This study investigated the expression of the water channel protein aquaporin-9 (AQP9) in 100 cases of human astrocytic tumour compared with normal brain tissue. AQP9 mRNA and protein were assessed using reverse transcriptionpolymerase chain reaction and Western blot, respectively. The expression of both AQP9 mRNA and protein in astrocytic tumours was significantly greater than in normal brain tissue and was positively correlated with pathological grade. No significant correlations were found between the level of AQP9 mRNA or protein expression and gender, age, tumour size or tumour site. This study indicates that AQP9 may play an important role in the malignant progression of brain astrocytic tumours and may, therefore, be useful as a biomarker in its diagnosis and as a new target for gene therapy. The molecular mechanisms by which AQP9 affects the proliferation and apoptosis of astrocytic tumours need to be studied further.

No abstract