EphB2 expression across 138 human tumor types in a tissue microarray: high levels of expression in gastrointestinal cancers

Potential role of the Eph/ephrin system in colorectal cancer: emerging druggable molecular targets

The Eph/ephrin system regulates many developmental processes and adult tissue homeostasis. In colorectal cancer (CRC), it is involved in different processes including tumorigenesis, tumor angiogenesis, metastasis development, and cancer stem cell regeneration. However, conflicting data regarding Eph receptors in CRC, especially in its putative role as an oncogene or a suppressor gene, make the precise role of Eph-ephrin interaction confusing in CRC development. In this review, we provide an overview of the literature and highlight evidence that collaborates with these ambiguous roles of the Eph/ephrin system in CRC, as well as the molecular findings that represent promising therapeutic targets.

Cell Death, by Any Other Name…

Studies trying to understand cell death, this ultimate biological process, can be traced back to a century ago. Yet, unlike many other fashionable research interests, research on cell death is more alive than ever. New modes of cell death are discovered in specific contexts, as are new molecular pathways. But what is "cell death", really? This question has not found a definitive answer yet. Nevertheless, part of the answer is irreversibility, whereby cells can no longer recover from stress or injury. Here, we identify the most distinctive features of different modes of cell death, focusing on the executive final stages. In addition to the final stages, these modes can differ in their triggering stimulus, thus referring to the initial stages. Within this framework, we use a few illustrative examples to examine how intercellular communication factors in the demise of cells. First, we discuss the interplay between cell-cell communication and cell death during a few steps in the early development of multicellular organisms. Next, we will discuss this interplay in a fully developed and functional tissue, the gut, which is among the most rapidly renewing tissues in the body and, therefore, makes extensive use of cell death. Furthermore, we will discuss how the balance between cell death and communication is modified during a pathological condition, i.e., colon tumorigenesis, and how it could shed light on resistance to cancer therapy. Finally, we briefly review data on the role of cell-cell communication modes in the propagation of cell death signals and how this has been considered as a potential therapeutic approach. Far from vainly trying to provide a comprehensive review, we launch an invitation to ponder over the significance of cell death diversity and how it provides multiple opportunities for the contribution of various modes of intercellular communication.

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.

The Ephrin B2 Receptor Tyrosine Kinase Is a Regulator of Proto-oncogene MYC and Molecular Programs Central to Barrett's Neoplasia

BACKGROUND & AIMS

Mechanisms contributing to the onset and progression of Barrett's (BE)-associated esophageal adenocarcinoma (EAC) remain elusive. Here, we interrogated the major signaling pathways deregulated early in the development of Barrett's neoplasia.

METHODS

Whole-transcriptome RNA sequencing analysis was performed in primary BE, EAC, normal esophageal squamous, and gastric biopsy tissues (n = 89). Select pathway components were confirmed by quantitative polymerase chain reaction in an independent cohort of premalignant and malignant biopsy tissues (n = 885). Functional impact of selected pathway was interrogated using transcriptomic, proteomic, and pharmacogenetic analyses in mammalian esophageal organotypic and patient-derived BE/EAC cell line models, in vitro and/or in vivo.

RESULTS

The vast majority of primary BE/EAC tissues and cell line models showed hyperactivation of EphB2 signaling. Transcriptomic/proteomic analyses identified EphB2 as an endogenous binding partner of MYC binding protein 2, and an upstream regulator of c-MYC. Knockdown of EphB2 significantly impeded the viability/proliferation of EAC and BE cells in vitro/in vivo. Activation of EphB2 in normal esophageal squamous 3-dimensional organotypes disrupted epithelial maturation and promoted columnar differentiation programs, notably including MYC. EphB2 and MYC showed selective induction in esophageal submucosal glands with acinar ductal metaplasia, and in a porcine model of BE-like esophageal submucosal gland spheroids. Clinically approved inhibitors of MEK, a protein kinase that regulates MYC, effectively suppressed EAC tumor growth in vivo.

CONCLUSIONS

The EphB2 signaling is frequently hyperactivated across the BE-EAC continuum. EphB2 is an upstream regulator of MYC, and activation of EphB2-MYC axis likely precedes BE development. Targeting EphB2/MYC could be a promising therapeutic strategy for this often refractory and aggressive cancer.

RNF186/EPHB2 Axis Is Essential in Regulating TNF Signaling for Colorectal Tumorigenesis in Colorectal Epithelial Cells

The receptor tyrosine kinase EPHB2 (EPH receptor B2) is highly expressed in many human cancer types, especially in gastrointestinal cancers, such as colorectal cancer. Several coding mutations of the EPHB2 gene have been identified in many cancer types, suggesting that EPHB2 plays a critical role in carcinogenesis. However, the exact functional mechanism of EPHB2 in carcinogenesis remains unknown. In this study, we find that EPHB2 is required for TNF-induced signaling activation and proinflammatory cytokine production in colorectal epithelial cells. Mechanistically, after TNF stimulation, EPHB2 is ubiquitinated by its E3 ligase RNF186. Then, ubiquitinated EPHB2 recruits and further phosphorylates TAB2 at nine tyrosine sites, which is a critical step for the binding between TAB2 and TAK1. Due to defects in TNF signaling in RNF186-knockout colorectal epithelial cells, the phenotype of colitis-propelled colorectal cancer model in RNF186-knockout mice is significantly reduced compared with that in wild-type control mice. Moreover, we find that a genetic mutation in EPHB2 identified in a family with colorectal cancer is a gain-of-function mutation that promoted TNF signaling activation compared with wild-type EPHB2. We provide evidence that the EPHB2-RNF186-TAB2-TAK1 signaling cascade plays an essential role in TNF-mediated signal transduction in colorectal epithelial cells and the carcinogenesis of colorectal cancer, which may provide potential targets for the treatment of colorectal cancer.

Role of EphB2/ephrin‑B1 signalling in the development and progression of obesity‑associated colorectal cancer

Obesity is a major problem worldwide and has been associated with colorectal cancer development, among other diseases. Ephrin receptors and ligands play an important role in the turnover of the intestinal mucosa and intestinal crypt compartmentalization. It has been hypothesised that obesity-induced inflammation affects ephrin signals, leading to carcinogenesis. Therefore, the aim of the present study was to assess the relationship between Eph-ephrin B signalling, obesity and obesity-associated colorectal cancer. An azoxymethane-induced obesity-associated cancer KKAy mouse model developed in our prior study was used. A total of 46 patients with consecutive colorectal cancer and 48 tumours were analysed. Immunohistological analyses were performed in mouse and human samples, and immunoreactive scores (IRS) were determined. KKAy mice were significantly more prone to cancer development compared with control C57/BL mice (2/15 in C57/BL vs. 10/10 in KKAy; P<0.001). TUNEL assay revealed a lower number of apoptotic cells in normal mucosa of KKAy mice (8.8% in C57/BL vs. 3.2% in KKAy; P<0.001) and obese patients (9.2% with BMI <25 vs. 3.6% with BMI ≥25; P=0.021). Immunohistological analysis revealed that ephrin-B1 was downregulated in normal mucosa from KKAy mice and obese patients (IRS, 2.86 with BMI <25 vs. 6.00 with BMI ≥25; P=0.002). Moreover, EphB2 was downregulated in tumours from KKAy mice and obese patients (IRS, 6.58 with BMI <25 vs. 3.83 with BMI ≥25; P<0.001). The distribution of infiltrated macrophages corresponded to the MCP-1 expression pattern in KKAy mice, and the number of macrophages was also significantly higher in those mice (36.3 in C57/BL vs. 120.0 in KKAy; P=0.029). The findings suggested that obesity results in disruption of EphB2/ephrin-B1 signalling, promoting colorectal cancer development and progression.

The Roles of EphB2 in Cancer

The erythropoietin-producing hepatocellular carcinoma (Eph) receptors and their Eph receptor-interacting (ephrin) ligands together constitute a vital cell communication system with diverse roles. Experimental evidence revealed Eph receptor bidirectional signaling with both tumor-promoting and tumor-suppressing activities in different cancer types and surrounding environment. Eph receptor B2 (EphB2), an important member of the Eph receptor family, has been proved to be aberrantly expressed in many cancer types, such as colorectal cancer, gastric cancer and hepatocellular carcinoma, resulting in tumor occurrence and progression. However, there are no reviews focusing on the dual roles of EphB2 in cancer. Thus, in this paper we systematically summarize and discuss the roles of EphB2 in cancer. Firstly, we review the main biological features and the related signaling regulatory mechanisms of EphB2, and then we summarize the roles of EphB2 in cancer through current studies. Finally, we put forward our viewpoint on the future prospects of cancer research focusing on EphB2, especially with regard to the effects of EphB2 on tumor immunity.

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 Value of EphB2 Receptor and Cognate Ephrin Ligands in Prognostic and Predictive Assessments of Human Breast Cancer

Cell–cell communication proteins Eph and ephrin constitute the largest family of receptor tyrosine kinases (RTKs). They are distinguished by the fact that both receptors and ligands are membrane-bound, and both can drive intracellular signaling in their respective cells. Ever since these RTKs have been found to be involved in cancer development, strategies to target them therapeutically have been actively pursued. However, before this goal can be rationally achieved, the contributions of either Eph receptors or their ephrin ligands to cancer development and progression should be scrutinized in depth. To assess the clinical pertinence of this concern, we performed a systematic review and meta-analysis of the prognostic/predictive value of EphB2 and its multiple cognate ephrin ligands in breast cancer. We found that EphB2 has prognostic value, as indicated by the association of higher EphB2 expression levels with lower distant metastasis-free survival (DMFS), and the association of lower EphB2 expression levels with poorer relapse-free survival (RFS). We also found that higher EphB2 expression could be a prognostic factor for distant metastasis, specifically in the luminal subtypes of breast cancer. EFNB2 showed a marked correlation between higher expression levels and shorter DMFS. EFNA5 or EFNB1 overexpression is correlated with longer RFS. Increased EFNB1 expression is correlated with longer OS in lymph node (LN)-negative patients and the luminal B subtype. Higher levels of EFNB2 or EFNA5 are significantly correlated with shorter RFS, regardless of LN status. However, while this correlation with shorter RFS is true for EFNB2 in all subtypes except basal, it is also true for EFNA5 in all subtypes except HER2+. The analysis also points to possible predictive value for EphB2. In systemically treated patients who have undergone either endocrine therapy or chemotherapy, we found that higher expression of EphB2 is correlated with better rates of RFS. Bearing in mind the limitations inherent to any mRNA-based profiling method, we complemented our analysis with an immunohistochemical assessment of expression levels of both the EphB2 receptor and cognate ephrin ligands. We found that the latter are significantly more expressed in cancers than in normal tissues, and even more so in invasive and metastatic samples than in ductal carcinoma in situ (DCIS). Finally, in an in vitro cellular model of breast cancer progression, based on H-Ras-transformation of the MCF10A benign mammary cell line, we observed dramatic increases in the mRNA expression of EphB2 receptor and EFNB1 and EFNB2 ligands in transformed and invasive cells in comparison with their benign counterparts. Taken together, these data show the clinical validity of a model whereby EphB2, along with its cognate ephrin ligands, have dual anti- and pro-tumor progression effects. In so doing, they reinforce the necessity of further biological investigations into Ephs and ephrins, prior to using them in targeted therapies.

Portrait of Cancer Stem Cells on Colorectal Cancer: Molecular Biomarkers, Signaling Pathways and miRNAome

Colorectal cancer (CRC) is a leading cause of cancer death worldwide, and about 20% is metastatic at diagnosis and untreatable. Increasing evidence suggests that the heterogeneous nature of CRC is related to colorectal cancer stem cells (CCSCs), a small cells population with stemness behaviors and responsible for tumor progression, recurrence, and therapy resistance. Growing knowledge of stem cells (SCs) biology has rapidly improved uncovering the molecular mechanisms and possible crosstalk/feedback loops between signaling pathways that directly influence intestinal homeostasis and tumorigenesis. The generation of CCSCs is probably connected to genetic changes in members of signaling pathways, which control self-renewal and pluripotency in SCs and then establish function and phenotype of CCSCs. Particularly, various deregulated CCSC-related miRNAs have been reported to modulate stemness features, controlling CCSCs functions such as regulation of cell cycle genes expression, epithelial-mesenchymal transition, metastasization, and drug-resistance mechanisms. Primarily, CCSC-related miRNAs work by regulating mainly signal pathways known to be involved in CCSCs biology. This review intends to summarize the epigenetic findings linked to miRNAome in the maintenance and regulation of CCSCs, including their relationships with different signaling pathways, which should help to identify specific diagnostic, prognostic, and predictive biomarkers for CRC, but also develop innovative CCSCs-targeted therapies.

Expression profile of intestinal stem cell and cancer stem cell markers in gastric cancers with submucosal invasion

Cancer stem cells (CSCs) are believed to be responsible for tumor growth, invasion, and metastasis. Submucosal invasion, which greatly enhances metastasis risk, is a critical step in gastric cancer (GC) progression. To identify stem cell-related markers associated with submucosal invasion and lymph node (LN) metastasis in GCs, we investigated the expression of candidate CSC markers (CD133, CD44, and ALDH1A) and intestinal stem cell (ISC) markers (EPHB2, OLFM4, and LGR5) in early GCs that manifested submucosal invasion. We discovered that EPHB2 and LGR5 expression was frequently confined to the basal area of the lamina propria (basal pattern) in mucosal cancer, and the proportion of stem cell marker-positive cells substantially increased during submucosal invasion. CD44 expression showed a focal pattern, ALDH1A was predominantly expressed diffusely, and there was no expansion of CD44 or ALDH1A expression in the submucosal cancer cells. Unexpectedly, no CSC markers showed any associations with LN metastasis, and only loss of EPHB2 expression was associated with increased LN metastasis. Treatment of RSPO2, a niche factor, along with Wnt 3a, to GC cells led to increased EPHB2 and LGR5 mRNA levels. RNA in situ hybridization confirmed specific RSPO2 expression in the smooth muscle cells of the muscularis mucosa, suggesting that RSPO2 is responsible for the increased expression of ISC markers in GC cells at the basal areas. In summary, no stem cell markers were associated with increased LN metastasis in early GCs. Conversely, isolated EPHB2 expression was associated with lower LN metastasis. EPHB2 and LGR5 showed a basal distribution pattern along with enhanced expression in submucosal invading cells in early GCs, which was induced by a niche factor, RSPO2, from the muscularis mucosa.

Emerging Role and Therapeutic Potential of lncRNAs in Colorectal Cancer

Maintenance of the intestinal epithelium is dependent on the control of stem cell (SC) proliferation and differentiation. The fine regulation of these cellular processes requires a complex dynamic interplay between several signaling pathways, including Wnt, Notch, Hippo, EGF, Ephrin, and BMP/TGF-β. During the initiation and progression of colorectal cancer (CRC), key events, such as oncogenic mutations, influence these signaling pathways, and tilt the homeostatic balance towards proliferation and dedifferentiation. Therapeutic strategies to specifically target these deregulated signaling pathways are of particular interest. However, systemic blocking or activation of these pathways poses major risks for normal stem cell function and tissue homeostasis. Interestingly, long non-coding RNAs (lncRNAs) have recently emerged as potent regulators of key cellular processes often deregulated in cancer. Because of their exceptional tissue and tumor specificity, these regulatory RNAs represent attractive targets for cancer therapy. Here, we discuss how lncRNAs participate in the maintenance of intestinal homeostasis and how they can contribute to the deregulation of each signaling pathway in CRC. Finally, we describe currently available molecular tools to develop lncRNA-targeted cancer therapies.

mTOR Signaling Combined with Cancer Stem Cell Markers as a Survival Predictor in Stage II Colorectal Cancer

PURPOSE

Wnt and mammalian target of rapamycin (mTOR) are major molecular signaling pathways associated with the development and progression of tumor, as well as the maintenance and proliferation of cancer stem cells (CSCs), in colorectal cancer (CRC). Identifying patients at risk of poor prognosis is important to determining whether to add adjuvant treatment in stage II CRC and thus improve survival. In the present study, we evaluated the prognostic value of Wnt, mTOR, and CSC markers as survival predictors in stage II CRC.

MATERIALS AND METHODS

We identified 148 cases of stage II CRC and acquired their tumor tissue. Tissue microarrays for immunohistochemical staining were constructed, and the expressions of CD166, CD44, EphB2, β-catenin, pS6 were evaluated using immunohistochemical staining.

RESULTS

The expressions of CD166 (p=0.045) and pS6 (p=0.045) and co-expression of pS6/CD166 (p=0.005), pS6/CD44 (p=0.042), and pS6/CD44/CD166 (p=0.013) were negatively correlated with cancer-specific survival. Cox proportional hazard analysis showed the combination of CD166/pS6 [hazard ratio, 9.42; 95% confidence interval, 2.36-37.59; p=0.002] to be the most significant predictor related with decreased cancer-specific survival. In addition, co-expression of CD44/CD166 (p=0.017), CD166/β-catenin (p=0.036), CD44/β-catenin (p=0.001), and CD44/CD166/β-catenin (p=0.001) were significant factors associated with liver metastasis.

CONCLUSION

Specific combinations of CSC markers and β-catenin/mTOR signaling could be a significant predictor of poor survival in stage II CRC.

EphB2 represents an independent prognostic marker in patients with gastric cancer and promotes tumour cell aggressiveness

Dysregulated expression of ephrin type-B receptor 2 (EphB2) has been linked with the development and progression of solid tumours. In the current study, we attempted to investigate the clinical relevance in GC and the effect of EphB2 expression on gastric cancer (GC) cells. EphB2 protein levels in GC and benign gastric tissues were determined using immunohistochemistry. EphB2 transcript expression in a GC cohort with GC tissue samples (n=171) and paired adjacent normal gastric tissues (n=97) was determined using qPCR. The EphB2 expression was over-activated using a CRISPR activator for the investigation of its cellular function. The expression levels of the EphB2 protein in the tumour tissues of tissue arrays were higher than the benign non-cancerous gastric tissues (P<0.05). EphB2 mRNA expression in GC tissues was also significantly elevated when compared with adjacent non-cancerous tissues (P<0.01). EphB2 activation promoted the migration and invasion abilities of the GC cell lines (P<0.01, respectively). In contrast, EphB2 activation significantly decreased the adhesion in GC cells (P<0.0001, respectively). The enrichment analysis of the correlated genes in a GC cohort indicates that EphB2 may function through mediating the cytokine-cytokine interaction, JAK-STAT and TP53 signaling pathways. In conclusion, EphB2 represents as a novel independent prognostic marker in GC. And activation of the EphB2 gene expression elevated the levels of migration and invasion, but suppressed adhesion of GC cells, indicating that EphB2 may act as a tumour promotor in GC. Our findings thus provide fundamental evidence for the consideration of the therapeutic potential of targeting EphB2 in GC.

Prognostic Significance of EPHB2 Expression in Colorectal Cancer Progression

Background

A receptor tyrosine kinase for ephrin ligands, EPHB2, is expressed in normal colorectal tissues and colorectal cancers (CRCs). The aim of this study was to investigate EPHB2 expression over CRC progression and determine its prognostic significance in CRC.

Methods

To measure EPHB2 mRNA and protein expression, real-time polymerase chain reaction and immunohistochemistry were performed in 32 fresh-frozen and 567 formalin-fixed paraffin-embedded CRC samples, respectively. We further investigated clinicopathological features and overall and recurrence-free survival according to EPHB2 protein expression.

Results

The EPHB2 level was upregulated in CRC samples compared to non-cancerous tissue in most samples and showed a strong positive correlation with AXIN2. Notably, CD44 had a positive association with both mRNA and protein levels of EPHB2. Immunohistochemical analysis revealed no difference in EPHB2 expression between adenoma and carcinoma areas. Although EPHB2 expression was slightly lower in invasive fronts compared to surface area (p < .05), there was no difference between superficial and metastatic areas. EPHB2 positivity was associated with lymphatic (p < .001) and venous (p = .001) invasion, TNM stage (p < .001), and microsatellite instability (p = .036). Kaplan–Meier analysis demonstrated that CRC patients with EPHB2 positivity showed better clinical outcomes in both overall (p = .049) and recurrence-free survival (p = .015). However, multivariate analysis failed to show that EPHB2 is an independent prognostic marker in CRCs (hazard ratio, 0.692; p = .692).

Conclusions

Our results suggest that EPHB2 is overexpressed in a subset of CRCs and is a significant prognostic marker.

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.

Investigation of the role of tyrosine kinase receptor EPHA3 in colorectal cancer

EPH signaling deregulation has been shown to be important for colorectal carcinogenesis and genome-wide sequencing efforts have identified EPHA3 as one of the most frequently mutated genes in these tumors. However, the role of EPHA3 in colorectal cancer has not been thoroughly investigated. We show here that ectopic expression of wild type EPHA3 in colon cancer cells did not affect their growth, motility/invasion or metastatic potential in vivo. Moreover, overexpression of mutant EPHA3 or deletion of the endogenous mutant EPHA3 in colon cancer cells did not affect their growth or motility. EPHA3 inactivation in mice did not initiate the tumorigenic process in their intestine, and had no effects on tumor size/multiplicity after tumor initiation either genetically or pharmacologically. In addition, immunohistochemical analysis of EPHA3 tumor levels did not reveal associations with survival or clinicopathological features of colorectal cancer patients. In conclusion, we show that EPHA3 does not play a major role in colorectal tumorigenesis. These results significantly contribute to our understanding of the role of EPH signaling during colorectal carcinogenesis, and highlighting the need for detailed functional studies to confirm the relevance of putative cancer driver genes identified in sequencing efforts of the cancer genome.

Somatic Ephrin Receptor Mutations Are Associated with Metastasis in Primary Colorectal Cancer

The contribution of somatic mutations to metastasis of colorectal cancers is currently unknown. To find mutations involved in the colorectal cancer metastatic process, we performed deep mutational analysis of 676 genes in 107 stages II to IV primary colorectal cancer, of which half had metastasized. The mutation prevalence in the ephrin (EPH) family of tyrosine kinase receptors was 10-fold higher in primary tumors of metastatic colorectal than in nonmetastatic cases and preferentially occurred in stage III and IV tumors. Mutational analyses in situ confirmed expression of mutant EPH receptors. To enable functional studies of EPHB1 mutations, we demonstrated that DLD-1 colorectal cancer cells expressing EPHB1 form aggregates upon coculture with ephrin B1 expressing cells. When mutations in the fibronectin type III and kinase domains of EPHB1 were compared with wild-type EPHB1 in DLD-1 colorectal cancer cells, they decreased ephrin B1-induced compartmentalization. These observations provide a mechanistic link between EPHB receptor mutations and metastasis in colorectal cancer. Cancer Res; 77(7); 1730-40. ©2017 AACR.

A review on Eph/ephrin, angiogenesis and lymphangiogenesis in gastric, colorectal and pancreatic cancers

Erythroprotein-producing human hepatocellular carcinoma receptors (Eph receptors) compose a subfamily of transmembrane protein-tyrosine kinases receptors that takes part in numerous physiological and pathological processes. Eph family receptor-interacting proteins (Ephrins) are ligands for those receptors. Eph/ephrin system is responsible for the cytoskeleton activity, cell adhesion, intercellular connection, cellular shape as well as cell motility. It affects neuron development and functioning, bone and glucose homeostasis, immune system and correct function of enterocytes. Moreover Eph/ephrin system is one of the crucial ones in angiogenesis and lymphangiogenesis. With such a wide range of impact it is clear that disturbed function of this system leads to pathology. Eph/ephrin system is involved in carcinogenesis and cancer progression. Although the idea of participation of ephrin in carcinogenesis is obvious, the exact way remains unclear because of complex bi-directional signaling and cross-talks with other pathways. Further studies are necessary to find a new target for treatment.

Kinase Gene Expression Profiling of Metastatic Clear Cell Renal Cell Carcinoma Tissue Identifies Potential New Therapeutic Targets

Kinases are therapeutically actionable targets. Kinase inhibitors targeting vascular endothelial growth factor receptors (VEGFR) and mammalian target of rapamycin (mTOR) improve outcomes in metastatic clear cell renal cell carcinoma (ccRCC), but are not curative. Metastatic tumor tissue has not been comprehensively studied for kinase gene expression. Paired intra-patient kinase gene expression analysis in primary tumor (T), matched normal kidney (N) and metastatic tumor tissue (M) may assist in identifying drivers of metastasis and prioritizing therapeutic targets. We compared the expression of 519 kinase genes using NanoString in T, N and M in 35 patients to discover genes over-expressed in M compared to T and N tissue. RNA-seq data derived from ccRCC tumors in The Cancer Genome Atlas (TCGA) were used to demonstrate differential expression of genes in primary tumor tissue from patients that had metastasis at baseline (n = 79) compared to those that did not develop metastasis for at least 2 years (n = 187). Functional analysis was conducted to identify key signaling pathways by using Ingenuity Pathway Analysis. Of 10 kinase genes overexpressed in metastases compared to primary tumor in the discovery cohort, 9 genes were also differentially expressed in TCGA primary tumors with metastasis at baseline compared to primary tumors without metastasis for at least 2 years: EPHB2, AURKA, GSG2, IKBKE, MELK, CSK, CHEK2, CDC7 and MAP3K8; p<0.001). The top pathways overexpressed in M tissue were pyridoxal 5'-phosphate salvage, salvage pathways of pyrimidine ribonucleotides, NF-kB signaling, NGF signaling and cell cycle control of chromosomal replication. The 9 kinase genes validated to be over-expressed in metastatic ccRCC may represent currently unrecognized but potentially actionable therapeutic targets that warrant functional validation.

Enhancer decommissioning by Snail1-induced competitive displacement of TCF7L2 and down-regulation of transcriptional activators results in EPHB2 silencing

Transcriptional silencing is a major cause for the inactivation of tumor suppressor genes, however, the underlying mechanisms are only poorly understood. The EPHB2 gene encodes a receptor tyrosine kinase that controls epithelial cell migration and allocation in intestinal crypts. Through its ability to restrict cell spreading, EPHB2 functions as a tumor suppressor in colorectal cancer whose expression is frequently lost as tumors progress to the carcinoma stage. Previously we reported that EPHB2 expression depends on a transcriptional enhancer whose activity is diminished in EPHB2 non-expressing cells. Here we investigated the mechanisms that lead to EPHB2 enhancer inactivation. We show that expression of EPHB2 and SNAIL1 - an inducer of epithelial-mesenchymal transition (EMT) - is anti-correlated in colorectal cancer cell lines and tumors. In a cellular model of Snail1-induced EMT, we observe that features of active chromatin at the EPHB2 enhancer are diminished upon expression of murine Snail1. We identify the transcription factors FOXA1, MYB, CDX2 and TCF7L2 as EPHB2 enhancer factors and demonstrate that Snail1 indirectly inactivates the EPHB2 enhancer by downregulation of FOXA1 and MYB. In addition, Snail1 induces the expression of Lymphoid enhancer factor 1 (LEF1) which competitively displaces TCF7L2 from the EPHB2 enhancer. In contrast to TCF7L2, however, LEF1 appears to repress the EPHB2 enhancer. Our findings underscore the importance of transcriptional enhancers for gene regulation under physiological and pathological conditions and show that SNAIL1 employs a combinatorial mechanism to inactivate the EPHB2 enhancer based on activator deprivation and competitive displacement of transcription factors.

Discovery of a small molecule targeting SET-PP2A interaction to overcome BCR-ABLT315I mutation of chronic myeloid leukemia

Despite the great success in using tyrosine kinase inhibitors (TKIs) to treat chronic myeloid leukemia (CML), the frequent development of multi-drug resistance, particularly the T315I mutation of BCR-ABL, remains a challenging issue. Enhancement of protein phosphatase 2A (PP2A) activity by dissociating its endogenous inhibitor SET is an effective approach to combat TKI-based resistance. Here, we report the identification of a novel 2-phenyloxypyrimidine compound TGI1002 to specifically disrupt SET-PP2A interaction. By binding to SET, TGI1002 inhibits SET-PP2A interaction and increases PP2A activity. In addition, knocking-down SET expression decreases tumor cell sensitivity to TGI1002. TGI1002 treatments also markedly increase dephosphorylation of BCR-ABL. Moreover, TGI1002 significantly inhibits tumor growth and prolongs survival of xenografted mice implanted with BaF3-p210^T315I cells. These findings demonstrate that TGI1002 is a novel SET inhibitor with important therapeutic potential for the treatment of drug-resistant CML.

ERBB3 Positively Correlates with Intestinal Stem Cell Markers but Marks a Distinct Non Proliferative Cell Population in Colorectal Cancer

Several studies have suggested ERBB3/HER3 may be a useful prognostic marker for colorectal cancer. Tumours with an intestinal stem cell signature have also been shown to be more aggressive. Here, we investigate whether ERBB3 is associated with intestinal stem cell markers in colorectal cancer and if cancer stem cells within tumours are marked by expression of ERBB3. Expression of ERBB3 and intestinal stem cell markers (LGR5, EPHB2, CD44s and CD44v6) was assessed by qRT-PCR in primary colorectal tumours (stages 0 to IV) and matched normal tissues from 53 patients. The localisation of ERBB3, EPHB2 and KI-67 within tumours was investigated using co-immunofluorescence. Expression of ERBB3 and intestinal stem cell markers were significantly elevated in adenomas and colorectal tumours compared to normal tissue. Positive correlations were found between ERBB3 and intestinal stem cell markers. However, co-immunofluorescence analysis showed that ERBB3 and EPHB2 marked specific cell populations that were mutually exclusive within tumours with distinct proliferative potentials, the majority of ERBB3+ve cells being non-proliferative. This pattern resembles cellular organisation within normal colonic epithelium where EPHB2 labelled proliferative cells reside at the crypt base and ERBB3+ve cells mark differentiated cells at the top of crypts. Our results show that ERBB3 and intestinal stem cell markers correlate in colorectal cancers. ERBB3 localises to differentiated cell populations within tumours that are non-proliferative and distinct from cancer stem cells. These data support the concept that tumours contain discrete stem, proliferative and differentiation compartments similar to that present in normal crypts.

EphB2 Promotes Progression of Cutaneous Squamous Cell Carcinoma

Keratinocyte-derived skin cancer, cutaneous squamous cell carcinoma (cSCC), is the most common metastatic skin cancer. We have examined the role of Eph/ephrin signaling in the progression of cSCC. Analysis of the expression of EPH and EFN families in cSCC cells and normal epidermal keratinocytes revealed overexpression of EPHB2 mRNA in cSCC cells and cSCC tumors in vivo. Tumor cell-specific overexpression of EphB2 was detected in human cSCCs and in chemically induced mouse cSCCs with immunohistochemistry, whereas the expression of EphB2 was low in premalignant lesions and normal skin. Knockdown of EphB2 expression in cSCC cells suppressed growth and vascularization of cSCC xenografts in vivo and inhibited proliferation, migration, and invasion of cSCC cells in culture. EphB2 knockdown downregulated expression of genes associated with biofunctions cell viability, migration of tumor cells, and invasion of tumor cells. Among the genes most downregulated by EphB2 knockdown were MMP1 and MMP13. Moreover, activation of EphB2 signaling by ephrin-B2-Fc enhanced production of invasion proteinases matrix metalloproteinase-13 (MMP13) and MMP1, and invasion of cSCC cells. These findings provide mechanistic evidence for the role of EphB2 in the early progression of cSCC to the invasive stage and identify EphB2 as a putative therapeutic target in this invasive skin cancer.

Sex-determination gene SRY potentially associates with poor prognosis but not sex bias in hepatocellular carcinoma

BACKGROUND

Gender disparity is well known in hepatocellular carcinoma (HCC). SRY is a critical sex-determination gene involved in embryonic development.

AIM

The potential relevance of SRY to HCC progression was evaluated.

METHODS

SRY expression in HCC cell lines and tissues was evaluated. Invasion and wound healing assays were used to evaluate the role of SRY in HCC cell migration. The prognostic value of SRY for HCC patient survival was evaluated.

RESULTS

SRY was highly expressed in HCC cell lines and tumor tissues. Downregulation of SRY expression decreased migration and invasion potential of HCC cells. High SRY levels correlated with poor HCC patient survival. Additionally, neither spatial position nor expression intensity of SRY was correlated with HCC gender disparity.

CONCLUSIONS

High levels of SRY expression correlated with cancer progression and poor HCC patient survival. However, high SRY levels are not significantly correlated with HCC sex bias.

EphB1 and Ephrin-B, new potential biomarkers for squamous cell/adenosquamous carcinomas and adenocarcinomas of the gallbladder

Squamous cell/adenosquamous carcinoma (SC/ASC) of the gallbladder are rare tumors and there are few clinical reports in the literature. Herein we report our clinical experience with 46 patients with SC/ASC and 80 with adenocarcinoma (AC). Expression of EphB1 and Ephrin-B in each tumor was determined using immunohistochemical methods for determination of correlations with prognosis. There was no difference in EphB1 and Ephrin-B expression between SC/ASC and AC tumors (P>0.05), but greater expression in those less than 3 cm in diameter, stage I or II (TNM stage), with no lymph node metastases, with no local invasion and treated with radical resection was apparent. Expression of EphB1 (P<0.05) and Ephrin-B (P<0.01) was higher in well differentiated than in poorly differentiated AC tumors. Kaplan-Meier survival analysis indicated that degree of differentiation, tumor diameter, lymph node metastases, local invasion, surgical approach and expression rate of EphB1 and Ephrin-B were closely related to the survival of SC/ASC (P<0.05) and AC patients (P<0.01). Patients with tumors that positive expressed EphB1 and Ephrin-B, whether it is SC/ASC (P SC/ASC =0.000) or AC (P AC =0.000 or P AC =0.002) had longer survival than those negative expression. Cox multivariate analysis indicated a negative correlation between expression of EphB1 or Ephrin-B and overall survival. Hence, EphB1 and Ephrin-B could be regarded as independent good prognostic factorsand important biological markers for SC/ASC and AC of gallbladder.

Goosecoid promotes the metastasis of hepatocellular carcinoma by modulating the epithelial-mesenchymal transition

The homeobox gene, goosecoid (GSC), is a transcription factor that participates in cell migration during embryonic development. Because cell migration during development has characteristics similar to cell invasion during metastasis, we evaluated the potential role of GSC in the metastasis of hepatocellular carcinoma (HCC). GSC expression in HCC cell lines and tissues was evaluated, and its effects on the migration potential of HCC cells were determined by GSC knock-down and overexpression methods. In addition, the prognostic role of GSC expression in the metastasis of cancer cells in HCC patients was determined. Our data showed that GSC was highly expressed in several HCC cell lines, particularly in a highly metastatic HCC cell line. Overexpression of GSC promoted cell migration and invasion of HCC cells in vitro. Gain-of-function induced the epithelial-mesenchymal transition but not collective cell migration, whereas loss-of-function induced the reverse change. High-level expression of GSC correlated closely with poor survival and lung metastasis in HCC patients; lung metastases showed more upregulated GSC expression than the primary tumor. We conclude that GSC promotes metastasis of HCC potentially through initiating the epithelial-mesenchymal transition. GSC is also a prognostic factor for poor survival and metastasis of HCC, which suggests its potential as a therapeutic target for metastatic HCC.

CXCR7 correlates with the differentiation of hepatocellular carcinoma and suppresses HNF4α expression through the ERK pathway

Hepatocellular carcinoma (HCC) is a malignancy with dysregulated differentiation. However, effective differentiation therapy for HCC is lacking. Previous evidence suggests that CXCR7 is associated with the differentiation of embryonic stem cells. Here, we evaluated the potential role of CXCR7 in the differentiation of HCC. In HCC cell lines, the expression of cancer stem cell-related markers was assessed by flow cytometry and confirmed by western blot and immunofluorescence analyses. Dimethyl sulfoxide, oncostatin M and dexamethasone were used to induce the differentiation of HCC. Immunohistochemical assay was performed on a tissue microarray based on 112 HCC cases that received hepatectomy. Ligand activation, inhibition assays and RNA interference were used to analyze the regulation of hepatocyte nuclear factor 4α (HNF4α) by the CXCR7 pathway. Huh7 and HCCLM3 cell lines were screened for differentiation induction based on biomarkers of hepatic cancer stem cells. CXCR7 was found to be closely associated with the differentiation of HCC, and an inverse expression trend between CXCR7 and HNF4α was found upon induced differentiation. Clinically, high CXCR7 expression was negatively correlated with HNF4α expression in patients with relatively well-differentiated HCC. Moreover, high CXCR7 expression was correlated with poor overall survival and accelerated post-resection metastasis in HCC with a low HNF4α level. Mechanistically, CXCR7 signaling inhibited HNF4α through extracellular regulated protein kinase (ERK) activation, which was inhibited by U0126, an inhibitor of MAPK/ERK kinases 1 and 2. Knockdown of CXCR7 further confirmed that CXCR7 signaling can regulate HNF4α expression. Taken together, our findings indicate that CXCR7 participates in the differentiation of HCC by regulating HNF4α. The CXCR7-ERK-HNF4α cascade represents a new target for the differentiation therapy of HCC.

High expression of erythropoietin-producing hepatoma cell line-B2 (EphB2) predicts the efficiency of the Qingyihuaji formula treatment in pancreatic cancer CFPAC-1 cells through the EphrinB1-EphB2 pathway

Our previous study demonstrated that inhibition of erythropoietin-producing hepatoma cell line-B2 (EphB2) expression resulted in the promotion of cancer growth, with EphB2 acting as a tumor suppressor in pancreatic cancer. Qingyihuaji formula (QYHJ), a traditional Chinese medicine, acts as an independent protective factor for pancreatic cancer patient survival and different patients have shown various responses to QYHJ treatment. In the current study, the different effects on tumor growth inhibition following QYHJ treatment in cells with different levels of EphB2 expression were investigated to reveal the mechanism. A subcutaneously transplanted tumor model using cancer cells with different levels of EphB2 expression were established in vivo and received a four-week QYHJ intervention. Tumor weight inhibitory rate and tumor volume deflation were evaluated. The cell cycle and apoptosis were analyzed by flow cytometry, and reverse transcription polymerase chain reaction and western blot analysis were used to assess mRNA and protein levels. The results showed that the tumor weight inhibitory rate was 31.40, 31.33 and 18.36% in CFPAC-1, CFPAC-1 control RNAi and CFPAC-1 EphB2 RNAi cells following QYHJ treatment, respectively. A statistically significant difference was identified in CFPAC-1 (P<0.05) and CFPAC-1 control RNAi (P<0.01) cells. In addition, a statistically significant increase was identified in the G0/G1 phase population (P<0.05) and a statistically significant decrease was identified in the S phase population (P<0.05) in CFPAC-1 and CFPAC-1 control RNAi cells; however, no significant difference was identified in the CFPAC-1 EphB2 RNAi cells following QYHJ treatment. QYHJ upregulated the mRNA and protein level of Eph receptor-interacting B1 (EphrinB1) in the cells that were expressing different levels of EphB2, however, QYHJ did not regulate EphB2 expression. In CFPAC-1 and CFPAC-1 control RNAi cells, the QYHJ treatment resulted in a statistically significant decrease in cyclin-dependent kinase 6 (CDK6) mRNA (P<0.05) and protein (P<0.05) levels. The high expression of EphB2 predicted the superior response rate to the QYHJ treatment through a mechanism of inhibiting the cell cycle by an EphrinB1-EphB2-induced CDK6 decrease in CFPAC-1 cells. Therefore, EphB2 acts as a predictive factor for QYHJ treatment in pancreatic cancer CFPAC-1 cells.

Involvement of ephrin receptor A4 in pancreatic cancer cell motility and invasion

Ephrin (EPH) receptors can be classified into EPHA and EPHB receptors and are important in diverse cellular processes. EPHA4, a member of the EPHA receptors, has been demonstrated to be elevated in various human cancers and involved in the tumor progression. However, the role of EPHA4 in pancreatic cancer cells remains unclear. Therefore, the present study transfected Panc-1 and BxPC-3 cells with small interfering RNA (siRNA) to knockdown the expression of EPHA4. Wound healing and invasion assays were then performed to assess the effect of EPHA4 knockdown on the motility and invasion of pancreatic cancer cells. The results demonstrated that the knockdown of EPHA4 by siRNA inhibits the motility and invasion of pancreatic cancer cells. Furthermore, gelatin zymography assay showed that EPHA4 may regulate the activity of matrix metalloproteinase (MMP)-2. In addition, the knockdown of EPHA4 increased the expression of epithelial (E)-cadherin, as well as decreased the expression of Snail. Overall, these results suggested that EPHA4 may promote the motility and invasion of pancreatic cancer cells via the upregulation of MMP-2 and Snail, as well as the downregulation of E-cadherin. Thus, EPHA4 may act as a useful target for the treatment of pancreatic cancer.

Role of the EphB2 receptor in autophagy, apoptosis and invasion in human breast cancer cells

The Eph and Ephrin proteins, which constitute the largest family of receptor tyrosine kinases, are involved in normal tissue development and cancer progression. Here, we examined the expression and role of the B-type Eph receptor EphB2 in breast cancers. By immunohistochemistry using a progression tissue microarray of human clinical samples, we found EphB2 to be expressed in benign tissues, but strongly increased in cancers particularly in invasive and metastatic carcinomas. Subsequently, we found evidence that EphB2, whose expression varies in established cell breast lines, possesses multiple functions. First, the use of a DOX-inducible system to restore EphB2 function to low expressers resulted in decreased tumor growth in vitro and in vivo, while its siRNA-mediated silencing in high expressers increased growth. This function involves the onset of apoptotic death paralleled by caspases 3 and 9 activation. Second, EphB2 was also found to induce autophagy, as assessed by immunofluorescence and/or immunoblotting examination of the LC3, ATG5 and ATG12 markers. Third, EphB2 also has a pro-invasive function in breast cancer cells that involves the regulation of MMP2 and MMP9 metalloproteases and can be blocked by treatment with respective neutralizing antibodies. Furthermore, EphB2-induced invasion is kinase-dependent and is impeded in cells expressing a kinase-dead mutant EphB2. In summary, we identified a mechanism involving a triple role for EphB2 in breast cancer progression, whereby it regulates apoptosis, autophagy, and invasion.

Mutated ephrin receptor genes in non-small cell lung carcinoma and their occurrence with driver mutations-targeted resequencing study on formalin-fixed, paraffin-embedded tumor material of 81 patients

Non-small cell lung carcinoma (NSCLC) is the most common subtype of lung cancer. The oncogenic potential of receptor tyrosine kinases (RTKs) is widely known and they are potential targets for tailored therapy. Ephrin receptors (Ephs) form the largest group of RTKs. Nevertheless, Ephs are not widely studied in NSCLC so far. The aim of our study was to investigate novel mutations of Eph genes (EPHA1-8, EPHB1-4, EPHB6) and their association with clinically relevant mutations in BRAF, EML4-ALK, EGFR, INSR, KDR, KRAS, MET, PDGFRA, PDGFRB, PIK3, PTEN, RET, and TP53 in NSCLC patients. Targeted resequencing was conducted on 81 formalin-fixed, paraffin-embedded NSCLC tumor specimens. We analyzed missense and nonsense mutations harbored in the coding regions of the selected genes. We found 18 novel mutations of Ephs in 20% (16 of 81) of the patients. Nearly half of these mutations occurred in the protein kinase domain. The mutations were not mutually exclusive with other clinically relevant mutations. Our study shows that Ephs are frequently mutated in NSCLC patients, and occur together with other known mutations relevant to the pathogenicity of NSCLC.

Ephrin b2 receptor and microsatellite status in lymph node-positive colon cancer survival

BACKGROUND

Ephrin B2 receptor (EphB2) is a target of the canonical wnt pathway implicated in colorectal carcinogenesis, and its down-regulation may be associated with adverse prognosis. We evaluated its prognostic value in resected colon cancer stratified by microsatellite status and other clinicopathologic characteristics.

METHODS

We identified all cases of resected stage III colon cancer from 1995 to 2009 managed in the Capital Health district of Nova Scotia. Tissue microarrays were constructed and immunohistochemistry (IHC) for tumor EphB2 staining assigned into quartiles. Microsatellite status was evaluated by IHC for MutL homolog 1 (MLH1) and MutS homolog 2 (MSH2). Microsatellite stable tumors were defined as both MLH1/MSH2 (+/+); tumors staining otherwise were classified with microsatellite instability (MSI-H). Primary and secondary outcomes were disease-free survival (DFS) and overall survival (OS), respectively.

RESULTS

We identified 159 cases with sufficient tissue for microarray analysis having a median follow-up of 3.47 years (range, 0.14-14). Median age was 61, 52% were male, 40% had an event, and 29% died. MSI-H was present in 18 (13%). Univariate analysis of EphB2 expression on DFS and OS showed a hazard ratio (HR) of 2.00 (P = .01) and 2.14 (P = .03), respectively. Multivariate analysis of EphB2 expression on DFS and OS showed an HR of 2.24 and 2.23, respectively, with tumor IHC ≤ 50%.

CONCLUSIONS

In this cohort, decreased EphB2 expression was an independent prognostic factor for recurrence and death and may have prognostic relevance in tumors with MSI-H. However, this would require prospective validation in a larger study.

In situ validation of an intestinal stem cell signature in colorectal cancer

OBJECTIVE

Wnt/Tcf, Lgr5, Ascl2 and/or Bmi1 signalling is believed to define the mouse intestinal stem cell niche(s) from which adenomas arise. The aim of this study was to determine the relevance of these putative intestinal stem cell markers to human colorectal cancer.

DESIGN

19 putative intestinal stem cell markers, including Ascl2 and Lgr5, were identified from published data and an evaluation of a human colorectal gene expression database. Associations between these genes were assessed by isotopic in situ hybridisation (ISH) in 57 colorectal adenocarcinomas. Multiplex fluorescent ISH and chromogenic non-isotopic ISH were performed to confirm expression patterns. The prognostic significance of Lgr5 was assessed in 891 colorectal adenocarcinomas.

RESULTS

Ascl2 and Lgr5 were expressed in 85% and 74% of cancers respectively, and expression was positively correlated (p=0.003). Expression of Bmi1 was observed in 47% of cancers but was very weak in 98% of cases with expression. Both Ascl2 and/or Lgr5 were positively correlated with the majority of genes in the signature but neither was correlated with Cdk6, Gpx2, Olfm4 or Tnfrsf19. Lgr5 did not have prognostic significance.

CONCLUSION

These data suggest that 74-85% of colorectal cancers express a Lgr5/Ascl2 associated signature and support the hypothesis that they derive from Lgr5(+)/Ascl2(+) crypt stem cells, not Bmi1(+) stem cells. However, Olfm4 was not found to be a useful marker of Lgr5(+) cells in normal colon or tumours. In this large series, Lgr5 expression is not associated with increased tumour aggressiveness, as might be expected from a cancer stem cell marker.

Transmembrane receptor CXCR7 increases the risk of extrahepatic metastasis of relatively well-differentiated hepatocellular carcinoma through upregulation of osteopontin

Recurrence and metastasis are the main obstacles to improving the survival of patients with post-resective hepato-cellular carcinoma (HCC). Our previous study suggests a critical role of CXCR7 in the metastasis of HCC. In the present study, the effect of CXCR7 as a risk factor for metastasis of HCC was evaluated. Immunohistochemical assay was performed on tissue microarrays based on HCC with extrahepatic metastases after hepatectomy. Two categories based on staining scores were used to evaluate the risk effect of CXCR7, respectively. The effect of CXCR7 on osteopontin (OPN) was explored by RNA interference. Based on the results, in both categories, highly expressed CXCR7 was a dependent risk factor for extrahepatic metastasis because of the potential association with relatively good cell differentiation. Stratification analyses indicated that CXCR7 was a strong independent risk factor (OR, 3.40; 95% CI, 1.07-18.84; P=0.038 in category 1 and OR, 6.40; 95% CI, 1.64-24.92; P=0.007 in category 2, respectively) in patients with Edmondson grade 1/2. Furthermore, CXCR7 correlated well and positively with expression of OPN (P=0.019 and P<0.001 in two categories, respectively) in HCC cases with Edmondson grade 1/2. Immunocytochemistry and RT-PCR demonstrated downregulation of OPN in a highly metastatic HCC cell line following knockdown of CXCR7. Taken together, these findings suggest that high expression of CXCR7 increases the risk of metastasis in post-resective HCC patients with relatively good differentiated tumors, potentially through upregulation of OPN. This group of patients may acquire a survival benefit from early detection and treatment of recurrence and metastasis.

The roles and therapeutic potentials of Ephs and ephrins in lung cancer

Eph receptors and their membrane-bound ephrin ligands are intimately involved in embryonic patterning, neuronal targeting, and vascular development during normal embryogenesis. In recent years, a growing number of studies revealed their participation in the development of various cancers. In this review, we concentrate on their involvement in lung cancer. In this context, we summarize their aberrant expressions, their pro- or anti-oncogenic effects as well as related mechanisms, and their potential as drug targets in lung cancer.

Regulation and misregulation of Eph/ephrin expression

The erythropoietin-producing hepatocellular (Eph) receptors form the largest family of receptor tyrosine kinases. Upon interaction of the Eph receptors with their ligands the ephrins, signaling cascades are initiated downstream of both receptor and ligand, a feature known as bidirectional signaling. The Eph receptors and ephrin ligands mediate important roles in embryonic development, particularly in establishing tissue organization by mediating cell adhesion or cell repulsion. In several adult tissues, at least one Eph/ephrin pair is found to play critical roles in tissue physiology and homeostasis. In recent years numerous members of this family have gained considerable attention since changes in their expression levels are a typical feature in cancer cells. Despite the fact that Eph/ephrin developmental expression profiles are well documented, little is known on transcriptional and post-transcriptional mechanisms that permits their highly specific, graded, complementary or overlapping expression patterns. Therefore understanding the transcriptional and post-transcriptional mechanisms regulating Eph/ephrin expression has far-reaching significance in biology. This review provides an overview of the mechanisms regulating Eph/ephrin expression. We highlight important emerging mechanisms of Eph/ephrin regulation or misregulation such as epigenetics and miRNAs.

EphB2 receptor controls proliferation/migration dichotomy of glioblastoma by interacting with focal adhesion kinase

Glioblastoma multiforme (GBM) are the most frequent and aggressive primary brain tumors in adults. Uncontrolled proliferation and abnormal cell migration are two prominent spatially and temporally disassociated characteristics of GBMs. In this study, we investigated the role of the receptor tyrosine kinase EphB2 in controlling the proliferation/migration dichotomy of GBM. We studied EphB2 gain-of-function and loss-of function in glioblastoma-derived stem-like neurospheres (GBM-SCs), whose in vivo growth pattern closely replicates human GBM. EphB2 expression stimulated GBM neurosphere cell migration and invasion, and inhibited neurosphere cell proliferation in vitro. In parallel, EphB2 silencing increased tumor cell proliferation and decreased tumor cell migration. EphB2 was found to increase tumor cell invasion in vivo using an internally controlled dual-fluorescent xenograft model. Xenografts derived from EphB2 overexpressing GBM neurospheres also showed decreased cellular proliferation. The non-receptor tyrosine kinase focal adhesion kinase (FAK) was found to be co-associated with and highly activated by EphB2 expression and FAK activation facilitated focal adhesion formation, cytoskeleton structure change and cell migration in EphB2-expression GBM neurosphere cells. Taken together, our findings indicate that EphB2 has pro-invasive and anti-proliferative actions in GBM stem-like neurospheres mediated, in part, by interactions between EphB2 receptors and FAK. These novel findings suggest that tumor cell invasion can be therapeutically targeted by inhibiting EphB2 signaling and that optimal anti-tumor responses to EphB2 targeting may require the concurrent use of anti-proliferative agents.

Clinical relevance of Ephs and ephrins in cancer: lessons from breast, colorectal, and lung cancer profiling

Pre-clinical studies provide compelling evidence that members of the Eph family of receptor tyrosine kinases and their ephrin ligands promote tumor growth, invasion and metastasis, and neovascularization. Tumor suppressive roles have also been reported for the receptors, and ligand-dependent versus ligand-independent signaling has emerged as one key mechanism underlying tumor suppressive function as opposed to oncogenic effects. Determining how these observations relate to clinical outcome is a crucial step for translating the biological and mechanistic data into new molecularly targeted therapies. Expression profiling in human patient samples bridges this gap and provides valuable clinical relevance to laboratory observations. In addition to analyses performed using privately assembled patient tumor samples, publically available microarray datasets and tissue microarrays linked to clinical data have emerged as tractable tools for addressing the clinical relevance of specific molecules and families of related molecules. This review summarizes the clinical relevance of specific Eph and ephrin molecules in human breast, colorectal, and lung cancers.

Complementary expression and repulsive signaling suggest that EphB receptors and ephrin-B ligands control cell positioning in the gastric epithelium

Eph receptors and ephrin ligands are membrane-bound cell-cell communication molecules with well-defined roles in development. However, their expression and functions in the gastric epithelium are virtually unknown. We detected several EphB receptors and ephrin-Bs in the gastric corpus mucosa of the adult rodent stomach by RT-PCR amplification. Immunostaining showed complementary expression patterns, with EphB receptors preferentially expressed in the deeper regions and ephrin-Bs in the superficial regions of the gastric units. EphB1, EphB2 and EphB3 are expressed in mucous neck, chief and parietal cells, respectively. In contrast, ephrin-B1 is in pit cells and proliferating cells of the isthmus. In a mouse ulcer model, EphB2 expression was upregulated in the regenerating epithelium and expanded into the isthmus. Thus, EphB/ephrin-B signaling likely occurs preferentially in the isthmus, where receptor-ligand overlap is highest. We show that EphB signaling in primary gastric epithelial cells promotes cell retraction and repulsion at least in part through RhoA activation. Based on these findings, we propose that the EphB-positive progeny of gastric stem cells migrates from the isthmus toward the bottom of the gastric glands due to repulsive signals arising from contact with ephrin-Bs, which are preferentially expressed in the more superficial regions of the isthmus and gastric pits.

Down-regulation of CXCR7 inhibits the growth and lung metastasis of human hepatocellular carcinoma cells with highly metastatic potential

CXCR7, a recently identified chemokine receptor, has been implicated in directing cancer metastasis. In the present study, the potential roles of CXCR7 in the growth and metastasis of hepatocellular carcinoma (HCC) were evaluated. A chemokine receptor gene chip was used to compare the expression of CXCR7 in HCC cell lines with different metastatic potential. Effects of targeting CXCR7 by RNA interference (RNAi) on the proliferation and metastasis of HCCLM3 cells were observed in vitro and in vivo. CXCR7 expression in 116 specimens from patients with or without metastatic HCC was assessed by tissue microarray. As a result, the gene chip showed that expression of CXCR7 was significantly higher in the highly metastatic HCCLM3 cells, which was confirmed by real-time RT-PCR and Western blotting. Chemotaxis assays showed that HCCLM3 cells responded to SDF-1α from 1 to 100 μg/l and lung extractions (1 g/l). Furthermore, down-regulation of CXCR7 in HCCLM3 cells by RNAi inhibited the proliferation and invasion of tumor cells in vitro. Moreover, CXCR7 knockdown significantly reduced the activity of matrix metalloproteinase-2 and matrix metalloproteinase-9. RNAi of CXCR7 in the HCCLM3 cells also decreased the growth of tumors and the number of lung metastases in nude mice. The tissue microarray showed that HCCs with high expression of CXCR7 were prone to metastasize to the lung. These findings suggest that CXCR7 plays critical roles in the growth and metastasis of HCC. RNAi of CXCR7 inhibits the growth and invasion of tumor cells, which indicates that CXCR7 may be a potential molecular target for use in HCC therapy.

Complex expression patterns of Eph receptor tyrosine kinases and their ephrin ligands in colorectal carcinogenesis

Aberrant expression of Eph and ephrin proteins in human cancers is extensively documented. However, data are frequently limited to one gene and therefore incomplete and in some instances conflicting. We analysed expression of all Eph and ephrin genes in colorectal cancer (CRC) cell lines and 153 clinical specimens, providing for the first time a comprehensive analysis of this system in CRC. Eph/ephrin mRNA expression was assessed by quantitative real-time PCR and correlated with protein expression (flow cytometry, Western blotting and immunocytochemistry). These data show that EphA1, EphA2, EphB2 and EphB4 were significantly over expressed in CRC. In all cases, at least one Eph gene was found in normal colon (EphA1, EphA2, EphB2, EphB4), where expression was observed at high levels in most CRCs. However, other Eph gene expression was lost in individual CRCs compared to the corresponding normal, EphA7 being a striking example. Loss of expression was more common in advanced disease and thus correlated with poor survival. This is consistent with the redundant functionality of Eph receptors, such that expression of a single Eph gene is sufficient for effector function. Overall, the data suggest a progressive loss of expression of individual Eph genes suggesting that individual CRCs need to be phenotyped to determine which Eph genes are highly expressed. Targeted therapies could then be selected from a group of specific antibodies, such as those developed for EphA1.

Dancing with the dead: Eph receptors and their kinase-null partners

Eph receptor tyrosine kinases and their ligands, ephrins, are membrane proteins coordinating a wide range of biological functions both in developing embryos and in adult multicellular organisms. Numerous studies have implicated Eph receptors in the induction of opposing responses, including cell adhesion or repulsion, support or inhibition of cell proliferation and cell migration, and progression or suppression of multiple malignancies. Similar to other receptor tyrosine kinases, Eph receptors rely on their ability to catalyze tyrosine phosphorylation for signal transduction. Interestingly, however, Eph receptors also actively utilize three kinase-deficient receptor tyrosine kinases, EphB6, EphA10, and Ryk, in their signaling network. The accumulating evidence suggests that the unusual flexibility of the Eph family, allowing it to initiate antagonistic responses, might be partially explained by the influence of the kinase-dead participants and that the exact outcome of an Eph-mediated action is likely to be defined by the balance between the signaling of catalytically potent and catalytically null receptors. We discuss in this minireview the emerging functions of the kinase-dead EphB6, EphA10, and Ryk receptors both in normal biological responses and in malignancy, and analyze currently available information related to the molecular mechanisms of their action in the context of the Eph family.

Influence of A9 region mutation in EphB2 gene in the prognosis of patients with colorectal adenocarcinoma

BACKGROUND

EphB2 is a transmembrane glycoprotein implicated in the regulation of cell growth, differentiation, and motility. It has been proposed as a tumor suppressor gene, and the role of EphB2 protein in tumorogenesis has been demonstrated. The aim of this study was to test the influence of mutation of A9 region in EphB2 gene in the prognosis of patients with sporadic CCR.

MATERIALS AND METHODS

A total of 473 patients with colorectal cancer were included. A9 region in exon 17 of EphB2 was amplified using specific primer and analyzed using Genescan. All mutations were confirmed by direct sequencing.

RESULTS

EphB2 mutation was detected in 13 of the 473 patients (2.7%). Mutation of EphB2 showed association with tumor site, 12 of 13 mutations were proximal tumors (P < 0.001). EphB2 mutation confers better prognosis in the adenocarcinoma group; 100% of patients carrying the mutation survived and were disease free after 72 months (P = 0.02 and 0.03, respectively).

CONCLUSIONS

Despite the low frequency of EphB2 gene, we got promising results. It would be very interesting to increase the population size to verify our results. If these findings are confirmed, EphB2 could help discriminate patients with adenocarcinoma with different prognosis and to improve the election of the most suitable treatment in each case.

EPH-EPHRIN in human gastrointestinal cancers

Ever since its discovery two decades ago, the erythropoietin-producing hepatoma (EPH)-EPHRIN system has been shown to play multifaceted roles in human gastroenterological cancer as well as neurodevelopment. Over-expression, amplification and point mutations have been found in many human cancers and many investigators have shown correlations between these up-regulations and tumor angiogenesis. Thus, the genes in this family are considered to be potential targets of cancer therapy. On the other hand, the down-regulation of some members as a result of epigenetic changes has also been reported in some cancers. Furthermore, the correlation between altered expressions and clinical prognosis seems to be inconclusive. A huge amount of protein-protein interaction studies on the EPH-EPHRIN system have provided a basic scheme for signal transductions, especially bi-directional signaling involving EPH-ERPHRIN molecules at the cell membrane. This information also provides a manipulative strategy for harnessing the actions of these molecules. In this review, we summarize the known alterations of EPH-EPHRIN genes in human tumors of the esophagus, stomach, colorectum, liver and pancreas and present the perspective that the EPH-EPHRIN system could be a potential target of cancer therapy.

Systematic assessment of protein phenotypes characterizing high-grade tumour budding in mismatch repair-proficient colorectal cancer

AIMS

A tumour bud is defined as a single tumour cell or tumour cell cluster of up to five cells at the invasive tumour front. Significant differences in survival have been detected in colorectal cancer patients with low- compared to high-grade budding. The aim of this study was to identify potential multi-marker phenotypes characterizing low- and high-grade budding in mismatch repair (MMR)-proficient colorectal cancer.

METHODS AND RESULTS

Established and promising prognostic proteins such as epidermal growth factor receptor (EGFR), pERK, RHAMM, RKIP, beta-catenin, E-cadherin, pAKT, p16, p21, Ki67, Bcl-2, vascular endothelial growth factor (VEGF), apoptotic protease activating factor-1 (APAF-1), MUC1, EphB2, matrix metalloproteinase 7, pSMAD2, CDX2, laminin5gamma2 and MST1 were analysed on 208 MMR-proficient colorectal cancers with complete clinicopathological data. The most accurate markers for predicting high-grade budding (more than six tumour buds) were EphB2 (P < 0.001), Bcl-2 (P < 0.001), RKIP (P < 0.001), E-cadherin (P = 0.004), laminin5gamma2 (P = 0.004) and APAF-1 (P = 0.005). On multivariable analysis, only loss of Bcl-2 (P < 0.001) and EphB2 (P < 0.001) were independent predictors of high-grade budding. Bcl-2-/EphB2- tumours were more frequently poorly differentiated (P < 0.001), of advanced pT stage (P = 0.002), lymph node positive (P = 0.023), presented vascular (P = 0.053) and lymphatic invasion (P = 0.005) and had a negative impact on patient survival (P = 0.012).

CONCLUSIONS

The multi-marker phenotype EphB2-/Bcl-2- is an independent predictor of high-grade budding and implies increased aggressive behaviour in MMR-proficient colorectal cancer.

Ephrins negatively regulate cell proliferation in the epidermis and hair follicle

Ephrins and their Eph tyrosine kinase receptors control many processes during embryonic development. They have more recently also been identified as important regulators of proliferation of stem/progenitor cells in the adult brain and intestine and have been implicated in tumorigenesis in a large number of tissues. We here describe the expression of a large number of ephrins and Eph receptors in the adult mouse skin. Disruption of the ephrin-Eph interaction in vivo with antagonists against the A or B class resulted in an approximate doubling of cell proliferation in the hair follicle and epidermis of adult mice. We conclude that ephrins are negative regulators of proliferation in the skin and that blocking the ephrin-Eph interaction may be an attractive strategy for regenerative therapies.

Reduced expression of EphB2 is significantly associated with nodal metastasis in Chinese patients with gastric cancer

AIMS

EphB2 is a member of the Eph receptor tyrosine kinase family that has been involved in the regulation of cytoskeleton organization and cell migration in various cell types. Its role and regulation in carcinogenesis is controversial, especially in gastric cancer. We detected EphB2 expression and determined its clinical significance and explored its underlying molecular mechanism in gastric cancers.

METHODS

Tissue microarray blocks containing primary gastric cancer, lymph node metastases, and adjacent normal mucosa specimens obtained from 337 Chinese patients were constructed. Expression of EphB2 in these specimens was analyzed using immunohistochemistry. Mutation analysis at the A9 tract in exon 17 and loss of heterozygosity analysis at the EphB2 gene locus were carried out in 13 sporadic EphB2-negative gastric cancers.

RESULTS

Complete loss of EphB2 expression was observed in 177 (52.5%) of the 337 primary tumor and 41 (82%) of the 50 nodal metastases. Loss of EphB2 expression was significantly associated with advanced T stage, nodal metastasis, advanced disease stage, and poor histological differentiation. Loss of EphB2 expression correlated significantly with poor survival rates in both univariate and multivariate analysis. No frameshift mutation, but a higher frequency of allelic loss, was found in EphB2-negative primary and metastatic tumor samples.

CONCLUSIONS

Frequent deletion and decreased expression of EphB2 protein suggested it as a negative biomarker for gastric carcinogenesis and a potential predictor of the outcome of patients with gastric cancer.

Guidance molecules in lung cancer

Guidance molecules were first described in the nervous system to control axon outgrowth direction. They are also widely expressed outside the nervous system where they control cell migration, tissue development and establishment of the vascular network. In addition, they are involved in cancer development, tumor angiogenesis and metastasis. This review is primarily focused on their functions in lung cancer and their involvement in lung development is also presented. Five guidance molecule families and their corresponding receptors are described, including the semaphorins/neuropilins/plexins, ephrins and Eph receptors, netrin/DCC/UNC5, Slit/Robo and Notch/Delta. In addition, the possibility to target these molecules as a therapeutic approach in cancer is discussed.