Aquaporin-4 expression is increased in edematous meningiomas.

Peritumoral edema is frequently present in meningiomas and can result in serious morbidity and mortality. The aquaporins (AQPs) are a family of membrane protein water channels with an integral role in water transport and maintenance of fluid balance. AQP4, increased in edematous human brain tumors such as astrocytomas and metastases, is present in the astrocytic foot processes adjacent to endothelial cells and may therefore have a role in cerebral edema formation. The objective of this study is to investigate the expression of AQP4 in meningiomas and to correlate their expression with peritumoral edema. Fresh human meningioma specimens (17) were obtained and immunohistochemical staining and Western blot analysis was performed for AQP4. The peritumoral edema index (EI) was calculated based on MRI post-processed to calculate the tumor and edema volume. Overexpression of AQP4 was associated with significant peritumoral edema. Immunohistochemistry showed upregulation of AQP4 throughout the specimens. Therefore, we conclude that increased expression of AQP4 is associated with peritumoral edema in meningiomas. This suggests that AQP4 overexpression can lead to abnormal water transport and edema formation in meningiomas. The inhibition of AQP4 water channels is a potential therapeutic option to reduce the adverse effects of peritumoral edema in meningiomas.