Abstract 1752: Prognostic significance of Aquaporin(AQP) expression in gastric and colorectal cancer

Introduction : Aquaporins (AQPs) are a membrane proteins involved in water transport and have been found to be expressed in several cancers. We have already reported that AQP 5 expression is associated with differentiation for gastric cancer (J Physiol Science 2009). However, the role of AQP family expression has not been well evaluated yet. In this study, we examined the expression of AQP 1, 4, 5 and 8 in gastric cancer and colorectal cancer, and compared them with the clinico-pathological characteristics of the patients. Method : The expression of AQP1, 4, 5, and 8 was comprehensively examined by tissue microarray (TMA1150) that has been established in our hospital. The specimens of gastric cancer and colorectal cancer were obtained from the patients who receive an operation between 1993 to 2004. Clinico-pathological data were obtained from the patients’ medical records. After careful examination of two independent pathologists, the results were scored according to the intensity and the distribution. Finally, AQP expressions were compared to the clinical pathologic finding of the patients. Result : In stomach cancer, positivity of AQP1, 4, 5, and 8 expressions were 40.7% (22/54), 43.2% (19/44), 97.6% (41/42) and 18.2% (8/44) respectively. AQP4 positive patients have a significant better prognosis than that of negative patients (p=0.004) and low expression of AQP4 tended to relate to poorly differentiated adenocarcinoma (p=0.07). However there was no significant difference between the prognosis, histological type, disease stage (TNM classification) and AQP1, 5, and 8 expressions. With regard to colorectal cancer, positivity of AQP1, 4, 5, and 8 expressions were 27.4% (20/73), 45.9% (34/74), 98.4% (61/62), and 76.4% (55/72) respectively. AQP4 positive patients tended to have a favorable prognosis (p=0.12), on the other hand AQP1 positive group tended to have a worse prognosis (p=0.06). There was the other relationship between low expression of AQP4 and N factor (p=0.04). Conclusion : AQP 1 and 4 expression have some roles in the progression of gastric cancer and colorectal cancer, however the role of AQP 5 and 8 are still unknown. Our findings suggested that AQP 1 and 4 may be a molecular target of gastric cancer and colorectal cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1752.