Immunohistochemical distribution and morphometric analysis of aquaporin-3 in oral squamous cell carcinoma.

This study aimed to evaluate the relationship of aquaporin-3 (AQP3) expression with clinico-pathological parameters and lymph node metastasis in patients with oral squamous cell carcinoma (SCC). The immunohistochemical distribution of AQP3 was investigated in normal squamous epithelium and SCC tissue of 48 cases of SCC of the tongue and floor of the mouth. The percentage of the total AQP3-positive SCC tissue area relative to the total tumour tissue area (T-AQP3) was calculated as a morphometric AQP3 parameter for each patient. Furthermore, the percentage of the AQP3-positive area relative to the SCC tissue area at the invasion front (F-AQP3) was calculated as another AQP3 parameter. The immunostaining pattern of AQP3 in SCC tissue was irregular and weaker than that in normal epithelium. Well-differentiated SCCs had higher T-AQP3 and F-AQP3 values than poorly differentiated SCCs. SCCs with an infiltrative invasion pattern had lower F-AQP3 than SCCs with expansive and intermediate patterns. SCCs with T-AQP3 <27% or F-AQP3 <17% showed an increased incidence of lymphatic metastasis, and multivariate analysis demonstrated that F-AQP3 was an independent prognostic factor of lymphatic metastasis. These results suggest that AQP3 is involved in keratinocyte differentiation and decreased AQP3 expression is associated with more aggressive tumour behaviour.