Identification of potential markers for the detection of pancreatic cancer through comparative serum protein expression profiling.
OBJECTIVE
Early detection is the only promising approach to significantly improve the survival of patients with pancreatic cancer (PCa). Noninvasive tools for the diagnosis, prognosis, and monitoring of this disease are of urgent need. The purpose of this study was to identify and validate new biomarkers in PCa patient serum samples.


METHODS
Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry has been applied to analyze serum protein alterations associated with PCa and to identify sets of potential biomarkers indicative for this disease. A cohort of 96 serum samples from patients undergoing PCa surgery was compared with sera from 96 healthy volunteers as controls. The sera were fractionated by anion exchange chromatography, and 3 of 6 fractions were analyzed onto 2 different chromatographic arrays.


RESULTS
Data analysis revealed 24 differentially expressed protein peaks (P < 0.001), of which 21 were downregulated in the PCa samples. The best single marker can predict 92% of the controls and 89% of the cancer samples correctly. In addition, multivariate pattern analysis was performed. The best pattern model using a set of 3 markers was obtained using fraction 6 on immobilized metal affinity capture, loaded with Cu-Cu arrays. With this pattern model, a sensitivity of 100% and a specificity of 98% for the training data set and a sensitivity of 83% and specificity of 77% for the test data set were achieved with the PCa group set as true positive. Several of protein peaks, including the best single marker at 17.27 kd and other proteins from the pattern models, were purified and identified by peptide mapping and postsource decay-matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Apolipoprotein A-II, transthyretin, and apolipoprotein A-I were identified as markers, and these identified proteins were decreased at least 2-fold in PCa serum when compared with the control group.


CONCLUSIONS
PCa is associated with a specific decrease of distinct serum proteins, which allows a reliable differentiation between pancreatic cancer and healthy controls.
Ehmann
Michael
M
Department of General Surgery, University of Heidelberg, INF 110, D-69120 Heidelberg, Germany.
Felix
Klaus
K
Hartmann
Daniel
D
Schnölzer
Martina
M
Nees
Matthias
M
Vorderwülbecke
Sonja
S
Bogumil
Ralf
R
Büchler
Markus W
MW
Friess
Helmut
H
D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D016632:Apolipoprotein A-I / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification; D016633:Apolipoprotein A-II / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification; D014408:Biomarkers, Tumor / Q000097:blood / Q000737:chemistry* / Q000302:isolation & purification*; D001798:Blood Proteins / Q000737:chemistry / Q000302:isolation & purification; D002845:Chromatography; D015331:Cohort Studies; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D010449:Peptide Mapping; D011228:Prealbumin / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D040081:Protein Array Analysis; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D016632:Apolipoprotein A-I; D016633:Apolipoprotein A-II; D014408:Biomarkers, Tumor; D001798:Blood Proteins; D011228:Prealbumin