title: Expression pattern of the water channel aquaporin-4 in human gliomas is associated with blood-brain barrier disturbance but not with patient survival.
abstract: Aquaporin-4 (AQP4), the most prominent CNS water channel, is restricted to the glia limitans and astrocytic endfeet. We previously showed the loss of spatial AQP4 expression in glioblastomas and a redistribution across the cell surface. However, opposing AQP4 functions have been described: protective in vasogenic but detrimental in cytotoxic brain edema. Thus, specific AQP4 induction to prevent or reduce vasogenic edema is suggested. To elucidate the AQP4 role in brain tumors, we investigated 189 WHO grade I-IV gliomas by immunohistochemistry and the prognostic significance for patients' survival. In gliomas, a remarkable de novo AQP4 redistribution was observed in comparison with normal CNS tissue. Surprisingly, the highest membraneous staining levels were seen in pilocytic astrocytomas WHO grade I and grade IV glioblastomas, both significantly higher than in WHO grade II astrocytomas. AQP4 up-regulation was associated with brain edema formation; however, no association between survival and WHO grade-dependent AQP4 expression was seen. Hence, AQP4 redistribution may go along with other tumor properties, such as vascular proliferation and resulting blood-brain barrier disturbance, features usually prominent in pilocytic astrocytomas WHO I and glioblastomas WHO grade IV. In summary, our findings question the protective role of AQP4 in vasogenic brain edema. Although AQP4 was associated with brain edema formation, one has to question the suitability of AQP4 induction as a promising approach in vasogenic brain edema prevention and treatment. In addition, our results provide unexpectedly high AQP4 levels in pilocytic astrocytomas and present AQP4 as tumor progression marker in WHO grade II-IV astrocytomas.
authors.affiliation: Institute of Pathology, University of Tuebingen, Tuebingen, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Warth
authors.forename: Perikles
authors.initials: P
authors.lastname: Simon
authors.forename: David
authors.initials: D
authors.lastname: Capper
authors.forename: Benjamin
authors.initials: B
authors.lastname: Goeppert
authors.forename: Ghazaleh
authors.initials: G
authors.lastname: Tabatabai
authors.forename: Hajo
authors.initials: H
authors.lastname: Herzog
authors.forename: Klaus
authors.initials: K
authors.lastname: Dietz
authors.forename: Florian
authors.initials: F
authors.lastname: Stubenvoll
authors.forename: Rami
authors.initials: R
authors.lastname: Ajaaj
authors.forename: Ralf
authors.initials: R
authors.lastname: Becker
authors.forename: Michael
authors.initials: M
authors.lastname: Weller
authors.forename: Richard
authors.initials: R
authors.lastname: Meyermann
authors.forename: Hartwig
authors.initials: H
authors.lastname: Wolburg
authors.forename: Michel
authors.initials: M
authors.lastname: Mittelbronn
mesh_terms: D051401:Aquaporin 4 / Q000235:genetics / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000503:physiopathology*; D001921:Brain / Q000378:metabolism; D001929:Brain Edema / Q000378:metabolism; D001932:Brain Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D005910:Glioma / Q000378:metabolism* / Q000401:mortality / Q000473:pathology*; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D040081:Protein Array Analysis / Q000379:methods; D012720:Severity of Illness Index; D012737:Sex Factors
chemical_list: C496030:AQP4 protein, human; D051401:Aquaporin 4