the expression of MTDH is strongly correlated with clinical prognosis, mutations and immune cell infiltration. MTDH could serve as a potential indicator of patient prognosis and potentially play a role in modulating the immune system. Given its potential as a novel immunological checkpoint, MTDH may be a viable target for tumor immunotherapy.

Metadherin promotes stem cell phenotypes and correlated with immune infiltration in hepatocellular carcinoma

BACKGROUND

Metadherin (MTDH) is a key oncogene in most cancer types, including hepatocellular carcinoma (HCC). Notably, MTDH does not affect the stemness pheno-type or immune infiltration of HCC.

AIM

To explore the role of MTDH on stemness and immune infiltration in HCC.

METHODS

MTDH expression in HCC tissues was detected using TCGA and GEO databases. Immunohistochemistry was used to analyze the tissue samples. MTDH was stably knocked down or overexpressed by lentiviral transfection in the two HCC cell lines. The invasion and migration abilities of HCC cells were evaluated using Matrigel invasion and wound healing assays. Next, we obtained liver cancer stem cells from the spheroids by culturing them in a serum-free medium. Gene expression was determined by western blotting and quantitative reverse transcri-ption PCR. Flow cytometry, immunofluorescence, and tumor sphere formation assays were used to characterize stem-like cells. The effects of MTDH inhibition on tumor growth were evaluated in vivo. The correlation of MTDH with immune cells, immunomodulators, and chemokines was analyzed using ssGSEA and TISIDB databases.

RESULTS

HCC tissues expressed higher levels of MTDH than normal liver tissues. High MTDH expression was associated with a poor prognosis. HCC cells overexpressing MTDH exhibited stronger invasion and migration abilities, exhibited a stem cell-like phenotype, and formed spheres; however, MTDH inhibition attenuated these effects. MTDH inhibition suppressed HCC progression and CD133 expression in vivo. MTDH was positively correlated with immature dendritic, T helper 2 cells, central memory CD8+ T, memory B, activated dendritic, natural killer (NK) T, NK, activated CD4+ T, and central memory CD4+ T cells. MTDH was negatively correlated with activated CD8+ T cells, eosinophils, activated B cells, monocytes, macrophages, and mast cells. A positive correlation was observed between the MTDH level and CXCL2 expression, whereas a negative correlation was observed between the MTDH level and CX3CL1 and CXCL12 expression.

CONCLUSION

High levels of MTDH expression in patients with HCC are associated with poor prognosis, promoting tumor stemness, immune infiltration, and HCC progression.

Bioinformatic analysis reveals an association between Metadherin with breast cancer prognosis and tumor immune infiltration

Breast cancer metastasis and invasion are both promoted by the oncoprotein Metadherin (MTDH). However, the the role of Metadherin in breast cancer progression and its role in the immune microenvironment. Are not clear. A bioinformatic analysis was performed to demonstrate the prognostic value of Metadherin in BC. In the present study, we found that Metadherin is overexpressed in BC and is significantly correlated with individual cancer stage, age, subclasses, menopause and nodal metastasis status. Metadherin overexpression was associated with a significant decrease in OS and DSS. Cox multivariate analysis indicated that Metadherin was an independent negative prognostic indicator for OS and DSS. Moreover, Metadherin hypomethylation status was associated with poor prognosis. A negative correlation was also noted between Metadherin overexpression and the number of plasmacytoid dendritic cells, cluster of differentiation 8+ T cells, and natural killer cells. Association patterns varied with different subtypes. Various associations between Metadherin levels and immune cell surface markers were revealed. A total of 40 groups of BC and adjacent normal breast tissue samples were collected. Metadherin mRNA was detected by PCR, and its expression levels in BC tissues were significantly increased compared with those noted in normal tissues. The expression levels of Metadherin were also measured in normal and BC cell lines, respectively, and similar conclusions were obtained. The Metadherin mRNA levels were knocked down in SK-BR3 and MDA-MB-231 cell lines and the cell proliferative and migratory activities were determined using Cell Counting Kit-8 and scratch assays, respectively. The results indicated that the cell proliferative and migratory abilities were reduced following knockdown of Metadherin expression. Therefore, Metadherin may be considered as a novel prognostic biomarker in BC.

Roles and Molecular Mechanisms of Biomarkers in Hepatocellular Carcinoma with Microvascular Invasion: A Review

Hepatocellular carcinoma (HCC) being a leading cause of cancer-related death, has high associated mortality and recurrence rates. It has been of great necessity and urgency to find effective HCC diagnosis and treatment measures. Studies have shown that microvascular invasion (MVI) is an independent risk factor for poor prognosis after hepatectomy. The abnormal expression of biomacromolecules such as circ-RNAs, lncRNAs, STIP1, and PD-L1 in HCC patients is strongly correlated with MVI. Deregulation of several markers mentioned in this review affects the proliferation, invasion, metastasis, EMT, and anti-apoptotic processes of HCC cells through multiple complex mechanisms. Therefore, these biomarkers may have an important clinical role and serve as promising interventional targets for HCC. In this review, we provide a comprehensive overview on the functions and regulatory mechanisms of MVI-related biomarkers in HCC.

DOT1L regulates MTDH-mediated angiogenesis in triple-negative breast cancer: intermediacy of NF-κB-HIF1α axis

DOT1L, a specific H3K79 methyltransferase, has a tumour-promoting role in various cancers, including triple-negative breast cancer (TNBC). However, the molecular mechanism by which the deregulated DOT1L promotes cancer progression is unclear. Herein, we show that a significantly higher basal level of DOTL1 strongly correlates with MTDH, an oncogene, in clinical TNBC patient cohorts and mediates TNBC progression by enhancing MTDH-induced angiogenesis. In parallel, severe combined immunodeficiency mice-bearing MDA-MB-231 cells with MTDH-Wt or MTDHΔ7 (spliced isoform of MTDH) overexpression constructs showed enhanced blood vessel formations at the tumour site in comparison with control groups. Selective inhibition of DOT1L by EPZ004777, a specific DOT1L inhibitor, or siDOT1L, significantly impaired MTDH-induced proliferation, invasion and angiogenic markers expression in TNBC cells. ChIP assay revealed that Dot1L promotes MTDH-Wt/Δ7 transcription by increasing H3K79me3 levels on its promoter. Dot1L depletion reversed this effect. Mechanistically, DOT1L-induced MTDH caused enhanced nuclear factor kappa B (NF-κB) occupancy on the hypoxia-inducible factor1α (HIF1α) promoter and increased its transcription, leading to elevated levels of proangiogenic mediators in TNBC cells. Moreover, the condition media obtained from MDA-MB-231 cells stably expressing either MTDH-Wt or MTDHΔ7 treated with EPZ004777 or Bay-11-7082 (NF-κB inhibitor) or FM19G11 (HIF1α inhibitor) significantly inhibited MTDH-induced tube formation in human umbilical vein endothelial cells, rat aortic ring sprouting and vessel formations by chick chorioallantoic membrane assay mimicking physiological angiogenic vasculature. Collectively, our findings reveal a novel epigenetic regulation of MTDH by DOTL1, which drives angiogenesis, and that the therapeutic disruption of the DOT1L-MTDH-NF-κB-HIF1α axis may have usefulness in the management of TNBC.

Pegylated Liposomal Doxorubicin, Docetaxel, and Trastuzumab as Neoadjuvant Treatment for HER2-Positive Breast Cancer Patients: A Phase II and Biomarker Study

Background

Combined neoadjuvant chemotherapy with trastuzumab and pertuzumab is the standard regimen for human epidermal growth receptor 2 (HER2)-positive breast cancer (BC). However, pertuzumab is not available because it is not on the market or covered by medicare in some regions or poor economy. Anthracyclines and taxanes are cornerstones in BC chemotherapy, and their combination contributes to satisfactory efficiency in neoadjuvant settings. Nonetheless, concomitant administration of trastuzumab and an anthracycline is generally avoided clinically due to cardiotoxicity. Pegylated liposomal doxorubicin (PLD) is less cardiotoxic compared with traditional anthracyclines. Here, we conducted this prospective study to evaluate the efficacy, safety, and potential biomarkers for PLD plus trastuzumab and docetaxel as neoadjuvant treatment in HER2-positive BC.

Patients and Methods

Patients with stage II or III HER2-positive BC were recruited in this multicenter, open-label, single-arm, phase II study. Eligible patients were given 6 cycles of PLD plus docetaxel and trastuzumab. Primary endpoint was total pathological complete response (tpCR, ypT0/is ypN0). Secondary endpoints were breast pathological complete response (bpCR, ypT0/is), objective response rate (ORR), operation rate, breast-conserving surgery rate, and safety. Metadherin (MTDH), glutaminyl-peptide cyclotransferase (QPCT), topoisomerase II alpha (TOP2A), programmed death ligand 1 (PD-L1), and tumor-infiltrating lymphocytes (TILs) were evaluated in BC tissues pre-neoadjuvant for potential biomarkers.

Results

Between March 2019 and February 2021, 54 patients were enrolled, 50 were included in the analysis, and 35 (70.0%) completed 6 cycles of neoadjuvant treatment. Forty-nine (98.0%) patients underwent surgery with a breast-conserving rate of 44.0%. The tpCR rate, bpCR rate, and ORR were 48.0% (95% CI, 33.7%–62.6%), 60.0% (95% CI, 45.2%–73.6%), and 84.0% (95% CI, 70.9%–92.8%), respectively. tpCR was associated with MTDH (p = 0.002) and QPCT (p = 0.036) expression but not with TOP2A (p = 0.75), PD-L1 (p = 0.155), or TILs (p = 0.76). Patients with HR-negative status were more likely to achieve bpCR compared with those with HR-positive status (76.2% vs. 48.3%, p = 0.047). Grade ≥3 adverse events occurred in 38.0% of patients. Left ventricular ejection fraction decline by ≥10% was reported in 18.0% of patients, and no patient experienced congestive heart failure.

Conclusions

PLD plus docetaxel and trastuzumab might be a potential neoadjuvant regimen for HER2-positive BC with a high tpCR rate and manageable tolerability. MTDH and QPCT are potential predictive markers for tpCR.

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.

circ-NOL10 regulated by MTDH/CASC3 inhibits breast cancer progression and metastasis via multiple miRNAs and PDCD4

Circular RNAs (circRNAs) play important roles in carcinogenesis. Here, we investigated the mechanisms and clinical significance of circ-NOL10, a highly repressed circRNA in breast cancer. Subsequently, we also identified RNA-binding proteins (RBPs) that regulate circ-NOL10. Bioinformatics analysis was utilized to predict regulatory RBPs as well as circ-NOL10 downstream microRNAs (miRNAs) and mRNA targets. RNA immunoprecipitation, luciferase assay, fluorescence in situ hybridization, cell proliferation, wound healing, Matrigel invasion, cell apoptosis assays, and a xenograft model were used to investigate the function and mechanisms of circ-NOL10 in vitro and in vivo. The clinical value of circ-NOL10 was evaluated in a large cohort of breast cancer by quantitative real-time PCR. Circ-NOL10 is downregulated in breast cancer and associated with aggressive characteristics and shorter survival time. Upregulation of circ-NOL10 promotes apoptosis, decreases proliferation, and inhibits invasion and migration. Furthermore, circ-NOL10 binds multiple miRNAs to alleviate carcinogenesis by regulating PDCD4. CASC3 and metadherin (MTDH) can bind directly to circ-NOL10 with characterized motifs. Accordingly, ectopic expression or depletion of CASC3 or MTDH leads to circ-NOL10 expression changes, suggesting that these two RBPs modulate circ-NOL10 in cancer cells. circ-NOL10 is a novel biomarker for diagnosis and prognosis in breast cancer. These results highlight the importance of therapeutic targeting of the RBP-noncoding RNA (ncRNA) regulation network.

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.

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

Breast cancer is one of the most common malignant diseases worldwide. Astrocyte elevated gene-1 (AEG-1) is upregulated in breast cancer and regulates breast cancer cell proliferation and invasion. However, the molecular mechanisms by which AEG-1 promotes breast cancer have yet to be fully elucidated. In order to delineate the function of AEG-1 in breast cancer development, we mapped the AEG-1 interactome via affinity purification followed by LC-MS/MS. We identified nucleolin (NCL) as a novel AEG-1 interacting protein, and co-immunoprecipitation experiments validated the interaction between AEG-1 and NCL in breast cancer cells. The silencing of NCL markedly reduced not only migration/invasion, but also the proliferation induced by the ectopic expression of AEG-1. Further, we found that the ectopic expression of AEG-1 induced the tyrosine phosphorylation of c-Met, and NCL knockdown markedly reduced this AEG-1 mediated phosphorylation. Taken together, our report identifies NCL as a novel mediator of the oncogenic function of AEG-1, and suggests that c-Met could be associated with the oncogenic function of the AEG-1-NCL complex in the context of breast cancer.

Expression of MTDH and IL-10 Is an Independent Predictor of Worse Prognosis in ER-Negative or PR-Negative Breast Cancer Patients

(1) Background: Tumor hypoxia leads to metastasis and certain immune responses, and interferes with normal biological functions. It also affects glucose intake, down-regulates oxidative phosphorylation, and inhibits fatty-acid desaturation regulated by hypoxia-inducible factor 1α (HIF-1α). Although tumor hypoxia has been found to promote tumor metastasis, the roles of HIF-1α-regulated genes and their application are not completely integrated in clinical practice. (2) Methods: We examined the correlation between HIF-1α, metadherin (MTDH), and interleukin (IL)-10 mRNA expression, as well as their expression patterns in the prognosis of breast cancer using the Gene Expression Profiling Interactive Analysis (GEPIA) databases via a web interface; tissue microarrays (TMAs) were stained for MTDH and IL-10 protein expression using immunohistochemistry. (3) Results: HIF-1α, MTDH, and IL-10 mRNA expression are highly correlated and strongly associated with poor prognosis. MTDH and IL-10 protein expression of breast cancer patients usually harbored negative estrogen receptor (ER) or progesterone receptor (PR) status, and late-stage tumors have higher IL-10 expression. With regard to MTDH and IL-10 protein expression status for using univariate and multivariate analysis, the results showed that the protein expression of MTDH and IL-10 in ER-negative or PR-negative breast cancer patients have the worse prognosis. (4) Conclusions: we propose a new insight into hypoxia tumors in the metabolism and immune evidence for breast cancer therapy.

LncRNA FAM83H-AS1 promotes triple-negative breast cancer progression by regulating the miR-136-5p/metadherin axis

In this study, we evaluated the function and regulation of the long non-coding RNA (lncRNA) FAM83H-AS1 in triple-negative breast cancer (TNBC). Our data show that the FAM83H-AS1 levels are increased in human TNBC cells and tissues. Proliferation, migration, and invasion of TNBC cells are decreased by FAM83H-AS1 suppression, but increased by FAM83H-AS1 overexpression. Bioinformatics analysis revealed that miR-136-5p is a potential target of FAM83H-AS1. MiR-136-5p expression is decreased in TNBC tissues, and its overexpression suppresses TNBC cell proliferation, migration, and invasion. MiR-136-5p suppression reverses the FAM83H-AS1 silencing-mediated inhibition of TNBC cell proliferation, migration, and invasion, suggesting that FAM83H-AS1 exerts its oncogenic effect by inhibiting miR-136-5p. Our data identify metadherin (MTDH) as the target gene of miR-136-5p, and demonstrate that the MTDH expression is increased in human TNBC tissues, which induces proliferation, migration, and invasion of TNBC cells. Importantly, our in vivo data show that FAM83H-AS1 also promotes tumor growth in TNBC mouse xenografts. Together, our results demonstrate that FAM83H-AS1 functions as an oncogenic lncRNA that regulates miR-136-5p and MTDH expression during TNBC progression, and suggest that targeting the FAM83H-AS1/miR-136-5p/MTDH axis may serve as a novel therapeutic target in TNBC.

A novel metadherinΔ7 splice variant enhances triple negative breast cancer aggressiveness by modulating mitochondrial function via NFĸB-SIRT3 axis

Metadherin (MTDH) expression inversely correlates with prognosis of several cancers including mammary carcinomas. In this work, we identified a novel splice variant of MTDH with exon7 skipping (MTDHΔ7) and its levels were found significantly high in triple negative breast cancer (TNBC) cells and in patients diagnosed with TNBC. Selective overexpression of MTDHΔ7 in MDA-MB-231 and BT-549 cells enhanced proliferation, invasion, and epithelial-to-mesenchymal (EMT) transition markers in comparison to its wildtype counterpart. In contrast, knockdown of MTDHΔ7 induced antiproliferative/antiinvasive effects. Mechanistically, MTDH-NFĸB-p65 complex activated SIRT3 transcription by binding to its promoter that in turn enhanced MnSOD levels and promoted EMT in TNBC cells. Intriguingly, mitochondrial OCR through Complex-I and -IV, and glycolytic rate (ECAR) were significantly high in MDA-MB-231 cells stably expressing MTDHΔ7. While depletion of SIRT3 inhibited MTDH-Wt/Δ7-induced OCR and ECAR, knockdown of MnSOD inhibited only ECAR. In addition, MTDH-Wt/Δ7-mediated pro-proliferative/-invasive effects were greatly obviated with either siSIRT3 or siMnSOD in these cells. The functional relevance of MTDHΔ7 was further proved under in vivo conditions in an orthotopic mouse model of breast cancer. Mice bearing labeled MDA-MB-231 cells stably expressing MTDHΔ7 showed significantly more tumor growth and metastatic ability to various organs in comparison to MTDH-Wt bearing mice. Taken together, MTDHΔ7 promotes TNBC aggressiveness through enhanced mitochondrial biogenesis/function, which perhaps serves as a biomarker.

Elevated expression of MTDH predicts better prognosis of locally advanced HER-2 positive breast cancer patients receiving neoadjuvant chemotherapy plus trastuzumab

Metadherin (MTDH), also known as astrocyte elevated gene-1 (AEG-1), is an oncoprotein closely related to the development of breast cancer. However, few studies have been done on the expression and clinical significance of MTDH in human epidermal growth factor receptor-2 (HER-2) positive breast cancer patients.This study aimed to investigate the expression of MTDH in locally advanced HER-2 positive breast cancer, and evaluate the clinical significance of MTDH in predicting the prognosis of patients with HER-2 positive advanced breast cancer who received the neoadjuvant chemotherapy plus trastuzumab.In 144 HER-2 positive breast cancer tissues, 79 cases showed high expression of MTDH and 65 cases showed low expression. The expression of MTDH in locally advanced HER-2 positive breast cancer tissues was correlated with TNM stage, lymph node metastasis, Miller-Payne (MP) grade, and pathologic complete response (pCR) status (P < .05), but was not correlated with patient age, estrogen receptor (ER) expression level, progesterone receptor (PR) expression level, and Ki-67 expression level (P > .05). Kaplan-Meier univariate analysis revealed a negative correlation between MTDH expression and the disease-free survival (DFS) and overall survival (OS) in the post-operative patients with locally advanced HER-2 positive breast cancer (log rank test: P < .001). By using the COX proportional hazard regression model, it was found that MTDH expression, TNM stage, lymph node metastasis, and Ki-67 expression were closely related to DFS in patients. The hazard ratio (HR) of high MTDH expression was 1.816 (95% CI: 1.165-2.829). In addition, MTDH expression, TNM stage, and lymph node metastasis were also closely related to the OS of patient. The HR of the high expression of MTDH was 2.512 (95% CI: 1.472-4.286). The expression of MTDH in tumor tissues of patients with HER2-positive locally advanced breast cancer was significantly elevated, which was related to the poor pathological features.High MTDH expression was closely correlated with poor prognosis of patients and was an important factor affecting tumor progression.

Metastatic heterogeneity of breast cancer: Molecular mechanism and potential therapeutic targets

Breast cancer is one of the most common malignancies among women throughout the world and is the major cause of most cancer-related deaths. Several explanations account for the high rate of mortality of breast cancer, and metastasis to vital organs is identified as the principal cause. Over the past few years, intensive efforts have demonstrated that breast cancer exhibits metastatic heterogeneity with distinct metastatic precedence to various organs, giving rise to differences in prognoses and responses to therapy in breast cancer patients. Bone, lung, liver, and brain are generally accepted as the primary target sites of breast cancer metastasis. However, the underlying molecular mechanism of metastatic heterogeneity of breast cancer remains to be further elucidated. Recently, the advent of novel genomic and pathologic approaches as well as technological breakthroughs in imaging analysis and animal modelling have yielded an unprecedented change in our understanding of the heterogeneity of breast cancer metastasis and provided novel insight for establishing more effective therapeutics. This review summarizes recent molecular mechanisms and emerging concepts on the metastatic heterogeneity of breast cancer and discusses the potential of identifying specific molecules against tumor cells or tumor microenvironments to thwart the development of metastatic disease and improve the prognosis of breast cancer patients.

MicroRNA-876 is sponged by long noncoding RNA LINC00707 and directly targets metadherin to inhibit breast cancer malignancy

Background: MicroRNA-876-5p (miR-876) dysregulation contributes to the aggressiveness of various types of human cancer. This study was aimed at measuring miR-876 expression in breast cancer, determining the specific roles of miR-876 in the progression of breast cancer and understanding the corresponding molecular mechanisms.

Materials and methods: miR-876 expression in breast cancer tissues and cell lines was quantified via RT-qPCR. The effect of miR-876 upregulation on the malignant phenotype of breast cancer cells was investigated using CCK-8 assays, flow cytometry, Transwell migration and invasion assays and tumor xenograft experiments. The mechanisms underlying the tumor-suppressive action of miR-876 in breast cancer cells were explored using bioinformatic analysis, luciferase reporter assays, RT-qPCR and Western blot analysis.

Results: miR-876 was found to be underexpressed in breast cancer tissues and cell lines. Decreased miR-876 expression notably correlated with lymphatic invasion metastasis, TNM stage and differentiation grade. Overall survival was lower among patients with breast cancer and low miR-876 expression than in patients with high miR-876 expression. Restoration of miR-876 expression decreased breast cancer cell proliferation, migration and invasion in vitro and restricted tumor growth in vivo as well as increased cell apoptosis. Metadherin (MTDH) was identified as a novel target of miR-876 in breast cancer cells. Furthermore, long intergenic nonprotein-coding RNA 707 (LINC00707) acted as a molecular sponge for miR-876, thereby regulating MTDH expression in breast cancer. Finally, silencing miR-876 expression attenuated the influence of a LINC00707 knockdown on the malignancy of breast cancer cells.

Conclusion: This study, thus, revealed the vital functions of the LINC00707–miR-876–MTDH pathway in breast cancer and provided attractive targets and markers for its treatment.

Metadherin: A Therapeutic Target in Multiple Cancers

Altered expression of many genes and proteins is essential for cancer development and progression. Recently, the affected expression of metadherin (MTDH), also known as AEG-1 (Astrocyte Elevated Gene 1) and Lyric, has been implicated in various aspects of cancer progression and metastasis. Elevated expression of MTDH/AEG-1 has been reported in many cancers including breast, prostate, liver, and esophageal cancers, whereas its expression is low or absent in non-malignant tissues. These expression studies suggest that MTDH may represent a potential tumor associated antigen. MTDH also regulates multiple signaling pathways including PI3K/Akt, NF-κB, Wnt/β-catenin, and MAPK which cooperate to promote the tumorigenic and metastatic potential of transformed cells. Several microRNA have also been found to be associated with the increased MTDH expression in different cancers. Increased MTDH levels were linked to the tumor chemoresistance making it an attractive novel therapeutic target. In this review, we summarize data on MTDH function in various cancers.

Ultrasound-Targeted Microbubble Destruction (UTMD) Combined with Liposome Increases the Effectiveness of Suppressing Proliferation, Migration, Invasion, and Epithelial- Mesenchymal Transition (EMT) via Targeting Metadherin (MTDH) by ShRNA

Background

Reports show that ultrasound-targeted microbubble destruction (UTMD) is a promising method of gene therapy, and metadherin (MTDH) is related to the development of breast cancer. Thus, we investigated the role of MTDH in breast cancer and compared the effect of suppressing MTDH by shRNA using liposome, UTMD, or the combination of these 2 methods.

Material/Methods

Graphing of survival curves of MTDH was analyzed by bioinformatics. UTMD was conducted using an ultrasonic therapeutic apparatus. Cell counting kit-8 (CCK-8) assay was used to measure cell viability. Migration and invasion rates were measured by wound healing test and Transwell invasion assay, respectively. The expression of MTDH, E-cadherin, metastasis-associated protein-1 (MTA-1), matrix metalloproteinase (MMP)-2, and MMP-9 were measured by Western blot and qPCR.

Results

The prognosis of breast cancer can be decreased by the high expression of MTDH, and elevated expression of MTDH was discovered in MCF-7, MCF-10A, and T47D cell lines. UTMD combined with liposome is most efficient in transfecting shRNA, clearly suppressing the expression of MTDH and thereby decreasing cell viability, migration, invasion rate, and epithelial- mesenchymal transition (EMT) processes in the MCF-7 cell line.

Conclusions

UTMD combined with liposome could be used as a more efficient way to transfect shRNA into cells to suppress the expression of MTDH and thus lead to the downregulation of proliferation, migration, and EMT processes of the MCF-7 cell line, showing the potential for use in gene therapy.

Lobaplatin inhibits breast cancer progression, cell proliferation while it induces cell apoptosis by downregulating MTDH expression

Objective

Lobaplatin shows antitumor activity against a wide range of tumors, including metastatic breast cancer (BCa). The overexpression of metadherin (MTDH) is associated with poor prognosis of BCa patients. This study was designed to investigate the effect of lobaplatin on MCF-7 cell proliferation and its association with MTDH expression.

Patients and methods

Clinical treatment for BCa using lobaplatin, in combination with other general chemotherapy drugs, was administered to 32 BCa patients. The safety, effectiveness, and prognosis in lobaplatin-treated BCa patients were compared with those in controls (n=32). In vitro experiments were performed in MCF-7 cells to investigate the effect of lobaplatin on cell proliferation, apoptosis, and MTDH expression.

Results

We found the intraoperative local chemotherapy using lobaplatin was safe and effective for BCa treatment, in comparison with the patients administered general chemotherapy drugs. Treatment of MCF-7 cell cultures with lobaplatin significantly reduced cell proliferation and increased cell apoptotic percentage. The expression of MTDH and Bcl-2 was inhibited by lobaplatin and that of Bax was increased by lobaplatin. Moreover, we observed the inhibition of MTDH by shRNA reduced cell proliferation and enhanced cell apoptosis.

Conclusion

Lobaplatin was a safe and effective adjuvant chemotherapy for BCa. The effect of lobaplatin on inhibiting MCF-7 cell proliferation and inducing cell apoptosis might be, as least in part, mediated by suppressing the expression of oncogene MTDH.

MiR-30b-5p modulates glioma cell proliferation by direct targeting MTDH

Malignant glioma is the most common and lethal type of primary tumor of the central nervous system. The incidence of glioma is increasing year by year. In recent years, a variety of new treatment methods have emerged, among which gene therapy has become a hotspot. MicroRNAs (miRNAs) are a class of small non-coding single-strand RNAs that negatively regulate gene expression at the post-transcriptional and/or translational level by binding loosely complimentary sequences in the 3′ untranslated regions (UTRs) of target mRNAs. Several miRNAs have been reported to modulate glioma progression. This study aimed to determine the function of miR-30b-5p in glioma and its underlying molecular mechanism. miR-30b-5p expression was significantly lower in gliomas than the normal brain tissues. Overexpression of miR-30b-5p was found to significantly inhibit glioma cell proliferation in vitro. Further, MTDH expression was significantly higher in the gliomas compared with the normal brain tissues. In addition, MTDH was validated as direct target of miR-30b-5p. Moreover, cellular proliferation was increased after MTDH overexpression in the glioma cells, which reversed the effects of miR-30b-5p. Taken together, these results reveal miR-30b-5p impacts glioma cell proliferation via direct targeting MTDH and could be a potential novel therapeutic target for the treatment of glioma.

Copy number profiling of oncogenes in ductal carcinoma in situ of the male breast

Characterizing male breast cancer (BC) and unraveling male breast carcinogenesis is challenging because of the rarity of this disease. We investigated copy number status of 22 BC-related genes in 18 cases of pure ductal carcinoma in situ (DCIS) and in 49 cases of invasive carcinoma (IC) with adjacent DCIS (DCIS-AIC) in males using multiplex ligation-dependent probe amplification (MLPA). Results were compared to female BC and correlated with survival. Overall, copy number ratio and aberration frequency including all 22 genes showed no significant difference between the 3 groups. Individual unpaired analysis revealed a significantly higher MTDH copy number ratio in IC compared to DCIS-AIC and pure DCIS (P = 0.009 and P = 0.038, respectively). ADAM9 showed a significantly lower copy number aberration frequency in male BC, compared to female BC (P = 0.020). In DCIS-AIC, MTDH, CPD, CDC6 and TOP2A showed a lower frequency of copy number increase in males compared to females (P < 0.001 for all 4 genes). In IC, CPD gain and CCNE1 gain were independent predictors of poor overall survival. In conclusion, male DCIS and IC showed a similar copy number profile for 21 out of 22 interrogated BC-related genes, illustrating their clonal relation and the genetically advanced state of male DCIS. MTDH showed a higher copy number ratio in IC compared to adjacent and pure DCIS and may therefore play a role in male breast carcinogenesis. Differences were detected between male and female DCIS for 4 genes pointing to differences in breast carcinogenesis between the sexes.

GABARAPL1 acts as a potential marker and promotes tumor proliferation and metastasis in triple negative breast cancer

GABA_A-receptor-associated protein like-1 (GABARAPL1) is involved in a variety of cancers. The purpose of this study was to investigate the expression, prognostic roles and functions of GABARAPL1 in triple negative breast cancer (TNBC). Quantitative real-time PCR (qRT-PCR) showed that GABARAPL1 was up regulated in both TNBC cell lines and clinical TNBC tissues. High GABARAPL1 expression level was associated with shorter overall survival (OS) and disease free survival (DFS). Furthermore, inhibition of GABARAPL1 suppressed cell proliferation, tumorigenesis, invasion and metastasis, and induced cell apoptosis. We found that metadherin (MTDH) was a downstream target of GABARAPL1. Inhibition of GABARAPL1 suppressed the mRNA and protein expression of MTDH, and overexpression of MTDH could reverse the effects of GABARAPL1 inhibition, which meant GABARAPL1 performed its function partly through MTDH. Our findings demonstrate that GABARAPL1 acts as a tumor promoter in TNBC partly through MTDH. Targeting at GABARAPL1 could be a potential therapeutic strategy for TNBC.

Metadherin promotes metastasis by supporting putative cancer stem cell properties and epithelial plasticity in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has a high metastatic potential. However, the mechanism of metastatic colonization in PDAC remains poorly understood. Metadherin (MTDH) has emerged in recent years as a crucial mediator of metastasis in several cancer types, although the biological role of MTDH in PDAC has not been investigated. Here, we demonstrated the functional roles of MTDH in PDAC progression, especially focusing on the metastatic cascade. In vitro studies showed that MTDH provides cancer stem cell (CSC) properties in metastatic PDAC cells and contributes to anoikis resistance with epithelial characteristics in PDAC cells. We also performed in vivo studies using both orthotopic transplantation and intra-portal vein injection as experimental models of liver metastasis to examine the function of MTDH at the metastatic site. MTDH knockdown dramatically reduced the incidence of liver metastases along with epithelial features in both experimental mouse models. Collectively, MTDH facilitates metastatic colonization with putative CSC and epithelial properties in PDAC cells. PDAC cells were transiently treated with TGF-β1 to investigate the roles of MTDH on epithelial plasticity. Intriguingly, MTDH expression was negatively correlated with Twist1 expression during the Mesenchymal-Epithelial transition (MET) induction in metastatic PDAC cells. These results suggest that MTDH may contribute to MET induction via downregulation of Twsit1. Lastly, immunohistochemistry indicated that MTDH overexpression is closely associated with hematogenous metastasis and predicts poor prognosis in patients with PDAC. This is the first demonstration of MTDH function in PDAC metastatic colonization. Our data suggest that MTDH targeting therapy could be applied to control PDAC metastasis.

Role of metadherin in estrogen-regulated gene expression

The disruption of estrogen signaling is widely associated with the development of breast, endometrial and ovarian cancers. As a multifunctional mediator of carcinogenesis, metadherin (MTDH)/astrocyte elevated gene-1 (AEG-1) overexpression has been associated with numerous types of cancer, with reported roles in tumor initiation, proliferation, invasion, metastasis and chemoresistance. At the molecular level, MTDH has been shown to interact with proteins that drive tumorigenesis, including nuclear factor-κB (NF-κB), promyelocytic leukaemia zinc finger (PLZF), BRCA2- and CDKN1A (p21Cip1/Waf-1/mda-6)-interacting protein α (BCCIPα) and staphylococcal nuclease and tudor domain containing 1 (SND1). Through the analysis of the Cancer Genome Atlas (TCGA) datasets for estrogen receptor (ER)-positive endometrial and breast cancers, we found that over 25% of all gene expression correlated with MTDH. Using Affymetrix microarrays, we characterized the differences in gene expression between estrogen-treated parental and MTDH-deficient endometrial and breast cancer cells. We also explored a possible interaction between MTDH and ER by immunoprecipitation, and found that MTDH and ER associated in both breast and endometrial cancer cells in response to estrogen. Reciprocal co-immunoprecipitation analysis demonstrated that acute estrogen stimulation promoted the interaction of MTDH with ER in the nucleus. These data, to the best of our knowledge, provide the first evidence that MTDH and ERα interact in the nucleus with estrogen treatment to regulate gene expression.

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.

MiR-630 suppresses breast cancer progression by targeting metadherin

MicroRNAs have been integrated into tumorigenic programs as either oncogenes or tumor suppressor genes. The miR-630 was reported to be deregulated and involved in tumor progression of several human malignancies. However, its expression regulation shows diversity in different kinds of cancers and its potential roles remain greatly elusive. Herein, we demonstrate that miR-630 is significantly suppressed in human breast cancer specimens, as well as in various breast cancer cell lines. In aggressive MDA-MB-231-luc and BT549 breast cancer cells, ectopic expression of miR-630 strongly inhibits cell motility and invasive capacity in vitro. Moreover, lentivirus delivered miR-630 bestows MDA-MB-231-luc cells with the ability to suppress cell colony formation in vitro and pulmonary metastasis in vivo. Further studies identify metadherin (MTDH) as a direct target gene of miR-630. Functional studies shows that MTDH contributes to miR-630-endowed effects including cell migration and invasion as well as colony formation in vitro. Taken together, these findings highlight an important role for miR-630 in the regulation of metastatic potential of breast cancer and suggest a potential application of miR-630 in breast cancer treatment.

Association of MTDH immunohistochemical expression with metastasis and prognosis in female reproduction malignancies: a systematic review and meta-analysis

Various literatures have demonstrated that overexpression of Metadherin (MTDH) is correlated with tumor metastasis and it can predict poor survival outcomes in female reproduction malignancies. In order to enhance the statistical power and reach a recognized conclusion, we conducted a systematic review and meta-analysis to thoroughly investigate the association of MTDH expression with tumor metastasis and survival outcomes following PRISMA guidelines. Odds ratios (ORs) and hazard ratios (HRs) were used to demonstrate the impact of MTDH on tumor metastasis and prognosis respectively. Data were pooled with appropriate effects model on STATA12.0. Our results indicated that high MTDH expression is significantly correlated with higher mortality for breast, ovarian and cervical cancer. High immunohistochemical expression of MTDH is remarkably associated with shorter disease-free survival (DFS) in breast cancer but not in ovarian cancer. The pooled results suggested that high level of MTDH significantly predicted distant metastasis and lymph node metastasis in breast cancer. Strong associations were observed between MTDH expression and lymph node metastasis in ovarian and cervical cancer. In conclusion, MTDH might be a novel biomarker which can effectively reflect metastasis status and prognosis of breast cancer. However, its application in clinical practice needs more prospective studies with large samples.

MTDH is an oncogene in multiple myeloma, which is suppressed by Bortezomib treatment

Metadherin (MTDH) is identified as an oncogene in multiple cancers including breast cancer, bladder cancer and endometrial cancer. However, the function of MTDH in multiple myeloma (MM) is still unexplored. In this study, we disclose that MTDH is an oncogene in MM. This is characterized by an elevation mRNA level of MTDH and chromosomal gain of MTDH locus in MM cells compared to normal samples. Moreover, MTDH expression significantly increased in MMSET translocation (MS) subgroup, one of the high-risk subgroups in MM, and was significantly correlated with MM patients' poor outcomes in Total Therapy 2 (TT2) cohort. Further knockdown of MTDH expression by shRNA in MM cells induced cell apoptosis, inhibited MM cells growth in vitro and decreased xenograft tumor formation in vivo. Interestingly, opposite to TT2, MM patients with high-MTDH expression showed favorable survival outcomes in the TT3 cohort, while Bortezomib treatment was the major difference between TT2 and TT3 cohort. Furthermore we proved that Bortezomib suppressed pre- and post-transcription levels of MTDH expression of MM cells in vitro and in vivo. Finally, our studies demonstrated that MTDH is a transcriptional gene of MMSET/NFκB /MYC signaling in MM cells, which is inhibited by Bortezomib treatment.

AEG-1/MTDH/LYRIC: A Promiscuous Protein Partner Critical in Cancer, Obesity, and CNS Diseases

Since its original discovery in 2002, AEG-1/MTDH/LYRIC has emerged as a primary regulator of several diseases including cancer, inflammatory diseases, and neurodegenerative diseases. AEG-1/MTDH/LYRIC has emerged as a key contributory molecule in almost every aspect of cancer progression, including uncontrolled cell growth, evasion of apoptosis, increased cell migration and invasion, angiogenesis, chemoresistance, and metastasis. Additionally, recent studies highlight a seminal role of AEG-1/MTDH/LYRIC in neurodegenerative diseases and obesity. By interacting with multiple protein partners, AEG-1/MTDH/LYRIC plays multifaceted roles in the pathogenesis of a wide variety of diseases. This review discusses the current state of understanding of AEG-1/MTDH/LYRIC regulation and function in cancer and other diseases with a focus on its association/interaction with several pivotal protein partners.

Metadherin regulates epithelial-mesenchymal transition in carcinoma

Metadherin (MTDH) was first identified in primary human fetal astrocytes exposed to HIV-1 in 2002 and then recognized as an important oncogene mediating tumorigenesis, progression, invasiveness, and metastasis of carcinomas. Epithelial–mesenchymal transition (EMT) is a vital process in embryonic development, organ repair, and cancer progression. MTDH and EMT have also been proved to be related to the prognosis of patients with cancers. Recent studies reveal a relationship between MTDH overexpression and EMT in some malignancies. This review highlights the overexpression of MTDH and EMT in cancers and their correlations in clinical studies. Positive correlations have been established between MTDH and mesenchymal biomarkers, and negative correlations between MTDH and epithelial biomarkers have also been established. Furthermore, experiments reveal EMT regulated by MTDH, and some signal pathways have been established. Some anticancer drugs targeting MTDH and EMT are introduced in this review. Some perspectives concerning EMT regulation by MTDH are also presented in this review.

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.

Knockdown of metadherin inhibits angiogenesis in breast cancer

Angiogenesis plays an important role in cancer growth, invasion and metastasis. It has been confirmed that metadherin (MTDH) is associated with angiogenesis. However, the detailed mechanism of MTDH on angiogenesis has not yet been reported. In this study, we demonstrate the anti-angiogenic function of MTDH in breast cancer. With RNA interference strategies, we found that knockdown of MTDH inhibits cellular angiogenesis both in vitro and ex vivo. Furthermore, we revealed that ERK1/2 pathway is involved in the anti-angiogenic function of MTDH, and the function can be partially reversed via upregulation of microRNA-21 (miR-21). In conclusion, knockdown of MTDH can inhibit angiogenesis in breast cancer. These results show that MTDH is a viable therapeutic target for anti-angiogenesis in breast cancer.

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.

miR-26a suppresses tumour proliferation and metastasis by targeting metadherin in triple negative breast cancer

It has been reported that miR-26a plays an important role in various cancers. In this study, we found that miR-26a was downregulated in triple-negative breast cancer (TNBC), and its expression levels were associated with lymph node metastasis and overall survival in TNBC. We also found that the ectopic expression of miR-26a inhibited TNBC cell proliferation and metastasis in vitro and in vivo by downregulating MTDH (a miR-26a' target gene) mRNA and protein and that the overexpression of MTDH could partially abrogate miR-26a-mediated suppression. Our data suggest that miR-26a functions as a tumour suppressor in TNBC development and serves as a prognostic marker for breast cancer.

MTDH mediates trastuzumab resistance in HER2 positive breast cancer by decreasing PTEN expression through an NFκB-dependent pathway

BACKGROUND

Trastuzumab resistance is almost inevitable in the management of human epidermal growth factor receptor (HER) 2 positive breast cancer, in which phosphatase and tensin homolog deleted from chromosome 10 (PTEN) loss is implicated. Since metadherin (MTDH) promotes malignant phenotype of breast cancer, we sought to define whether MTDH promotes trastuzumab resistance by decreasing PTEN expression through an NFκB-dependent pathway.

METHODS

The correlations between MTDH and PTEN expressions were analyzed both in HER2 positive breast cancer tissues and trastuzumab resistant SK-BR-3 (SK-BR-3/R) cells. Gene manipulations of MTDH and PTEN levels by knockdown or overexpression were utilized to elucidate molecular mechanisms of MTDH and PTEN implication in trastuzumab resistance. For in vivo studies, SK-BR-3 and SK-BR-3/R cells and modified derivatives were inoculated into nude mice alone or under trastuzumab exposure. Tumor volumes, histological examinations as well as Ki67 and PTEN expressions were revealed.

RESULTS

Elevated MTDH expression indicated poor clinical benefit, shortened progression free survival time, and was negatively correlated with PTEN level both in HER2 positive breast cancer patients and SK-BR-3/R cells. MTDH knockdown restored PTEN expression and trastuzumab sensitivity in SK-BR-3/R cells, while MTDH overexpression prevented SK-BR-3 cell death under trastuzumab exposure, probably through IκBα inhibition and nuclear translocation of p65 which subsequently decreased PTEN expression. Synergized effect of PTEN regulation were observed upon MTDH and p65 co-transfection. Forced PTEN expression in SK-BR-3/R cells restored trastuzumab sensitivity. Furthermore, decreased tumor volume and Ki67 level as well as increased PTEN expression were observed after MTDH knockdown in subcutaneous breast cancer xenografts from SK-BR-3/R cells, while the opposite effect were found in grafts from MTDH overexpressing SK-BR-3 cells.

CONCLUSIONS

MTDH overexpression confers trastuzumab resistance in HER2 positive breast cancer. MTDH mediates trastuzumab resistance, at least in part, by PTEN inhibition through an NFκB-dependent pathway, which may be utilized as a promising therapeutic target for HER2 positive breast cancer.

microRNA-22 acts as a metastasis suppressor by targeting metadherin in gastric cancer

microRNA (miR)-22 has been reported to be downregulated in hepatocellular, lung, colorectal, ovarian and breast cancer, acting as a tumor suppressor. The present study investigated the potential effects of miR-22 on gastric cancer invasion and metastasis and the molecular mechanism. miR-22 expression was examined in tumor tissues of in 89 gastric cancer patients by in situ hybridization (ISH) analysis. Additionally, the association between miR-22 levels and clinicopathological parameters was analyzed. A luciferase assay was conducted for target identification. The ability of invasion and metastasis of gastric cancer cells in vitro and in vivo was evaluated by cell migration and invasion assays and in a xenograft model. The results showed that miR-22 was downregulated in the gastric cancer specimens and significantly correlated with the advanced clinical stage and lymph node metastasis. In addition, metadherin (MTDH) was shown to be a direct target of miR-22 and the expression of MTDH was inversely correlated with miR-22 expression in gastric cancer. Ectopic expression of miR-22 suppressed cell invasion and metastasis in vitro and in vivo. The present study suggested that miR-22 may be a valuable prognostic factor in gastric cancer. miR-22 inhibited gastric cancer cell invasion and metastasis by directly targeting MTDH. The novel miR-22/MTDH link confirmed in the present study provided a novel, potential therapeutic target for the treatment of gastric cancer.

Metadherin in prostate, bladder, and kidney cancer: A systematic review

Metadherin (MTDH) has been identified as an important oncogene in carcinogenesis, tumor progression and metastasis in numerous malignancies, through signal transduction pathways. MTDH is a potential biomarker and therapeutic target in cancers. The present systematic review was performed to search for studies regarding MTDH and prostate, bladder and kidney cancer using several databases and the eligible studies were reviewed. MTDH expression was found to significantly increase in prostate, bladder and kidney cancers, not only in clinical tissue samples, but also in cancer cell lines. Reviewing the clinical and statistical analysis revealed that MTDH may be involved in urologic cancer progression, metastasis and prognosis. MTDH may be an independent or one of the cofactors in urologic cancers for prediction of patient survival, and may be involved in potential anticancer strategies. MTDH may be associated with several signal transduction pathways in urologic cancers, indicating latent targets to develop anticancer therapeutic strategy. Further studies are required to confirm these findings.

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.

Pleiotropic roles of AEG-1/MTDH/LYRIC in breast cancer

Since the initial discovery of AEG-1/MTDH/LYRIC, our appreciation for this novel protein's involvement in cancer has increased dramatically over the past few years. AEG-1/MTDH/LYRIC is a key functional target of the 8q22 genomic gain that is frequently observed in poor-prognosis breast cancer, where it plays a dual role in promoting chemoresistance and metastasis. Beyond this, growing evidence from clinical research indicates a strong correlation between AEG-1/MTDH/LYRIC expression and the pathogenesis of a large spectrum of cancer types, and multiple studies employing in vitro cell culture systems and in vivo xenograft models have revealed multifaceted roles of AEG-1/MTDH/LYRIC in cancer biology, including tumor cell proliferation, apoptosis, angiogenesis, and autophagy. With increasing mechanistic understanding of AEG-1/MTDH/LYRIC, discovery of agents that can block AEG-1/MTDH/LYRIC and its regulated pathways will be beneficial to cancer patients with aberrant expression of AEG-1/MTDH/LYRIC.

Drug resistance mediated by AEG-1/MTDH/LYRIC

AEG-1/MTDH/LYRIC has been shown to promote cancer progression and development. Overexpression of AEG-1/MTDH/LYRIC correlates with angiogenesis, metastasis, and chemoresistance to various chemotherapy agents in cancer cells originating from a variety of tissues. In this chapter, we focus on the role of AEG-1/MTDH/LYRIC in drug resistance. Mechanistic studies have shown that AEG-1/MTDH/LYRIC is involved in classical oncogenic pathways including Ha-Ras, myc, NFκB, and PI3K/Akt. AEG-1/MTDH/LYRIC also promotes protective autophagy by activating AMP kinase and autophagy-related gene 5. Another reported mechanism by which AEG-1/MTDH/LYRIC regulates drug resistance is by increasing loading of multidrug resistance gene (MDR) 1 mRNA to the polysome, thereby facilitating MDR1 protein translation. More recently, a novel function for AEG-1/MTDH/LYRIC as an RNA-binding protein was elucidated, which has the potential to impact expression of drug sensitivity or resistance genes. Finally, AEG-1/MTDH/LYRIC acts in microRNA-directed gene silencing via an interaction with staphylococcal nuclease and tudor domain containing 1, a component of the RNA-induced silencing complex. Altered microRNA expression and activity induced by AEG-1/MTDH/LYRIC represent an additional way that AEG-1/MTDH/LYRIC may cause drug resistance in cancer. The multiple functions of AEG-1/MTDH/LYRIC in drug resistance highlight that it is a viable target as an anticancer agent for a wide variety of cancers.

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.