title: Expression of aquaporin 3 (AQP3) in normal and neoplastic lung tissues.
abstract: Aquaporin 3 (AQP3) acts as the membrane channel of water and other small solutes and plays a major role in fluid homeostasis. To investigate the expression of AQP3 in normal and neoplastic lung tissues, we studied a series of 149 lung carcinoma tissues and 2 cell lines by immunohistochemistry, Western blotting, and reverse transcriptase-polymerase chain reaction. In normal lung tissues, immunohistochemical expression of AQP3 was demonstrated in bronchial basal cells, alveolar type II cells, bronchiolar epithelial cells, and secretory cells of submucosal glands. In lung carcinomas, AQP3 expression was observed in 59 (70.2%) of 84 adenocarcinomas. Squamous cell carcinoma and large cell carcinoma had rather low positive ratios (35.8% and 13.4%, respectively). No AQP3 expression was demonstrated in small cell carcinoma, pleomorphic carcinoma, or metastatic colon adenocarcinoma. In adenocarcinomas, AQP3 was detected in all tumors of bronchioloalveolar subtype. Papillary subtype also showed a higher positive ratio of AQP3 compared with that in acinar and solid with mucin subtypes. In addition, AQP3 expression was related to tumor differentiation and clinical stage in adenocarcinomas. Western blotting and reverse transcriptase-polymerase chain reaction analyses confirmed the expression of AQP3 protein and messenger RNA in cell lines and tissues of lung adenocarcinoma. We conclude that AQP3 is widely expressed in the normal respiratory tract and can play an important role in the maintenance of water homeostasis. In addition, lung carcinomas, especially adenocarcinomas, can produce AQP3, possibly in connection with their functional and/or biological nature, although the detailed mechanism of AQP3 expression in lung carcinomas remains to be clarified.
authors.affiliation: Department of Pathology, University of Yamanashi Interdisciplinary Graduate School of Medicine and Engineering, Yamanashi 409-3898, Japan.
authors.forename: Ya Lan
authors.initials: YL
authors.lastname: Liu
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Matsuzaki
authors.forename: Tadao
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Murata
authors.forename: Nobuki
authors.initials: N
authors.lastname: Nakamura
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kondo
authors.forename: Masanori
authors.initials: M
authors.lastname: Iwashina
authors.forename: Kunio
authors.initials: K
authors.lastname: Mochizuki
authors.forename: Tetsu
authors.initials: T
authors.lastname: Yamane
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Takata
authors.forename: Ryohei
authors.initials: R
authors.lastname: Katoh
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051400:Aquaporin 3 / Q000032:analysis / Q000235:genetics*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008168:Lung / Q000378:metabolism*; D008175:Lung Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D051400:Aquaporin 3