Expression of EphrinB2 and EphB4 in glioma tissues correlated to the progression of glioma and the prognosis of glioblastoma patients

Master regulators of neurogenesis: the dynamic roles of Ephrin receptors across diverse cellular niches

The ephrin receptors (EphRs) are the largest family of receptor tyrosine kinases (RTKs) that are abundantly expressed in the developing brain and play important roles at different stages of neurogenesis ranging from neural stem cell (NSC) fate specification to neural migration, morphogenesis, and circuit assembly. Defects in EphR signalling have been associated with several pathologies including neurodevelopmental disorders (NDDs), intellectual disability (ID), and neurodegenerative diseases (NDs). Here, we review our current understanding of the complex and dynamic role of EphRs in the brain and discuss how deregulation of these receptors contributes to disease, highlighting their potential as valuable druggable targets.

TGIF2 is a potential biomarker for diagnosis and prognosis of glioma

Background

TGFB-induced factor homeobox 2 (TGIF2), a member of the Three-Amino-acid-Loop-Extension (TALE) superfamily, has been implicated in various malignant tumors. However, its prognostic significance in glioma, impact on tumor immune infiltration, and underlying mechanisms in glioma development remain elusive.

Methods

The expression of TGIF2 in various human normal tissues, normal brain tissues, and gliomas was investigated using HPA, TCGA, GTEx, and GEO databases. The study employed several approaches, including Kaplan-Meier analysis, ROC analysis, logistic regression, Cox regression, GO analysis, KEGG analysis, and GSEA, to explore the relationship between TGIF2 expression and clinicopathologic features, prognostic value, and potential biological functions in glioma patients. The impact of TGIF2 on tumor immune infiltration was assessed through Estimate, ssGSEA, and Spearman analysis. Genes coexpressed with TGIF2 were identified, and the protein-protein interaction (PPI) network of these coexpressed genes were constructed using the STRING database and Cytoscape software. Hub genes were identified using CytoHubba plugin, and their clinical predictive value was explored. Furthermore, in vitro experiments were performed by knocking down and knocking out TGIF2 using siRNA and CRISPR/Cas9 gene editing, and the role of TGIF2 in glioma cell invasion and migration was analyzed using transwell assay, scratch wound-healing assay, RT-qPCR, and Western blot.

Results

TGIF2 mRNA was found to be upregulated in 21 cancers, including glioma. High expression of TGIF2 was associated with malignant phenotypes and poor prognosis in glioma patients, indicating its potential as an independent prognostic factor. Furthermore, elevated TGIF2 expression positively correlated with cell cycle regulation, DNA synthesis and repair, extracellular matrix (ECM) components, immune response, and several signaling pathways that promote tumor progression. TGIF2 showed correlations with Th2 cells, macrophages, and various immunoregulatory genes. The hub genes coexpressed with TGIF2 demonstrated significant predictive value. Additionally, in vitro experiments revealed that knockdown and knockout of TGIF2 inhibited glioma cell invasion, migration and suppressed the epithelial-mesenchymal transition (EMT) phenotype.

Conclusion

TGIF2 emerges as a potential biomarker for glioma, possibly linked to tumor immune infiltration and EMT.

Development of an Anti-EphB4 Monoclonal Antibody for Multiple Applications Against Breast Cancers

The erythropoietin-producing hepatocellular carcinoma (Eph) receptors are the largest receptor tyrosine kinase family. EphB4 is essential for cell adhesion and motility during embryogenesis. Pathologically, EphB4 is overexpressed and contributes to poor prognosis in various tumors. Therefore, specific monoclonal antibodies (mAbs) should be developed to predict the prognosis for multiple tumors with high EphB4 expression, including breast and gastric cancers. This study aimed to develop specific anti-EphB4 mAbs for multiple applications using the Cell-Based Immunization and Screening method. EphB4-overexpressed Chinese hamster ovary (CHO)-K1 (CHO/EphB4) cells were immunized into mice, and we established an anti-EphB4 mAb (clone B4Mab-7), which is applicable for flow cytometry, Western blot, and immunohistochemistry (IHC). B4Mab-7 reacted with endogenous EphB4-positive breast cancer cell line, MCF-7, but did not react with EphB4-knockout MCF-7 (BINDS-52) in flow cytometry. Dissociation constant (KD) values were determined to be 2.9 × 10-9 M and 1.3 × 10-9 M by flow cytometric analysis for CHO/EphB4 and MCF-7 cells, respectively. B4Mab-7 detected the EphB4 protein bands from breast cancer cells in Western blot, and stained breast cancer tissues in IHC. Altogether, B4Mab-7 is very useful for detecting EphB4 in various applications.

The role of m6A-modified CircEPHB4 in glioma pathogenesis: Insights into cancer stemness metastasis

OBJECTIVE

While existing literature has provided insights into involvement of circEPHB4, SOX2 in glioma, their precise molecular mechanisms and synergistic implications in glioma pathogenesis still dim. This study aims to investigate significance and underlying mechanism of m6A-modified circEPHB4 in regulating SOX2/PHLDB2 axis in gliomas.

METHODS

The mRNA and protein expression were tested by qRT-PCR and Western blot, respectively. ChIP assay was performed to detect SOX2 enrichment on the PHLDB2 promoter. Cell sphere-forming assay to detect self-renewal ability, flow cytometry to determine positivity of CD133 expressions, Malignant behavior of glioma cells were detected by CCK-8, plate colony formation, scratch, and transwell assays. Glioma xenograft models were constructed to investigate effects of CircEPHB4 in tumor development in vivo.

RESULTS

Methyltransferase MELLT3 upregulated m6A modification of CircEPHB4, and YTHDC1 promoted cytoplasmic localization of m6A-modified CircEPHB4. Overexpression of wild-type CircEPHB4 enhanced glioma cells' stemness, metastasis, and proliferation. Cytoplasmic CircEPHB4 increased SOX2 mRNA stability by binding to IGF2BP2, and the effects observed by SOX2 knockdown were reversed by CircEPHB4 in glioma cells. SOX2 promoted transcriptional expression of PHLDB2 by enriching the PHLDB2 promoter region. SOX2 reversed the inhibition of PHLDB2 knockdown on stemness of glioma, cell proliferation, and metastasis. In vivo experiments also revealed that CircEPHB4 upregulated PHLDB2 expression by stabilizing SOX2 mRNA, which promoted in vivo tumor growth and accelerated stemness of glioma cells and metastasis.

CONCLUSION

This study reveals functional interaction and molecular mechanisms of m6A-modified circEPHB4 in regulating SOX2/PHLDB2 axis, highlighting their importance in glioma pathogenesis and potential as therapeutic targets.

Signals transduced by Eph receptors and ephrin ligands converge on MAP kinase and AKT pathways in human cancers

Eph receptors, the largest known family of receptor tyrosine kinases, and ephrin ligands have been implicated in a variety of human cancers. The novel bidirectional signaling events initiated by binding of Eph receptors to their cognate ephrin ligands modulate many cellular processes such as proliferation, metastasis, angiogenesis, invasion, and apoptosis. The relationships between the abundance of a unique subset of Eph receptors and ephrin ligands with associated cellular processes indicate a key role of these molecules in tumorigenesis. The combinatorial expression of these molecules converges on MAP kinase and/or AKT/mTOR signaling pathways. The intracellular target proteins of the initial signal may, however, vary in some cancers. Furthermore, we have also described the commonality of up- and down-regulation of individual receptors and ligands in various cancers. The current state of research in Eph receptors illustrates MAP kinase and mTOR pathways as plausible targets for therapeutic interventions in various cancers.

Shaping the brain vasculature in development and disease in the single-cell era

The CNS critically relies on the formation and proper function of its vasculature during development, adult homeostasis and disease. Angiogenesis - the formation of new blood vessels - is highly active during brain development, enters almost complete quiescence in the healthy adult brain and is reactivated in vascular-dependent brain pathologies such as brain vascular malformations and brain tumours. Despite major advances in the understanding of the cellular and molecular mechanisms driving angiogenesis in peripheral tissues, developmental signalling pathways orchestrating angiogenic processes in the healthy and the diseased CNS remain incompletely understood. Molecular signalling pathways of the 'neurovascular link' defining common mechanisms of nerve and vessel wiring have emerged as crucial regulators of peripheral vascular growth, but their relevance for angiogenesis in brain development and disease remains largely unexplored. Here we review the current knowledge of general and CNS-specific mechanisms of angiogenesis during brain development and in brain vascular malformations and brain tumours, including how key molecular signalling pathways are reactivated in vascular-dependent diseases. We also discuss how these topics can be studied in the single-cell multi-omics era.

EphrinB2-EphB4 Signaling in Neurooncological Disease

EphrinB2-EphB4 signaling is critical during embryogenesis for cardiovascular formation and neuronal guidance. Intriguingly, critical expression patterns have been discovered in cancer pathologies over the last two decades. Multiple connections to tumor migration, growth, angiogenesis, apoptosis, and metastasis have been identified in vitro and in vivo. However, the molecular signaling pathways are manifold and signaling of the EphB4 receptor or the ephrinB2 ligand is cancer type specific. Here we explore the impact of these signaling pathways in neurooncological disease, including glioma, brain metastasis, and spinal bone metastasis. We identify potential downstream pathways that mediate cancer suppression or progression and seek to understand it´s role in antiangiogenic therapy resistance in glioma. Despite the Janus-faced functions of ephrinB2-EphB4 signaling in cancer Eph signaling remains a promising clinical target.

Protein-Protein Interaction Inhibitors Targeting the Eph-Ephrin System with a Focus on Amino Acid Conjugates of Bile Acids

The role of the Eph-ephrin system in the etiology of pathological conditions has been consolidated throughout the years. In this context, approaches directed against this signaling system, intended to modulate its activity, can be strategic therapeutic opportunities. Currently, the most promising class of compounds able to interfere with the Eph receptor-ephrin protein interaction is composed of synthetic derivatives of bile acids. In the present review, we summarize the progresses achieved, in terms of chemical expansions and structure-activity relationships, both in the steroidal core and the terminal carboxylic acid group, along with the pharmacological characterization for the most promising Eph-ephrin antagonists in in vivo settings.

EphB4 as a Novel Target for the EGFR-Independent Suppressive Effects of Osimertinib on Cell Cycle Progression in Non-Small Cell Lung Cancer

Osimertinib is the latest generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor used for patients with EGFR-mutated non-small cell lung cancer (NSCLC). We aimed to explore the novel mechanisms of osimertinib by particularly focusing on EGFR-independent effects, which have not been well characterized. We explored the EGFR-independent effects of osimertinib on cell proliferation using NSCLC cell lines, an antibody array analysis, and the association between the action of osimertinib and the ephrin receptor B4 (EphB4). We also studied the clinicopathological significance of EphB4 in 84 lung adenocarcinoma patients. Osimertinib exerted significant inhibitory effects on cell growth and cell cycle progression by promoting the phosphorylation of p53 and p21 and decreasing cyclin D1 expression independently of EGFR. EphB4 was significantly suppressed by osimertinib and promoted cell growth and sensitivity to osimertinib. The EphB4 status in carcinoma cells was positively correlated with tumor size, T factor, and Ki-67 labeling index in all patients and was associated with poor relapse-free survival in EGFR mutation-positive patients. EphB4 is associated with the EGFR-independent suppressive effects of osimertinib on cell cycle and with a poor clinical outcome. Osimertinib can exert significant growth inhibitory effects in EGFR-mutated NSCLC patients with a high EphB4 status.

The Clinical Impact of the EPH/Ephrin System in Cancer: Unwinding the Thread

Erythropoietin-producing human hepatocellular receptors (EPHs) compose the largest known subfamily of receptor tyrosine kinases (RTKs). They bind and interact with the EPH family receptor interacting proteins (ephrins). EPHs/ephrins are implicated in a variety of physiological processes, as well as in cancer pathogenesis. With neoplastic disease remaining a leading cause of death world-wide, the development of novel biomarkers aiding in the field of diagnosis, prognosis, and disease monitoring is of utmost importance. A multitude of studies have proven the association between the expression of members of the EPH/ephrin system and various clinicopathological parameters, including disease stage, tumor histologic grade, and patients' overall survival. Besides their utilization in timely disease detection and assessment of outcome, EPHs/ephrins could also represent possible novel therapeutic targets. The aim of the current review of the literature was to present the existing data regarding the association between EPH/ephrin system expression and the clinical characteristics of malignant tumors.

The Role of the Eph Receptor Family in Tumorigenesis

Simple Summary

The Eph receptor family is implicated in both tumour promotion and suppression, depending on the tissue-specific context of available receptor interactions with ligands, adaptor proteins and triggered downstream signalling pathways. This complex interplay has not only consequences for tumorigenesis but also offers a basis from which new cancer-targeting strategies can be developed. This review comprehensively summarises the current knowledge of Eph receptor implications in oncogenesis in a tissue- and receptor-specific manner, with the aim to develop a better understanding of Eph signalling pathways for potential targeting in novel cancer therapies.

Abstract

The Eph receptor tyrosine kinase family, activated by binding to their cognate ephrin ligands, are important components of signalling pathways involved in animal development. More recently, they have received significant interest due to their involvement in oncogenesis. In most cases, their expression is altered, affecting the likes of cell proliferation and migration. Depending on the context, Eph receptors have the potential to act as both tumour promoters and suppressors in a number of cancers, such as breast cancer, colorectal cancer, lung cancer, prostate cancer, brain cancer and Kaposi’s sarcoma (KS), the latter being intrinsically linked to EphA2 as this is the receptor used for endothelial cell entry by the Kaposi’s sarcoma-associated herpesvirus (KSHV). In addition, EphA2 deregulation is associated with KS, indicating that it has a dual role in this case. Associations between EphA2 sequence variation and KSHV infection/KS progression have been detected, but further work is required to formally establish the links between EphA2 signalling and KS oncogenesis. This review consolidates the available literature of the role of the Eph receptor family, and particularly EphA2, in tumorigenesis, with the aim to develop a better understanding of Eph signalling pathways for potential targeting in novel cancer therapies.

Creation of a Prognostic Risk Prediction Model for Lung Adenocarcinoma Based on Gene Expression, Methylation, and Clinical Characteristics

Background

This study aimed to identify important marker genes in lung adenocarcinoma (LACC) and establish a prognostic risk model to predict the risk of LACC in patients.

Material/Methods

Gene expression and methylation profiles for LACC and clinical information about cases were downloaded from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases, respectively. Differentially expressed genes (DEGs) and differentially methylated genes (DMGs) between cancer and control groups were selected through meta-analysis. Pearson coefficient correlation analysis was performed to identify intersections between DEGs and DMGs and a functional analysis was performed on the genes that were correlated. Marker genes and clinical factors significantly related to prognosis were identified using univariate and multivariate Cox regression analyses. Risk prediction models were then created based on the marker genes and clinical factors.

Results

In total, 1975 DEGs and 2095 DMGs were identified. After comparison, 16 prognosis-related genes (EFNB2, TSPAN7, INPP5A, VAMP2, CALML5, SNAI2, RHOBTB1, CKB, ATF7IP2, RIMS2, RCBTB2, YBX1, RAB27B, NFATC1, TCEAL4, and SLC16A3) were selected from 265 overlapping genes. Four clinical factors (pathologic N [node], pathologic T [tumor], pathologic stage, and new tumor) were associated with prognosis. The prognostic risk prediction models were constructed and validated with other independent datasets.

Conclusions

An integrated model that combines clinical factors and gene markers is useful for predicting risk of LACC in patients. The 16 genes that were identified, including EFNB2, TSPAN7, INPP5A, VAMP2, and CALML5, may serve as novel biomarkers for diagnosis of LACC and prediction of disease prognosis.

PDCD10-Deficiency Promotes Malignant Behaviors and Tumor Growth via Triggering EphB4 Kinase Activity in Glioblastoma

We previously reported an angiogenic and tumor-suppressor-like function of programmed cell death 10 (PDCD10) in glioblastoma (GBM). However, the underlying mechanism remains to be elucidated. We hypothesized that loss of PDCD10 activates GBM cells and tumor progression via EphB4. To this end, PDCD10 was knocked down in U87 and T98g by lentiviral mediated shRNA transduction (shPDCD10). GBM cell phenotype in vitro and tumor growth in a mouse xenograft model were investigated in presence or absence of the treatment with a specific EphB4 kinase inhibitor NVP-BHG712 (NVP). We demonstrated that knockdown of PDCD10 in GBM cells significantly upregulated the mRNA and protein expression of EphB4 accompanied by the activation of Erk1/2. EphB4 kinase activity, reflected by phospho-EphB4, significantly increased in shPDCD10 GBM cells, and in tumors derived from shPDCD10 GBM xenografts, which was abolished by the treatment with NVP. Furthermore, NVP treatment significantly suppressed PDCD10-knockdown mediated aggressive GBM cell phenotype in vitro and extensive tumor cell proliferation, the tumor neo-angiogenesis, and a quick progression of tumor formation in vivo. In summary, loss of PDCD10 activates GBM cells and promotes tumor growth via triggering EphB4. Targeting EphB4 might be an effective strategy particularly for the personalized therapy in GBM patients with PDCD10-deficiency.

The effects of ephrinB2 signaling on proliferation and invasion in glioblastoma multiforme

The aggressive nature of glioblastoma multiforme (GBM) may be attributed to the dysregulation of pathways driving both proliferation and invasion. EphrinB2, a membrane-bound ligand for some of the Eph receptors, has emerged as a critical target regulating these pathways. In this study, we investigated the role of ephrinB2 in regulating proliferation and invasion in GBM using intracranial and subcutaneous xenograft models. The Cancer Genome Atlas analysis suggested high transcript and low methylation levels of ephrinB2 as poor prognostic indicators in GBM, consistent with its role as an oncogene. EphrinB2 knockdown, however, increased tumor growth, an effect that was reversed by ephrinB2 Fc protein. This was associated with EphB4 receptor activation, consistent with the data showing a significant decrease in tumor growth with ephrinB2 overexpression. Mechanistic analyses showed that ephrinB2 knockdown has anti-invasive but pro-proliferative effects in GBM. EphB4 stimulation following ephrinB2 Fc treatment in ephrinB2 knockdown tumors was shown to impart strong anti-proliferative and anti-invasive effects, which correlated with decrease in PCNA, p-ERK, vimentin, Snail, Fak, and increase in the E-cadherin levels. Overall, our study suggests that ephrinB2 cannot be used as a sole therapeutic target. Concomitant inhibition of ephrinB2 signaling with EphB4 activation is required to achieve maximal therapeutic benefit in GBM.

Angiocrine endothelium: from physiology to cancer

The concept of cancer as a cell-autonomous disease has been challenged by the wealth of knowledge gathered in the past decades on the importance of tumor microenvironment (TM) in cancer progression and metastasis. The significance of endothelial cells (ECs) in this scenario was initially attributed to their role in vasculogenesis and angiogenesis that is critical for tumor initiation and growth. Nevertheless, the identification of endothelial-derived angiocrine factors illustrated an alternative non-angiogenic function of ECs contributing to both physiological and pathological tissue development. Gene expression profiling studies have demonstrated distinctive expression patterns in tumor-associated endothelial cells that imply a bilateral crosstalk between tumor and its endothelium. Recently, some of the molecular determinants of this reciprocal interaction have been identified which are considered as potential targets for developing novel anti-angiocrine therapeutic strategies.

Ephrin‑B2 inhibits cell proliferation and motility in vitro and predicts longer metastasis‑free survival in breast cancer

The tyrosine kinase receptor EphB4 and its ligand ephrin‑B2 interact through cell‑to‑cell contacts. Upon interaction, EphB4 transmits bidirectional signals. A forward signal inside EphB4‑expressing cells is believed to suppress tumor growth, while inside the ephrin‑expressing cells, an oncogenic reverse signal arises. In breast cancer cells with a high EphB4 receptor expression the forward signal is low, in part due to the low expression of the ligand ephrin‑B2. Therefore, we hypothesized that by re‑introducing the ligand in EphB4‑positive cells, tumor suppression could be induced by the stimulation of the forward signal. This question was addressed in vitro by the stable lentiviral infection of breast cancer cells with either wild‑type EFNB2 or with a mutant EFNB2‑5F, unable to transmit reverse signaling. Furthermore, we investigated ephrin‑B and EphB4 protein expression in 216 paraffin‑embedded tumors using immunohistochemistry. The in vitro results indicated that ephrin‑B2 expression was associated with a lower cell proliferation, migration and motility compared with the control cells. These effects were more pronounced when the cells lacked the ability to transmit the reverse signal (B2‑5F). In clinical material, ephrin‑B protein expression was associated with a positive estrogen receptor (ER) status, a low HER‑2 expression and was negatively associated with Nottingham histologic grade (NHG) III. Ephrin‑B expression indicated a good prognosis, whereas EphB4 expression was associated with a shorter metastasis‑free survival in univariate and multivariate analysis. Furthermore, the prognostic value of EFNB2 and EPHB4 was confirmed at the gene expression level in public datasets. Thus, on the whole, the findings of this study suggest that ephrin‑B2 expression is associated with less proliferation and lower motility of breast cancer cells and with a longer patient survival in breast cancer.

The Small Molecule Ephrin Receptor Inhibitor, GLPG1790, Reduces Renewal Capabilities of Cancer Stem Cells, Showing Anti-Tumour Efficacy on Preclinical Glioblastoma Models

Therapies against glioblastoma (GBM) show a high percentage of failure associated with the survival of glioma stem cells (GSCs) that repopulate treated tumours. Forced differentiation of GSCs is a promising new approach in cancer treatment. Erythropoietin-producing hepatocellular (Eph) receptors drive tumourigenicity and stemness in GBM. We tested GLPG1790, a first small molecule with inhibition activity versus inhibitor of various Eph receptor kinases, in preclinical GBM models using in vitro and in vivo assays. GLPG1790 rapidly and persistently inhibited Ephrin-A1-mediated phosphorylation of Tyr⁵⁸⁸ and Ser⁸⁹⁷, completely blocking EphA2 receptor signalling. Similarly, this compound blocks the ephrin B2-mediated EphA3 and EphB4 tyrosine phosphorylation. This resulted in anti-glioma effects. GLPG1790 down-modulated the expression of mesenchymal markers CD44, Sox2, nestin, octamer-binding transcription factor 3/4 (Oct3/4), Nanog, CD90, and CD105, and up-regulated that of glial fibrillary acidic protein (GFAP) and pro-neural/neuronal markers, βIII tubulin, and neurofilaments. GLPG1790 reduced tumour growth in vivo. These effects were larger compared to radiation therapy (RT; U251 and T98G xenografts) and smaller than those of temozolomide (TMZ; U251 and U87MG cell models). By contrast, GLPG1790 showed effects that were higher than Radiotherapy (RT) and similar to Temozolomide (TMZ) in orthotopic U87MG and CSCs-5 models in terms of disease-free survival (DFS) and overall survival (OS). Further experiments were necessary to study possible interactions with radio- and chemotherapy. GLPG1790 demonstrated anti-tumor effects regulating both the differentiative status of Glioma Initiating Cells (GICs) and the quality of tumor microenvironment, translating into efficacy in aggressive GBM mouse models. Significant common molecular targets to radio and chemo therapy supported the combination use of GLPG1790 in ameliorative antiglioma therapy.

Antitumor effects of circ-EPHB4 in hepatocellular carcinoma via inhibition of HIF-1α

The protein EPHB4 plays a vital role in various tumor types. However, few studies into the function of circ-EPHB4 (hsa_circ_0001730) in tumors have been conducted. This study aimed to investigate the functions of circ-EPHB4 and the underlying mechanism of circ-EPHB4 in regulating hepatocellular carcinoma (HCC). The expression of circ-EPHB4 was found to be downregulated in HCC tumor tissues, whereas circ-EPHB4 overexpression suppressed cell viability, induced apoptosis, and inhibited cell migration and invasion in Huh7 and HepG2 cells. circ-EPHB4 levels were negatively correlated with tumor weight, size, and metastasis foci in nude mouse models, suggesting circ-EPHB4 inhibits tumorigenesis, tumor development, and metastasis. In addition, HIF-1α and PI3K-AKT pathways were markedly affected by circ-EPHB4 overexpression. HIF-1α could potentially be the target of circ-EPHB4. By overexpressing both HIF-1α and circ-EPHB4, the antitumor effect of circ-EPHB4 should be most probably correlated with HIF-1α. In conclusion, circ-EPHB4 is a tumor inhibitor in HCC and functions by inhibiting HIF-1α expression.

Receptor-Targeted Glial Brain Tumor Therapies

Among primary brain tumors, malignant gliomas are notably difficult to manage. The higher-grade tumors represent an unmet need in medicine. There have been extensive efforts to implement receptor-targeted therapeutic approaches directed against gliomas. These approaches include immunotherapies, such as vaccines, adoptive immunotherapy, and passive immunotherapy. Targeted cytotoxic radio energy and pro-drug activation have been designed specifically for brain tumors. The field of targeting through receptors progressed significantly with the discovery of an interleukin 13 receptor alpha 2 (IL-13RA2) as a tumor-associated receptor over-expressed in most patients with glioblastoma (GBM) but not in normal brain. IL-13RA2 has been exploited in novel experimental therapies with very encouraging clinical responses. Other receptors are specifically over-expressed in many patients with GBM, such as EphA2 and EphA3 receptors, among others. These findings are important in view of the heterogeneity of GBM tumors and multiple tumor compartments responsible for tumor progression and resistance to therapies. The combined targeting of multiple receptors in different tumor compartments should be a preferred way to design novel receptor-targeted therapeutic approaches in gliomas.

High serum Ephrin-B2 levels predict poor prognosis for patients with gastric cancer

Gastric cancer is an intractable disease with a poor prognosis and limited treatment options. Its treatment remains a major clinical challenge worldwide. Ephrin-B2 is upregulated and involved in tumor growth in various types of cancer. However, the association between ephrin-B2 and prognosis of gastric cancer, and the potential of ephrin-B2 as a therapeutic target remains unknown. The present study investigated ephrin-B2 as a prognostic factor and a therapeutic target for gastric cancer. Reverse transcription-quantitative polymerase chain reaction was performed to detect the protein expression level of ephrin-B2 in gastric cancer serum samples (n=162) and healthy serum samples (n=165). It was revealed that the protein expression level of ephrin-B2 was significantly upregulated in gastric cancer serum samples compared with the healthy samples. Ephrin-B2 protein expression was associated with tumor size (P<0.001), metastasis (P=0.02) and TNM stage (P=0.03), and was indicated to be an independent prognostic factor for gastric cancer. Furthermore, the Kaplan-Meier survival curve demonstrated that patients with high ephrin-B2 protein expression had shorter overall and progression-free survival rates than those with low ephrin-B2 protein expression. Ephrin-B2 protein expression was induced by small interfering RNA (siRNA) transfection of HGC27 and MKN-45 cells, significantly impeding cell viability and inducing apoptosis of HGC27 and MKN-45 cells compared with the respective negative control (NC) group. Thus, to the best of our knowledge, the present study indicates that ephrin-B2 functions as an oncogene in gastric cancer, and that serum ephrin-B2 level may be a promising non-invasive prognostic indicator, as well as a therapeutic target for gastric cancer.

An Experimenter's Guide to Glioblastoma Invasion Pathways

Glioblastoma is a highly aggressive brain tumor that is characterized by its unparalleled invasiveness. Invasive glioblastoma cells not only escape surgery and focal therapies but also are more resistant to current radio- and chemo-therapeutic approaches. Thus, any curative therapy for this deadly disease likely should include treatment strategies that interfere with glioblastoma invasiveness. Understanding glioblastoma invasion mechanisms is therefore critical. We discuss the strengths and weaknesses of various glioblastoma invasion models and conclude that robust experimental evidence has been obtained for a pro-invasive role of Ephrin receptors, Rho GTPases, and casein kinase 2 (CK2). Extensive interplay occurs between these proteins, suggesting the existence of a glioblastoma invasion signaling network that comprises several targets for therapy.

EphB4 mediates resistance to antiangiogenic therapy in experimental glioma

INTRODUCTION

Alterations in vascular morphogenesis are hallmarks of antiangiogenesis-resistant tumor vessels. Vascular morphogenesis is regulated by ephrinB2-EphB4 system which may induce different biological effects depending on the oncological and molecular contexts. It was the aim of the current study to characterize the influence of EphB4 on tumor microcirculation after antiangiogenic treatment using different SF126 glioma models.

MATERIALS AND METHODS

Using an ecotropic transfection system, empty vector (pLXSN) or EphB4 (EphB4^OE) overexpressing Phoenix-ECO cells were coimplanted with SF126 glioma cells subcutaneously (dorsal skinfold chamber, DSC) and orthotopically (cranial window, CW). Tumor volume was assessed by MRI. Intravital microscopy (IVM) allowed microcirculatory analysis (total {TVD} and functional vessel density {FVD}, diameter {D}, and permeability index {PI}) before and after antiangiogenic treatment (Sunitinib: DSC: 40 mg/kg BW, 6 days; CW: 80 mg/kg BW, 4 days). Immunohistochemistry included Pecam-Desmin, Ki67, TUNEL, and Caspase 3 stainings.

RESULTS

EphB4^OE induced large and treatment-resistant tumor vessels (FVD: Control/Su: 110 ± 23 cm/cm² vs. EphB4^OE/Su: 103 ± 42 cm/cm²). Maintenance of pericyte-endothelial cell interactions (Control: 80 ± 12 vs. Control/Su: 47 ± 26%; EphB4^OE: 88 ± 9 vs. EphB4^OE/Su: 74 ± 25%) and reduced antiproliferative (Control: 637 ± 80 vs. Control/Su: 110 ± 22; EphB4^OE: 298 ± 108 vs. EphB4^OE/Su: 213 ± 80) and proapoptotic responses (Control: 196 ± 25 vs. Control / Su: 404 ± 60; EphB4^OE: 183 ± 20 vs. EphB4^OE/Su: 270 ± 66) were observed under EphB4 overexpression.

CONCLUSION

EphB4 overexpression leads to vascular resistance by altering vascular morphogenesis, pericyte coverage, and cellular proliferation/apoptosis in experimental SF126 glioma models.

Differential Expression Patterns of Eph Receptors and Ephrin Ligands in Human Cancers

Eph receptors constitute the largest family of receptor tyrosine kinases, which are activated by ephrin ligands that either are anchored to the membrane or contain a transmembrane domain. These molecules play important roles in the development of multicellular organisms, and the physiological functions of these receptor-ligand pairs have been extensively documented in axon guidance, neuronal development, vascular patterning, and inflammation during tissue injury. The recognition that aberrant regulation and expression of these molecules lead to alterations in proliferative, migratory, and invasive potential of a variety of human cancers has made them potential targets for cancer therapeutics. We present here the involvement of Eph receptors and ephrin ligands in lung carcinoma, breast carcinoma, prostate carcinoma, colorectal carcinoma, glioblastoma, and medulloblastoma. The aberrations in their abundances are described in the context of multiple signaling pathways, and differential expression is suggested as the mechanism underlying tumorigenesis.

Tenascin-C Orchestrates Glioblastoma Angiogenesis by Modulation of Pro- and Anti-angiogenic Signaling

High expression of the extracellular matrix component tenascin-C in the tumor microenvironment correlates with decreased patient survival. Tenascin-C promotes cancer progression and a disrupted tumor vasculature through an unclear mechanism. Here, we examine the angiomodulatory role of tenascin-C. We find that direct contact of endothelial cells with tenascin-C disrupts actin polymerization, resulting in cytoplasmic retention of the transcriptional coactivator YAP. Tenascin-C also downregulates YAP pro-angiogenic target genes, thus reducing endothelial cell survival, proliferation, and tubulogenesis. Glioblastoma cells exposed to tenascin-C secrete pro-angiogenic factors that promote endothelial cell survival and tubulogenesis. Proteomic analysis of their secretome reveals a signature, including ephrin-B2, that predicts decreased survival of glioma patients. We find that ephrin-B2 is an important pro-angiogenic tenascin-C effector. Thus, we demonstrate dual activities for tenascin-C in glioblastoma angiogenesis and uncover potential targeting and prediction opportunities.

Eph-B4 regulates adaptive venous remodeling to improve arteriovenous fistula patency

Low rates of arteriovenous fistula (AVF) maturation prevent optimal fistula use for hemodialysis; however, the mechanism of venous remodeling in the fistula environment is not well understood. We hypothesized that the embryonic venous determinant Eph-B4 mediates AVF maturation. In human AVF and a mouse aortocaval fistula model, Eph-B4 protein expression increased in the fistula vein; expression of the arterial determinant Ephrin-B2 also increased. Stimulation of Eph-B-mediated signaling with Ephrin-B2/Fc showed improved fistula patency with less wall thickness. Mutagenesis studies showed that tyrosine-774 is critical for Eph-B4 signaling and administration of inactive Eph-B4-Y774F increased fistula wall thickness. Akt1 expression also increased in AVF; Akt1 knockout mice showed reduced fistula diameter and wall thickness. In Akt1 knockout mice, stimulation of Eph-B signaling with Ephrin-B2/Fc showed no effect on remodeling. These results show that AVF maturation is associated with acquisition of dual arteriovenous identity; increased Eph-B activity improves AVF patency. Inhibition of Akt1 function abolishes Eph-B-mediated venous remodeling suggesting that Eph-B4 regulates AVF venous adaptation through an Akt1-mediated mechanism.

EphB4 forward signalling mediates angiogenesis caused by CCM3/PDCD10-ablation

CCM3, also named as PDCD10, is a ubiquitous protein expressed in nearly all tissues and in various types of cells. It is essential for vascular development and post-natal vessel maturation. Loss-of-function mutation of CCM3 predisposes for the familial form of cerebral cavernous malformation (CCM). We have previously shown that knock-down of CCM3 stimulated endothelial angiogenesis via impairing DLL4-Notch signalling; moreover, loss of endothelial CCM3 stimulated tumour angiogenesis and promoted tumour growth. The present study was designed to further elucidate the inside signalling pathway involved in CCM3-ablation-mediated angiogenesis. Here we report for the first time that silencing endothelial CCM3 led to a significant up-regulation of EphB4 mRNA and protein expression and to an increased kinase activity of EphB4, concomitantly accompanied by an activation of Erk1/2, which was reversed by treatment with the specific EphB4 kinase inhibitor NVP-BHG712 (NVP), indicating that silencing CCM3 activates EphB4 kinase forward signalling. Furthermore, treatment with NVP rescued the hyper-angiogenic phenotype induced by knock-down of endothelial CCM3 in vitro and in vivo. Additional study demonstrated that the activation of EphB4 forward signalling in endothelial cells under basal condition and after CCM3-silence was modulated by DLL4/Notch signalling, relying EphB4 at downstream of DLL4/Notch signalling. We conclude that angiogenesis induced by CCM3-silence is mediated by the activation of EphB4 forward signalling. The identified endothelial signalling pathway of CCM3-DLL4/Notch-EphB4-Erk1/2 may provide an insight into mechanism of CCM3-ablation-mediated angiogenesis and could potentially contribute to novel therapeutic concepts for disrupting aberrant angiogenesis in CCM and in hyper-vascularized tumours.

The antitumor effect of arsenic trioxide on hepatocellular carcinoma is enhanced by andrographolide

High concentrations of arsenic trioxide (As₂O₃) are used to treat acute promyelocytic leukemia and solid tumors, with negative side effects to normal cells. Andrographolide is a traditional Chinese medicine that exerts anti-cancer, anti-inflammatory, anti-virus, and anti-diabetic effects. Here, we tested the effects of combined andrographolide with As₂O₃ against hepatocellular carcinoma (HCC). We found that by increasing apoptosis, andrographolide synergistically enhanced the anti-tumor effects of As2O3 in HepG2 cells in vitro and in vivo. Furthermore, results from our microarray assays and experiments with mouse xenografts showed that EphB4 was downregulated by the combination of As₂O₃ plus andrographolide. These findings suggest that the combination of andrographolide and As₂O₃ could yield therapeutic benefits in the treatment of HCC.

The coexpression of EphB4 and EphrinB2 is associated with poor prognosis in HER2-positive breast cancer

Objective

HER2 overexpression is associated with aggressive phenotypes in breast cancer, including increased tumor proliferation, greater invasiveness, and reduced overall survival. The overall response rate to HER2-targeted therapies remains <30%. There is an urgent need for the identification of efficient markers to predict patients with a poor prognosis. This study was designed to investigate the correlation between EphB4 and EphrinB2 expression and the clinicopathological characteristics of HER2-positive breast cancer.

Materials and methods

A total of 111 primary HER2-positive breast cancer patients were enrolled in this study (diagnosed since December 2005 to November 2010 from the Second Hospital of Dalian Medical University). The protein expression of EphB4 and EphrinB2 was examined by immunohistochemistry using paraffin-embedded tumor tissues.

Results

There was a significant correlation between EphB4 and EphrinB2 expression (P=0.013, r=0.255). Kaplan–Meier analysis showed that the prognosis of patients with a high expression of both EphB4 and EphrinB2 was significantly worse than the prognosis of patients with either EphB4 or EphrinB2 expression and patients with negative expression (hazard ratio [HR] =1.935, P=0.0224). However, high expression of EphB4 or EphrinB2 alone was not an independent prognostic factor to predict worse overall survival. To summarize, HER2-positive breast cancer patients with overexpression of both EphB4 and EphrinB2 were associated with the worst prognosis.

Conclusion

High expression of EphB4 and EphrinB2 correlated with poor overall survival, which can serve as an independent prognostic indicator in primary HER2-positive breast cancer patients.

KSR1 and EPHB4 Regulate Myc and PGC1β To Promote Survival of Human Colon Tumors

Identification and characterization of survival pathways active in tumor cells but absent in normal tissues provide opportunities to develop effective anticancer therapies with reduced toxicity to the patient. We show here that, like kinase suppressor of Ras 1 (KSR1), EPH (erythropoietin-producing hepatocellular carcinoma) receptor B4 (EPHB4) is aberrantly overexpressed in human colon tumor cell lines and selectively required for their survival. KSR1 and EPHB4 support tumor cell survival by promoting the expression of downstream targets, Myc and the transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator 1β (PGC1β). While KSR1 promotes the aberrant expression of Myc and the PGC1β protein via a posttranscriptional mechanism, EPHB4 has a greater effect on Myc and PGC1β expression via its ability to elevate mRNA levels. Subsequent analysis of the posttranscriptional regulation demonstrated that KSR1 promotes the translation of Myc protein. These findings reveal novel KSR1- and EPHB4-dependent signaling pathways supporting the survival of colorectal cancer cells through regulation of Myc and PGC1β, suggesting that inhibition of KSR1 or EPHB4 effectors may lead to selective toxicity in colorectal tumors.

EphrinB2 repression through ZEB2 mediates tumour invasion and anti-angiogenic resistance

Diffuse invasion of the surrounding brain parenchyma is a major obstacle in the treatment of gliomas with various therapeutics, including anti-angiogenic agents. Here we identify the epi-/genetic and microenvironmental downregulation of ephrinB2 as a crucial step that promotes tumour invasion by abrogation of repulsive signals. We demonstrate that ephrinB2 is downregulated in human gliomas as a consequence of promoter hypermethylation and gene deletion. Consistently, genetic deletion of ephrinB2 in a murine high-grade glioma model increases invasion. Importantly, ephrinB2 gene silencing is complemented by a hypoxia-induced transcriptional repression. Mechanistically, hypoxia-inducible factor (HIF)-1α induces the EMT repressor ZEB2, which directly downregulates ephrinB2 through promoter binding to enhance tumour invasiveness. This mechanism is activated following anti-angiogenic treatment of gliomas and is efficiently blocked by disrupting ZEB2 activity. Taken together, our results identify ZEB2 as an attractive therapeutic target to inhibit tumour invasion and counteract tumour resistance mechanisms induced by anti-angiogenic treatment strategies.

Ephrins are transmembrane proteins involved in cell-cell communication, and implicated in cancer cell growth and progression. Here, the authors show that EphrinB2 expression is reduced in glioma cells both by genetic and epigenetic alterations and under hypoxia, through a HIF1α-mediated direct regulation of ZEB2, which enhances invasion and anti-angiogenic resistance.

EphrinB2 drives perivascular invasion and proliferation of glioblastoma stem-like cells

Glioblastomas (GBM) are aggressive and therapy-resistant brain tumours, which contain a subpopulation of tumour-propagating glioblastoma stem-like cells (GSC) thought to drive progression and recurrence. Diffuse invasion of the brain parenchyma, including along preexisting blood vessels, is a leading cause of therapeutic resistance, but the mechanisms remain unclear. Here, we show that ephrin-B2 mediates GSC perivascular invasion. Intravital imaging, coupled with mechanistic studies in murine GBM models and patient-derived GSC, revealed that endothelial ephrin-B2 compartmentalises non-tumourigenic cells. In contrast, upregulation of the same ephrin-B2 ligand in GSC enabled perivascular migration through homotypic forward signalling. Surprisingly, ephrin-B2 reverse signalling also promoted tumourigenesis cell-autonomously, by mediating anchorage-independent cytokinesis via RhoA. In human GSC-derived orthotopic xenografts, EFNB2 knock-down blocked tumour initiation and treatment of established tumours with ephrin-B2-blocking antibodies suppressed progression. Thus, our results indicate that targeting ephrin-B2 may be an effective strategy for the simultaneous inhibition of invasion and proliferation in GBM.

Clinical Significance of EphB4 and EphB6 Expression in Human Malignant and Benign Thyroid Lesions

Ephrin receptors (Ephs) are frequently overexpressed in a wide variety of human malignant tumors, being associated with tumor growth, invasion, angiogenesis and metastasis. The present study aimed to evaluate the clinical significance of EphB4 and EphB6 protein expression in human malignant and benign thyroid lesions. EphB4 and EphB6 protein expression was assessed immunohistochemically on paraffin-embedded thyroid tissues obtained from 127 patients with benign (n = 71) and malignant (n = 56) thyroid lesions. Enhanced EphB4 and EphB6 expression was more frequently observed in malignant compared to benign thyroid lesions (p = 0.0508 and p = 0.0006, respectively). EphB4 and EphB6 expression also provided a distinct discrimination between papillary carcinoma and hyperplastic nodules (p = 0.0302 and p = 0.0013, respectively). In malignant thyroid lesions, enhanced EphB4 expression was significantly associated with larger tumor size (p = 0.0366). Enhanced EphB6 expression was significantly associated with larger tumor size (p = 0.0366), the presence of lymph node metastases (p = 0.0023), the presence of capsular (p = 0.0038), lymphatic (p = 0.0053) and vascular invasion (p = 0.0018) and increased risk of recurrence rate (p = 0.0038). The present study supported evidence that EphB4 and mainly EphB6 may participate in the malignant thyroid transformation, reinforcing their utility as useful biomarkers and possible therapeutic targets in this type of neoplasia.

EphB1 Suppression in Acute Myelogenous Leukemia: Regulating the DNA Damage Control System

Loss of ephrin receptor (EphB1) expression may associate with aggressive cancer phenotypes; however, the mechanism of action remains unclear. To gain detailed insight into EphB1 function in acute myelogenous leukemia (AML), comprehensive analysis of EphB1 transcriptional regulation was conducted. In AML cells, EphB1 transcript was inversely correlated with EphB1 promoter methylation. The presence of EphB1 allowed EfnB1 ligand-mediated p53 DNA binding, leading to restoration of the DNA damage response (DDR) cascade by the activation of ATR, Chk1, p53, p21, p38, CDK1(tyr15), and Bax, and downregulation of HSP27 and Bcl2. Comparatively, reintroduction of EphB1 expression in EphB1-methylated AML cells enhanced the same cascade of ATR, Chk1, p21, and CDK1(tyr15), which consequently enforced programmed cell death. Interestingly, in pediatric AML samples, EphB1 peptide phosphorylation and mRNA expression were actively suppressed as compared with normal bone marrow, and a significant percentage of the primary AML specimens had EphB1 promoter hypermethylation. Finally, EphB1 repression associated with a poor overall survival in pediatric AML. Combined, the contribution of EphB1 to the DDR system reveals a tumor-suppressor function for EphB1 in pediatric AML.

IMPLICATIONS

The tumor-suppressor function of EphB1 is clinically relevant across many malignancies, suggesting that EphB1 is an important regulator of common cancer cell transforming pathways.

Expression of ephrinB2 and EphB4 in a neonatal rat model of periventricular white matter damage

BACKGROUND

Periventricular white matter damage (PWMD), also termed periventricular leukomalacia, is the predominant neurologic lesion in preterm infants. It appears to relate in part to the development of the vascular supply to the cerebral white matter. We investigated whether, in case of severe hypoxia-ischemia, the vascular system would be subject to severe damage or remodeled.

AIMS

To evaluate microvessel density (MVD) and the use of ephrinB2 and its receptor EphB4 to mark arterioles and venules to establish the correct anatomic assignment of the remodeled vessels in a hypoxia-induced PWMD rat model.

METHODS

Postnatal day 3 rats underwent permanent ligation of the right common carotid artery followed by 6% O2 for 4 h (hypoxia-ischemia) or sham operation and normoxic exposure (sham). MVD and levels of ephrinB2 and EphB4, which are respectively regarded as relatively specific molecular markers of arteries and veins, were determined at postnatal day 7.

RESULTS

Compared with sham rats, MVD, ephrinB2 and EphB4 levels were higher in the brains of hypoxic-ischemic rats. Similar percentages of vessels expressed ephrinB2 and EphB4 in sham rats, but expression of ephrinB2 was greater in brains injured by hypoxia-ischemia.

CONCLUSIONS

Following hypoxic-ischemic injury to the rat brain, microvessels were remodeled and more arterioles than venules were acquired.

Ephs and Ephrins in malignant gliomas

Eph receptor tyrosine kinases and the corresponding ephrin ligands play a pivotal role in the glioma development and progression. Aberrant protein expression levels of the Eph receptors and ephrins are often associated with higher tumor grade and poor prognosis. Their function in tumorigenesis is complex due to the intricate network of possible co-occurring interactions between neighboring tumor cells and tumor microenvironment. Both Ephs and ephrins localize on the surface of tumor cells, tumor vasculature, glioma stem cells, tumor cells infiltrating brain, and immune cells infiltrating tumors. They can both promote and inhibit tumorigenicity depending on the downstream forward and reverse signalling generated. All the above-mentioned features make the Ephs/ephrins system an intriguing candidate for the development of new therapeutic strategies in glioma treatment. This review will give a general overview on the structure and the function of Ephs and ephrins, with a particular emphasis on the state of the knowledge of their role in malignant gliomas.

Eph receptors as therapeutic targets in glioblastoma

The dismal outlook for patients with the most aggressive and common form of adult brain cancer, glioblastoma (GBM), motivates a search for new therapeutic strategies and targets for this aggressive disease. Here we review the findings to date on the role of Eph family receptor tyrosine kinases and their ephrin ligands in brain cancer. Expression of the Eph family of cell surface proteins is generally downregulated to very low levels in normal adult tissues making them particularly attractive for directed therapeutic targeting. Recent Eph targeting studies in pre-clinical models of GBM have been very encouraging and may provide an avenue to treat these highly refractory aggressive tumours.

Expression of Potential Regulatory Genes in Abdominal Adipose Tissue of Broiler Chickens during Early Development

The identities of genes that underlie population variation in adipose tissue development in farm animals are poorly understood. Previous studies in our laboratory have suggested that increased fat tissue involves the expression modulation of an array of genes in broiler chickens. Of special interest are eight genes, FGFR3, EPHB2, IGFBP2, GREM1, TNC, COL3A1, ACBD7, and SCD. To understand their expression regulation and response to dietary manipulation, we investigated their mRNA levels after dietary manipulation during early development. Chickens were fed either a recommended standard or a high caloric diet from hatch to eight weeks of age (WOA). The high caloric diet markedly affected bodyweight of the broiler birds. mRNA levels of the eight genes in the abdominal adipose tissue were assayed at 2, 4, 6, and 8 WOA using RT-qPCR. Results indicate that (1) FGFR3 mRNA level was affected significantly by diet, age, and diet:age interaction; (2) COL3A mRNA level was repressed by high caloric diet; (3) mRNA levels of EPHB2, ACBD7, and SCD were affected by age; (4) mRNA level of TNC was modulated by age:diet interaction; (5) changes in GREM1 and IGFBP2 mRNA levels were not statistically different.

Ligand-dependent EphB1 signaling suppresses glioma invasion and correlates with patient survival

BACKGROUND

Extensive evidence implicates the Eph receptor family of tyrosine kinases and its ligand, ephrin, in glioma invasion, but it remains incompletely understood how these receptors affect chemotactic behavior of glioma. We sought to identify the Eph family members that correlate with patients' survival and to reveal the function of Eph in glioma invasion.

METHODS

Clinical relevance of EphB genes was confirmed in a clinically annotated expression data set of 195 brain biopsy specimens. The function of EphB was analyzed in vitro and in vivo.

RESULTS

Levels of mRNA of certain EphB members were significantly different in histological grades of glioma. According to Kaplan-Meier analysis, only the EphB1 level among 5 members of EphB emerged to be a powerful predictor of favorable survival in malignant glioma (n = 97, P = .0048), although the levels of EphB1 expression did not vary across the tumor grades. Immunoprecipitation showed that tyrosine phosphorylated EphB1 was not detected in all glioma cells tested. Forced overexpression and autophosphorylation of EphB1 in low expressor cell lines (U251, U87) did not affect cell migration or invasion in vitro, whereas EphB1 phosphorylation induced by ephrin-B2/Fc significantly decreased migration and invasion. Cells expressing ephrin-B2 showed noteworthy morphological changes consistent with migration induction; this alteration was negated by EphB1 overexpression. Concomitantly, overexpression of EphB1 abrogated the increased migration and invasion induced by ephrin-B2 in vitro and in vivo.

CONCLUSIONS

These data suggest that ligand-dependent EphB1 signaling negatively regulates glioma cell invasion, identifying EphB1 as a favorable prognostic factor in malignant glioma.

Eph receptors and their ligands: promising molecular biomarkers and therapeutic targets in prostate cancer

Although at present, there is a high incidence of prostate cancer, particularly in the Western world, mortality from this disease is declining and occurs primarily only from clinically significant late stage tumors with a poor prognosis. A major current focus of this field is the identification of new biomarkers which can detect earlier, and more effectively, clinically significant tumors from those deemed "low risk", as well as predict the prognostic course of a particular cancer. This strategy can in turn offer novel avenues for targeted therapies. The large family of Receptor Tyrosine Kinases, the Ephs, and their binding partners, the ephrins, has been implicated in many cancers of epithelial origin through stimulation of oncogenic transformation, tumor angiogenesis, and promotion of increased cell survival, invasion and migration. They also show promise as both biomarkers of diagnostic and prognostic value and as targeted therapies in cancer. This review will briefly discuss the complex roles and biological mechanisms of action of these receptors and ligands and, with regard to prostate cancer, highlight their potential as biomarkers for both diagnosis and prognosis, their application as imaging agents, and current approaches to assessing them as therapeutic targets. This review demonstrates the need for future studies into those particular family members that will prove helpful in understanding the biology and potential as targets for treatment of prostate cancer.