A significant correlation was observed between EphA2 expression and regional lymph node metastasis (p=0.023), number of lymph node metastases (p=0.011) and poor degree of tumor differentiation (p=0.004).
Infection with HAd-EphrinA1-Fc (HAd vector expressing extracellular domain of human EphrinA1 attached to Fc portion of human IgG1 heavy chain) caused increased EphA2 activation and turnover and consequently decreased tumor cell viability in soft agar assays.
Three weeks of treatment with EphA2-targeting siRNA-DOPC (150 microg/kg twice weekly) reduced tumor growth when compared with a nonsilencing siRNA (SKOV3ip1: 0.35 versus 0.70 g; P = 0.020; HeyA8: 0.98 versus 1.51 g; P = 0.16).
Inducing EphA2 downregulation by any one of several mechanisms (antibody-mediated inhibition of signalling, antibody-mediated downregulation of total EphA2 expression and siRNA-mediated inhibition of expression) has been shown to decrease tumour growth, prolong survival and inhibit angiogenesis in multiple preclinical models of ovarian, breast and pancreatic cancer.
No significant association was observed between EphA2 and EphrinA-1 protein expressions and age, tumour location, tumour size, histological differentiation or clinical stage.
Cox multivariate analyses revealed that residual tumor after surgery, histological type, and EphA2 protein expression were of independent prognostic significance.
When evaluated specifically for labeling intensity, primary and metastatic carcinomas were more strongly positive compared to benign ducts and PanIN lesions (P < 0.00001 and P < 0.01, respectively) and poorly differentiated carcinomas were more strongly positive for EphA2 than well and moderately differentiated tumors (P < 0.005).
Validation experiments showed that EphA2 mRNA overexpression correlated inversely with patient survival in a panel of 21 glioblastomas, and ligand-mediated EphA2 receptor activation increased glioblastoma proliferation and tumor growth via a mitogen-activated protein kinase-dependent pathway.
In mice with orthotopic ovarian tumors, treatment with combined paclitaxel and IP EphA2-targeting siRNA-DOPC reduced tumor growth by 48-81% compared to paclitaxel/control siRNA-DOPC IP (HeyA8: 0.34 g v 0.66 g; SKOV3ip1: 0.04 v 0.21, p<0.01).
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).
In this study, we investigated the expression of EphA2 mRNA and protein in 90 cases of human astrocytic tumors by reverse transcription polymerase chain reaction and immunohistochemistry, respectively.
These data suggest that EphA2 cooperates with ErbB2 to promote tumor progression in mice and may provide a novel therapeutic target for ErbB2-dependent tumors in humans.
We analyzed a panel of human melanoma tumor cell lines derived from patient tissues classified as primary (either radial growth phase or vertical growth phase) and/or metastatic for the expression of EphA2 and found a correlation between increased EphA2 expression and metastatic potential.
EphA2 plus FAK siRNA-DOPC treatment resulted in a significant reduction (SKOV3ip1: 76%, p < 0.007, HeyA8: 90%, p < 0.003) in tumor growth compared to control siRNA-DOPC.
To determine if EphA2 can promote NSCLC progression, we examined the relationship of EphA2 with proliferation and migration in cell lines and with metastases in patient tumors.
Dosing of EphA2 antibody in the SCID murine tumor model resulted in a 6.2-fold reduction in tumor volume, whereas the SCID/nonobese diabetic model showed a 1.6-fold reduction over the isotype controls.
Of 85 EEC samples, EphA2 was overexpressed in 47% of tumors and was significantly associated with high VEGF expression (p=0.001) and high MVD counts (p=0.02).