Role and mechanism of EphB3 in epileptic seizures and epileptogenesis through Kalirin.

BACKGROUND: The EphB receptor tyrosine kinase family participates in intricate signaling pathways that orchestrate neural networks, guide neuronal axon development, and modulate synaptic plasticity through interactions with surface-bound ephrinB ligands. Additionally, Kalirin, a Rho guanine nucleotide exchange factor, is notably expressed in the postsynaptic membrane of excitatory neurons and plays a role in synaptic morphogenesis. This study postulates that Kalirin may act as a downstream effector of EphB3 in epilepsy. This investigation focuses on understanding the link between EphB3 and epilepsy. MATERIALS AND METHODS: Chronic seizure models using LiCl-pilocarpine (LiCl/Pilo) and pentylenetetrazol were developed in rats. Neuronal excitability was gauged through whole-cell patch clamp recordings on rat hippocampal slices. Real-time PCR determined Kalirin's mRNA expression, and Western blotting was employed to quantify EphB3 and Kalirin protein levels. Moreover, dendritic spine density in epileptic rats was evaluated using Golgi staining. RESULTS: Modulation of EphB3 functionality influenced acute seizure severity, latency duration, and frequency of spontaneous recurrent seizures. Golgi staining disclosed an EphB3-driven alteration in dendritic spine density within the hippocampus of epileptic rats, underscoring its pivotal role in the reconfiguration of hippocampal neural circuits. Furthermore, our data propose Kalirin as a prospective downstream mediator of the EphB3 receptor. CONCLUSIONS: Our findings elucidate that EphB3 impacts the action potential dynamics in isolated rat hippocampal slices and alters dendritic spine density in the inner molecular layer of epileptic rat hippocampi, likely through Kalirin-mediated pathways. This hints at EphB3's significant role in shaping excitatory circuit loops and recurrent seizure activity via Kalirin.

EphB3 protein is a potential ancillary diagnostic biomarker for thyroid cancers.

OBJECTIVE: To investigate the expression of ephrin type B receptor 3 (EphB3) in thyroid tumors and its usage as an ancillary diagnostic biomarker for thyroid tumors. METHODS: Formalin-fixed and paraffin-embedded (FFPE) tissue samples (78 cases) and FNAC samples (57 cases) were assessed with the EphB3 antibody using immunohistochemistry. PTC and other thyroid follicular tumors were compared regarding their EphB3 expression. Sanger sequencing was used to assess for the presence of a BRAF V600E mutation. RESULTS: EphB3 was positive in 81.8 % (27/33) of papillary thyroid carcinoma (PTC), 83.3 % (5/6) of medullary thyroid carcinoma (MTC), 25 % (1/4) of hyperplastic/adenomatoid nodule (HN), 14.3 % (1/7) of follicular adenoma (FA), and negative in follicular tumors of uncertain malignant potential (FT-UMP) (0/13), noninvasive follicular neoplasm with papillary-like nuclear features (NIFTP) (0/7), thyroid follicular carcinoma (TFC) (0/4), Hashimoto's thyroiditis (0/4), and normal thyroid follicular tissues (0/33). In cellular blocks, EphB3 was positive in 87.1 % (20/23) of PTC, 75 % (3/4) of MTC, 20 % (2/10) of HN, and negative in atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) (0/20) and normal thyroid follicular cells (0/10). CONCLUSION: EphB3 is expressed in the majority of PTC, but less so in benign follicular nodules. EphB3 expression in fine needle aspiration cytology (FNAC) specimens can be used as a diagnostic tool to differentiate thyroid cancer from other follicular lesions in its differential diagnosis, especially AUS/FLUS and PTC.

EphB3 Stimulates Cell Migration and Metastasis in a Kinase-dependent Manner through Vav2-Rho GTPase Axis in Papillary Thyroid Cancer.

Eph receptors, the largest subfamily of transmembrane tyrosine kinase receptors, have been increasingly implicated in various physiologic and pathologic processes, and the roles of the Eph family members during tumorigenesis have recently attracted growing attentions. In the present study, we explored the function of EphB3, one member of Eph family, in papillary thyroid cancer (PTC). We found that the expression of EphB3 was significantly elevated in PTC. Either overexpression of EphB3 or activation of EphB3 by EfnB1-Fc/EfnB2-Fc stimulated in vitro migration of PTC cells. In contrast, siRNA-mediated knockdown of EphB3 or EphB3-Fc treatment, which only blocked EphB3-mediated forward signaling, inhibited migration and metastasis of PTC cells. A mechanism study revealed that EphB3 knockdown led to suppressed activity of Rac1 and enhanced activity of RhoA. Moreover, we found that Vav2, an important regulator of Rho family GTPases, was activated by EphB3 in a kinase-dependent manner. Altogether, our work suggested that EphB3 acted as a tumor promoter in PTC by increasing the in vitro migration as well as the in vivo metastasis of PTC cells through regulating the activities of Vav2 and Rho GTPases in a kinase-dependent manner.

EphB3-targeted regulation of miR-149 in the migration and invasion of human colonic carcinoma HCT116 and SW620 cells.

microRNAs play key roles during various crucial cell processes such as proliferation, migration, invasion and apoptosis. Also, microRNAs have been shown to possess oncogenic and tumor-suppressive functions in human cancers. Here, we describe the regulation and function of miR-149 in colorectal cancer cell lines. miR-149 expression patterns were detected in human colorectal cell lines and tissue samples, and then focused on its role in regulation of cell growth, migration, invasion, and its target gene identification. Furthermore, the function of the target gene of miR-149 was analyzed in vitro and in vivo. miR-149 expression was downregulated in human colorectal cancer HCT116 and SW620 cell lines compared to the normal colon epithelial NCM460 cell line using quantitative real-time polymerase chain reaction methods. Further studies indicated that introduction of miR-149 was able to suppress cell migration and invasion. Then, EphB3 was identified as a direct target gene of miR-149 in colorectal cancer cells. Moreover, experiments in vitro showed that knockdown expression of EphB3 could suppress cell proliferation and invasion, and ectopic expression of EphB3 restored the phenotypes of CRC cell lines transfected with miR149. In addition, silencing of EphB3 significantly affected cycle progression distribution and increased apoptosis in CRC cell lines. Finally, in vivo results demonstrated that knockdown of EphB3 by siRNA inhibited tumor growth. In conclusion,the important role of miR-149 in colorectal cancer progression suggesting that miR-149 may serve as a therapeutic target for colorectal cancer treatment.

Cell type-specific localization of Ephs pairing with ephrin-B2 in the rat postnatal pituitary gland.

Sox2-expressing stem/progenitor cells in the anterior lobe of the pituitary gland form two types of micro-environments (niches): the marginal cell layer and dense cell clusters in the parenchyma. In relation to the mechanism of regulation of niches, juxtacrine signaling via ephrin and its receptor Eph is known to play important roles in various niches. The ephrin and Eph families are divided into two subclasses to create ephrin/Eph signaling in co-operation with confined partners. Recently, we reported that ephrin-B2 localizes specifically to both pituitary niches. However, the Ephs interacting with ephrin-B2 in these pituitary niches have not yet been identified. Therefore, the present study aims to identify the Ephs interacting with ephrin-B2 and the cells that produce them in the rat pituitary gland. In situ hybridization and immunohistochemistry demonstrated cell type-specific localization of candidate interacting partners for ephrin-B2, including EphA4 in cells located in the posterior lobe, EphB1 in gonadotropes, EphB2 in corticotropes, EphB3 in stem/progenitor cells and EphB4 in endothelial cells in the adult pituitary gland. In particular, double-immunohistochemistry showed cis-interactions between EphB3 and ephrin-B2 in the apical cell membranes of stem/progenitor cell niches throughout life and trans-interactions between EphB2 produced by corticotropes and ephrin-B2 located in the basolateral cell membranes of stem/progenitor cells in the early postnatal pituitary gland. These data indicate that ephrin-B2 plays a role in pituitary stem/progenitor cell niches by selective interaction with EphB3 in cis and EphB2 in trans.

EphB3 signaling propagates synaptic dysfunction in the traumatic injured brain.

Traumatic brain injury (TBI), ranging from mild concussion to severe penetrating wounds, can involve brain regions that contain damaged or lost synapses in the absence of neuronal death. These affected regions significantly contribute to sensory, motor and/or cognitive deficits. Thus, studying the mechanisms responsible for synaptic instability and dysfunction is important for protecting the nervous system from the consequences of progressive TBI. Our controlled cortical impact (CCI) injury produces ~20% loss of synapses and mild changes in synaptic protein levels in the CA3-CA1 hippocampus without neuronal losses. These synaptic changes are associated with functional deficits, indicated by >50% loss in synaptic plasticity and impaired learning behavior. We show that the receptor tyrosine kinase EphB3 participates in CCI injury-induced synaptic damage, where EphB3(-/-) mice show preserved long-term potentiation and hippocampal-dependent learning behavior as compared with wild type (WT) injured mice. Improved synaptic function in the absence of EphB3 results from attenuation in CCI injury-induced synaptic losses and reduced d-serine levels compared with WT injured mice. Together, these findings suggest that EphB3 signaling plays a deleterious role in synaptic stability and plasticity after TBI.

Circular RNA circRest regulates manganese induced cell apoptosis by targeting the mmu-miR-6914-5p/Ephb3 axis.

Overexposure to manganese (Mn) can lead to neurotoxicity, the underlying mechanisms remain incompletely understood. Circular RNAs (circRNAs) have emerged as important regulators in various biological processes. It is plausible that circRNAs may be involved in the biological mechanisms underlying Mn caused neurotoxicity. Here, circRest was downregulated in Mn-exposed mouse neuroblastoma cells (N2a cells) by RNA sequencing and quantitative real-time PCR. When circRest was overexpressed, it led to an increase in cell viability and a decrease in apoptosis following Mn exposure. Conversely, silencing circRest resulted in opposite effects in N2a cells. Further investigation revealed that circRest acts as a mmu-miR-6914-5p sponge, and mmu-miR-6914-5p could bind and inhibit Ephb3, thereby promoting apoptosis in N2a cells. This was confirmed through RNA antisense purification and dual luciferase reporter assays. Additionally, the circRest/mmu-miR-6914-5p/Ephb3 axis may influence memory and learning in mice following Mn exposure. In conclusion, our study uncovers a novel mechanism by which circRest may attenuate Mn caused neurotoxicity via the mmu-miR-6914-5p/Ephb3 axis.

EphB3 receptor suppressor invasion, migration and proliferation in glioma by inhibiting EGFR-PI3K/AKT signaling pathway.

Eph receptors are the largest subfamily of receptor tyrosine kinases, and they have been shown to play a crucial role in glioma. The EphB3 receptor is a member of this family, and its effect on the invasion, migration and proliferation of glioma cells was examined in this study. It was found that the expression of EphB3 was decreased in glioma specimens with increasing tumor grade. Additionally, the U87MG and U251 cell lines showed low levels of EphB3 expression. This finding was consistent with the negative correlation between EphB3 expression in glioma tissues and tumor grade. Depletion of EphB3 gene in U87MG and U251 cell lines resulted in a substantial enhancement of their invasion, migration, and proliferation capacities in vitro. Furthermore, the knockdown of EphB3 led to an upregulation of EGFR, p-PI3K, and p-AKT protein levels. On the other hand, EphB3 overexpression reduced the invasiveness, proliferative capacity and migration rate of U87MG and U251 cells, and downregulated EGFR, p-PI3K and p-AKT. These findings indicate that EphB3 functions as a tumor suppressor in glioma, and its downregulation enhances the malignant potential of glioma cells by activating the EGFR-PI3K/AKT pathway. Thus, EphB3 is a promising diagnostic marker for glioma, and the EphB3-EGFR-PI3K / AKT axis deserves further investigation as a potential therapeutic target.

YTHDF2 promotes temozolomide resistance in glioblastoma by activation of the Akt and NF-κB signalling pathways via inhibiting EPHB3 and TNFAIP3.

Objectives: Temozolomide (TMZ) resistance is a key factor that restricts the therapeutic effect of glioblastoma (GBM). YTH-domain family member 2 (YTHDF2) is highly expressed in GBM tissues, while the mechanism of YTHDF2 in TMZ resistance in GBM remains not fully elucidated. Methods: The YTHDF2 expression in TMZ-resistant tissues and cells was detected. Kaplan-Meier analysis was employed to evaluate the prognostic value of YTHDF2 in GBM. Effect of YTHDF2 in TMZ resistance in GBM was explored via corresponding experiments. RNA sequence, FISH in conjugation with fluorescent immunostaining, RNA immunoprecipitation, dual-luciferase reporter gene and immunofluorescence were applied to investigate the mechanism of YTHDF2 that boosted TMZ resistance in GBM. Results: YTHDF2 was up-regulated in TMZ-resistant tissues and cells, and patients with high expression of YTHDF2 showed lower survival rate than the patients with low expression of YTHDF2. The elevated YTHDF2 expression boosted TMZ resistance in GBM cells, and the decreased YTHDF2 expression enhanced TMZ sensitivity in TMZ-resistant GBM cells. Mechanically, YTHDF2 bound to the N6-methyladenosine (m6A) sites in the 3'UTR of EPHB3 and TNFAIP3 to decrease the mRNA stability. YTHDF2 activated the PI3K/Akt and NF-κB signals through inhibiting expression of EPHB3 and TNFAIP3, and the inhibition of the two pathways attenuated YTHDF2-mediated TMZ resistance. Conclusion: YTHDF2 enhanced TMZ resistance in GBM by activation of the PI3K/Akt and NF-κB signalling pathways via inhibition of EPHB3 and TNFAIP3.

Knockdown of EphB3 inhibits cell proliferation partly through the AKT signaling pathway and represses epithelial-mesenchymal transition in esophageal squamous cell carcinoma.

Background: To investigate the role and mechanism of erythropoietin-producing hepatocyte receptor B3 (EphB3) in cancer of esophageal squamous cells. Methods: EphB3 expression in esophageal carcinoma squamous tissue and cell lines was determined by immunohistochemistry, western blotting and qRT-PCR. The viability, invasion and migration of cells were assessed by Transwell assay, formation of colonies, CCK-8, and healing of wounds, respectively. Flow cytometry analysis was employed to evaluate the actions of EphB3 on the activity of the cell cycle and the degree of apoptosis. The activity of EphB3 on the growth of tumors in vivo was examined in a mouse xenograft model. Results: EphB3 was highly expressed in esophageal squamous cell cancer tissue and was positively correlated with cell differentiation, metastasis in lymph node and the TNM stage. Patients with higher EphB3 expression had poorer prognosis in 3-year overall survival rate. EphB3 also overexpressed in esophageal squamous cell cancer cell lines. Knock down of EphB3 expression suppressed proliferation, migration and the invasion of cells in vitro and was shown to delay the growth of tumors in vivo. Silencing of EphB3 reduced the expression of pAKT, cyclinD1 and altered the epithelial-mesenchymal transition (EMT) process. Furthermore, AKT signal pathway agonist SC79 reversed EphB3 downregulation-mediated inhibition of cell proliferation, migration, invasion and EMT process. Conclusions: EphB3 knockdown inhibited the proliferation of esophageal squamous cell cancer partly through the AKT signaling pathway and repressed cell migration and invasion via EMT reversion. The findings of the study suggested that EphB3 might be a novel target for the therapy of esophageal carcinoma.

Low Expression of EphB2, EphB3, and EphB4 in Bladder Cancer: Novel Potential Indicators of Muscular Invasion.

PURPOSE: Eph receptors are differentially expressed in numerous malignant tumors. This study intended to analyze the roles of EphB receptors (EphB2, B3, and B4) in urinary bladder cancer. MATERIALS AND METHODS: Tissue microarray-based immunohistochemical analysis was used to investigate the expression patterns of EphB2, EphB3, and EphB4 in 154 bladder cancer specimens. Immunohistochemical staining was conducted examining the extent of stained cells and staining intensity. EphB was considered to be highly expressed when the intensity of staining was more than moderate in >25% of cells in the tissue section. Small interfering RNA (siRNA) was used to knock down EphB expression in bladder cancer cell lines (T24, 5637) to determine the effects of EphB on tumor cell invasion, proliferation, and migration. RESULTS: EphB receptors (B2, B3, and B4) were detected in 40.9% (EphB2, 63/154), 71.4% (EphB3, 110/154), and 53.2% (EphB4, 82/154) of bladder cancer specimens. Low expression of EphB2, B3, and B4 receptors were significantly associated with higher tumor grade (EphB2, p<0.001; EphB3, p=0.032; EphB4, p<0.001) and muscular invasion (EphB2, p=0.002; EphB3, p=0.009; EphB4, p<0.001). No obvious correlation was observed with other clinicopathological variables, such as age, sex, recurrence, lymph node involvement, metastasis, and overall survival. Inactivation of EphB receptors by siRNA transfection increased cell viability, tumor cell invasion, proliferation, and migration in comparison with untransfected cancer cells. CONCLUSION: Low expression of EphB receptors (B2, B3, and B4) can be a predictive marker for muscular invasion of bladder cancer.

Hit Identification of a Novel Quinazoline Sulfonamide as a Promising EphB3 Inhibitor: Design, Virtual Combinatorial Library, Synthesis, Biological Evaluation, and Docking Simulation Studies.

EphB3 is a major key player in a variety of cellular activities, including cell migration, proliferation, and apoptosis. However, the exact role of EphB3 in cancer remains ambiguous. Accordingly, new EphB3 inhibitors can increase the understanding of the exact roles of the receptor and may act as promising therapeutic candidates. Herein, a hybrid approach of structure-based design and virtual combinatorial library generated 34 quinazoline sulfonamides as potential selective EphB3 inhibitors. A molecular docking study over EphB3 predicted the binding affinities of the generated library, and the top seven hit compounds (3a and 4a-f), with GlideScore ≥ -6.20 Kcal/mol, were chosen for further MM-GBSA calculations. Out of the seven top hits, compound 4c showed the highest MM-GBSA binding free energy (-74.13 Kcal/mol). To validate these predicted results, compounds 3a and 4a-f were synthesized and characterized using NMR, HRMS, and HPLC. The biological evaluation revealed compound 4c as a potent EphB3 inhibitory lead (IC50 = 1.04 µM). The screening of 4c over a mini-panel of kinases consisting of EGFR, Aurora A, Aurora B, CDK2/cyclin A, EphB1, EphB2, EphB4, ERBB2/HER2, and KDR/VEGFR2, showed a promising selective profile against EphB3 isoform. A dose-dependent assay of compound 4c and a molecular docking study over the different forms of EphB provided insights into the elicited biological activities and highlighted reasonable explanations of the selectivity.

Prognostic and Clinicopathological Significance of EphB3 and Dysadherin Expression in Extrahepatic Cholangiocarcinoma.

AIM: EphB3 and dysadherin are involved in tumorigenesis and progression of many neoplasms. However, the roles of EphB3 and dysadherin in extrahepatic cholangiocarcinoma (ECC) remain to be revealed. In this study, we aimed to evaluate the expression of EphB3 and dysadherin, and investigate their clinicopathological significance in ECC. METHODS: We examined EphB3 and dysadherin expression in 100 ECC, 30 peritumoral tissues, 10 adenoma and 15 normal biliary tract tissues using EnVision immunohistochemistry. The relationship between EphB3 or dysadherin expression and clinicopathological features was evaluated using the χ 2 test or Fisher's exact test. The overall survival of ECC patients was analyzed using Kaplan-Meier univariate survival analysis and Log rank tests. RESULTS: We found that EphB3 expression was significantly down-regulated and dysadherin expression was significantly up-regulated in ECC tissues compared with normal tissues (P < 0.01). EphB3 expression was negatively correlated with dysadherin expression in ECC (P < 0.01). The positive rate of EphB3 expression and negative rate of dysadherin expression was significantly higher in patients with well-differentiated type, no lymph node metastasis, no surrounding tissues and organs invasion, early TNM stages (I + II) and radical resection (P < 0.01). The survival of ECC patients with positive EphB3 or negative dysadherin expression was significantly longer than patients with negative EphB3 or positive dysadherin expression (P < 0.01). Cox multivariate analysis demonstrated that negative EphB3 or positive dysadherin expression were independent poor prognostic factors in ECC patients. The ROC curves suggested that EphB3 and dysadherin combined diagnostic efficacy (AUC=0.688, 95%CI: 0.603-0.772) was significantly higher EphB3 diagnostic efficacy (AUC=0.654, 95%CI: 0.564-0.743) or dysadherin diagnostic efficacy (AUC=0.648, 95%CI: 0.558-0.737) alone. CONCLUSION: EphB3 and dysadherin are involved in the carcinogenesis and progression of ECC, and ECC patients with negative EphB3 or positive dysadherin expression have a poor prognosis.

Expression Profile and Prognostic Significance of EPHB3 in Colorectal Cancer.

The protein tyrosine kinase Ephrin type-B receptor 3 (EPHB3) is expressed in cells at the base of intestinal crypts, acting as a cellular guide in the maintenance of intestinal crypt architecture. We aimed to investigate the expression profile of EPHB3 in colorectal precancerous lesions and colorectal cancers (CRCs), and assess its prognostic value. EPHB3 expression was higher in CRCs than in normal mucosa and was associated with the intestinal stem cell markers EPHB2, OLFM4, LRIG1, and a proposed cancer stem cell marker, CD44. Enhanced EPHB3 expression significantly declined during the transformation from adenoma to carcinoma and as the tumor invaded into deeper tissue layers. Namely, a substantial reduction of EPHB3 expression was observed in the budding cancer cells at the invasive tumor fronts, which was more extensive than E-cadherin downregulation. In an azoxymethane/dextran sulfate sodium-induced, colitis-associated, CRC model, EPHB3 expression increased along with tumor development. In a large cohort of CRC patients, EPHB3 positivity was observed in 24% of 610 CRCs and was negatively correlated with tumor differentiation, lympho-vascular invasion, and tumor, node, and metastasis stages. EPHB3 was positively associated with microsatellite instability but was associated with neither CpG island methylation, nor with KRAS and BRAF mutations. Notably, EPHB3 positivity was associated with better clinical outcomes, although it was not an independent prognostic marker. Overexpression of EPHB3 in the colon cancer cell line, DLD1, led to decreased cell growth and migration and reduced mitogen-activated protein kinase signaling. Taken together, our data demonstrate the suppressive role of EPHB3 in CRC progression.

Receptor Tyrosine Kinase EphB3: a Prognostic Indicator in Colorectal Carcinoma.

Although EphB3 expression is down-regulated in colorectal cancer (CRC) cells compared with normal intestinal epithelial cells, the relationship between EphB3 expression and clinicopathological parameters in CRC is unclear. We examined EphB3 expression in 128 CRC tissue specimens and in 19 adenoma specimens using immunohistochemistry. The relationships between EphB3 expression and clinicopathological parameters, KRAS mutations, BRAF V600E mutation, MSI and survival were evaluated using Spearman's rank correlation and Kaplan-Meier survival analyses, respectively. CpG methylation in the EphB3 promoter was examined in four human CRC cell lines and tissues. EphB3 was strongly expressed in all normal intestinal epithelial cells (128/128) and adenoma cells (19/19). In CRC tumor cells, EphB3 expression was negative or weak in 41.4% (53/128), moderate in 26.6% (34/128), and strong in 32.0% (41/128) of samples. EphB3 expression was negatively associated with invasive depth (P = 0.016, rs = -0.213), lymph node metastasis (P = 0.000, rs = -0.490), and TNM stage (P = 0.000, rs = -0.390), and was positively associated with poor differentiation (P = 0.001, rs = 0.290), BRAF V600E mutation (P = 0.008, rs = 0.235), and longer overall survival (P < 0.001). In multivariate analysis, EphB3 expression (P = 0.007) and lymph node metastasis (P < 0.001) were independent prognostic factors for poor survival. Hypermethylation of the EphB3 promoter was detected in cell lines and CRC tissues. EphB3 is down-regulated in CRC compared to normal mucosa. Hypermethylation of CpG island is contributed to downregulation of EphB3 in CRC. EphB3 expression in tumor cells may be a useful prognostic indicator for patients with CRC.

EphB3 interacts with initiator caspases and FHL-2 to activate dependence receptor cell death in oligodendrocytes after brain injury.

Clinical trials examining neuroprotective strategies after brain injury, including those targeting cell death mechanisms, have been underwhelming. This may be in part due to an incomplete understanding of the signalling mechanisms that induce cell death after traumatic brain injury. The recent identification of a new family of death receptors that initiate pro-cell death signals in the absence of their ligand, called dependence receptors, provides new insight into the factors that contribute to brain injury. Here, we show that blocking the dependence receptor signalling of EphB3 improves oligodendrocyte cell survival in a murine controlled cortical impact injury model, which leads to improved myelin sparing, axonal conductance and behavioural recovery. EphB3 also functions as a cysteine-aspartic protease substrate, where the recruitment of injury-dependent adaptor protein Dral/FHL-2 together with capsase-8 or -9 leads to EphB3 cleavage to initiate cell death signals in murine and human traumatic brain-injured patients, supporting a conserved mechanism of cell death. These pro-apoptotic responses can be blocked via exogenous ephrinB3 ligand administration leading to improved oligodendrocyte survival. In short, our findings identify a novel mechanism of oligodendrocyte cell death in the traumatically injured brain that may reflect an important neuroprotective strategy in patients.

Long noncoding RNA HAS2-AS1 accelerates non-small cell lung cancer chemotherapy resistance by targeting LSD1/EphB3 pathway.

The essential roles of long noncoding RNA (lncRNA) have been identified by emerging literature in the non-small cell lung cancer (NSCLC). However, the role of lncRNA hyaluronan synthase 2 antisense 1 (HAS2-AS1) in the NSCLC tumorigenesis is not clear. Here, we investigate the role and mechanism of HAS2-AS1 in the NSCLC tumorigenesis. In the NSCLC tissue and cells, HAS2-AS1 was found to be up-regulated, which, in turn, indicated the poor prognosis of NSCLC patients. Functional experiments illustrated that HAS2-AS1 promoted the proliferation, invasion and gefitinib chemotherapy resistance of NSCLC cells. In vivo, HAS2-AS1 knockdown suppressed the tumor growth. Mechanically, HAS2-AS1 recruited the lysine-specific demethylase 1 (LSD1) to the EphB3 promoter region to inhibit its transcription. In conclusion, this finding elucidates the essential roles of HAS2-AS1 in the NSCLC tumorigenesis, providing a possible treatment strategy for the NSCLC.

Sonic hedgehog pathway activation is associated with cetuximab resistance and EPHB3 receptor induction in colorectal cancer.

A major problem of colorectal cancer (CRC) targeted therapies is relapse caused by drug resistance. In most cases of CRC, patients develop resistance to anticancer drugs. Cetuximab does not show many of the side effects of other anticancer drugs and improves the survival of patients with metastatic CRC. However, the molecular mechanism of cetuximab resistance is not fully understood. Methods: EPHB3-mediated cetuximab resistance was confirmed by in vitro western blotting, colony-forming assays, WST-1 colorimetric assay, and in vivo xenograft models (n = 7 per group). RNA-seq analysis and receptor tyrosine kinase assays were performed to identify the cetuximab resistance mechanism of EPHB3. All statistical tests were two-sided. Results: The expression of EFNB3, which upregulates the EPHB3 receptor, was shown to be increased via microarray analysis. When resistance to cetuximab was acquired, EPHB3 protein levels increased. Hedgehog signaling, cancer stemness, and epithelial-mesenchymal transition signaling proteins were also increased in the cetuximab-resistant human colon cancer cell line SW48R. Despite cells acquiring resistance to cetuximab, STAT3 was still responsive to EGF and cetuximab treatment. Moreover, inhibition of EPHB3 was associated with decreased STAT3 activity. Co-immunoprecipitation confirmed that EGFR and EPHB3 bind to each other and this binding increases upon resistance acquisition, suggesting that STAT3 is activated by the binding between EGFR and EPHB3. Protein levels of GLI-1, SOX2, and Vimentin, which are affected by STAT3, also increased. Similar results were obtained in samples from patients with CRC. Conclusion: EPHB3 expression is associated with anticancer drug resistance.

EZH2-mediated epigenetic suppression of EphB3 inhibits gastric cancer proliferation and metastasis by affecting E-cadherin and vimentin expression.

EphB3 is a member of the EPH family of receptors and has been found to play a role in the carcinogenesis of some human cancers. However, its expression and clinical significance in gastric cancer (GC) have not been well documented. In the present study, we detected the expression of EphB3 in GC and adjacent noncancerous tissues and explored its relationships with the clinicopathological features and prognosis of GC patients. It was found that EphB3 silenced GC cells epigenetically by direct transcriptional repression of GC cells via polycomb group protein EZH2 mediation. EphB3 was downregulated in GC cells and tissues, and EphB3 depletion promoted GC cell growth and invasion, while ectopic overexpression of EphB3 produced a significant anti-tumor effect. EphB3 was found to be involved in epithelial-mesenchymal transition by regulating E-cadherin and vimentin expression. In addition, patients with reduced EphB3 expression had shorter disease-free survival (DFS), indicating that EphB3 may prove to be a biomarker for prognosis of GC. These results demonstrated that EphB3 functioned as a tumor-suppressor and prognostic biomarker in GC.

Upregulation of EphB3 in gastric cancer with acquired resistance to a FGFR inhibitor.

Amplification of fibroblast growth factor receptor2 (FGFR2) has been regarded as a druggable target in gastric cancer (GC). Despite known potential of AZD4547, a selective inhibitor of FGFR 1-3, to suppress tumorigenic effects of activated FGFR2, resistance to the targeted agent has been an unresolved issue. This study was performed to elucidate the mechanism of AZD4547 resistance in GC cells. SNU-16 cells were used to establish an AZD4547-resistant GC cell line, SNU-16R. Elevated phosphorylation of EphB3 was confirmed using the Human Phospho-Receptor Tyrosine Kinase Array kit. A tyrosine kinase inhibitor (TKI) of EphB3 was used to investigate the effects of suppressed EphB3 activity in the SNU-16R cell line. SNU-16R cells exhibited upregulated phosphorylation of EphB3. Treatment of SNU-16R cells with the EphB3 TKI resulted in induction of apoptosis, decreased cellular viability, and cell cycle arrest at sub-G1 phase. SNU-16R cells expressed upregulated levels of N-cadherin, vimentin, Snail, matrix metalloproteinase 2 (MMP-2), and MMP-9, and reduced levels of E-cadherin, characteristic of epithelial to mesenchymal transition (EMT). Matrigel invasion assay also demonstrated the increased invasiveness of SNU-16R cells. EphB3 TKI treatment inhibited EMT of SNU-16R cells. Activation of mammalian target of rapamycin (mTOR) through the Ras-ERK1/2 pathway was suggested as the signal transduction mechanism downstream EphB3 by showing enhanced phosphorylation of Raf-1, MEK1/2, ERK1/2, mTOR and its downstream substrates in SNU-16R cells. As expected, EphB3 TKI decreased phosphorylation of these proteins. Our data suggest phosphorylation of mTOR through signaling by EphB3 is a potential mechanism of AZD4547 resistance in GC cells.