TY - JOUR

T1 - Helicobacter pylori infection induces genetic instability of nuclear and mitochondrial DNA in gastric cells

AU - Machado, Ana Manuel Dantas

AU - Figueiredo, Ceu

AU - Touati, Eliette

AU - Máximo, Valdemar

AU - Sousa, Sonia

AU - Michel, Valérie

AU - Carneiro, Fátima

AU - Nielsen, Finn Cilius

AU - Seruca, Raquel

AU - Rasmussen, Lene Juel

N1 - Keywords: Adenocarcinoma; Adult; Animals; Apoptosis; Blotting, Western; Cell Nucleus; Cell Proliferation; Cells, Cultured; DNA Repair; DNA, Mitochondrial; Dinucleotide Repeats; Female; Genomic Instability; Helicobacter Infections; Helicobacter pylori; Humans; Male; Mice; Mice, Inbred C57BL; Middle Aged; RNA, Messenger; Reverse Transcriptase Polymerase Chain Reaction; Stomach Neoplasms

PY - 2009

Y1 - 2009

N2 - PURPOSE: Helicobacter pylori is a major cause of gastric carcinoma. To investigate a possible link between bacterial infection and genetic instability of the host genome, we examined the effect of H. pylori infection on known cellular repair pathways in vitro and in vivo. Moreover, various types of genetic instabilities in the nuclear and mitochondrial DNA (mtDNA) were examined. EXPERIMENTAL DESIGN: We observed the effects of H. pylori infection on a gastric cell line (AGS), on C57BL/6 mice, and on individuals with chronic gastritis. In AGS cells, the effect of H. pylori infection on base excision repair and mismatch repair (MMR) was analyzed by reverse transcription-PCR, Western blot, and activity assays. In mice, MMR expression was analyzed by reverse transcription-PCR and the CA repeat instabilities were examined by Mutation Detection Enhancement gel electrophoresis. Mutation spectra in AGS cells and chronic gastritis tissue were determined by PCR, single-stranded conformation polymorphism, and sequencing. H. pylori vacA and cagA genotyping was determined by multiplex PCR and reverse hybridization. RESULTS: Following H. pylori infection, the activity and expression of base excision repair and MMR are down-regulated both in vitro and in vivo. Moreover, H. pylori induces genomic instability in nuclear CA repeats in mice and in mtDNA of AGS cells and chronic gastritis tissue, and this effect in mtDNA is associated with bacterial virulence. CONCLUSIONS: Our results suggest that H. pylori impairs central DNA repair mechanisms, inducing a transient mutator phenotype, rendering gastric epithelial cells vulnerable to the accumulation of genetic instability and thus contributing to gastric carcinogenesis in infected individuals.

AB - PURPOSE: Helicobacter pylori is a major cause of gastric carcinoma. To investigate a possible link between bacterial infection and genetic instability of the host genome, we examined the effect of H. pylori infection on known cellular repair pathways in vitro and in vivo. Moreover, various types of genetic instabilities in the nuclear and mitochondrial DNA (mtDNA) were examined. EXPERIMENTAL DESIGN: We observed the effects of H. pylori infection on a gastric cell line (AGS), on C57BL/6 mice, and on individuals with chronic gastritis. In AGS cells, the effect of H. pylori infection on base excision repair and mismatch repair (MMR) was analyzed by reverse transcription-PCR, Western blot, and activity assays. In mice, MMR expression was analyzed by reverse transcription-PCR and the CA repeat instabilities were examined by Mutation Detection Enhancement gel electrophoresis. Mutation spectra in AGS cells and chronic gastritis tissue were determined by PCR, single-stranded conformation polymorphism, and sequencing. H. pylori vacA and cagA genotyping was determined by multiplex PCR and reverse hybridization. RESULTS: Following H. pylori infection, the activity and expression of base excision repair and MMR are down-regulated both in vitro and in vivo. Moreover, H. pylori induces genomic instability in nuclear CA repeats in mice and in mtDNA of AGS cells and chronic gastritis tissue, and this effect in mtDNA is associated with bacterial virulence. CONCLUSIONS: Our results suggest that H. pylori impairs central DNA repair mechanisms, inducing a transient mutator phenotype, rendering gastric epithelial cells vulnerable to the accumulation of genetic instability and thus contributing to gastric carcinogenesis in infected individuals.

U2 - 10.1158/1078-0432.CCR-08-2686

DO - 10.1158/1078-0432.CCR-08-2686

M3 - Journal article

C2 - 19383819

VL - 15

SP - 2995

EP - 3002

JO - Clinical Cancer Research

JF - Clinical Cancer Research

SN - 1078-0432

IS - 9

ER -