Expression of the plasma membrane markers aquaporin 1 (AQP1), glucose transporter 1 (GLUT1) and Na, K-ATPase in canine mammary glands and mammary tumours

This study investigated the expression of the plasma membrane markers aquaporin 1 (AQP1), glucose transporter 1 (GLUT1) and the α1 subunit of Na, K-ATPase in normal canine mammary glands and in benign and malignant mammary tumours, using immunohistochemistry and semi-quantitative histomorphometry. AQP1 immunoreactivity was absent from the majority of specimens studied. GLUT1 immunoreactivity was observed in normal mammary tissue and particularly in the epithelial and mesenchymal cells of benign, and in the epithelial cells of malignant tumours, respectively. Na, K-ATPase immunoreactivity was present in normal and neoplastic mammary epithelium and was significantly increased in the epithelium of both benign and malignant tumours. These results suggest that GLUT1 is more highly expressed in neoplastic epithelium and mesenchyme and that Na, K-ATPase is more highly expressed in neoplastic mammary epithelium. In consequence, these membrane proteins may have potential as diagnostic and prognostic biomarkers of canine mammary neoplasia.