title: Serum peptidome profiling revealed platelet factor 4 as a potential discriminating Peptide associated with pancreatic cancer.
abstract: OBJECTIVE
  Mass spectrometry-based serum peptidome profiling is a promising tool to identify novel disease-associated biomarkers, but is limited by preanalytic factors and the intricacies of complex data processing. Therefore, we investigated whether standardized sample protocols and new bioinformatic tools combined with external data validation improve the validity of peptidome profiling for the discovery of pancreatic cancer-associated serum markers.
  
  
  METHODS
  For the discovery study, two sets of sera from patients with pancreatic cancer (n = 40) and healthy controls (n = 40) were obtained from two different clinical centers. For external data validation, we collected an independent set of samples from patients (n = 20) and healthy controls (n = 20). Magnetic beads with different surface functionalities were used for peptidome fractionation followed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Data evaluation was carried out by comparing two different bioinformatic strategies. Following proteome database search, the matching candidate peptide was verified by MALDI-TOF MS after specific antibody-based immunoaffinity chromatography and independently confirmed by an ELISA assay.
  
  
  RESULTS
  Two significant peaks (m/z 3884; 5959) achieved a sensitivity of 86.3% and a specificity of 97.6% for the discrimination of patients and healthy controls in the external validation set. Adding peak m/z 3884 to conventional clinical tumor markers (CA 19-9 and CEA) improved sensitivity and specificity, as shown by receiver operator characteristics curve analysis (AUROC(combined) = 1.00). Mass spectrometry-based m/z 3884 peak identification and following immunologic quantitation revealed platelet factor 4 as the corresponding peptide.
  
  
  CONCLUSIONS
  MALDI-TOF MS-based serum peptidome profiling allowed the discovery and validation of platelet factor 4 as a new discriminating marker in pancreatic cancer.
authors.affiliation: Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig, Leipzig, Germany.
authors.forename: Georg Martin
authors.initials: GM
authors.lastname: Fiedler
authors.forename: Alexander Benedikt
authors.initials: AB
authors.lastname: Leichtle
authors.forename: Julia
authors.initials: J
authors.lastname: Kase
authors.forename: Sven
authors.initials: S
authors.lastname: Baumann
authors.forename: Uta
authors.initials: U
authors.lastname: Ceglarek
authors.forename: Klaus
authors.initials: K
authors.lastname: Felix
authors.forename: Tim
authors.initials: T
authors.lastname: Conrad
authors.forename: Helmut
authors.initials: H
authors.lastname: Witzigmann
authors.forename: Arved
authors.initials: A
authors.lastname: Weimann
authors.forename: Christof
authors.initials: C
authors.lastname: Schütte
authors.forename: Johann
authors.initials: J
authors.lastname: Hauss
authors.forename: Markus
authors.initials: M
authors.lastname: Büchler
authors.forename: Joachim
authors.initials: J
authors.lastname: Thiery
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood; D001798:Blood Proteins / Q000032:analysis*; D018395:CA-19-9 Antigen / Q000097:blood; D002272:Carcinoembryonic Antigen / Q000097:blood; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D010190:Pancreatic Neoplasms / Q000097:blood* / Q000175:diagnosis; D010978:Platelet Factor 4 / Q000097:blood*; D040901:Proteomics / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: D014408:Biomarkers, Tumor; D001798:Blood Proteins; D018395:CA-19-9 Antigen; D002272:Carcinoembryonic Antigen; D010978:Platelet Factor 4