Background: Proteomic analysis is a powerful tool for complete establishment of protein expression. Comparative proteomic analysis of human bile from malignant and benign gallbladder diseases may be helpful in research into gallbladder cancer.
Aims: Our objective was to establish biliary protein content for gallbladder cancer, gallbladder adenoma, and chronic calculous cholecystitis for comparative proteomic analysis.
Methods: Bile samples were collected from patients with gallbladder cancer, gallbladder adenoma, and chronic calculous cholecystitis. Peptides of biliary proteins were separated by two-dimensional liquid chromatography then identified by tandem mass spectrometry.
Results: Up to 544, 221, and 495 unique proteins were identified in bile samples from gallbladder cancer, gallbladder adenoma, and chronic calculous cholecystitis. Forty-three, 16, and 28 proteins with more than one unique peptide, respectively, were identified in the three groups. Among these, 30 proteins including S100A8 were overexpressed in gallbladder cancer, compared with benign gallbladder diseases. We also confirmed, by immunohistochemical analysis, that S100A8 is more abundant in tumor-infiltrating immune cells in cancerous tissue.
Conclusions: Compared with benign gallbladder diseases, consistently elevated S100A8 levels in malignant gallbladder bile and tissue indicate that gallbladder cancer is an inflammation-associated cancer. S100A8 may be a biomarker for gallbladder cancer.