Aquaporins in human breast cancer: Identification and involvement in carcinogenesis of breast cancer

BACKGROUND AND OBJECTIVES: Aquaporins (AQPs) play important roles in water and glycerol transport. Recently, the role of AQPs in human carcinogenesis has become an area of great interest. However, little is known about the function of AQPs in human breast cancer. The aim of this study was to investigate the expression profile of AQPs in human breast cancer and its significance. METHODS: In this study, we screened the expression profile of AQP0-12 in breast cancer tissues and corresponding normal tissues by RT-PCR, Western blotting and immunohistochemistry. RESULTS: AQP1, 3-5, and 10-12 were expressed in human breast cancer and/or normal breast tissues, and AQP1 and 3-5 exhibited differential expression. AQP1 was expressed in cell membranes and its expression was higher in cancer than that in normal tissues. AQP4 was expressed in the cell membrane and cytoplasm and was detected markedly stronger in normal than in cancer tissues. AQP5 was expressed mainly in cell membranes in carcinoma tissues, but was almost absent in normal breast tissues. Expression of AQP5 was associated with cellular differentiation, lymph node invasion, and clinicopathological staging. CONCLUSIONS: These observations suggested that several subtypes of the AQP family play a role in human breast carcinogenesis.