EphA2 Is a Therapy Target in EphA2-Positive Leukemias but Is Not Essential for Normal Hematopoiesis or Leukemia

Constitutive activation of the Src-family kinases Fgr and Hck enhances the tumor burden of acute myeloid leukemia cells in immunocompromised mice

Overexpression of the myeloid Src-family kinases Fgr and Hck has been linked to the development of acute myeloid leukemia (AML). Here we characterized the contribution of active forms of these kinases to AML cell cytokine dependence, inhibitor sensitivity, and AML cell engraftment in vivo. The human TF-1 erythroleukemia cell line was used as a model system as it does not express endogenous Hck or Fgr. To induce constitutive kinase activity, Hck and Fgr were fused to the coiled-coil (CC) oligomerization domain of the breakpoint cluster region protein associated with the Bcr-Abl tyrosine kinase in chronic myeloid leukemia. Expression of CC-Hck or CC-Fgr transformed TF-1 cells to a granulocyte-macrophage colony-stimulating factor (GM-CSF)-independent phenotype that correlated with enhanced phosphorylation of the kinase domain activation loop. Both CC-Hck and CC-Fgr cell populations became sensitized to growth arrest by Src-family kinase inhibitors previously shown to suppress the growth of bone marrow cells from AML patients in vitro and decrease AML cell engraftment in immunocompromised mice. Methionine substitution of the 'gatekeeper' residue (Thr338) also stimulated Hck and Fgr kinase activity and transformed TF-1 cells to GM-CSF independence without CC fusion. TF-1 cells expressing either active form of Hck or Fgr engrafted immunocompromised mice faster and developed more extensive tumors compared to mice engrafted with the parent cell line, resulting in shorter survival. Expression of wild-type Hck also significantly enhanced bone marrow engraftment without an activating mutation. Reverse phase protein array analysis linked active Hck and Fgr to the mammalian target of rapamycin complex-1/p70 S6 ribosomal protein (mTORC-1/S6) kinase and focal adhesion kinase (Fak) signaling pathways. Combining Hck and Fgr inhibitors with existing mTORC-1/S6 kinase or Fak inhibitors may improve clinical responses and reduce the potential for acquired resistance.

A multi-model approach identifies ALW-II-41-27 as a promising therapy for osteoarthritis-associated inflammation and endochondral ossification

Low-grade inflammation and pathological endochondral ossification are key processes underlying the progression of osteoarthritis, the most prevalent joint disease worldwide. In this study, we employed a multi-faceted approach, integrating publicly available datasets, in silico analyses, in vitro experiments and in vivo models to identify new therapeutic candidates targeting these processes. Data mining of transcriptomic datasets identified EPHA2, a receptor tyrosine kinase associated with cancer, as being linked to both inflammation and endochondral ossification in osteoarthritis. A computational model of cellular signaling networks in chondrocytes predicted that in silico activation of EPHA2 in healthy chondrocytes increases inflammatory mediators and induces hypertrophic differentiation, a hallmark of endochondral ossification. We then evaluated the effect of EPHA2 inhibition using the tyrosine kinase inhibitor ALW-II-41-27 in cultured human chondrocytes from individuals with osteoarthritis, demonstrating significant reductions in both inflammation and hypertrophy. Additionally, systemic subcutaneous administration of ALW-II-41-27 in a mouse osteoarthritic model attenuated joint degeneration by reducing local inflammation and pathological endochondral ossification. Collectively, this study demonstrates a novel drug discovery pipeline that integrates computational, experimental, and animal models, paving the way for the development of disease-modifying treatments for osteoarthritis.

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.

EPH/Ephrin Signaling in Normal Hematopoiesis and Hematologic Malignancies: Deciphering Their Intricate Role and Unraveling Possible New Therapeutic Targets

Erythropoietin-producing hepatocellular carcinoma receptors (EPHs) represent the largest family of receptor tyrosine kinases (RTKs). EPH interaction with ephrins, their membrane-bound ligands, holds a pivotal role in embryonic development, while, though less active, it is also implicated in various physiological functions during adult life. In normal hematopoiesis, different patterns of EPH/ephrin expression have been correlated with hematopoietic stem cell (HSC) maintenance and lineage-committed hematopoietic progenitor cell (HPC) differentiation, as well as with the functional properties of their mature offspring. Research in the field of hematologic malignancies has unveiled a rather complex involvement of the EPH/ephrinsignaling pathway in the pathophysiology of these neoplasms. Aberrations in genetic, epigenetic, and protein levels have been identified as possible players implicated both in tumor progression and suppression, while correlations have also been highlighted regarding prognosis and response to treatment. Initial efforts to therapeutically target the EPH/ephrin axis have been undertaken in the setting of hematologic neoplasia but are mainly confined to the preclinical level. To this end, deciphering the complexity of this signaling pathway both in normal and malignant hematopoiesis is necessary.

A novel TanCAR targeting IL13Rα2 and EphA2 for enhanced glioblastoma therapy

Chimeric antigen receptor T cell (CAR-T) therapy has been shown to be an effective strategy for combatting non-solid tumors; however, CAR-T therapy is still a challenge for solid tumors, such as glioblastoma. To improve CAR-T therapy for glioblastoma, a new TanCAR, comprising the tandem arrangement of IL13 (4MS) and EphA2 scFv, was generated and validated in vitro and in vivo. In vitro, the novel TanCAR-redirected T cells killed glioblastoma tumor cells by recognizing either IL-13 receptor α2 (IL13Rα2) or EphA2 alone or together upon simultaneous encounter of both targets, but did not kill normal cells bearing only the IL13Rα1/IL4Rα receptor. As further proof of principle, the novel TanCAR was tested in a subcutaneous glioma xenograft mouse model. The results indicated that the novel TanCAR-redirected T cells produced greater glioma tumor regression than single CAR-T cells. Thus, the novel TanCAR-redirected T cells kill gliomas more efficiently and selectively than a single IL13 CAR or EphA2 scFv CAR, with the potential for preventing antigen escape and reduced off-target cytotoxicity.

Antibody Drug Conjugates in Glioblastoma - Is There a Future for Them?

Glioblastoma (GBM) is an aggressive and fatal malignancy that despite decades of trials has limited therapeutic options. Antibody drug conjugates (ADCs) are composed of a monoclonal antibody which specifically recognizes a cellular surface antigen linked to a cytotoxic payload. ADCs have demonstrated superior efficacy and/or reduced toxicity in a range of haematological and solid tumors resulting in nine ADCs receiving regulatory approval. ADCs have also been explored in patients with brain tumours but with limited success to date. While earlier generations ADCs in glioma patients have had limited success and high toxicity, newer and improved ADCs characterised by low immunogenicity and more effective payloads have shown promise in a range of tumour types. These newer ADCs have also been tested in glioma patients, however, with mixed results. Factors affecting the effectiveness of ADCs to target the CNS include the blood brain barrier which acts as a physical and biochemical barrier, the pro-cancerogenic and immunosuppressive tumor microenvironment and tumour characteristics like tumour volume and antigen expression. In this paper we review the data regarding the ongoing the development of ADCs in glioma patients as well as potential strategies to overcome these barriers to maximise their therapeutic potential.

Blocking of EphA2 on Endometrial Tumor Cells Reduces Susceptibility to Vδ1 Gamma-Delta T-Cell-Mediated Killing

Background

Endometriosis is a common gynecological disease characterized by the presence of endometrial tissue outside the uterus causing chronic inflammation, severe pain, and infertility. However, the innate immunity of gamma-delta (γδ) T lymphocytes in endometriosis has not been characterized. Women with endometriosis present numerous endocrine and immune dysfunctions and elevated risk for endometrial, ovarian, and breast cancers. The tyrosine kinase EphA2 is often overexpressed in cancer including endometrial carcinoma.

Methods

We analyzed Vδ1 and Vδ2 γδ T cells in peripheral blood and paired peritoneal fluid samples in endometriosis patients (n = 19) and compared the counts with that of age- and sex-matched healthy donors (n = 33) using flow cytometry. Vδ1 and Vδ2 T cells isolated from healthy donors were used against KLE, RL-95, and Ishikawa endometrial tumor cells in 4 h flow cytometric cytotoxicity assays. The EphA2 blocking studies were performed using antibody, small-molecule inhibitor ALW-II-41-27, and the CRISPR/Cas9.

Results

We determined Vδ1 T cells substantially reduced in patients’ peripheral blood (p < 0.01) and peritoneal fluid (p < 0.001). No differences were found for circulating Vδ2 T cells compared with peritoneal fluid samples. We observed inherent cytotoxic reactivity of Vδ1 and Vδ2 γδ T lymphocytes against endometrial tumor cells. Importantly, we found reduced specific lysis of EphA2-positive cell lines KLE and RL-95 by Vδ1 T cells in the EphA2 antibody blocking studies and by the EphA2 inhibitor. Furthermore, Vδ1 T-cell-mediated killing was significantly decreased in RL-95 cell EPHA2 knockout. Finally, potent cytolytic activity exerted by Vδ1 T cells was significantly reduced in EPHA2 knockouts in renal A-498 and colon HT-29 carcinoma cell lines.

Conclusions

We determined variable levels of Vδ1 and Vδ2 γδ T cells in endometriosis patients. We observed inherent cytotoxic reactivity of γδ T-cell subsets against endometrial cell lines. Specifically, we found that blocking of EphA2 expression resulted in significant inhibition of endometrial tumor killing mediated by Vδ1 γδ T cells. These results suggest that EphA2 is involved in tumor cell lysis and contributes to susceptibility to Vδ1 γδ T cells cytotoxic reactivity.

Coupling of Cell Surface Biotinylation and SILAC-Based Quantitative Proteomics Identified Myoferlin as a Potential Therapeutic Target for Nasopharyngeal Carcinoma Metastasis

Distant metastasis is a major cause of treatment failure in nasopharyngeal carcinoma (NPC) patients. Cell surface proteins represent attractive targets for cancer diagnosis or therapy. However, the cell surface proteins associated with NPC metastasis are poorly understood. To identify potential therapeutic targets for NPC metastasis, we isolated cell surface proteins from two isogenic NPC cell lines, 6-10B (low metastatic) and 5-8F (highly metastatic), through cell surface biotinylation. Stable isotope labeling by amino acids in cell culture (SILAC) based proteomics was applied to comprehensively characterize the cell surface proteins related with the metastatic phenotype. We identified 294 differentially expressed cell surface proteins, including the most upregulated protein myoferlin (MYOF), two receptor tyrosine kinases(RTKs) epidermal growth factor receptor (EGFR) and ephrin type-A receptor 2 (EPHA2) and several integrin family molecules. These differentially expressed proteins are enriched in multiple biological pathways such as the FAK-PI3K-mTOR pathway, focal adhesions, and integrin-mediated cell adhesion. The knockdown of MYOF effectively suppresses the proliferation, migration and invasion of NPC cells. Immunohistochemistry analysis also showed that MYOF is associated with NPC metastasis. We experimentally confirmed, for the first time, that MYOF can interact with EGFR and EPHA2. Moreover, MYOF knockdown could influence not only EGFR activity and its downstream epithelial–mesenchymal transition (EMT), but also EPHA2 ligand-independent activity. These findings suggest that MYOF might be an attractive potential therapeutic target that has double effects of simultaneously influencing EGFR and EPHA2 signaling pathway. In conclusion, this is the first study to profile the cell surface proteins associated with NPC metastasis and provide valuable resource for future researches.

Insights on the Functional Role of Beta-Glucans in Fungal Immunity Using Receptor-Deficient Mouse Models

Understanding the host anti-fungal immunity induced by beta-glucan has been one of the most challenging conundrums in the field of biomedical research. During the last couple of decades, insights on the role of beta-glucan in fungal disease progression, susceptibility, and resistance have been greatly augmented through the utility of various beta-glucan cognate receptor-deficient mouse models. Analysis of dectin-1 knockout mice has clarified the downstream signaling pathways and adaptive effector responses triggered by beta-glucan in anti-fungal immunity. On the other hand, assessment of CR3-deficient mice has elucidated the compelling action of beta-glucans in neutrophil-mediated fungal clearance, and the investigation of EphA2-deficient mice has highlighted its novel involvement in host sensing and defense to oral mucosal fungal infection. Based on these accounts, this review focuses on the recent discoveries made by these gene-targeted mice in beta-glucan research with particular emphasis on the multifaceted aspects of fungal immunity.

Antibody Targeting of Eph Receptors in Cancer

The Eph subfamily of receptor tyrosine kinases mediate cell-cell communication controlling cell and tissue patterning during development. While generally less active in adult tissues, they often re-emerge in cancers, particularly on undifferentiated or progenitor cells in tumors and the tumor microenvironment, associated with tumor initiation, angiogenesis and metastasis. Eph receptors are thus attractive therapeutic targets, and monoclonal antibodies have been commonly developed and tested for anti-cancer activity in preclinical models, and in some cases in the clinic. This review summarizes 20 years of research on various antibody-based approaches to target Eph receptors in tumors and the tumor microenvironment, including their mode of action, tumor specificity, and efficacy in pre-clinical and clinical testing.

Ephrin or not? Six tough questions on Eph targeting

Introduction: The Eph-ephrin is a cell-cell communication system generating a forward signal in cell expressing Eph receptors and a reverse signal in ephrin-ligand expressing cells. While clearly involved in the insurgence and progression of cancer, the understanding of the molecular mechanisms regulated by this system needs development; this is a hurdle to the development of therapeutic strategies that can target the Eph receptors and/or their ephrin ligands.Areas covered: We have taken the opportunity to share some key questions on the most effective strategies to target the Eph-ephrin system. This article is based on our experience of the field and therefore is a Perspective and not comprehensive examination of the literature.Expert opinion: Targeting of the Eph-ephrin system has emerged as a potentially valuable approach for cancer therapy. Pharmacological tools have been reported in the last 15 years and these include forward signaling blockers such as kinases inhibitors and antagonists of forward and reverse signaling. Also, biologics including antibodies and recombinant proteins have been developed and some have reached early clinical stages. Data deem the Eph-ephrin system as a signaling axis that is an elusive target. A better understanding of the basic pharmacology behind the activity of available agents and a comprehensive knowledge of the ephrin biology are necessary. We are looking forward to knowing the opinion of the readers.

Emerging Roles for Eph Receptors and Ephrin Ligands in Immunity

Eph receptors are the largest family of receptor tyrosine kinases and mediate a myriad of essential processes in humans from embryonic development to adult tissue homeostasis through interactions with membrane-bound ephrin ligands. The ubiquitous expression of Eph receptors and ephrin ligands among the cellular players of the immune system underscores the importance of these molecules in orchestrating an optimal immune response. This review provides an overview of the various roles of Eph receptors and ephrin ligands in immune cell development, activation, and migration. We also discuss the role of Eph receptors in disease pathogenesis as well as the implications of Eph receptors as future immunotherapy targets. Given the diverse and critical roles of Eph receptors and ephrin ligands throughout the immune system during both resting and activated states, this review aims to highlight the critical yet underappreciated roles of this family of signaling molecules in the immune system.

Therapeutic potential of targeting the Eph/ephrin signaling complex

The Eph-ephrin signaling pathway mediates developmental processes and the proper functioning of the adult human body. This distinctive bidirectional signaling pathway includes a canonical downstream signal cascade inside the Eph-bearing cells, as well as a reverse signaling in the ephrin-bearing cells. The signaling is terminated by ADAM metalloproteinase cleavage, internalization, and degradation of the Eph/ephrin complexes. Consequently, the Eph-ephrin-ADAM signaling cascade has emerged as a key target with immense therapeutic potential particularly in the context of cancer. An interesting twist was brought forth by the emergence of ephrins as the entry receptors for the pathological Henipaviruses, which has spurred new studies to target the viral entry. The availability of high-resolution structures of the multi-modular Eph receptors in complexes with ephrins and other binding partners, such as peptides, small molecule inhibitors and antibodies, offers a wealth of information for the structure-guided development of therapeutic intervention. Furthermore, genomic data mining of Eph mutants involved in cancer provides information for targeted drug development. In this review we summarize the distinct avenues for targeting the Eph-ephrin signaling pathway, including its termination by ADAM proteinases. We highlight the latest developments in Eph-related pharmacology in the context of Eph-ephrin-ADAM-based antibodies and small molecules. Finally, the future prospects of genomics- and proteomics-based medicine are discussed.

Pharmacological targeting of the ephrin receptor kinase signalling by GLPG1790 in vitro and in vivo reverts oncophenotype, induces myogenic differentiation and radiosensitizes embryonal rhabdomyosarcoma cells

Background

EPH (erythropoietin-producing hepatocellular) receptors are clinically relevant targets in several malignancies. This report describes the effects of GLPG1790, a new potent pan-EPH inhibitor, in human embryonal rhabdomyosarcoma (ERMS) cell lines.

Methods

EPH-A2 and Ephrin-A1 mRNA expression was quantified by real-time PCR in 14 ERMS tumour samples and in normal skeletal muscle (NSM). GLPG1790 effects were tested in RD and TE671 cell lines, two in vitro models of ERMS, by performing flow cytometry analysis, Western blotting and immunofluorescence experiments. RNA interfering experiments were performed to assess the role of specific EPH receptors. Radiations were delivered using an x-6 MV photon linear accelerator. GLPG1790 (30 mg/kg) in vivo activity alone or in combination with irradiation (2 Gy) was determined in murine xenografts.

Results

Our study showed, for the first time, a significant upregulation of EPH-A2 receptor and Ephrin-A1 ligand in ERMS primary biopsies in comparison to NSM. GLPG1790 in vitro induced G1-growth arrest as demonstrated by Rb, Cyclin A and Cyclin B1 decrease, as well as by p21 and p27 increment. GLPG1790 reduced migratory capacity and clonogenic potential of ERMS cells, prevented rhabdosphere formation and downregulated CD133, CXCR4 and Nanog stem cell markers. Drug treatment committed ERMS cells towards skeletal muscle differentiation by inducing a myogenic-like phenotype and increasing MYOD1, Myogenin and MyHC levels. Furthermore, GLPG1790 significantly radiosensitized ERMS cells by impairing the DNA double-strand break repair pathway. Silencing of both EPH-A2 and EPH-B2, two receptors preferentially targeted by GLPG1790, closely matched the effects of the EPH pharmacological inhibition. GLPG1790 and radiation combined treatments reduced tumour mass by 83% in mouse TE671 xenografts.

Conclusions

Taken together, our data suggest that altered EPH signalling plays a key role in ERMS development and that its pharmacological inhibition might represent a potential therapeutic strategy to impair stemness and to rescue myogenic program in ERMS cells.

High expression of EphA4 is associated with invasion and lymph node metastasis in colorectal carcinomas

Eph receptors and ephrin ligands have been implicated in development of embryo, especially in vascular and nervous system. Increasing evidence suggests that Eph/ephrin signaling plays important roles in carcinogenesis. EphA4 is a member of Eph receptors and its role has been found in development of nerve and in tumorigenesis. Till now, EphA4 expression and its clinical significance in colorectal carcinoma have not been well investigated. In the present study, a set of 102 colorectal carcinoma tissue specimens were subjected to immunohistochemistry by using a specific polycolonal antibody for EphA4. Expression of EphA4 protein was more often detected in colorectal carcinoma than in normal mucosa (P<0.001). High expression of EphA4 protein in colorectal carcinomas was positively associated with tumor size (P=0.008, r_s =0.260), depth of invasion (P=0.004, r_s =0.286), lymph node metastasis (P=0.013, r_s =0.244), and TNM stage (P=0.005, r_s =0.279), and was negatively associated with age of patients (P=0.027, r_s =-0.219). No significant relationship between expression of EphA4 and sex and tumor location was found. The survival analyses showed that patients whose carcinoma exhibited high expression of EphA4 had a poor outcome (P=0.006). Our results suggest that EphA4 play a role in the invasion and lymph node metastasis of colorectal carcinoma. The EphA4 protein expression level may be used as a potential prognostic marker in colorectal carcinoma. Furthermore, the EphA4 gene may provide a novel target for therapy of colorectal carcinoma.

Targeted therapies in hematological malignancies using therapeutic monoclonal antibodies against Eph family receptors

The use of monoclonal antibodies (mAbs) and molecules derived from them has achieved considerable attention and success in recent years, establishing this mode of therapy as an important therapeutic strategy in many cancers, in particular hematological tumors. mAbs recognize cell surface antigens expressed on target cells and mediate their function through various mechanisms such as antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, or immune system modulation. The efficacy of mAb therapy can be improved when they are conjugated to a highly potent payloads, including cytotoxic drugs and radiolabeled isotopes. The Eph family of proteins has received considerable attention in recent years as therapeutic targets for treatment of both solid and hematological cancers. High expression of Eph receptors on cancer cells compared with low expression levels in normal adult tissues makes them an attractive candidate for cancer immunotherapy. In this review, we detail the modes of action of antibody-based therapies with a focus on the Eph family of proteins as potential targets for therapy in hematological malignancies.

EphA3 as a target for antibody immunotherapy in acute lymphoblastic leukemia

The human EphA3 gene was discovered in a pre-B acute lymphoblastic leukemia (pre-B-ALL) using the EphA3-specific monoclonal antibody (mAb), IIIA4, which binds and activates both human and mouse EphA3. We use two models of human pre-B-ALL to examine EphA3 function, demonstrating effects on pre-B-cell receptor signaling. In therapeutic targeting studies, we demonstrated antitumor effects of the IIIA4 mAb in EphA3-expressing leukemic xenografts and no antitumor effect in the xenografts with no EphA3 expression providing evidence that EphA3 is a functional therapeutic target in pre-B-ALL. Here we show that the therapeutic effect of the anti-EphA3 antibody was greatly enhanced by adding an α-particle-emitting ²¹³Bismuth payload.

Chronic TCDD exposure results in the dysregulation of gene expression in splenic B-lymphocytes and in the impairments in T-cell and B-cell differentiation in mouse model

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exposure in humans is associated with marked immune suppressions and increased incidence of lymphoblastic diseases. To elucidate mechanisms of impairments in humoral immune responses, we used a murine model. Following a 20-week administration of low doses of TCDD, we observed severely reduced antibody titers, dramatically decreased number of splenic Th1 and Th2 cells and an increase in CD19(+) B cells. Transcriptional profiling of CD19(+) B cells showed that markers of pre-B cells were significantly elevated, indicating delayed B cell maturation. These changes in B cells were accompanied by decreases of T helper cell numbers and reduced IgM and IgG titers. A transcriptome analysis of splenic B cells followed by Ingenuity Pathway Analysis (IPA) revealed a set of differentially expressed genes known to play roles in tumorigenesis, cell-proliferation and cell-migration. The most up-regulated transcript gene was Eph receptor A2 (EphA2), a known oncogene, and the most down-regulated transcript was ZBTB16 that codes for a negative transcriptional regulator important in epigenetic chromatin remodeling. IPA identified cAMP-responsive element modulator (CREM) and cAMP-responsive element binding protein 1 (CREB1) as top upstream regulators. Consistently, a MAPPER promoter database analysis showed that all top dysregulated genes had CREM and/or CREB1 binding sites in their promoter regions. In summary, our data showed that chronic TCDD exposure in mice caused suppressed humoral immunity accompanied with profound dysregulation of gene expression in splenic B-lymphocytes, likely through cAMP-dependent pathways. This dysregulation resulted in impairments in T-cell and B-cell differentiation and activation of the tumorigenic transcription program.

Expression of EphA2 protein is positively associated with age, tumor size and Fuhrman nuclear grade in clear cell renal cell carcinomas

The receptor tyrosine kinase of EphA2 has been shown frequently overexpressed in various types of human carcinomas, which implicated that it plays important roles in carcinogenesis. Although EphA2 protein expression has been investigated in many types of human carcinomas, the relationship between the expression of EphA2 protein in clear cell renal cell carcinoma was not well documented. In the present study, using specific anit-EphA2 polyclonal antibody and immunohistochemistry, we evaluated EphA2 protein expression levels in clear cell RCC specimens surgically resected from 90 patients. Our results shows that EphA2 protein was positively expressed in all normal renal tubes of 90 samples (100%, 3+), which was expressed at low levels in renal cortex but high levels in the collecting ducts of the renal medulla and papilla. EphA2 was negatively or weakly expressed in 30 out of 90 samples (33.3%, 0/1+), moderately expressed in 24 samples (26.7%, 2+) and strongly expressed in 36 samples (40%, 3+). Expression of EphA2 was positively associated with age (P=0.029), tumor diameters (P<0.001) and Fuhrman nuclear grade (P<0.001). Our results indicate that EphA2 variably expressed in clear cell renal cell carcinomas. High expression of EphA2 was more often found in big size and high nuclear grade tumors, which indicated EphA2 protein may be used as a new marker for the prognosis of clear cell renal cell carcinoma.