Absence of pepsinogen A3 gene expression in the gastric mucosa of patients with gastric cancer

Proteomics signature of autoimmune atrophic gastritis: towards a link with gastric cancer

BACKGROUND

Autoimmune atrophic gastritis (AAG) is a chronic disease that can progress to gastric cancer (GC). To better understand AAG pathology, this proteomics study investigated gastric proteins whose expression levels are altered in this disease and also in GC.

METHODS

Using two-dimensional difference gel electrophoresis (2D-DIGE), we compared protein maps of gastric corpus biopsies from AAG patients and controls. Differentially abundant spots (|fold change|≥ 1.5, P < 0.01) were selected and identified by LC-MS/MS. The spots were further assessed in gastric antrum biopsies from AAG patients (without and with Helicobacter pylori infection) and from GC patients and unaffected first-degree relatives of GC patients.

RESULTS

2D-DIGE identified 67 differentially abundant spots, with 28 more and 39 less abundant in AAG-corpus than controls. LC-MS/MS identified these as 53 distinct proteins. The most significant (adjusted P < 0.01) biological process associated with the less abundant proteins was "tricarboxylic acid cycle". Of the 67 spots, 57 were similarly differentially abundant in AAG-antrum biopsies irrespective of H. pylori infection status. The differential abundance was also observed in GC biopsies for 14 of 28 more abundant and 35 of 39 less abundant spots, and in normal gastric biopsies of relatives of GC patients for 6 and 25 spots, respectively. Immunoblotting confirmed the different expression levels of two more abundant proteins (PDIA3, GSTP gene products) and four less abundant proteins (ATP5F1A, PGA3, SDHB, PGC).

CONCLUSION

This study identified a proteomics signature of AAG. Many differential proteins were shared by GC and may be involved in the progression of AAG to GC.

In through the out door: serology for atrophic gastritis

Gastric cancer remains the second biggest cause of cancer death worldwide. The most common type of gastric cancer, the intestinal type, is usually preceded by chronic atrophic gastritis. Gastritis serology is therefore of crucial importance for population-based screening and prevention studies. Helicobacter pylori serum antibodies can adequately diagnose inflammation of the gastric mucosa, but the serological diagnosis of atrophic gastritis is more hazardous. Many tests have been used for this purpose, either alone or in various combinations. Depending on the population, pepsinogens and gastrin often have a high specificity but low sensitivity for the diagnosis of atrophic gastritis, whereas antibodies against H. pylori or CagA have a high sensitivity but low specificity. A combination of two tests, e.g. H. pylori antibodies and pepsinogen I, may balance this issue and provide adequate screening tools, although there is a clear need for further improvement and simplification of serological testing for atrophic gastritis.