Clinical and biological impact of EphA2 overexpression and angiogenesis in endometrial cancer

Objective

EphA2 overexpression predicts poor prognosis in endometrial cancer. To explore mechanisms for this association and assess its potential as therapeutic target, the relationship of EphA2 expression to markers of angiogenesis was examined using patient samples and an orthotopic mouse model of uterine cancer.

Results

Of 85 EE C 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). High EphA2 expression, high VEGF expression and high MVD counts were significantly associated with shorter disease-specific survival. EA5 led to decrease in EphA2 expression and phosphorylation in vitro. In the murine model, while EA5 (33–88%) and docetaxel (23–55%) individually led to tumor inhibition over controls, combination therapy had the greatest efficacy (78–92%, p < 0.001). In treated tumors, combination therapy resulted in significant reduction in MVD counts, percent proliferation and apoptosis over controls.

Experimental Design

Expression of EphA2, estrogen receptor (ER), progesterone receptor (PR), Ki-67, vascular endothelial growth factor (VEGF) and microvessel density (MVD) was evaluated using immunohistochemistry in 85 endometrioid endometrial adenocarcinomas (EEC) by two independent investigators. Results were correlated with clinicopathological characteristics. The effect of EphA2-agonist monoclonal antibody EA5, alone or in combination with docetaxel was studied in vitro and in vivo. Samples were analyzed for markers of angiogenesis, proliferation and apoptosis.

Conclusions

EphA2 overexpression is associated with markers of angiogenesis and is predictive of poor clinical outcome. EphA2 targeted therapy reduces angiogenesis and tumor growth in orthotopic uterine cancer models and should be considered for future clinical trials.Key words: endometrial cancer, EphA2, VEGF, microvessel density, angiogenesis