title: Proteomic analysis identifies MMP-9, DJ-1 and A1BG as overexpressed proteins in pancreatic juice from pancreatic ductal adenocarcinoma patients.
abstract: BACKGROUND
  There is an urgent need to discover more sensitive and specific biomarkers to improve early diagnosis and screen high-risk patients for pancreatic ductal adenocarcinoma (PDAC). Pancreatic juice is an ideal specimen for PDAC biomarkers discovery, because it is an exceptionally rich source of proteins released from pancreatic cancer cells.
  
  
  METHODS
  To identify novel potential biomarkers for PDAC from pancreatic juice, we carried out difference gel electrophoresis (DIGE) and tandem mass spectrometry (MS/MS) to compare the pancreatic juice profiling from 9 PDAC patients and 9 cancer-free controls. Of the identified differently expressed proteins, three up-regulated proteins in pancreatic cancer juice, matrix metalloproteinase-9 (MMP-9), oncogene DJ1 (DJ-1) and alpha-1B-glycoprotein precursor (A1BG), were selected for validation by Western blot and immunohistochemistry. Serum MMP-9 levels were also detected by enzyme linked immunosorbent assay (ELISA).
  
  
  RESULTS
  Fourteen proteins were up-regulated and ten proteins were down-regulated in cancerous pancreatic juice compared with cancer-free controls. Increased MMP-9, DJ-1 and A1BG expression in cancerous pancreatic juice were confirmed by Western blot. Immunohistochemical study showed MMP-9, DJ-1 and A1BG positively expressed in 82.4%, 72.5% and 86.3% of pancreatic cancer tissues, significantly higher than that in normal pancreas tissues. Up-regulation of DJ-1 was associated with better differentiation (p < 0.05). Serum MMP-9 levels were significantly higher in PDAC (255.14 ng/ml) than those in chronic pancreatitis (210.22 ng/ml, p = 0.009) and healthy control (203.77 ng/ml, p = 0.027).
  
  
  CONCLUSIONS
  The present proteome analysis revealed MMP-9, DJ-1 and A1BG proteins as elevated in pancreatic juice from PDAC, which suggest their further utility in PDAC diagnosis and screening. This is the first time A1BG was identified as a potential biomarker in pancreatic cancer associated samples. The measurement of serum MMP-9 might be clinically useful for PDAC diagnosis.
authors.affiliation: Key Laboratory of Ministry of Health for Biotech-Drug, Key Laboratory for Modern Medicine and Technology of Shandong Province, Shandong Medicinal Biotechnology Center, Shandong Academy of Medical Sciences, Jinan 250062, PR China. genomeresearch@163.com
authors.forename: Mei
authors.initials: M
authors.lastname: Tian
authors.forename: Ya-Zhou
authors.initials: YZ
authors.lastname: Cui
authors.forename: Guan-Hua
authors.initials: GH
authors.lastname: Song
authors.forename: Mei-Juan
authors.initials: MJ
authors.lastname: Zong
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Zhou
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Jin-Xiang
authors.initials: JX
authors.lastname: Han
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D021441:Carcinoma, Pancreatic Ductal / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008875:Middle Aged; D015513:Oncogene Proteins / Q000378:metabolism*; D010189:Pancreatic Juice / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D010195:Pancreatitis / Q000378:metabolism; D000071617:Protein Deglycase DJ-1; D040901:Proteomics / Q000379:methods*
chemical_list: C048566:A1BG protein, human; D014408:Biomarkers, Tumor; D006023:Glycoproteins; D007136:Immunoglobulins; D047908:Intracellular Signaling Peptides and Proteins; D015513:Oncogene Proteins; C105131:PARK7 protein, human; D000071617:Protein Deglycase DJ-1; D020780:Matrix Metalloproteinase 9