Characterization of gastric cardia tumors : differences in Helicobacter pylori strains and genetic polymorphisms

Abstract

Background Gastric cancer results from a multifactorial process and is one of the most common causes of death worldwide. These tumors can arise in the distal stomach (non-cardia) and in the cardia region, presenting different characteristics and frequency of occurrence worldwide. Aims To search for differences between tumors of dif- ferent locations that could explain the presence of cardia tumors, considering Helicobacter pylori strains and genetic polymorphisms. Materials and Methods DNA was extracted from gastric adenocarcinoma tissue of 127 patients. Helicobacter pylori genes were detected by PCR, and polymorphisms by PCR– RFLP. Results Most of the tumors were located in non-cardia. The genotype 28152GA of XRCC1 showed an increase in risk of cardia tumors. In analysis performed considering gender, women carrying TNF -308GA genotype showed a decreased risk of non-cardia tumors, while in men the decreased risk of non-cardia tumors was associated with TNF -308GG genotype. Genotypes combinations showed that the SNPs RAD51 135G [ C, XRCC3 18067C [ T, and XRCC1 28152G [ A had some combinations more frequent in cardia tumors, with an increased risk. Patients infected by cag E-positive strains presented a positive correlation with non-cardia tumors. Conclusion The results showed some susceptibility dif- ferences between tumors of different locations. There was an increased risk relationship between three repair enzyme SNPs and cardia tumors, and the G allele of the cytokine gene TNF negatively influenced the development of non- cardia tumors. Helicobacter pylori strains seemed to be different in the cardia region, where they were less virulent than those located in the distal region of the stomach.