title: Over-expression of a poor prognostic marker in prostate cancer: AQP5 promotes cells growth and local invasion.
abstract: BACKGROUND
  The aquaporins (AQPs), water channel proteins, are known playing a major role in transcellular and transepithelial water movement; they also exhibit several properties related to tumor development. The aim of the present study is to elucidate whether the expression of AQP5 is a strong prognostic biomarker for prostate cancer, and the potential role in the progression of prostate cancer cells.
  
  
  METHODS
  AQP5 expression was measured in 60 prostate cancer tissues and cells (both PC-3 and LNCaP) by immunohistochemistry and immunofluorescence assay. AQP5 gene amplification was detected with FISH (fluorescence in situ hybridization). Proliferation and migration of cells and AQP5 siRNA cells were detected with MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) and Boyden chambers. Circulating tumor cells (CTCs) were detected by imFISH staining (CEP8-CD45-DAPI) assay.
  
  
  RESULTS
  The results showed that in 60 tumor specimens, 19 (31.7%) patients showed high level of AQP5 expression, while 30 (50.0%) showed a moderate, intermediate level of staining, and 11 (18.3%) showed an absence of AQP5 staining, respectively. High-expression of AQP5 protein frequently accompanied gene amplification detection with FISH. The AQP5 over-expression was also associated with TNM stage (P=0.042), and lymph node metastasis (P=0.001). The relationships between age or tumor size with the expression of AQP5 were not significant (P>0.05). A positive correlation between the number of CTCs and AQP5 expression (P<0.05) was demonstrated. In addition, patients who were negative for AQP5 had superior cumulative survival rate than those who were positive for it. Over-expression of AQP5 protein was also found in prostate cancer cells and cell proliferation and migration were significantly attenuated by AQP5-siRNA.
  
  
  CONCLUSIONS
  We concluded that AQP5 in prostate cancer was an independent prognostic indicator. AQP5 over-expression was likely to play a role in cell growth and metastasis. These conclusions suggest that AQP5 may be an effective therapeutic target for prostate cancer.
authors.forename: Jianping
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Urology, the Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710004, China. JianpingLi0292@163.com.
authors.forename: Ziming
authors.initials: Z
authors.lastname: Wang
authors.forename: Tie
authors.initials: T
authors.lastname: Chong
authors.forename: Haiwen
authors.initials: H
authors.lastname: Chen
authors.forename: Hechen
authors.initials: H
authors.lastname: Li
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Zhai
authors.forename: Youfang
authors.initials: Y
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D051402:Aquaporin 5 / Q000235:genetics / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005500:Follow-Up Studies; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011379:Prognosis; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000601:surgery; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016019:Survival Analysis; D015854:Up-Regulation
chemical_list: C496036:AQP5 protein, human; D051402:Aquaporin 5; D014408:Biomarkers, Tumor