Aquaporin 4 and vascular endothelial growth factor participate in the formation of peritumoral edema of gliomas and brain metastases

Objective To investigate the expression of vascular endothelial growth factor (VEGF) and aquaporin 4 (AQP4) in giiomas and brain metastases, and explore the role of VEGF and AQP4 in the histopathology and formation of peritumoral edema of primary and metastatic gliomas. Methods Immunohistocbemical method was used to examine the protein expression of VEGF and AQP4 in 73 paraffin-embeded, pathologically confirmed glioma and 15 metastatic tumor specimens collected between 1999 and 2001. Eight normal brain tissue specimens were used as the control. Results VEGF protein was not detected in normal brain tissues. VEGF expression was detected in gliomas and the expression level increased obviously along with the histological grade of the tumor. Significant differences were found in VEGF expression between malignant and low-grade gliomas, between low-grade gliomas and normal brain tissues, and between intracranial metastatic tumors and normal brain tissues and low-grade gliomas (P 0.05). AQP4 protein expression was found in all the collected samples, and its expression differed significantly between normal brain tissues and malignant gliomas or intracranial metastatic tumors, and also between low-grade gliomas and malignant gliomas or intracranial metastatic tumors (P 0.05). VEGF protein expression showed a significant positive correlation to AQP4 protein expression (r=0.516, P<0.05). Conclusion As important molecular biological factors, VEGF and AQP4 participate in the formation peritumoral brain edema of gliomas and exhibit a synergie effect in this process. Key words: Gliomas; Brain metastatic tumors; Vascularendothelial growth factor; Aquaporin 4