Human Pancreatic Juice Proteomics Research

Proteomics represents a novel methodological approach to investigate the expression of all proteins of a cell, body fluid or organism, to analyze their structure, function, interaction and modification. Pancreatic cancer is one of the most formidable malignant tumors worldwide. According to the report of China's Disease Surveillance Point System, pancreatic cancer accounted for 2.26% of all deaths due to tumor in 2000, with the 6-8^th rank for men and the 9-10^th rank for women. Unfortunately, most cases were in advanced stage when the diagnosis of pancreatic cancer could be made. Therefore, to improve the prognosis and survival rate of pancreatic cancer patients, the important strategy is to discover novel biomarkers for early diagnosis. 2-DE is a traditional proteomic technique, which is a powerful method to find new biomarker for cancer diagnosis. The use of proteomic profiling for pancreatic cancer biomarker discovery is still at its early stage. At present there is no report on pancreatic juice proteomics analyses using 2-DE method.Effective sample preparation is important for 2-DE analysis. According to the biological charicateristics of pancreatic juice samples, salt removing, protein concentration and protease inhibitor are mainly preparation steps. In our study, several sample preparation methods were tested to remove salt and concentrate proteins. Among three preparation methods—precipitation with acetone, precipitation with PlusOne 2-D Clean-up kit and ultramenbrane centrifugation, the last one has best performance in salt removal and protein enrichment, which was proved to be a very effective technique in pancreatic juice preparation. To prevent the degradation of protein, the high concentration protease inhibitor was used and all components were mixed on ice. Using our sample preparation, 2-DE gel images of pancreatic juice showed an excellent reproducibility.Coomassie staining gels were applied in MALDI-TOF identifed, after in-gel digestion, 80 protein spots representing 22 different proteins were identified. As expect, proteases represented a large part of identified proteins and a majority of...