title: East Asian-type Helicobacter pylori cytotoxin-associated gene A protein has a more significant effect on growth of rat gastric mucosal cells than the Western type.
abstract: OBJECTIVE
  Cytotoxin-associated gene A (CagA) protein from H. pylori was reported to be injected into host gastric epithelial cells via a bacterial type IV secretion system, thereby modifying signal transduction. It is classified into two major subtypes, Western and East Asian. The present study aimed to compare the effects of East Asian-type and Western-type CagA on host cell growth.
  
  
  METHODS
  A tetracycline (tet)-off system and cagA genes from Western and East Asian-type H. pylori (NCTC 11637 and F32) were transfected into untransformed rat gastric mucosal (RGM1) cells to establish RGM1-CagA cell lines in which CagA expression could be controlled by tetracycline. These cell lines were used to investigate the effect of CagA protein expression on cell growth with BrdU and water-soluble tetrazolium reagent (WST-8) assays. CagA expression, phosphorylation and extracellular signal-regulated kinase (ERK) activation were examined with immunoprecipitation and Western blotting analysis.
  
  
  RESULTS
  5-Bromo-2'deoxyuridine (BrdU) and WST-8 assays demonstrated significant increases in DNA replication and RGM1 cell growth after CagA protein expression. ERK phosphorylation was enhanced when CagA protein was expressed in RGM1-CagA cells. Moreover, the East Asian-type CagA showed a significantly greater effect on ERK activation and host cell growth than the Western type. PD98059, a mitogen-activated protein kinase kinase (MEK) inhibitor, suppressed ERK phosphorylation and the CagA protein-induced increase in RGM1-CagA cell growth.
  
  
  CONCLUSIONS
  CagA protein expression induces an increase in RGM1-CagA cell proliferation via the mitogen-activated protein kinase (MAPK) signal pathway. The East Asian-type CagA showed a significantly greater effect on cell growth than the Western type, suggesting that the East Asian CagA-positive strain may have an important role in pathogenesis.
authors.affiliation: Department of Clinical Laboratory Science, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Hai Ying
authors.initials: HY
authors.lastname: Fu
authors.forename: Kayoko
authors.initials: K
authors.lastname: Asahi
authors.forename: Yujiro
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Eguchi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Murata
authors.forename: Masahiko
authors.initials: M
authors.lastname: Tsujii
authors.forename: Shingo
authors.initials: S
authors.lastname: Tsuji
authors.forename: Takeshi
authors.initials: T
authors.lastname: Azuma
authors.forename: Sunao
authors.initials: S
authors.lastname: Kawano
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000145:classification* / Q000235:genetics* / Q000502:physiology; D001426:Bacterial Proteins / Q000145:classification* / Q000235:genetics* / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D005753:Gastric Mucosa / Q000166:cytology*; D016480:Helicobacter pylori / Q000235:genetics*; D051381:Rats
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori