To examine the proteomic background of lymph node metastasis (LNM) in gastric cancer, we performed protein expression profiling of paired non-tumor, primary tumor, and LNM tissues. Using a label-free proteomic approach, we generated protein expression profiles of 3894 unique proteins and identified 109 differentially expressed proteins. Functional pathway analysis of the differentially expressed proteins showed that members of the beta-3 integrin (ITGB3) pathway were significantly enriched. Aberrations of ITGB3 were reported in various malignancies
however, ITGB3 in LNM tissues has not been examined to date. Different level of ITGB3 expression was confirmed in 20 gastric cancer cases by Western blotting. We analyzed the mRNA levels of the differentially expressed proteins by using a public mRNA expression database
38.8% of the proteins examined, including those involved in oxidation and reduction, showed correlation between protein and mRNA levels. Proteins without such correlation included factors related to cell adhesion. Our study suggests a novel role for the integrin pathway in the development of LNM in gastric cancer and indicated possible benefits of observational transcriptomic analysis for proteomic studies. © 2014 The Authors.