Abstract: Objective To investigate the expression of aquaporin 3 （AQP3） in lesions of four cutaneous tumors. Methods Immunohistochemistry was utilized to measure the expression of AQP3 in tissue samples from 30 patients with seborrheic keratosis, 15 patients with Bowen′s disease, 32 patients with squamous cell carcinoma, 17 patients with malignant melanoma and 15 normal human controls. Results AQP3 was observed in all the tissue samples from both patients and controls. A significant increment was noticed in the expression of AQP3 in patients with Bowen′s disease, squamous cell carcinoma and malignant melanoma compared with the normal controls （all P < 0.01）, while no significant difference was found between patients with seborrheic keratosis and the controls （P > 0.05）. The highest expression of AQP3 was obtained in lesions from patients with squamous cell carcinoma and malignant melanoma, followed by those with Bowen′s disease （both P < 0.01）, and there was no significant difference between squamous cell carcinoma and malignant melanoma （P > 0.05）. The differentiation status of squamous cell carcinoma significantly correlated with the expression of AQP3 （P < 0.01）. AQP3 was significantly higher in malignant melanoma with metastasis than that in malignant melanoma without metastasis （P < 0.05）. Conclusion The expression of AQP3 is upregulated in malignant skin tumors.

Key words: squamous carcinoma, melanoma