Discovery of a tumor-specific biomarker for gastric cancer using proteomic analysis in tissue and serum

Abstract

e15582 Background: Gastric cancer is curable at an early stage. However, most cases are diagnosed at an advanced stage because of the lack of screening programs. Therefore, for early detection, there is a need for serum biomarkers to be identified. Methods: We explored surface-enhanced laser desorption/ionization time-of-flight mass spectrometry to elucidate potential protein biomarkers of gastric cancer. Twenty-one resected gastric cancer samples were compared with matched adjacent normal mucosa samples. Serum from patients with gastric cancer (n=51) was compared with patients with benign gastric diseases (n=29). Samples were analyzed on Cu2+-loaded IMAC protein chips via surface-enhanced laser desorption /ionization time-of-flight mass spectrometry. Results: Comparisons of surface-enhanced laser desorption /ionization time-of-flight mass spectrometry spectra of 21 gastric cancer tissue extracts with paired adjacent normal mucosa showed a total of 56 differentially expressed protein peaks (p<0.05; Wilcoxon test). Twenty-two were up-regulated in gastric cancer tissue, whereas 34 were down-regulated. The surface- enhanced laser desorption /ionization time-of-flight mass spectrometry spectra of serum contained 130 peaks, of which 67 were significantly associated with gastric cancer (p<0.05; Wilcoxon test). We found five proteomic features (mass charge values of 2273, 3143, 3372, 3444, 3485) that were significantly up-regulated in both gastric cancer tissue and serum from gastric cancer patients. The peak intensities of tumor-specific proteomic features were used to develop a linear regression model for calculating a diagnostic index. The area under the receiver operating characteristic curve of the corresponding diagnostic index was 0.87. Conclusions: Serum biomarker panels associated with tumor tissue are capable of distinguishing gastric cancer patients from non-cancer ones. No significant financial relationships to disclose.