title: Overexpression of periostin in stroma positively associated with aggressive prostate cancer.
abstract: BACKGROUND
  Periostin is an important extracellular matrix protein involved in cell development and adhesion. Previously, we identified periostin to be up-regulated in aggressive prostate cancer (CaP) using quantitative glycoproteomics and mass spectrometry. The expression of periostin was further evaluated in primary radical prostatectomy (RP) prostate tumors and adjacent non-tumorous prostate tissues using immunohistochemistry (IHC). Our IHC results revealed a low background periostin levels in the adjacent non-tumorous prostate tissues, but overexpressed periostin levels in the peritumoral stroma of primary CaP tumors.
  
  
  METHODS
  In this study, periostin expression in CaP was further examined on multiple tissue microarrays (TMAs), which were conducted in four laboratories. To achieve consistent staining, all TMAs were stained with same protocol and scored by same image computation tool to determine the total periostin staining intensities. The TMAs were further scored by pathologists to characterize the stromal staining and epithelial staining.
  
  
  RESULTS
  The periostin staining was observed mainly in peritumoral stromal cells and in some cases in tumor epithelial cells though the stronger staining was found in peritumoral stromal cells. Both periostin stromal staining and epithelial staining can differentiate BPH from CaP including low grade CaP (Gleason score ≤6), with significant p-value of 2.2e-16 and 0.001, respectively. Periostin epithelial staining differentiated PIN from low grade CaP (Gleason score ≤6) (p=0.001), while periostin stromal staining differentiated low grade Cap (Gleason score ≤6) from high grade Cap (Gleason score ≤6) (p=1.7e-05). In addition, a positive correlation between total periostin staining and Gleason score was observed (r=0.87, p=0.002).
  
  
  CONCLUSIONS
  The results showed that periostin staining was positively correlated with increasing Gleason score and the aggressiveness of prostate disease.
authors.affiliation: Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Caitlin H
authors.initials: CH
authors.lastname: Choi
authors.affiliation: Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Qing Kay
authors.initials: QK
authors.lastname: Li
authors.affiliation: Department of Pathology, University of California at Irvine, Irvine, California, United States of America.
authors.forename: Farah B
authors.initials: FB
authors.lastname: Rahmatpanah
authors.affiliation: Department of Pathology, University of California at Irvine, Irvine, California, United States of America.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Sara Ruth
authors.initials: SR
authors.lastname: Kim
authors.affiliation: Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Robert
authors.initials: R
authors.lastname: Veltri
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Chia
authors.affiliation: Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Pathology, University of California at Irvine, Irvine, California, United States of America.
authors.forename: Dan
authors.initials: D
authors.lastname: Mercola
authors.affiliation: Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
mesh_terms: D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D017154:Stromal Cells / Q000378:metabolism / Q000473:pathology; D046888:Tissue Array Analysis
chemical_list: D015815:Cell Adhesion Molecules; D009363:Neoplasm Proteins; C512835:POSTN protein, human