Examining the effect of cagPAI variety on gene expression pattern related to gastric cancer.

Objectives: We aimed to determine possible association between heterogeneity of cytotoxin-associated gene pathogenicity island and gene expression profiles in patients with distinct histopathological changes.

Methods: Gastric biopsies were obtained from seventy five patients. Microbiological and pathological examinations were done and intactness of PAI was determined by PCR using 11 pairs of primers flanking - regions and PAI empty site. Alterations at mRNA levels of eight genes were investigated by real-time PCR and their association with PAI intactness and histopathological changes examined statistically.

Results: A larger proportion of PAI positive strains colonized patients with SAG (52.4%), followed by CG (33.3%), and IM (14.3%). Intact PAI was found in 87.5% of the strains obtained from patients with SAG, while significantly lower frequency was detected among those with CG (12.5%) and IM (0%). No significant difference was found among the studied histological groups and fold changes in gene expression of gastric biopsies of infected patients with distinct PAI status. However, in each histological group, the strains with more complete gene cluster induced (, , , and in SAG and IM groups) or reduced (, in CG group) expression of the GC associated genes in relatively higher levels. , and were down-regulated in patients with SAG and IM compared with CG patients, irrespective to the status of PAI integrity.

Conclusions: strains that carry more complete PAI segment could induce remarkably higher levels of mRNA changes of GC associated genes in all histopathological groups.