title: Periostin identified as a potential biomarker of prostate cancer by iTRAQ-proteomics analysis of prostate biopsy.
abstract: BACKGROUND
  Proteomics may help us better understand the changes of multiple proteins involved in oncogenesis and progression of prostate cancer(PCa) and identify more diagnostic and prognostic biomarkers. The aim of this study was to screen biomarkers of PCa by the proteomics analysis using isobaric tags for relative and absolute quantification(iTRAQ).
  
  
  METHODS
  The patients undergoing prostate biopsies were classified into 3 groups according to pathological results: benign prostate hyperplasia (BPH, n = 20), PCa(n = 20) and BPH with local prostatic intraepithelial neoplasm(PIN, n = 10). Then, all the specimens from these patients were analyzed by iTRAQ and two-dimensional liquid chromatography-tandem mass spectrometry (2DLC-MS/MS). The Gene Ontology(GO) function and the transcription regulation networks of the differentially expressed were analyzed by MetaCore software. Western blotting and Immunohistochemical staining were used to analyze the interesting proteins.
  
  
  RESULTS
  A total of 760 proteins were identified from 13787 distinct peptides, including two common proteins that enjoy clinical application: prostate specific antigen (PSA) and prostatic acid phosphatase(PAP). Proteins that expressed differentially between PCa and BPH group were further analyzed. Compared with BPH, 20 proteins were significantly differentially up-regulated (>1.5-fold) while 26 were significantly down-regulated in PCa(<0.66-fold). In term of GO database, the differentially expressed proteins were divided into 3 categories: cellular component(CC), molecular function (MF) and biological process(BP). The top 5 transcription regulation networks of the differentially expressed proteins were initiated through activation of SP1, p53, YY1, androgen receptor(AR) and c-Myc The overexpression of periostin in PCa was verified by western blotting and immunohistochemical staining.
  
  
  CONCLUSIONS
  Our study indicates that the iTRAQ technology is a new strategy for global proteomics analysis of the tissues of PCa. A significant up-regulation of periostin in PCa compared to BPH may provide clues for not only a promising biomarker for the prognosis of PCa but also a potential target for therapeutical intervention.
authors.affiliation: Department of Urology, Huashan Hospital, FudanUniversity, Shanghai, 200040, China.
authors.forename: Chuanyu
authors.initials: C
authors.lastname: Sun
authors.affiliation: Institute of Psychology, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Song
authors.affiliation: Department of Urology, Huashan Hospital, FudanUniversity, Shanghai, 200040, China.
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Ma
authors.affiliation: Department of Urology, Huashan Hospital, FudanUniversity, Shanghai, 200040, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Xu
authors.affiliation: Institutes of Biomedical Sciences, FudanUniversity, Shanghai, 200032, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institutes of Biomedical Sciences, FudanUniversity, Shanghai, 200032, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Jin
authors.affiliation: Department of Urology, Huashan Hospital, FudanUniversity, Shanghai, 200040, China.
authors.forename: Shijun
authors.initials: S
authors.lastname: Tong
authors.affiliation: Department of Urology, Huashan Hospital, FudanUniversity, Shanghai, 200040, China.
authors.forename: Weihong
authors.initials: W
authors.lastname: Ding
authors.affiliation: Department of Urology, Huashan Hospital, FudanUniversity, Shanghai, 200040, China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Xia
authors.affiliation: Department of Urology, Huashan Hospital, FudanUniversity, Shanghai, 200040, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Ding