抄録
Molecular biomarkers are biological molecules that are indicators of physiologic state and also of change during a disease process like cancer. Mass spectrometry-based protein/peptide expression as diagnostic biomarkers has been reported. To identify sensitive and accurate diagnostic biomarkers, differential peptide/protein profiling using blood is required. Here we established comprehensive and sensitive analytical platform using automated 2-dimensional LC-MALDI-TOF MS and identified several peptide biomarkers which discriminate liver caner and non-cancer disease. Serum samples were pretreated and peptides (Mr<10,000) fractions were obtained and separated by two-dimensional HPLC; strong cation exchange (SCX) for the 1st dimension and reverse phase (RP) for the 2nd dimension. The separated samples were spotted onto three MALDI targets automatically. More than 10,000 fractions were analyzed automatically by MALDI-TOF MS in reflector mode. Our system identified angiotensin II as a spike in processed serum at 1nM concentration. Huge data of the peptide expression profiles generated from mass spectrometry were analyzed by the differential analysis tools originally developed by us. Without re-purification of peptides, sequential analysis by MSn on MALDI-QIT-TOF MS revealed that some of these biomarkers were post-translationally modified. Analysis of human serum from liver cancer patients and non-cancer patients by our system revealed several differentially-expressed peptides. Our analytical platform for comprehensive differential peptidomics may useful for identification of the novel biomarkers which may improve the early diagnosis of cancer.
