Expression of AQP1 and AQP4 in paediatric brain tumours

Aquaporins (AQP) are water-channel proteins with roles in tumour cell migration, angiogenesis, cerebral oedema and cell-cell adhesion. We aimed to determine the expression of AQP1 and AQP4 in paediatric brain tumours. Twenty tumour bank specimens were subject to Western blot analysis and quantitative polymerase chain reaction (PCR) to determine the expression of AQP1 and 4. Immunohistochemical staining was used to determine the distribution of AQP1 and 4 expression. Medulloblastomas, primitive neuroectodermal tumour, germinomas and higher grade gliomas did not express AQP1 and 4. Of the ependymomas, those in the posterior fossa all demonstrated markedly increased expression of AQP1 and 4. A supratentorial ependymoma demonstrated a moderate increase in AQP1 but not AQP4. Pilocytic astrocytomas demonstrated high levels of AQP1 and 4 but had a more variable pattern of staining. AQP1 and 4 have relevance to paediatric brain tumours and are worthy of further investigation in developing potential therapeutic strategies.