Quantitative proteomic analysis reveals that proteins required for fatty acid metabolism may serve as diagnostic markers for gastric cancer

Gastric cancer is one of the leading causes of cancer-related deaths worldwide. The sensitivities and specificities of current biomarkers for gastric cancer are insufficient for clinical detection, and new diagnostic tests are therefore urgently required. A discovery set of gastric cancer and adjacent normal tissues were analyzed for differentially expressed proteins by labeling of peptide digests with isobaric tag for relative and absolute quantitation (iTRAQ) reagents followed by liquid chromatography-electrospray ionization-tandem mass spectrometry. A validation set of 70 pairs of gastric cancer and adjacent normal tissues were examined to confirm the expression levels of the potential biomarkers identified by iTRAQ labeling. We detected 431 proteins associated with 16 KEGG pathways that were differentially expressed in gastric cancer tissues, of which 224 were upregulated and 207 were downregulated in gastric cancer tissues. Coexpression of fatty acid binding protein (FABP1) and fatty acid synthase (FASN) in gastric cancer tissues (61.4% sensitivity and 77.1% specificity) was strongly associated with lymph node metastasis and Tumor, Node, Metastasis stage I/II. Quantitative proteomic analysis of gastric cancer tissues revealed that coexpression of FABP1 and FASN may serve as a biomarker for detection of early gastric cancer. •iTRAQ labeled proteomics identified 431 proteins differentially expressed in gastric cancer tissues.•FASN and FABP1 were significantly overexpressed in gastric cancer tissues and may be useful biomarkers for early GC.•Coexpression of FASN and FABP1 was significantly related to lymph node metastasis and TNM stage I/II.