title: H. pylori-induced promoter hypermethylation downregulates USF1 and USF2 transcription factor gene expression.
abstract: Helicobacter pylori infection is associated with the development of gastric adenocarcinoma. Upstream stimulatory factors USF1 and USF2 regulate the transcription of genes related to immune response, cell cycle and cell proliferation. A decrease in their expression is observed in human gastric epithelial cells infected with H. pylori, associated to a lower binding to their DNA E-box recognition site as shown by electrophoretic mobility shift assay. DNA methylation leads to gene silencing. The treatment of cells with 5'-azacytidine, an inhibitor of DNA methylation, restored the USF1 and USF2 gene expression in the presence of infection. Using promoter PCR methylation assay, a DNA hypermethylation was shown in the promoter region of USF1 and USF2 genes, in infected cells. The inhibition of USF1 and USF2 expression by H. pylori and the DNA hypermethylation in their gene promoter region was confirmed in gastric tissues isolated from 12 to 18 months infected mice. Our study demonstrated the involvement of USF1 and USF2 as molecular targets of H. pylori and the key role of DNA methylation in their regulation. These mechanisms occurred in the context of metaplastic lesions, suggesting that alteration of USF1 and USF2 levels could participate in the promotion of neoplastic process during H. pylori infection.
authors.affiliation: Institut Pasteur, Unité de Pathogenèse de Helicobacter, Paris, France.
authors.forename: Françoise I
authors.initials: FI
authors.lastname: Bussière
authors.forename: Valérie
authors.initials: V
authors.lastname: Michel
authors.forename: Sylvie
authors.initials: S
authors.lastname: Mémet
authors.forename: Patrick
authors.initials: P
authors.lastname: Avé
authors.forename: José Ramos
authors.initials: JR
authors.lastname: Vivas
authors.forename: Michel
authors.initials: M
authors.lastname: Huerre
authors.forename: Eliette
authors.initials: E
authors.lastname: Touati
mesh_terms: D000818:Animals; D002460:Cell Line; D019175:DNA Methylation; D015536:Down-Regulation; D024202:Electrophoretic Mobility Shift Assay; D004847:Epithelial Cells / Q000382:microbiology; D015870:Gene Expression; D016480:Helicobacter pylori / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011401:Promoter Regions, Genetic; D051720:Upstream Stimulatory Factors / Q000096:biosynthesis*
chemical_list: C497181:USF1 protein, human; C497184:USF2 protein, human; D051720:Upstream Stimulatory Factors; C497183:Usf1 protein, mouse; C497186:Usf2 protein, mouse