Levels Of EphA2 Research Articles

Expression of EphA2 and VEGF in squamous cell carcinoma of the tongue: Correlation with the angiogenesis and clinical outcome

Eph-ephrin binding has been linked to tumor biology and VEGF has been reported to participate in the tumor angiogenesis regulated by Eph-ephrin. The present study was designed to evaluate the expression of EphA2 and VEGF in relation to angiogenesis and clinical outcome in squamous cell carcinoma of oral tongue. Immunohistochemical staining was used to determine the protein expression levels of EphA2 and VEGF in 59 surgically resected tongue carcinomas and 10 tumor-free mucosas. In all cases, microvessel density (MVD) was evaluated by counting CD34-reactive endothelial cells or endothelial cell clusters. Both EphA2 and VEGF staining activities in squamous cell carcinoma of oral tongue were more significant than those in normal mucosa (P<0.01). MVD had significant correlations with EphA2 and VEGF expression (P<0.01). The EphA2, VEGF, and MVD were significantly correlated with tumor size, clinical stage, lymph invasion, recurrence, and distant metastasis (P<0.05). Multivariate analysis showed EphA2, VEGF expression, MVD, and clinical stage had an independent prognostic effect on overall survival. We conclude that the overexpression of EphA2 and VEGF are related to malignancy in squamous cell carcinoma of oral tongue. Clinical outcomes raised the possibility that the overexpression of those proteins might contribute to tumor angiogenesis and have prognostic value in tongue cancer.

Expressions of EphA2 and EphrinA-1 in early squamous cell cervical carcinomas and their relation to prognosis

By using immunohistochemistry we investigated the expression of EphA2 and EphrinA-1 in 217 early squamous cell cervical carcinomas and examine their prognostic relevance. For EphA2 expression, 21 tumors (10%) showed negative, 108 (50%) weak positive, 69 (32%) moderate positive and 19 (9%) strong positive, whereas for EphrinA-1 expression, 33 tumors (15%) showed negative, 91 (42%) weak positive, 67 (31%) moderate positive and 26 (12%) strong positive. In univariate analysis high expression (strong staining) of EphrinA-1 was associated with poor disease-free (P = 0.033) and disease-specific (P = 0.039) survival. However, in the multivariate analyses neither EphrinA-1 nor EphA2 was significantly associated to survival. The increased levels of EphA2 and EphrinA-1 in a relative high number of early stage squamous cell carcinomas suggested that these two proteins may play an important role in the development of a subset of early cervical cancers. However, EphA2 and EphrinA-1 were not independently associated with clinical outcome.

Analysis of EphA2 expression and mutant p53 in ovarian carcinoma

The EphA2 tyrosine kinase receptor is frequently overexpressed in ovarian cancer and this feature is predictive of poor clinical outcome. Pre-clinical investigation has also linked EphA2 with p53. In our present study, we examined EphA2 and p53 status (both expression and full-length mutation status) in 6 ovarian cell lines and 79 human ovarian cancers to determine potential associations. EphA2 was overexpressed in 80% of ovarian cancer cell lines and in 75% of clinical specimens. In particular, high levels of EphA2 occurred in 91% of tumors with p53 null mutations compared to 68% in tumors with wild-type or missense mutations (p=0.027). EphA2 expression did not relate to critical versus non-critical site missense p53 mutations or the location of mutations on specific p53 exons. We also demonstrated that while EphA2 and p53 can provide independent information regarding clinical status, the combination of EphA2 and p53 status can predict poor clinical outcome. In particular, the combination of EphA2 overexpression and p53 null status was associated with decreased overall patient survival and related to increased incidence of ascites and distant metastasis. Taken together, these data indicate a complex relationship between EphA2 and p53 that appears to regulate EphA2 expression and clinical outcome.

Anti-EphA2 Antibodies Decrease EphA2 Protein Levels in Murine CT26 Colorectal and Human MDA-231 Breast Tumors But Do Not Inhibit Tumor Growth

The EphA2 receptor tyrosine kinase has been shown to be over-expressed in cancer and a monoclonal antibody (mAb) that activates and down-modulates EphA2 was reported to inhibit the growth of human breast and lung tumor xenografts in nude mice. Reduction of EphA2 levels by treatment with anti-EphA2 siRNA also inhibited tumor growth, suggesting that the anti-tumor effects of these agents are mediated by decreasing the levels of EphA2. As these studies employed human tumor xenograft models in nude mice with reagents whose crossreactivity with murine EphA2 is unknown, we generated a mAb (Ab20) that preferentially binds, activates, and induces the degradation of murine EphA2. Treatment of established murine CT26 colorectal tumors with Ab20 reduced EphA2 protein levels to ~12% of control tumor levels, yet had no effect on tumor growth. CT26 tumor cell colonization of the lung was also not affected by Ab20 administration despite having barely detectable levels of EphA2. We also generated and tested a potent agonistic mAb against human EphA2 (1G9-H7). No inhibition of human MDA-231 breast tumor xenograft growth was observed despite evidence for >85% reduction of EphA2 protein levels in the tumors. These results suggest that molecular characteristics of the tumors in addition to EphA2 over-expression may be important for predicting responsiveness to EphA2-directed therapies.

The clinical significance of EphA2 and Ephrin A-1 in epithelial ovarian carcinomas

Objectives. To examine the expressions of the protein and mRNA of EPHA2 and EphrinA-1 in epithelial ovarian carcinomas/ovarian cancer cell lines and explore their prognostic value. Methods. To validate the immunohistochemical method, two ovarian cancer cell lines (OVCAR3 and SKOV3) were examined with RT-PCR, Western blot, and immunohistochemistry for EphA2 and EphrinA-1 expressions. Tumors from 118 patients with advanced epithelial ovarian cancer were then evaluated for EPHA2 and Ephrin A-1 protein expression, and frozen tissues from 30 cases were used for laser capture microdissection (LCM) assistant RT-PCR RNA analysis. Results. 11 (9.3%), 67 (56.8%), 26 (22.0%), and 14 (11.9%) tumors demonstrated negative, weak, moderate, and strong EphA2 protein expressions, respectively, while 3 (2.5%), 67 (56.8%), 32 (27.1%), and 16 (13.8%) tumors were negative, weak, moderate, and strong for Ephrin A-1 protein expression, respectively. Variable amount of mRNA expression was observed in the 30 tumors analyzed by the method of LCM assistant RT-PCR. There was a trend for association between higher levels of either EphA2 or Ephrin A-1 expression and higher histological grade ( P = 0.05 for both factors). No significant correlation between the expressions of EphA2 or Ephrin A-1 and age, histological type, and FIGO stage was observed. Patients with higher levels of EphA2 protein expressions had significantly shorter survival. Cox multivariate analyses revealed that residual tumor after surgery, histological type, and EphA2 protein expression were of independent prognostic significance. Conclusions. High level of EphA2 protein expression is significantly associated with a shorter patient survival and EphA2 receptor is a valuable prognostic marker for ovarian carcinoma.

Expression of EphA2 is Prognostic of Disease-Free Interval and Overall Survival in Surgically Treated Patients with Renal Cell Carcinoma

Whereas normally expressed at sites of cell-to-cell contact in adult epithelial tissues, recent studies have shown that the receptor tyrosine kinase EphA2 is overexpressed in numerous epithelial-type carcinomas, with the greatest level of EphA2 expression observed in metastatic lesions. In the current study, we have assessed EphA2 expression in archived renal cell carcinoma (RCC) tissues as it relates to patient disease course. Using specific anti-EphA2 monoclonal antibody 208 and immunohistochemistry, we evaluated EphA2 protein expression levels in RCC specimens surgically resected from 34 patients (including 30 conventional clear-cell RCC, 3 papillary, and 1 chromophobic RCC cases) resulting in clinical cures. Regardless of histopathologic subtype, RCC lesions expressing higher levels of EphA2 tended to be of a higher grade (P < 0.05) and larger (P = 0.093), more-highly-vascularized tumors (P = 0.005). Perhaps most notable, the degree of EphA2 overexpression (versus normal matched autologous kidney tissue) seemed predictive of short-term (<1 year) versus longer-term (> or =1 year) disease-free interval (P < 0.001) and of overall survival (P < 0.001) among the RCC patients evaluated. These data suggest that EphA2 expression level may serve as a useful prognostic tool in the clinical management of patients who have been successfully treated with surgery, but who are at greater risk for accelerated disease recurrence and who have a poorer prognosis.

EphA2 ligation by Ephrin-A1::Fc attenuates pancreatic adenocarcinoma cellular invasiveness

Abstract Introduction: The Eph tyrosine kinases interact with ligands of the Ephrin family and have diverse cellular functions. EphA2 has been recognized to be an oncoprotein of importance in a range of cancers. We examined the effects of EphA2 overexpression and ligation on the invasive phenotype of pancreatic adenocarcinoma cells. Methods: Capan2 pancreatic adenocarcinoma cells were stably transfected with an EphA2 expression construct. Empty vector transfectants served as controls. Cellular invasiveness was quantified by Matrigel Boyden chamber assay. The role of focal adhesion kinase (FAK) in EphA2 signaling was determined using RNA interference to suppress FAK expression. A chimeric protein comprising Ephrin-A1 fused to the immunoglobulin Fc region (Ephrin-A1::Fc) was used to ligate EphA2 in vitro. Levels of EphA2, FAK and matrix metalloproteinase-2 (MMP-2) expression were quantified using Western blotting. MMP-2 activity was quantified by Biotrack assay. In vivo tumor growth was assessed using a nude mouse xenograft model. Results: Stable overexpression of EphA2 induced a 2.5-fold increase in cellular invasiveness (P Conclusions: EphA2 represents a rational therapeutic target and ligation by Ephrin-A1::Fc is a strategy to modulate levels of this oncoprotein.

Prognostic value of EphA2 and EphrinA-1 in squamous cell cervical carcinoma

Objectives. To analyze the expressions of the protein and mRNA of EphA2 and EphrinA-1 in squamous cell cervical carcinomas and explore their prognostic value in cervical carcinoma. Methods. Immunohistochemistry was used to assess the protein expressions of EphA2 and EphrinA-1 in 206 patients with squamous cervical carcinoma FIGO stage Ia-IVb. Frozen tissues from 20 cases in which the tumors showed variable EphA2 and EphrinA-1protein expressions were used for laser capture microdissection (LCM). About 50 cancer cells in each frozen section were captured with the LCM method and processed for RT-PCR detection of EphA2 and EphrinA-1 mRNA. Results. Among the 206 squamous cervical carcinomas, 23 (11.2%) showed negative, 94(45.6%) weakly positive, 72 (35.0%) moderately positive, and 17 (8.3%) strongly positive for EphA2 immunostaining. For EphrinA-1 protein expression, 17 tumors (8.3%) showed negative, 95 (46.1%) weakly positive, 71(34.5%) moderately positive, and 23 (11.2%) strongly positive. EphA2 and EphrinA-1 often colocalized in the same tumor areas and vascular endothelial cells. Variable amount of mRNA expressions of EphA2 and EphrinA-1 were observed in the 20 tumors analyzed. There was no significant correlation between the overexpressions of EphA2/EphrinA-1 and age and FIGO stage. High level of EphA2 was significantly associated with overall survival in univariate and multivariate analysis. Moderate to high EphrinA-1 protein expression was significantly associated with overall survival in multivariate analysis. The combined high level of expression of EhpA2 and moderate to high level of expression of EphrinA-1 was a strong predictor of overall survival. Conclusions. High levels of EphA2 together with moderate to high level of EphrinA-1 protein expressions in squamous cervical carcinoma were predictive for a shorter overall survival and these proteins may be valuable prognostic markers.

Expression of EphA2 and E-cadherin in colorectal cancer: Correlation with cancer metastasis

Recently, overexpression of EphA2, a member of the Eph family of receptor tyrosine kinases, has been reported in several cancers. Reduced expression of E-cadherin, an intercellular adhesion molecule of epithelial cells, has been reported to be associated with aggressive clinicopathological phenotypes in various cancers. In epithelial cells, EphA2 and E-cadherin co-localize to sites of cell-cell contact, and it has been shown that E-cadherin regulates EphA2. This study aimed to clarify the relationship between the expression of the EphA2 and E-cadherin proteins and clinicopathological characteristics, with reference to the expression levels of both EphA2 and E-cadherin, in patients with colorectal cancer. We performed immunohistochemical staining of EphA2 and E-cadherin with EphA2 and E-cadherin monoclonal antibodies in samples from 194 primary lesions of colorectal cancer. The expression level of EphA2 had a statistically significant relationship with liver metastasis, lymphatic vessel invasion and clinical stage (p=0.0477, 0.0316 and 0.0467, respectively). In addition, the positivity rate of EphA2 was significantly higher in primary lesions with lymph node metastasis than in those without metastasis (p=0.0014). However, the expression level of E-cadherin had an inverse relationship with both differentiation level of the tumor and lymphatic vessel invasion (p=0.0430 and 0.0320, respectively). Furthermore, a significant relationship between the expression of EphA2 and E-cadherin was observed. In conclusion, our study revealed that the overexpression of EphA2 protein in colorectal carcinoma tissue correlates closely with cancer progression and hematogenous and lymphogenous metastasis, suggesting that both EphA2 and E-cadherin may play an important role in tumor metastasis in colorectal cancer.

High-Level Expression of EphA2 Receptor Tyrosine Kinase in Prostatic Intraepithelial Neoplasia

EphA2 is a transmembrane receptor tyrosine kinase that is overexpressed in many carcinomas. Specific targeting of EphA2 with monoclonal antibodies is sufficient to inhibit the growth, migration and invasiveness of aggressive cancers in animal models. Using immunohistochemical analyses, we measured the expression of EphA2 in prostatic adenocarcinoma, high-grade prostatic intraepithelial neoplasia, and adjacent benign prostate tissue from ninety-three radical prostatectomy specimens. These results were related to multiple clinical and pathologicalcharacteristics. The fraction of cells staining positively with EphA2 in benign prostatic epithelium (mean, 12%) was significantly lower than that in high-grade prostatic intraepithelial neoplasia (mean, 67%, P < 0.001) and prostatic adenocarcinoma (mean, 85%, P < 0.001). Moreover, the intensity of EphA2 immunoreactivity in prostatic adenocarcinoma was significantly higher than in benign prostatic tissue (P < 0.001) or high-grade prostatic intraepithelial neoplasia (P < 0.001). Benign prostatic epithelium showed weak or no immunoreactivity for EphA2 in all cases examined. Whereas EphA2 immunoreactivity related to neoplastic transformation, it did not correlate with other clinical and pathological parameters examined. Our data suggest that EphA2 levels increase as prostatic epithelial cells progress toward a more aggressive phenotype. Progressively higher levels of EphA2 in high-grade prostatic intraepithelial neoplasia and prostatic carcinoma are consistent with recent evidence that EphA2 functions as a powerful oncogene. Moreover, the presence of high levels of EphA2 in these cells suggests opportunities for prostate cancer prevention and treatment.