2D proteomics of gastric cancer: identification of proteins with increased level of synthesis

Highly sensitive techniques of comparative 2D-proteomic analysis were used as a prospective tool in the search for protein markers with consistently differing levels in normal and tumor tissues in stomach cancer patients. We performed the proteomic analysis of protein extracts which are primarily depleted of major physiologically insoluble structural proteins. After the evaluation of four paired gels, we selected six proteins the level of which in two or more tumor specimens was at least 10-fold higher than in the paired normal tissue (thymosin beta-10, cathepsin D (CTSD), S100 calcium binding protein A9 (S100A9), tropomyosin 3 and cyclophillin A. These proteins were identified by mass-spectrometry. For five of the six proteins, the observed upregulation in gastric adenocarcinoma is in agreement with the data of other recent studies. At the same time, our study is the first one to report consistently increased hCG1816442 levels in gastric tumors. Cyclophilin A is the most promising to further investigation to assay its prognostic value, since its expression level is low in most normal tissues and tumors of other localizations