Aquaporin 3 is expressed in the basaloid cells of canine sebaceous glands.

The role of aquaporin proteins (AQPs) in tumor biology has attracted attention over the past 20 years. However, the expression profiles of AQPs in canine sebaceous gland tumors remain obscure. This study was performed to clarify the expression of AQP1, 3, 5, the most studied AQPs in tumor biology, in sebaceous adenoma and sebaceous epithelioma. Among these AQPs, only AQP3 was expressed in normal tissue and both tumor types and located to only undifferentiated sebocytes (basaloid cells). A cellular proliferation marker, Ki-67, was detected only in the area including basaloid cells in both tumor types. These findings suggest that AQP3 is useful for clarifying the origin of sebaceous gland tumors, and that AQP3 may be related to sebaceous gland development.