Characterization of Pepsinogen C as a Potential Biomarker for Gastric Cancer Using a Histo-Proteomic Approach

We analyzed 74 cryostat sections of central gastric tumor, tumor margin, and normal gastric epithelium using ProteinChip Arrays and SELDI-TOF MS. One peak was significantly down-regulated in tumor tissue (P = 1.43 × 10-6) and identified as pepsinogen C using MS/MS analysis and immunodepletion. This signal was further characterized by immunohistochemistry. This work demonstrates that differentially expressed signals can be identified and assessed using a proteomic approach comprising tissue-microdissection, protein profiling, and immunohistochemistry. Keywords: gastric cancer • proteomics • biomarker • ProteinChip technology • SELDI • microdissection • immunohistochemistry