BACKGROUND Helicobacter pylori, a human pathogen responsible for many digestive disorders, induces complex changes in patterns of gene expression in infected tissues. cDNA expression arrays provide a useful tool for studying these complex phenomena.

AIM To identify genes that showed altered expression after H pylori infection of human gastric cells compared with uninfected controls.

RESULTS Over 24 hours, coincubation with H pylori inhibited AGS cell growth but did not cause a noticeable degree of cell death.H pylori treatment altered the pattern of gene expression in AGS cells. We identified 21 overexpressed genes and 17 suppressed genes from the cDNA expression arrays. The majority of genes were transcription factors such asc-jun, BTEB2, andETR101. Other genes were involved in signal transduction pathways, such as MAP kinase, interleukin 5, and insulin-like growth factor. Genes involved in cell cycle regulation and differentiation, such as CDC25B andNM23-H2, were also identified. In patients with H pylori infection (n=20), there was a significant difference forERCC3, Id-2, andNM23-H2 mRNA levels in infected gastric mucosa compared with uninfected gastric mucosa in patients without peptic diseases (n=20) (ERCC3 4.75 molecules/10⁴ β-actin mRNA moleculesv 13.65, p<0.001;Id-2 16.1 v 23.4, p<0.05; NM23-H2 17.5v 45.5, p<0.001). There was no significant difference between mRNA levels of c-jun andCDC25B in H pylori colonised gastric mucosa and uninfected mucosa.

CONCLUSION We demonstrated that H pylori infection caused alteration of gene expression in AGS cells. The differential hybridisation technique of Atlas human cDNA expression array is a useful method to identify host genes involved in pathogenic mechanisms in H pylori infection.