Relationship between the diversity of the cagA gene of Helicobacter pylori and gastric cancer in Okinawa, Japan

Abstract
Helicobacter pylori CagA protein is considered to be one of the virulence factors associated with gastric cancer. CagA is injected into gastric epithelial cells, undergoes tyrosine phosphorylation, and binds to Src homology 2 domain-containing protein-tyrosine phosphatase (SHP-2). Two major subtypes of CagA have been observed in the SHP-2-binding site, the Western and East Asian types. The East Asian-type CagA binds to SHP-2 more strongly than the Western-type CagA. The diversity of CagA, which collectively determines the binding affinity of CagA to SHP-2, may be an important variable in determining the clinical outcome of infection by different H. pylori strains.