Proteomic differential display analysis shows up-regulation of 14-3-3 sigma protein in human scirrhous-type gastric carcinoma cells.

This study performed proteomic differential display analysis of human scirrhous-type gastric carcinoma (SGC) cell lines and normal gastric mucosa (NGM) tissues by using two-dimensional gel electrophoresis (2-DE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The human SGC cell lines were OCUM-1, OCUM-2M, OCUM-2MLN, OCUM-2D, OCUM-D3, OCUM-9 and OCUM-12. Among the SGC cell lines and the NGM tissues, 28 protein spots were found whose expression levels were different from the results of 2-DE: 19 protein spots appeared higher, and 9 other protein spots appeared lower in SGCs than in NGM tissues. These spots were analysed by LC-MS/MS analysis and identified by a peptide sequence tag. Identified increased spots included elongation factor 1-beta, 14-3-3 sigma, tropomyosin alpha-4 chain, protein DJ-1, nucleoside diphosphate kinase A, elongation factor Tu and peroxiredoxin-1. Western blot analysis showed increased protein level of 14-3-3 sigma in SGCs. Although OCUM-1 and AGS (gastric cancer) showed up-regulation of 14-3-3 sigma, MiaPaca-2 (pancreatic cancer), Huh-7 (HCC) and NCI-H2052 (malignant pleural mesothelioma) showed very weak expression of 14-3-3 sigma. The up-regulation of 14-3-3 sigma may play an important role in SGC carcinogenesis and progression and may be used as a diagnostic biomarker of SGC.