The emergence of mass spectrometry (MS)-based signatures as
biomarkers has generated considerable enthusiasm among oncologists. However, variations in normal individuals also exist, and a better understanding of serum
peptide patterns of healthy individuals will be important for further exploring disease-specific serum
peptide patterns. Following development of a serum
peptide pattern platform, we analyzed 500 serum samples obtained from healthy individuals. Samples from breast (n = 84), lung (n = 70), and rectal (n = 30)
cancer patients were also examined. Extensive data analysis revealed negligible contributions of age to serum
peptide patterns except in healthy individuals between 20-30 and 60+ years of age. Gender-related variations in the serum patterns of healthy individuals were only observed in 20-30 year-old individuals. Our results revealed substantial variation in individual
peptide profiles, but 65
peptides were detected at a 20% higher frequency in the healthy population. A
peptide profile was developed for each type of
cancer, containing 10 discriminating
peptides not prevalent in healthy individuals. Sequence identification of 111 signature
peptides revealed that they fell into several tight clusters and most were
exopeptidase products of serum resident
proteins. We have obtained a MS-based serum
peptide profile for healthy individuals, providing a reference for observing the occurrence of
cancer-specific
peptides.