Multiple Intracranial Metastatic Tumor Case Report and Aquaporin Water Channel-Related Research

This case report deals with multiple intracranial metastatic tumors and studies of expression and regulation characteristics of aquaporins (AQPs) of cerebellar metastatic tumor and brain tissue surrounding tumor. In this work, we try to understand the role of abnormal expression of AQPs in formation and elimination of brain edema and provide new ideas for the treatment of brain edema induced by tumor. The work involves resection of intracranial occupying lesions to get cerebellar metastatic tumor organization. Total RNA was extracted, RT-PCR was done, and immunohistochemical staining was done to study the expression and regulation characteristics of AQPs. We found that AQP4 had a high expression in the peritumoral brain tissue and no expression in the center of brain metastasis tumor organization. Around the tumor tissue, the AQP4 staining was junior in the more distant region from tumor and it added significantly in close to the tumor tissue region. It demonstrated that the AQP4 expression was upregulated, obviously with the distance drawing near gradually to tumor tissue. In addition, stained AQP1 was not observed on cerebellar metastatic tumor and peritumoral brain microvascular endothelial cells. The phenomenon that AQP4 had an increased expression in the surrounding region of cerebellar metastatic tumor and, moreover, increased significantly in the region next to the cerebellar metastatic tumor tightly is probably related to the formation of peritumoral brain edema and plays an important role in cytotoxic brain edema mechanism. AQP1 was not expressed on cerebellar metastatic tumor and peritumoral brain tissue microvascular endothelial cells, and this may be an important factor that the peritumoral interstitial brain edema is removed ineffectively to cause ‘small tumor, big edema.’