Expression of EphA2 in human astrocytic tumors: correlation with pathologic grade, proliferation and apoptosis

Abstract

A high expression of EphA2 has been detected in many non-central nervous system tumors; however, the EphA2 expression in brain astrocytic tumors remains unclear. 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. The proliferative index (PI) of tumor cells was evaluated by Ki-67 immunohistochemistry, and the apoptotic index (AI) was determined by TdT-mediated dUTP nick end labeling assay. The correlation between EphA2 expression, pathologic grade, proliferation and apoptosis of astrocytic tumors was further analyzed. The results showed that 47.8% of cases expressed EphA2 mRNA and 43.3% of cases expressed EphA2 protein. With increasing pathologic grade, the positive rate of EphA2 mRNA and protein, as well as the EphA2 immunoreactivity score (IRS), increased markedly. The PI in the EphA2-positive group was significantly higher than in the EphA2-negative group. In addition, the PI was positively correlated with EphA2 IRS. Although there was no significant difference between the AI in the EphA2-positive group and that in the EphA2-negative group, the AI was inversely correlated with EphA2 IRS. Therefore, EphA2 may be a new biomarker for astrocytic tumors. It may also affect the proliferation and apoptosis of tumor cells and be an attractive therapy target for astrocytic tumors.