Effect of treatment failure on the Cag A EPIYA motif in Helicobacter pylori strains from Colombian subjects

AIM To evaluate effect of treatment failure on cag A and vac A genotypes in Helicobacter pylori(H. pylori) isolates from Colombia.METHODS One hundred and seventy-six participants infected with H. pylori from Colombia were treated during 14 d with the triple-standard therapy. Six weeks later, eradication was evaluated by 13C-Urea breath test. Patients with treatment failure were subjected to endoscopy control; biopsies obtained were used for histopathology and culture. DNA from H. pylori isolates was amplified using primers specific for cag A and vac A genes. The phylogenetic relationships among isolates obtained before and after treatment were established by conglomerate analysis based on random amplified polymorphic DNA(RAPD) fingerprinting.RESULTS Treatment effectiveness was at 74.6%. Of the par-ticipants with treatment failure, 25 accepted subjected to a second endoscopy. Prevalence of posttreatment infection was 64%(16/25) and 40%(10/25) by histology and culture, respectively. Upon comparing the cag A and vac A genotypes found before and after therapy, multiple cag A genotypes(cag A-positive and cag A-negative) were found before treatment; in contrast, cag A-negative genotypes decreased after treatment. vac A s1m1 genotype was highly prevalent in patients before and after therapy. The 3'cag A region was successfully amplified in 95.5%(21/22) of the isolates obtained before and in 81.8%(18/22) of the isolates obtained after treatment. In the isolates obtained from patients with treatment failure, it was found that 72.7%(16/22) presented alterations in the number of EPIYA motifs, compared to isolates found before treatment.CONCLUSION Unsuccessful treatment limits colonization by lowvirulence strains resulting in partial and selective eradication in mixed infections, and acts on the cag A-positive strains inducing genetic rearrangements in cag A variable region that produces a loss or gain of EPIYA repetitions.

Influence of Helicobacter pylori oncoprotein CagA in gastric cancer:A critical-reflective analysis

Gastric cancer is the fifth most common malignancy and third leading cancerrelated cause of death worldwide.Helicobacter pylori is a Gram-negative bacterium that inhabits the gastric environment of 60.3%of the world’s population and represents the main risk factor for the onset of gastric neoplasms.CagA is the most important virulence factor in H.pylori,and is a translocated oncoprotein that induces morphofunctional modifications in gastric epithelial cells and a chronic inflammatory response that increases the risk of developing precancerous lesions.Upon translocation and tyrosine phosphorylation,CagA moves to the cell membrane and acts as a pathological scaffold protein that simultaneously interacts with multiple intracellular signaling pathways,thereby disrupting cell proliferation,differentiation and apoptosis.All these alterations in cell biology increase the risk of damaged cells acquiring pro-oncogenic genetic changes.In this sense,once gastric cancer sets in,its perpetuation is independent of the presence of the oncoprotein,characterizing a“hit-and-run”carcinogenic mechanism.Therefore,this review aims to describe H.pylori-and CagA-related oncogenic mechanisms,to update readers and discuss the novelties and perspectives in this field.