title: Involvement of aquaporin-5 in differentiation of human gastric cancer cells.
abstract: Litttle is known about the function of aquaporin (AQP) water channels in human gastric cancer. In the upper or middle part of human stomach, we found that expression level of AQP5 protein in intestinal type of adenocarcinoma was significantly higher than that in accompanying normal mucosa. AQP5 was localized in the apical membrane of the cancer cells. On the other hand, both AQP3 and AQP4 were not up-regulated in the adenocarcinoma. To elucidate the role of AQP5 in cancer cells, AQP5 was exogenously expressed in a cell line of poorly differentiated human gastric adenocarcinoma (MKN45). The AQP5 expression significantly increased the proportion of differentiated cells with a spindle shape, the activity of alkaline phosphatase, a marker for the intestinal epithelial cell type of cancer cells, and the expression level of laminin, an epithelial cell marker. Treatment of the MKN45 cells stably expressing AQP5 with HgCl(2), an inhibitor of aquaporins, significantly decreased the proportion of differentiated cells and the activity of alkaline phosphatase. Our results suggest that up-regulation of AQP5 may be involved in differentiation of human gastric cancer cells.
authors.affiliation: Department of Surgery II, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Watanabe
authors.forename: Takuto
authors.initials: T
authors.lastname: Fujii
authors.forename: Takeshi
authors.initials: T
authors.lastname: Oya
authors.forename: Naoki
authors.initials: N
authors.lastname: Horikawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Tabuchi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Magotoshi
authors.initials: M
authors.lastname: Morii
authors.forename: Noriaki
authors.initials: N
authors.lastname: Takeguchi
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tsukada
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai