Soluble Eph A receptors inhibit tumor angiogenesis and progression in vivo

Ephrin receptor type-A2 (EphA2) targeting in cancer: a patent review (2018-present)

INTRODUCTION

EphA2 is a tyrosine kinase receptor and is considered a promising target in cancer. Different approaches are used to target EphA2 receptor, and a lot of preclinical data demonstrate the potential exploitation of this receptor in clinical oncology for diagnosis and cancer therapy, including immunotherapy.

AREAS COVERED

In this review, we have summarized the recent patents involving the EphA2 targeting in cancer. For this aim, we used the patent database Patentscope covering the time period of 2018-present. Preclinical and clinical data of the inventions were considered when published on peer reviewed journals. Moreover, the clinicalTrial.gov identifiers (NCT numbers) were included when available. For an easier and more immediate reading, we classify the patents in different categories, considering the nature (aptamers, small molecules, antibodies, peptides, antigens and chimeric antigen receptors) of the inventions exploiting EphA2 in clinical oncology.

EXPERT OPINION

Despite the availability of a plethora of chemically diverse agents, there are no approved anticancer drugs targeting EphA2 yet. However, these intellectual properties, some of which supported by strong preclinical evidence, keep the hope that, after more than 30 years from its discovery, we will finally see the first EphA2 targeting agent approved in clinical oncology.

Ephs in cancer progression: complexity and context-dependent nature in signaling, angiogenesis and immunity

Eph receptors constitute the largest family of receptor tyrosine kinases, comprising 14 distinct members classified into two subgroups: EphAs and EphBs.. Despite their essential functions in normal physiological processes, accumulating evidence suggests that the involvement of the Eph family in cancer is characterized by a dual and often contradictory nature. Research indicates that Eph/ephrin bidirectional signaling influences cell-cell communication, subsequently regulating cell migration, adhesion, differentiation and proliferation. The contradictory functionalities may arise from the diversity of Eph signaling pathways and the heterogeneity of different cancer microenvironment. In this review, we aim to discuss the dual role of the Eph receptors in tumor development, attempting to elucidate the paradoxical functionality through an exploration of Eph receptor signaling pathways, angiogenesis, immune responses, and more. Our objective is to provide a comprehensive understanding of the molecular mechanisms underlying tumor development. Additionally, we will explore the evolving landscape of utilizing Eph receptors as potential targets for tumor therapy and diagnostic tools.

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.

Inhibition of EphA3 Expression in Tumour Stromal Cells Suppresses Tumour Growth and Progression

Tumour progression relies on interactions with untransformed cells in the tumour microenvironment (TME), including cancer-associated fibroblasts (CAFs), which promote blood supply, tumour progression, and immune evasion. Eph receptor tyrosine kinases are cell guidance receptors that are most active during development but re-emerge in cancer and are recognised drug targets. EphA3 is overexpressed in a wide range of tumour types, and we previously found expression particularly in stromal and vascular tissues of the TME. To investigate its role in the TME, we generated transgenic mice with inducible shRNA-mediated knockdown of EphA3 expression. EphA3 knockdown was confirmed in aortic mesenchymal stem cells (MSCs), which displayed reduced angiogenic capacity. In mice with syngeneic lung tumours, EphA3 knockdown reduced vasculature and CAF/MSC-like cells in tumours, and inhibited tumour growth, which was confirmed also in a melanoma model. Single cell RNA sequencing analysis of multiple human tumour types confirmed EphA3 expression in CAFs, including in breast cancer, where EphA3 was particularly prominent in perivascular- and myofibroblast-like CAFs. Our results thus indicate expression of the cell guidance receptor EphA3 in distinct CAF subpopulations is important in supporting tumour angiogenesis and tumour growth, highlighting its potential as a therapeutic target.

Neo-vascularization-based therapeutic perspectives in advanced ovarian cancer

The process of angiogenesis is well described for its potential role in the development of normal ovaries, and physiological functions as well as in the initiation, progression, and metastasis of ovarian cancer (OC). In advanced stages of OC, cancer cells spread outside the ovary to the pelvic, abdomen, lung, or multiple secondary sites. This seriously limits the efficacy of therapeutic options contributing to fatal clinical outcomes. Notably, a variety of angiogenic effectors are produced by the tumor cells to initiate angiogenic processes leading to the development of new blood vessels, which provide essential resources for tumor survival, dissemination, and dormant micro-metastasis of tumor cells. Multiple proangiogenic effectors and their signaling axis have been discovered and functionally characterized for potential clinical utility in OC. In this review, we have provided the current updates on classical and emerging proangiogenic effectors, their signaling axis, and the immune microenvironment contributing to the pathogenesis of OC. Moreover, we have comprehensively reviewed and discussed the significance of the preclinical strategies, drug repurposing, and clinical trials targeting the angiogenic processes that hold promising perspectives for the better management of patients with OC.

Anti-angiogenic therapy in ovarian cancer: Current understandings and prospects of precision medicine

Ovarian cancer (OC) remains the most fatal disease of gynecologic malignant tumors. Angiogenesis refers to the development of new vessels from pre-existing ones, which is responsible for supplying nutrients and removing metabolic waste. Although not yet completely understood, tumor vascularization is orchestrated by multiple secreted factors and signaling pathways. The most central proangiogenic signal, vascular endothelial growth factor (VEGF)/VEGFR signaling, is also the primary target of initial clinical anti-angiogenic effort. However, the efficiency of therapy has so far been modest due to the low response rate and rapidly emerging acquiring resistance. This review focused on the current understanding of the in-depth mechanisms of tumor angiogenesis, together with the newest reports of clinical trial outcomes and resistance mechanism of anti-angiogenic agents in OC. We also emphatically summarized and analyzed previously reported biomarkers and predictive models to describe the prospect of precision therapy of anti-angiogenic drugs in OC.

EFNA1 in gastrointestinal cancer: Expression, regulation and clinical significance

Ephrin-A1 is a protein that in humans is encoded by the EFNA1 gene. The ephrins and EPH-related receptors comprise the largest subfamily of receptor protein-tyrosine kinases which play an indispensable role in normal growth and development or in the pathophysiology of various tumors. The role of EFNA1 in tumorigenesis and development is complex and depends on the cell type and microenvironment which in turn affect the expression of EFNA1. This article reviews the expression, prognostic value, regulation and clinical significance of EFNA1 in gastrointestinal tumors.

Association Between Polymorphisms in Gastric Cancer Related Genes and Risk of Gastric Cancer: A Case-Control Study

Gastric cancer has the second highest incidence among all the malignancies in China, just below lung cancer. Gastric cancer is likewise one of the main sources of cancer related passings. Gastric cancer therefore remains a huge threat to human health. The primary reason is absence of high sensitivity and specificity for early detection while the pathogenesis of GC is stayed muddled. During the last few decades, a lot of GC related genes have been identified. To find candidate GC related variant in these GC related genes, we conducted this case-control study. 29 tagSNPs located in 7 GC related genes were included. 228 gastric cancer patients and 299 healthy controls were enrolled. Significant differences were found between the genotype frequencies of EFNA1 rs4971066 polymorphism between gastric cancer patients and healthy controls. The result indicated that ephrin-A1 tagSNP rs4971066 GT/TT genotypes was significantly associated with reduced susceptibility of gastric cancer development.

Inhibition of Tumor VEGFR2 Induces Serine 897 EphA2-Dependent Tumor Cell Invasion and Metastasis in NSCLC

Anti-angiogenic treatment targeting vascular endothelial growth factor (VEGF)-VEGFR2 signaling has shown limited efficacy in lung cancer patients. Here, we demonstrate that inhibition of VEGFR2 in tumor cells, expressed in ∼20% of non-squamous non-small cell lung cancer (NSCLC) patients, leads to a pro-invasive phenotype. Drug-induced inhibition of tumor VEGFR2 interferes with the formation of the EphA2/VEGFR2 heterocomplex, thereby allowing RSK to interact with Serine 897 of EphA2. Inhibition of RSK decreases phosphorylation of Serine 897 EphA2. Selective genetic modeling of Serine 897 of EphA2 or inhibition of EphA2 abrogates the formation of metastases in vivo upon VEGFR2 inhibition. In summary, these findings demonstrate that VEGFR2-targeted therapy conditions VEGFR2-positive NSCLC to Serine 897 EphA2-dependent aggressive tumor growth and metastasis. These data shed light on the molecular mechanisms explaining the limited efficacy of VEGFR2-targeted anti-angiogenic treatment in lung cancer patients.

EphA2 Is a Clinically Relevant Target for Breast Cancer Bone Metastatic Disease

EphA2 receptor tyrosine kinase (RTK) is highly expressed in breast tumor cells across multiple molecular subtypes and correlates with poor patient prognosis. In this study, the potential role of EphA2 in this clinically relevant phenomenon is investigated as metastasis of breast cancer to bone is a major cause of morbidity and mortality in patients. It was found that the EphA2 function in breast cancer cells promotes osteoclast activation and the development of osteolytic bone disease. Blocking EphA2 function molecularly and pharmacologically in breast tumors reduced the number and size of bone lesions and the degree of osteolytic disease in intratibial and intracardiac mouse models, which correlated with a significant decrease in the number of osteoclasts at the tumor-bone interface. EphA2 loss of function in tumor cells impaired osteoclast progenitor differentiation in coculture, which is mediated, at least in part, by reduced expression of IL-6. EPHA2 transcript levels are enriched in human breast cancer bone metastatic lesions relative to visceral metastatic sites; EphA2 protein expression was detected in breast tumor cells in bone metastases in patient samples, supporting the clinical relevance of the study's findings. These data provide a strong rationale for the development and application of molecularly targeted therapies against EphA2 for the treatment of breast cancer bone metastatic disease. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Ephrin Receptors (Eph): EphA1, EphA5, and EphA7 Expression in Uveal Melanoma-Associations with Clinical Parameters and Patient Survival

Uveal melanoma is the most common primary intraocular malignancy in adults. The development of distant metastases is associated with a poor prognosis. Ephrine receptors (Eph) are the largest subpopulation of tyrosine kinase receptors. They play an important role in processes related to the formation and progression of cancer. The aim of the study was to evaluate the expression of ephrin receptors EphA1, EphA5, and EphA7 in uveal melanoma and its associations with clinicopathological parameters, overall survival, and disease-free survival. The study included 94 previously untreated patients who underwent enucleation due to uveal melanoma. High expression of EphA1 was positively correlated with a smaller tumor size, less frequent extra-scleral extension, lower mitotic activity, and more frequent vitreous hemorrhage. High expression of EphA5 was associated with less frequent chromosome 3 loss, absence of distant metastases, and more frequent vitreous hemorrhage. High expression of EphA7 was associated with a more frequent primary tumor location in the posterior pole. High EphA5 expression was associated with longer overall survival time. The above findings indicate that high expression of EphA1 and EphA5 can be considered a beneficial prognostic factor in uveal melanoma.

EphrinA1-Fc Attenuates Ventricular Remodeling and Dysfunction in Chronically Nonreperfused WT but not EphA2-R-M mice

Background: EphrinA1-Fc abolishes acute I/R injury and attenuates nonreperfused cardiac injury 4 days after permanent occlusion in mice. The goal of this study was to assess the capacity of a single intramyocardial administration of ephrinA1-Fc at the time of coronary artery ligation, to determine the degree to which early salvage effects translate to reduced adverse remodeling after 4 weeks of nonreperfused myocardial infarction (MI) in wild-type B6 and EphA2-R-M (EphA2 receptor null) mice. Methods: At 4 weeks post-MI, echocardiography, histologic and immunohistochemical analyses of B6 mouse hearts were performed. Primary mouse cardiac fibroblasts (FBs) isolated from B6 mice cultured in the presence of low and high dose ephrinA1-Fc, both with and without pro-fibrotic TGF-β stimulation and Western blots, were probed for relative expression of remodeling proteins MMP-2, MMP-9 and TIMP-1, in addition to DDR2 and (p)SMAD2/3/totalSMAD2/3. Results: EphrinA1-Fc preserved a significant degree of contractile function, decreased adverse left ventricular remodeling, attenuated excessive compensatory hypertrophy, and decreased interstitial fibrosis in wild-type (WT) B6 mouse hearts. In contrast, most of these parameters were poorer in ephrinA1-Fc-treated EphA2-R-M mice. Of note, fibrosis was proportionately decreased, implying that other EphA receptor(s) are more important in regulating the pro-fibrotic response. Primary FBs showed disparate alteration of MMP-2, MMP-9 and TIMP-1, as well as DDR2 and p-SMAD2/3/totalSMAD2/3, which indicates that matrix remodeling and cardiac fibrosis in the injured heart are influenced by ephrinA1-Fc. Conclusion: This study demonstrates the capacity of a single administration of ephrinA1-Fc at the onset of injury to attenuate long-term nonreperfused post-MI ventricular remodeling that results in progressive heart failure, and the important role of EphA2 in mitigating the deleterious effects.

High expression of EphA2 led to secondary injury by destruction of BBB integrity though the ROCK pathway after diffuse axonal injury

Blood-brain barrier (BBB) disruption exacerbates diffuse axonal injury (DAI), but the underlying mechanisms are not fully understood. Inactivation or deletion of erythropoietin-producing hepatoma (EPH) receptor A2 (EphA2) attenuated BBB damage and promoted tight junction formation. In this study, we aimed to investigate the role of EphA2 in the protection of BBB integrity and the relevant mechanisms involved in a rat model of DAI. Blocking activation of the EphA receptor by EphA2-Fc ameliorated axonal injury, cell apoptosis, and glial activation, protected BBB integrity and increased expression of the tight junction-associated proteins ZO-1, claudin-5 and occludin-1. In vitro BBB models established by human brain microvascular endothelial cells (HBMECs) were subjected to oxygen deprivation (OGD). Treatment with EphrinA1, which activates EphA2, exacerbated the OGD-induced destruction of permeability and integrity of the BBB models by reducing the expression of tight junction-associated proteins. However, inhibition of Rho-associated coiled coil-containing protein kinases 1 and 2 (ROCK1 and 2) abrogated all of the effects of EphrinA1 on the BBB models in vitro. In conclusion, we provide evidence that EphA2 plays an important role in the destruction of BBB integrity by decreasing the expression of tight junction proteins through the ROCK pathway.

Supervillin promotes tumor angiogenesis in liver cancer

Tumor angiogenesis is a hallmark of liver cancer and is necessary for tumor growth and progression. Supervillin (SVIL) is highly expressed and implicated in several malignant processes of liver cancer. However, the functional relationships between SVIL and tumor angiogenesis in liver cancer have not yet been fully elucidated. The present study was based on bioinformatics analysis, patient tissue sample detection, three-dimensional simulated blood vessel formation, a series of cytological experiments and mouse models. The results demonstrated the important role of SVIL in the progression of malignant liver cancer and tumor angiogenesis, both in terms of vasculogenic mimicry (VM) and endothelium-dependent vessel (EDV) development. SVIL knockdown inhibited VM formation and induced tumor cell apoptosis via the VEGF-p38 signaling axis and through various VM-associated transcriptional factors, including vascular endothelial-cadherin, matrix metalloproteinase 9/12 and migration-inducing protein 7. SVIL may therefore be considered a potential tumor vascular biomarker and a promising therapeutic target for patients with liver cancer.

Early Blockade of EphA4 Pathway Reduces Trigeminal Neuropathic Pain

Background

Although the Eph receptor plays an important role in the development of neuropathic pain following nerve injury, there has been no evidence of the participation of the ephrin A4 receptor (EphA4) in the development of trigeminal neuropathic pain. The present study investigated the role of EphA4 in central nociceptive processing in rats with inferior alveolar nerve injury.

Materials and Methods

Male Sprague-Dawley rats were used in all our experiments. A rat model for trigeminal neuropathic pain was produced using malpositioned dental implants. The left mandibular second molar was extracted under anesthesia, followed by the placement of a miniature dental implant to injure the inferior alveolar nerve.

Results

Our current findings show that nerve injury induced by malpositioned dental implants evokes significant mechanical allodynia and up-regulation of EphA4 expression in the ipsilateral trigeminal subnucleus caudalis. Although daily treatment with EphA4-Fc, an EphA4 antagonist, did not produce prolonged anti-allodynic effects after the chronic neuropathic pain had been already established, an early treatment protocol with repeated EphA4-Fc administration significantly attenuated mechanical allodynia before initiation of chronic neuropathic pain. Finally, we confirmed the participation of the central EphA4 pathway in the development of trigeminal neuropathic pain by reducing EphA4 expression using EphA4 siRNA. This suppression of EphA4 produced significantly prolonged anti-allodynic effects.

Conclusion

These results suggest that early blockade of central EphA4 signaling provides a new therapeutic target for the treatment of trigeminal neuropathic pain.

Progranulin/EphA2 axis: A novel oncogenic mechanism in bladder cancer

The growth factor progranulin plays a critical role in bladder cancer by modulating tumor cell motility and invasion. Progranulin regulates remodeling of the actin cytoskeleton by interacting with drebrin, an actin binding protein that regulates tumor growth. We previously discovered that progranulin depletion inhibits epithelial-to-mesenchymal transition and markedly reduces in vivo tumor growth. Moreover, progranulin depletion sensitizes urothelial cancer cells to cisplatin treatment, further substantiating a pro-survival function of progranulin. Until recently, the progranulin signaling receptor remained unidentified, precluding a full understanding of progranulin action in tumor cell biology. We recently identified EphA2, a member of a large family of receptor tyrosine-kinases, as the functional receptor for progranulin. However, it is not established whether EphA2 plays an oncogenic role in bladder cancer. Here we demonstrate that progranulin, and not ephrin-A1, the canonical ligand for EphA2, is the predominant EphA2 ligand in bladder cancer. Progranulin evoked Akt- and Erk1/2-mediated EphA2 phosphorylation at Ser897, which could drive bladder tumorigenesis. We discovered that EphA2 depletion severely blunted progranulin-dependent motility and anchorage-independent growth, and sensitized bladder cancer cells to cisplatin treatment. We further defined the mechanisms of progranulin/EphA2-dependent motility by identifying liprin-α1 as a novel progranulin-dependent EphA2 interacting protein and establishing its critical role in cell motility. The discovery of EphA2 as the functional signaling receptor for progranulin and the identification of novel downstream effectors offer a new avenue for understanding the underlying mechanism of progranulin action and may constitute novel clinical and therapeutic targets in bladder cancer.

Host deficiency in ephrin-A1 inhibits breast cancer metastasis

Background: The conventional dogma of treating cancer by focusing on the elimination of tumor cells has been recently refined to include consideration of the tumor microenvironment, which includes host stromal cells. Ephrin-A1, a cell surface protein involved in adhesion and migration, has been shown to be tumor suppressive in the context of the cancer cell. However, its role in the host has not been fully investigated. Here, we examine how ephrin-A1 host deficiency affects cancer growth and metastasis in a murine model of breast cancer.

Methods: 4T1 cells were orthotopically implanted into the mammary fat pads or injected into the tail veins of ephrin-A1 wild-type ( Efna1^+/+), heterozygous ( Efna1^+/-), or knockout ( Efna1^-/-) mice. Tumor growth, lung metastasis, and tumor recurrence after surgical resection were measured. Flow cytometry and immunohistochemistry (IHC) were used to analyze various cell populations in primary tumors and tumor-bearing lungs.

Results: While primary tumor growth did not differ between Efna1^+/+, Efna1^+/-, and Efna1^-/- mice, lung metastasis and primary tumor recurrence were significantly decreased in knockout mice. Efna1^-/- mice had reduced lung colonization of 4T1 cells compared to Efna1^+/+ littermate controls as early as 24 hours after tail vein injection. Furthermore, established lung lesions in Efna1^-/- mice had reduced proliferation compared to those in Efna1^+/+ controls.

Conclusions: Our studies demonstrate that host deficiency of ephrin-A1 does not impact primary tumor growth but does affect metastasis by providing a less favorable metastatic niche for cancer cell colonization and growth. Elucidating the mechanisms by which host ephrin-A1 impacts cancer relapse and metastasis may shed new light on novel therapeutic strategies.

Host deficiency in ephrin-A1 inhibits breast cancer metastasis

Background: The conventional dogma of treating cancer by focusing on the elimination of tumor cells has been recently refined to include consideration of the tumor microenvironment, which includes host stromal cells. Ephrin-A1, a cell surface protein involved in adhesion and migration, has been shown to be tumor suppressive in the context of the cancer cell. However, its role in the host has not been fully investigated. Here, we examine how ephrin-A1 host deficiency affects cancer growth and metastasis in a murine model of breast cancer. Methods: 4T1 cells were orthotopically implanted into the mammary fat pads or injected into the tail veins of ephrin-A1 wild-type ( Efna1 ^+/+), heterozygous ( Efna1 ^+/-), or knockout ( Efna1 ^-/-) mice. Tumor growth, lung metastasis, and tumor recurrence after surgical resection were measured. Flow cytometry and immunohistochemistry (IHC) were used to analyze various cell populations in primary tumors and tumor-bearing lungs. Results: While primary tumor growth did not differ between Efna1 ^+/+, Efna1 ^+/-, and Efna1 ^-/- mice, lung metastasis and primary tumor recurrence were significantly decreased in knockout mice. Efna1 ^-/- mice had reduced lung colonization of 4T1 cells compared to Efna1 ^+/+ littermate controls as early as 24 hours after tail vein injection. Furthermore, established lung lesions in Efna1 ^-/- mice had reduced proliferation compared to those in Efna1 ^+/+ controls. Conclusions: Our studies demonstrate that host deficiency of ephrin-A1 does not impact primary tumor growth but does affect metastasis by providing a less favorable metastatic niche for cancer cell colonization and growth. Elucidating the mechanisms by which host ephrin-A1 impacts cancer relapse and metastasis may shed new light on novel therapeutic strategies.

Helicobacter Pylori Targets the EPHA2 Receptor Tyrosine Kinase in Gastric Cells Modulating Key Cellular Functions

Helicobacter pylori, a stomach-colonizing Gram-negative bacterium, is the main etiological factor of various gastroduodenal diseases, including gastric adenocarcinoma. By establishing a life-long infection of the gastric mucosa, H. pylori continuously activates host-signaling pathways, in particular those associated with receptor tyrosine kinases. Using two different gastric epithelial cell lines, we show that H. pylori targets the receptor tyrosine kinase EPHA2. For long periods of time post-infection, H. pylori induces EPHA2 protein downregulation without affecting its mRNA levels, an effect preceded by receptor activation via phosphorylation. EPHA2 receptor downregulation occurs via the lysosomal degradation pathway and is independent of the H.pylori virulence factors CagA, VacA, and T4SS. Using small interfering RNA, we show that EPHA2 knockdown affects cell–cell and cell–matrix adhesion, invasion, and angiogenesis, which are critical cellular processes in early gastric lesions and carcinogenesis mediated by the bacteria. This work contributes to the unraveling of the underlying mechanisms of H. pylori–host interactions and associated diseases. Additionally, it raises awareness for potential interference between H. pylori infection and the efficacy of gastric cancer therapies targeting receptors tyrosine kinases, given that infection affects the steady-state levels and dynamics of some receptor tyrosine kinases (RTKs) and their signaling pathways.

A new scfv-based recombinant immunotoxin against EPHA2-overexpressing breast cancer cells; High in vitro anti-cancer potency

Immunotoxin therapy is one of the immunotherapy strategies providing a new, effective and high potency treatment against various cancers. Breast cancer is the most common cancer among women in many countries. The EPH receptors are a large part of tyrosine kinase receptors family and play an effective role in tumor development and angiogenesis. Among EPH receptors, EPHA2 is more commonly well-known and widely expressed in many cancers like breast cancer. In this study, we evaluated the specification of a designed immunotoxin formed by EPHA2-specific scfv linked with PE38KDEL on EPHA2-overexpressing breast cancer cell line. This new scfv-based recombinant immunotoxin was studied in terms of features such as binding potency, cytotoxicity effects, apoptosis induction ability, and internalization. The flow cytometry results showed that the immunotoxin can significantly (approximately 99%) bind to EPHA2-overexpressing breast cancer cell line (MDA-MB-231) in a low concentration (2.5 ng/ul) while cannot significantly bind to the normal cell line (HEK-293) or even EPHA2-very low expressing cell line (MCF-7). Using the MTT assay and Annexin V/Propidium iodide (PI) double staining method by flow cytometry, we observed significant killing and apoptosis induction of the MDA-MB-231 cells at different concentrations. Immunotoxin tracking by confocal microscopy at 2 h and 6 h revealed a massive presence of immunotoxin in the cytoplasm. Finally, given the in vitro results, it seems that this immunotoxin is competent enough to serve as a good candidate for in vivo studies to further explore the possibility of breast cancer treatment.

Tumor angiogenesis: causes, consequences, challenges and opportunities

Tumor vascularization occurs through several distinct biological processes, which not only vary between tumor type and anatomic location, but also occur simultaneously within the same cancer tissue. These processes are orchestrated by a range of secreted factors and signaling pathways and can involve participation of non-endothelial cells, such as progenitors or cancer stem cells. Anti-angiogenic therapies using either antibodies or tyrosine kinase inhibitors have been approved to treat several types of cancer. However, the benefit of treatment has so far been modest, some patients not responding at all and others acquiring resistance. It is becoming increasingly clear that blocking tumors from accessing the circulation is not an easy task to accomplish. Tumor vessel functionality and gene expression often differ vastly when comparing different cancer subtypes, and vessel phenotype can be markedly heterogeneous within a single tumor. Here, we summarize the current understanding of cellular and molecular mechanisms involved in tumor angiogenesis and discuss challenges and opportunities associated with vascular targeting.

EphA2 antagonism alleviates LPS-induced acute lung injury via Nrf2/HO-1, TLR4/MyD88 and RhoA/ROCK pathways

Eph receptor tyrosine kinases have a wide range of biological functions and have gradually been recognized increasingly as key regulators of inflammation and injury diseases. Although previous studies suggested that EphA2 receptor may be involved in the regulation of inflammation and vascular permeability in injured lung, the detailed effects of EphA2 on LPS-induced acute lung injury (ALI) are still inadequate and the underlying mechanism remains poorly understood. In this study, we detected the effects of EphA2 antagonism on inflammation, pulmonary vascular permeability and oxidative stress in LPS-induced ALI and investigate the potential mechanism. Our results showed that EphA2 antagonism markedly inhibited the cytokines release and inflammatory cells infiltration in BALF, prevented the LPS-induced elevations of MPO activity and MDA level in lung tissues. Our study also found that EphA2 antagonism significantly decreased the wet/dry ratios, reduced the Evans blue albumin extravasation in lung tissues and obviously alleviated the LPS-induced increment of pulmonary vascular permeability. Mechanistically, EphA2 antagonism significantly increased the activation of Nrf2 along with its target antioxidant enzyme HO-1 and inhibited the expressions of TLR4/MyD88 in lung tissues and A549 alveolar epithelial cells. Furthermore, EphA2 antagonism dramatically inhibited the LPS-evoked activations of RhoA/ROCK in lung tissues. In conclusion, our data indicate that EphA2 receptor plays an essential role in LPS-induced ALI and EphA2 antagonism has protective effects against LPS-induced ALI via Nrf2/HO-1, TLR4/MyD88 and RhoA/ROCK pathways. These results suggest that antagonism of EphA2 may be an effective therapeutic strategy for the treatment of ALI.

Roles of EphA2 Receptor in Angiogenesis Signaling Pathway of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is one of the most common primary brain tumours in adults, accounting for almost 65% of all cases. Among solid tumours, GBM is characterised by strong angiogenesis, including the highest degree of vascular proliferation and endothelial cell hyperplasia. Despite numerous improvements in existing treatment approaches, the prognosis of GBM patients remains poor, with a mean survival of only 14.6 months. Growing evidence has shown significant overexpression of the ephrin type-A receptor 2 (EphA2) receptor in various malignancies, including GBM, as well as a correlation to poor prognoses. It is believed that EphA2 receptors play important roles in mediating GBM tumourigenesis, including invasion, metastasis, and angiogenesis. Despite the clinical and pathological importance of tumour-associated vasculature, the underlying mechanism involving EphA2 is poorly known. Here, we have summarised the current knowledge in the field regarding EphA2 receptors’ roles in the angiogenesis of GBM.

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.

Aggregation-Induced Emission Luminogens: Union Is Strength, Gathering Illuminates Healthcare

The rapid development of healthcare techniques encourages the emergence of new molecular imaging agents and modalities. Fluorescence imaging that enables precise monitoring and detection of biological processes/diseases is extensively investigated as this imaging technique has strengths in terms of high sensitivity, excellent temporal resolution, low cost, and good safety. Aggregation-induced emission luminogens (AIEgens) have recently emerged as a new class of emitters that possess several notable features, such as high brightness, large Stokes shift, marked photostability, good biocompatibility, and so on. So far, AIEgens are widely explored and exhibit superb performance in the area of biomedicine and life sciences. Herein, this review summarizes and discusses the recent investigations of AIEgens for in vivo diagnosis and therapy including long-term tracking, 3D angiography, multimodality imaging, disease theranostics, and activatable sensing. Collectively, these results reveal that AIEgens are of great promise for in vivo biomedical applications. It is hoped that this review will lead to new insights into the development of advanced healthcare materials.

Inhibition of HDACs-EphA2 Signaling Axis with WW437 Demonstrates Promising Preclinical Antitumor Activity in Breast Cancer

Histone deacetylase inhibitors (HDACi) are small molecules targeting epigenetic enzymes approved for hematologic neoplasms, which have also demonstrated clinical activities in solid tumors. In our present study, we screened our internal compound library and discovered a novel HDACi, WW437, with potent anti-breast cancer ability in vitro and in vivo. WW437 significantly inhibited phosphorylated EphA2 and EphA2 expression. Further study demonstrated WW437 blocked HDACs-EphA2 signaling axis in breast cancer. In parallel, we found that EphA2 expression positively correlates with breast cancer progression; and combined use of WW437 and an EphA2 inhibitor (ALW-II-41-27) exerted more remarkable effect on breast cancer growth than either drug alone. Our findings suggested inhibition of HDACs-EphA2 signaling axis with WW437 alone or in combination with other agents may be a promising therapeutic strategy for advanced breast cancer.

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WW437 is a novel HDACi, which displays potent anticancer activity in breast cancer.

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HDACs-EphA2 signaling axis represents a novel target in breast cancer.

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WW437 is a promising therapeutic agent for advanced breast cancer, alone or in combination with EphA2 inhibitor.

Histone deacetylase inhibitors (HDACi) are small molecules targeting epigenetic enzymes approved for cutaneous T-cell lymphoma (CTCL), peripheral T-cell lymphoma (PTCL) and multiple myeloma (MM) treatment, which have also demonstrated clinical activities in solid tumors, including lung cancer and breast cancer. Herein we report a novel HDACi WW437, which displays potent anticancer activity in both cultured cancer cells and xenograft models. Importantly, our work reveals WW437 significantly blocked the HDACs-EphA2 signaling axis in breast cancer. WW437 exhibited significant inhibitory effects on tumor growth and metastases with little toxicity, and tumors from treated mice showed decreased EphA2 expression, suggesting that EphA2 may be a useful biomarker of response to WW437. We also found that EphA2 expression positively correlates with tumor progression in aggressive breast cancer.

Viewing the Eph receptors with a focus on breast cancer heterogeneity

Aberrant expression of different family members of the Eph/ephrin system, which comprises the Eph receptors (Ephs) and their ligands (ephrins), has been implicated in various malignancies including breast cancer. The latter presents as a heterogeneous disease with diverse molecular, morphologic and clinical behavior signatures. This review reflects the existing Eph/ephrin literature while focusing on breast cancer heterogeneity. Hormone positive, HER2 positive and triple negative breast cancer (TNBC) cell lines, xenografts/mutant animal models and patient samples are examined separately as, in humans, they represent entities with differences in prognosis and treatment. EphA2, EphB4 and EphB6 are the members most extensively studied in breast cancer. Existing research points to the potential use of various Eph/ephrin members as biomarkers for assessing prognosis and selecting the most suitable therapeutic strategies in variable clinical scenarios, also for overcoming drug resistance, in the era of breast cancer heterogeneity.

Light-driven transformable optical agent with adaptive functions for boosting cancer surgery outcomes

Fluorescence and photoacoustic imaging have different advantages in cancer diagnosis; however, combining effects in one agent normally requires a trade-off as the mechanisms interfere. Here, based on rational molecular design, we introduce a smart organic nanoparticle whose absorbed excitation energy can be photo-switched to the pathway of thermal deactivation for photoacoustic imaging, or to allow opposed routes for fluorescence imaging and photodynamic therapy. The molecule is made of a dithienylethene (DTE) core with two surrounding 2-(1-(4-(1,2,2-triphenylvinyl)phenyl)ethylidene)malononitrile (TPECM) units (DTE-TPECM). The photosensitive molecule changes from a ring-closed, for photoacoustic imaging, to a ring-opened state for fluorescence and photodynamic effects upon an external light trigger. The nanoparticles’ photoacoustic and fluorescence imaging properties demonstrate the advantage of the switch. The use of the nanoparticles improves the outcomes of in vivo cancer surgery using preoperative photoacoustic imaging and intraoperative fluorescent visualization/photodynamic therapy of residual tumours to ensure total tumour removal.

The combination of imaging techniques in cancer treatment often involves a trade-off in properties due to the opposite working mechanisms. Here, the authors report on a material that avoids the trade-off by switching from photoacoustic imaging to fluorescence imaging upon an external light trigger

Epha3 acts as proangiogenic factor in multiple myeloma

This study investigates the role of ephrin receptor A3 (EphA3) in the angiogenesis of Multiple Myeloma (MM) and the effects of a selective target of EphA3 by a specific monoclonal antibody on primary bone marrow endothelial cells (ECs) of MM patients.

EphA3 mRNA and protein were evaluated in ECs of MM patients (MMECs), in ECs of patients with monoclonal gammopathies of undetermined significance (MGECs) and in ECs of healthy subjects (control ECs). The effects of EphA3 targeting by mRNA silencing (siRNA) or by the anti EphA3 antibody on the angiogenesis were evaluated. We found that EphA3 is highly expressed in MMECs compared to the other EC types. Loss of function of EphA3 by siRNA significantly inhibited the ability of MMECs to adhere to fibronectin, to migrate and to form tube like structures in vitro, without affecting cell proliferation or viability. In addition, gene expression profiling showed that knockdown of EphA3 down modulated some molecules that regulate adhesion, migration and invasion processes. Interestingly, EphA3 targeting by an anti EphA3 antibody reduced all the MMEC angiogenesis-related functions in vitro. In conclusion, our findings suggest that EphA3 plays an important role in MM angiogenesis.

EphA2 blockade enhances the anti-endothelial effect of radiation and inhibits irradiated tumor cell-induced migration of endothelial cells

BACKGROUND

EphA2 tyrosine kinase plays an important role in tumor angiogenesis, but whether targeting this pathway can affect response to ionizing radiation (IR) remains unknown.

METHODS

We investigated, using a soluble EphA2-Fc chimera, whether EphA2 inhibition could sensitize A549 and MCF-7 tumor cells, as well as human umbilical vein endothelial cells (HUVEC) and dermal microvascular endothelial cells (HDMEC), to IR.

RESULTS

EphA2-Fc resulted in a greater response of endothelial cells (EC) to IR than either treatment alone. EphA2-Fc significantly increased apoptosis and decreased clonogenic survival, tube formation and migration in irradiated EC after stimulation with vascular endothelial growth factor (VEGF), without an affecting their proliferation. No difference in proliferation or survival was found in A549 and MCF-7 tumor cells. In a co-culture model, EphA2-Fc inhibited an irradiated A549 cell-induced increase in EC migration. VEGF supplementation, as well as condiotioned medium from irradiated A549 cells, phosphorylated EphA2 in EC. The latter was abrogated by EphA2-Fc.

CONCLUSIONS

EC were most sensitive to a combination of EphA2 inhibition and radiotherapy. The induction of paracrine growth factors and activation of EphA2 in EC suggest a protective mechanism that tumors probably use to attenuate IR-induced antivascular effects. Our data justify further investigation to explore targeting EphA2 in tumor radiosensitivity in vivo.

EphrinA1-Fc attenuates myocardial ischemia/reperfusion injury in mice

EphrinA1, a membrane-bound receptor tyrosine kinase ligand expressed in healthy cardiomyocytes, is lost in injured cells following myocardial infarction. Previously, we have reported that a single intramyocardial injection of chimeric ephrinA1-Fc at the time of ischemia reduced injury in the nonreperfused myocardium by 50% at 4 days post-MI by reducing apoptosis and inflammatory cell infiltration. In a clinically relevant model of acute ischemia (30min)/reperfusion (24hr or 4 days) injury, we now demonstrate that ephrinA1-Fc reduces infarct size by 46% and completely preserves cardiac function (ejection fraction, fractional shortening, and chamber dimensions) in the short-term (24hrs post-MI) as well as long-term (4 days). At 24 hours post-MI, diminished serum inflammatory cell chemoattractants in ephrinA1-Fc-treated mice reduces recruitment of neutrophils and leukocytes into the myocardium. Differences in relative expression levels of EphA-Rs are described in the context of their putative role in mediating cardioprotection. Validation by Western blotting of selected targets from mass spectrometry analyses of pooled samples of left ventricular tissue homogenates from mice that underwent 30min ischemia and 24hr of reperfusion (I/R) indicates that ephrinA1-Fc administration alters several regulators of signaling pathways that attenuate apoptosis, promote autophagy, and shift from FA metabolism in favor of increased glycolysis to optimize anaerobic ATP production. Taken together, reduced injury is due a combination of adaptive metabolic reprogramming, improved cell survival, and decreased inflammatory cell recruitment, suggesting that ephrinA1-Fc enhances the capacity of the heart to withstand an ischemic insult.

The receptor tyrosine kinase EphA2 promotes glutamine metabolism in tumors by activating the transcriptional coactivators YAP and TAZ

Malignant tumors reprogram cellular metabolism to support cancer cell proliferation and survival. Although most cancers depend on a high rate of aerobic glycolysis, many cancer cells also display addiction to glutamine. Glutamine transporters and glutaminase activity are critical for glutamine metabolism in tumor cells. We found that the receptor tyrosine kinase EphA2 activated the TEAD family transcriptional coactivators YAP and TAZ (YAP/TAZ), likely in a ligand-independent manner, to promote glutamine metabolism in cells and mouse models of HER2-positive breast cancer. Overexpression of EphA2 induced the nuclear accumulation of YAP and TAZ and increased the expression of YAP/TAZ target genes. Inhibition of the GTPase Rho or the kinase ROCK abolished EphA2-dependent YAP/TAZ nuclear localization. Silencing YAP or TAZ substantially reduced the amount of intracellular glutamate through decreased expression of SLC1A5 and GLS, respectively, genes that encode proteins that promote glutamine uptake and metabolism. The regulatory DNA elements of both SLC1A5 and GLS contain TEAD binding sites and were bound by TEAD4 in an EphA2-dependent manner. In patient breast cancer tissues, EphA2 expression positively correlated with that of YAP and TAZ, as well as that of GLS and SLC1A5 Although high expression of EphA2 predicted enhanced metastatic potential and poor patient survival, it also rendered HER2-positive breast cancer cells more sensitive to glutaminase inhibition. The findings define a previously unknown mechanism of EphA2-mediated glutaminolysis through YAP/TAZ activation in HER2-positive breast cancer and identify potential therapeutic targets in patients.

Pharmacological evaluation of new bioavailable small molecules targeting Eph/ephrin interaction

Eph/ephrin system is an emerging target for cancer therapy but the lack of potent, stable and orally bioavailable compounds is impairing the development of the field. Since 2009 our research group has been devoted to the discovery and development of small molecules targeting Eph/ephrin system and our research culminated with the synthesis of UniPR129, a potent but problematic Eph/ephrin antagonist. Herein, we describe the in vitro pharmacological properties of two derivatives (UniPR139 and UniPR502) stemmed from structure of UniPR129. These two compounds acted as competitive and reversible antagonists of all Eph receptors reducing both ephrin-A1 and -B1 binding to EphAs and EphBs receptors in the low micromolar range. The compounds acted as antagonists inhibiting ephrin-A1-dependent EphA2 activation and UniPR139 exerted an anti-angiogenic effect, inhibiting HUVEC tube formation in vitro and VEGF-induced vessel formation in the chick chorioallantoic membrane assay. Finally, the oral bioavailability of UniPR139 represents a step forward in the search of molecules targeting the Eph/ephrin system and offers a new pharmacological tool useful for future in vivo studies.

EphA3 targeting reduces in vitro adhesion and invasion and in vivo growth and angiogenesis of multiple myeloma cells

PURPOSE

Multiple myeloma (MM) is a hematologic malignancy characterized by a clonal expansion of plasma cells (PCs) in the bone marrow (BM). Since MM has so far remained incurable, further insights into its pathogenesis and the concomitant identification of new therapeutic targets are urgently needed. The tyrosine kinase receptor EphA3 is known to be involved in various cellular processes including cell viability, cell movement and cell-cell interactions. Recently, EphA3 has emerged as a potential therapeutic target in several hematologic and solid tumors. Here, we aimed to uncover the role of EphA3 in MM.

METHODS

EphA3 mRNA and protein expression in primary MM bone marrow plasma cells (BMPCs), in MM-derived cell lines and in healthy controls (HCs) was assessed using qRT-PCR, Western blotting and flow cytometry. The effects of siRNA-mediated EphA3 silencing and anti EphA3 antibody (EphA3mAb) treatment on MM PC trafficking and viability were evaluated using in vitro assays. The effects of EphA3mAb treatment were also assessed in two MM-derived mouse xenograft models.

RESULTS

We found that EphA3 was overexpressed in primary MM BMPCs and MM-derived cell lines compared to HCs. We also found that siRNA-mediated EphA3 silencing and EphA3mAb treatment significantly inhibited the ability of MM PCs to adhere to fibronectin and stromal cells and to invade in vitro, without affecting cell proliferation and viability. Gene expression profiling showed that EphA3 silencing resulted in expression modulation of several molecules that regulate adhesion, migration and invasion processes. Importantly, we found that EphA3mAb treatment significantly inhibited in vivo tumor growth and angiogenesis in two MM-derived mouse xenograft models.

CONCLUSIONS

Our findings suggest that EphA3 plays an important role in the pathogenesis of MM and provide support for the notion that its targeting may represent a novel therapeutic opportunity for MM.

Anti-angiogenic agents for the treatment of solid tumors: Potential pathways, therapy and current strategies - A review

Recent strategies for the treatment of cancer, other than just tumor cell killing have been under intensive development, such as anti-angiogenic therapeutic approach. Angiogenesis inhibition is an important strategy for the treatment of solid tumors, which basically depends on cutting off the blood supply to tumor micro-regions, resulting in pan-hypoxia and pan-necrosis within solid tumor tissues. The differential activation of angiogenesis between normal and tumor tissues makes this process an attractive strategic target for anti-tumor drug discovery. The principles of anti-angiogenic treatment for solid tumors were originally proposed in 1972, and ever since, it has become a putative target for therapies directed against solid tumors. In the early twenty first century, the FDA approved anti-angiogenic drugs, such as bevacizumab and sorafenib for the treatment of several solid tumors. Over the past two decades, researches have continued to improve the performance of anti-angiogenic drugs, describe their drug interaction potential, and uncover possible reasons for potential treatment resistance. Herein, we present an update to the pre-clinical and clinical situations of anti-angiogenic agents and discuss the most recent trends in this field.

Targeting EphA2 impairs cell cycle progression and growth of basal-like/triple-negative breast cancers

Basal-like/triple-negative breast cancers (TNBCs) are among the most aggressive forms of breast cancer, and disproportionally affects young premenopausal women and women of African descent. Patients with TNBC suffer a poor prognosis due in part to a lack of molecularly targeted therapies, which represents a critical barrier for effective treatment. Here, we identify EphA2 receptor tyrosine kinase as a clinically relevant target for TNBC. EphA2 expression is enriched in the basal-like molecular subtype in human breast cancers. Loss of EphA2 function in both human and genetically engineered mouse models of TNBC reduced tumor growth in culture and in vivo. Mechanistically, targeting EphA2 impaired cell cycle progression through S-phase via downregulation of c-Myc and stabilization of the cyclin-dependent kinase inhibitor p27/KIP1. A small molecule kinase inhibitor of EphA2 effectively suppressed tumor cell growth in vivo, including TNBC patient-derived xenografts. Thus, our data identify EphA2 as a novel molecular target for TNBC.

Nanoplasmonic Quantification of Tumor-derived Extracellular Vesicles in Plasma Microsamples for Diagnosis and Treatment Monitoring

Tumour-derived extracellular vesicles (EVs) are of increasing interest as a resource of diagnostic biomarkers. However, most EV assays require large samples, are time-consuming, low-throughput and costly, and thus impractical for clinical use. Here, we describe a rapid, ultrasensitive and inexpensive nanoplasmon-enhanced scattering (nPES) assay that directly quantifies tumor-derived EVs from as little as 1 μL of plasma. The assay uses the binding of antibody-conjugated gold nanospheres and nanorods to EVs captured by EV-specific antibodies on a sensor chip to produce a local plasmon effect that enhances tumour-derived EV detection sensitivity and specificity. We identified a pancreatic cancer EV biomarker, ephrin type-A receptor 2 (EphA2), and demonstrate that an nPES assay for EphA2-EVs distinguishes pancreatic cancer patients from pancreatitis patients and healthy subjects. EphA2-EVs were also informative in staging tumour progression and in detecting early responses to neoadjuvant therapy, with better performance than a conventional enzyme-linked immunosorbent assay. The nPES assay can be easily refined for clinical use, and readily adapted for diagnosis and monitoring of other conditions with disease-specific EV biomarkers.

EphA2 is a functional receptor for the growth factor progranulin

The receptor for the growth factor progranulin has remained unclear. Neill et al. show that the Ephrin receptor tyrosine kinase EphA2 is a functional signaling receptor for progranulin and mediates its effects in capillary morphogenesis and autoregulation.

Although the growth factor progranulin was discovered more than two decades ago, the functional receptor remains elusive. Here, we discovered that EphA2, a member of the large family of Ephrin receptor tyrosine kinases, is a functional signaling receptor for progranulin. Recombinant progranulin bound with high affinity to EphA2 in both solid phase and solution. Interaction of progranulin with EphA2 caused prolonged activation of the receptor, downstream stimulation of mitogen-activated protein kinase and Akt, and promotion of capillary morphogenesis. Furthermore, we found an autoregulatory mechanism of progranulin whereby a feed-forward loop occurred in an EphA2-dependent manner that was independent of the endocytic receptor sortilin. The discovery of a functional signaling receptor for progranulin offers a new avenue for understanding the underlying mode of action of progranulin in cancer progression, tumor angiogenesis, and perhaps neurodegenerative diseases.

Mutational load and mutational patterns in relation to age in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is a cancer with well-defined tumor causes such as HPV infection, smoking and drinking. Using The Cancer Genome Atlas (TCGA) HNSCC cohort we systematically studied the mutational load as well as patterns related to patient age in HNSCC. To obtain a homogenous set we excluded all patients with HPV infection as well as wild type TP53. We found that the overall mutational load is higher in patients of old age. Through unsupervised hierarchical clustering, we detected distinct mutational clusters in very young as well as very old patients. In the group of old patients, we identified four enriched pathways ("Axon Guidance", "ECM-Receptor Interaction", "Focal Adhesion" and "Notch Signaling") that are only sporadically mutated in the other age groups. Our findings indicate that the four pathways regulate cell motility, tumor invasion and angiogenesis supposedly leading to less aggressive tumors in older age patients. Importantly, we did not see a strict pattern of genes always mutated in older age but rather an accumulation of mutations in the same pathways. Our study provides indications of age-dependent differences in mutational backgrounds of tumors that might be relevant for treatment approaches of HNSCCs patients.

Bidirectional signalling between EphA2 and ephrinA1 increases tubular cell attachment, laminin secretion and modulates erythropoietin expression after renal hypoxic injury

Acute kidney injury (AKI) is common in hospitalized patients and has a poor prognosis, the severity of AKI being linked to progression to chronic kidney disease. This stresses the need to search for protective mechanisms during the acute phase. We investigated kidney repair after hypoxic injury using a rat model of renal artery branch ligation, which led to an oxygen gradient vertical to the corticomedullary axis. Three distinct zones were observed: tubular necrosis, infarction border zone and preserved normal tissue. EphA2 is a receptor tyrosine kinase with pivotal roles in cell architecture, migration and survival, upon juxtacrine contact with its membrane-bound ligand EphrinA1. Following hypoxia, EphA2 was up-regulated in cortical and medullary tubular cells, while EphrinA1 was up-regulated in interstitial cells adjacent to peritubular capillaries. Moreover, erythropoietin (EPO) messenger RNA (mRNA) was strongly expressed in the border zone of infarcted kidney within the first 6 h. To gain more insight into the biological impact of EphA2 and EphrinA1 up-regulation, we activated the signalling pathways in vitro using recombinant EphrinA1/Fc or EphA2/Fc proteins. Stimulation of EphA2 forward signalling in the proximal tubular cell line HK2 increased cell attachment and laminin secretion at the baso-lateral side. Conversely, activation of reverse signalling through EphrinA1 expressed by Hep3B cells promoted EPO production at both the transcriptional and protein level. Strikingly, in co-culture experiments, juxtacrine contact between EphA2 expressing MDCK and EphrinA1 expressing Hep3B was sufficient to induce a significant up-regulation of EPO mRNA production in the latter cells, even in the absence of hypoxic conditions. The synergistic effects of EphA2 and hypoxia led to a 15-20-fold increase of EPO expression. Collectively, our results suggest an important role of EphA2/EphrinA1 signalling in kidney repair after hypoxic injury through stimulation of (i) tubular cell attachment, (ii) secretion of basal membrane proteins and (iii) EPO production. These findings could thus pave the way to new therapeutic approaches.

Overexpression of Ephrin A3 Receptor in Canine Prostatic Carcinoma

Ephrin A3 (EphA3), a member of the ephrin receptor tyrosine kinase family, is involved in a variety of functions in normal cells, especially during embryonic development, and alterations in its expression profile have been observed in several human cancers. However, there are no reports of the expression of EphA3 in normal, hyperplastic or neoplastic canine prostate tissue or in other types of canine tumours. Six normal, 15 hyperplastic and 21 neoplastic canine prostates were examined immunohistochemically with a polyclonal antibody specific for human EphA3. The percentage of positive cells in all prostatic carcinomas was increased, with a mean of 89.28 ± 5.18% compared with normal (9.17 ± 6.72%) and hyperplastic prostates (20.00 ± 8.28%). EphA3 expression was not correlated with the histological subtypes of prostate cancer or with the Gleason score. The increase in EphA3 expression in canine prostatic carcinomas suggests the involvement of this receptor in prostatic carcinogenesis and its potential use as a target for new therapeutic strategies.

EPHA2 Blockade Overcomes Acquired Resistance to EGFR Kinase Inhibitors in Lung Cancer

Despite the success of treating EGFR-mutant lung cancer patients with EGFR tyrosine kinase inhibitors (TKI), all patients eventually acquire resistance to these therapies. Although various resistance mechanisms have been described, there are currently no FDA-approved therapies that target alternative mechanisms to treat lung tumors with acquired resistance to first-line EGFR TKI agents. Here we found that EPHA2 is overexpressed in EGFR TKI-resistant tumor cells. Loss of EPHA2 reduced the viability of erlotinib-resistant tumor cells harboring EGFR(T790M) mutations in vitro and inhibited tumor growth and progression in an inducible EGFR(L858R+T790M)-mutant lung cancer model in vivo. Targeting EPHA2 in erlotinib-resistant cells decreased S6K1-mediated phosphorylation of cell death agonist BAD, resulting in reduced tumor cell proliferation and increased apoptosis. Furthermore, pharmacologic inhibition of EPHA2 by the small-molecule inhibitor ALW-II-41-27 decreased both survival and proliferation of erlotinib-resistant tumor cells and inhibited tumor growth in vivo. ALW-II-41-27 was also effective in decreasing viability of cells with acquired resistance to the third-generation EGFR TKI AZD9291. Collectively, these data define a role for EPHA2 in the maintenance of cell survival of TKI-resistant, EGFR-mutant lung cancer and indicate that EPHA2 may serve as a useful therapeutic target in TKI-resistant tumors.

Anti-angiogenic alternatives to VEGF blockade

Angiogenesis is a major requirement for tumour formation and development. Anti-angiogenic treatments aim to starve the tumour of nutrients and oxygen and also guard against metastasis. The main anti-angiogenic agents to date have focused on blocking the pro-angiogenic vascular endothelial growth factors (VEGFs). While this approach has seen some success and has provided a proof of principle that such anti-angiogenic agents can be used as treatment, the overall outcome of VEGF blockade has been somewhat disappointing. There is a current need for new strategies in inhibiting tumour angiogenesis; this article will review current and historical examples in blocking various membrane receptors and components of the extracellular matrix important in angiogenesis. Targeting these newly discovered pro-angiogenic proteins could provide novel strategies for cancer therapy.

Dissecting the roles of Ephrin-A3 in malignant peripheral nerve sheath tumor by TALENs

Malignant peripheral nerve sheath tumor (MPNST) is a rare and aggressive soft tissue sarcoma for which effective treatments have not yet been established due to poor understanding of its pathogenesis. Our previous study indicated that miR-210-mediated Ephrin-A3 (EFNA3) promotion of proliferation and invasion of MPNST cells plays an important role in MPNST tumorigenesis and progression. The purpose of the present study was to further investigate the roles of EFNA3 in MPNST. Constructed transcription activator-like effector nucleases (TALENs) and lentiviral vectors were transfected into MPNST ST88-14 (NF1 wild-type) and sNF96.2 (NF1 mutant type) cell lines to obtain gain- and loss-of-function cell lines for the EFNA3 function study. The results showed that the knockout of ENFA3 increased cellular viability and invasiveness of the MPNST cells. However, the adhesion ability of MPNST cells was enhanced or inhibited when EFNA3 was overexpressed or knocked out, respectively. It was also observed that knockout of EFNA3 significantly decreased the expression of phosphorylated FAK (p-FAK) and the tumor necrosis factor α (TNF-α) compared to that in the control cells, yet the expression of phosphatidylinositol 3-kinase (PI3K), GTPase, integrins, vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1α (HIF-α) increased significantly. Inversely, overexpression of EFNA3 significantly increased the expression of p-FAK and TNF-α compared to that in the control cells, yet the expression of PI3K, GTPase, integrins, VEGF and HIF-α decreased significantly. The results indicated that EFNA3 serves as a tumor suppressor in MPNST cells and it may play a critical role in the focal adhesion kinase (FAK) signaling and VEGF-associated tumor angiogenesis pathway. These findings may not only facilitate the better understanding of MPNST pathogenesis, but also suggest EFNA3 as a promising target for MPNST treatment.

Advanced research on vasculogenic mimicry in cancer

Vasculogenic mimicry (VM) is a brand-new tumour vascular paradigm independent of angiogenesis that describes the specific capacity of aggressive cancer cells to form vessel-like networks that provide adequate blood supply for tumour growth. A variety of molecule mechanisms and signal pathways participate in VM induction. Additionally, cancer stem cell and epithelial-mesenchymal transitions are also shown to be implicated in VM formation. As a unique perfusion way, VM is associated with tumour invasion, metastasis and poor cancer patient prognosis. Due to VM's important effects on tumour progression, more VM-related strategies are being utilized for anticancer treatment. Here, with regard to the above aspects, we make a review of advanced research on VM in cancer.

rs12904 polymorphism in the 3'UTR of EFNA1 is associated with colorectal cancer susceptibility in a Chinese population

Accumulated evidence has indicated that Ephrin A1 (EFNA1) is associated with angiogenesis and tumorigenesis in various types of malignancies, including colorectal cancer (CRC). In the current study, we performed an online search using the public microarray database to investigate whether EFNA1 expression might be altered in CRC tissues. We then conducted a case-control study including 306 subjects (102 cases and 204 well-matched controls) in Xiaoshan County to assess any association between genetic polymorphisms in EFNA1 and CRC susceptibility. Searches in the Oncomine expression profiling database revealed EFNA1 to be overexpressed in CRC tissue compared with adjacent normal tissue. The rs12904 G-A variant located in the 3' untranslated region (UTR) of EFNA1 was observed to be associated with CRC susceptibility. Compared with the AA homozygous genotype, those carrying GA genotype had a decreased risk of developing CRC (odds ratio (OR) =0.469, 95% confidence interval (CI): 0.225-0.977, and P =0.043). The association was stronger among smokers and tea drinkers, however, no statistical evidence of interaction between rs12904 polymorphism and smoking or tea drinking on CRC risk was found. Our results suggest that EFNA1 is involved in colorectal tumorigenesis, and rs12904 A>G polymorphism in the 3' UTR of EFNA1 is associated with CRC susceptibility. Larger studies and further mechanistic investigations are warranted to confirm our findings.