title: Expression of aquaporin 5 (AQP5) promotes tumor invasion in human non small cell lung cancer.
abstract: The aquaporins (AQP) are water channel proteins playing a major role in transcellular and transepithelial water movement. Recently, the role of AQPs in human carcinogenesis has become an area of great interest. Here, by immunohistochemistry (IHC), we have found an expression of AQP5 protein in 35.3% (IHC-score: > or = 1, 144/408) of the resected NSCLC tissue samples. Cases with AQP5-positive status (IHC-score: > or = 2) displayed a higher rate of tumor recurrence than negative ones in NSCLC (54.7% vs. 35.1%, p = 0.005) and worse disease-free survival (p = 0.033; OR = 1.52; 95%CI: 1.04-2.23). Further in vitro invasion assay using BEAS-2B and NIH3T3 cells stably transfected with overexpression constructs for full length wild-type AQP5 (AQP5) and its two mutants, N185D which blocks membrane trafficking and S156A which blocks phosphorylation on Ser156, showed that AQP5 induced cell invasions while both mutants did not. In BEAS-2B cells, the expression of AQP5 caused a spindle-like and fibroblastic morphologic change and losses of cell-cell contacts and cell polarity. Only cells with AQP5, not either of two mutants, exhibited a loss of epithelial cell markers and a gain of mesenchymal cell markers. In a human SH3-domains protein array, cellular extracts from BEAS-2B with AQP5 showed a robust binding activity to SH3-domains of the c-Src, Lyn, and Grap2 C-terminal. Furthermore, in immunoprecipitation assay, activated c-Src, phosphorylated on Tyr416, showed a stronger binding activity to cellular extracts from BEAS-2B with AQP5 compared with N185D or S156A mutant. Fluorescence in situ hybridization (FISH) analysis failed to show evidence of genomic amplification, suggesting AQP5 expression as a secondary event. Based on these clinical and molecular observations, we conclude that AQP5, through its phosphorylation on Ser156 and subsequent interaction with c-Src, plays an important role in NSCLC invasion and, therefore, may provide a unique opportunity for developing a novel therapeutic target as well as a prognostic marker in NSCLC.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, United States of America [corrected]
authors.forename: Young Kwang
authors.initials: YK
authors.lastname: Chae
authors.forename: Janghee
authors.initials: J
authors.lastname: Woo
authors.forename: Mi-Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Sung Koo
authors.initials: SK
authors.lastname: Kang
authors.forename: Myoung Sook
authors.initials: MS
authors.lastname: Kim
authors.forename: Juna
authors.initials: J
authors.lastname: Lee
authors.forename: Seung Koo
authors.initials: SK
authors.lastname: Lee
authors.forename: Gyungyub
authors.initials: G
authors.lastname: Gong
authors.forename: Yong Hee
authors.initials: YH
authors.lastname: Kim
authors.forename: Jean Charles
authors.initials: JC
authors.lastname: Soria
authors.forename: Se Jin
authors.initials: SJ
authors.lastname: Jang
authors.forename: David
authors.initials: D
authors.lastname: Sidransky
authors.forename: Chulso
authors.initials: C
authors.lastname: Moon
mesh_terms: D000818:Animals; D051402:Aquaporin 5 / Q000378:metabolism*; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism*; D045744:Cell Line, Tumor; D004847:Epithelial Cells / Q000166:cytology; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology*; D008648:Mesoderm / Q000166:cytology; D051379:Mice; D009361:Neoplasm Invasiveness; D010766:Phosphorylation; D010957:Plasmids; D011379:Prognosis; D046888:Tissue Array Analysis
chemical_list: C496036:AQP5 protein, human; D051402:Aquaporin 5