ABSTRACT
<p><b>OBJECTIVE</b>To investigate the relationship between the helicobacter pylori (HP) infection and the genetic instability of mitochondrial DNA (mtDNA) in human gastric adenocarcinoma epithelial cells (AGS).</p><p><b>METHODS</b>After treated with extracts of HP11638 (CagA+, VacA+) or Hp11638 mutant strain (CagA+, VacA-), AGS cells were collected, and mitochondrial DNA was extracted and Cox-I, Cox-II, Cox-III, ATPase6, ATPase8 and Cytb genes and the D-Loop region were amplified by PCR and then sequenced.</p><p><b>RESULTS</b>The mutation rates of the mtDNA in AGS cells were correlated with the extracts of the two HP strains in a concentration- and time-dependent manner. But the mtDNA mutation rate in AGS cells treated with the HP11638 extract was higher than that treated with the Hp11638 mutant extract. Total of 616 mutations in D-Loop region were detected, including 489 point mutations, 81 insertions and 46 deletions. Among them, 70.9% (437/616) belonged to GC to AT and AT to GC transition. Seventeen out of 20 (85%) AGS cells treated with extract of HP had mutations in 303PolyC, 16184PolyC and 514CA regions of mtDNA D-Loop. No mutation was detected in Cox-I, Cox-II, Cox-III, ATPase6 and ATPase8 genes, three point mutations were found in the Cytb gene.</p><p><b>CONCLUSION</b>HP can cause the accumulation of mutations in mtDNA, in particular, in the D-Loop region, and the VacA participated in the process.</p>