Investigate the influence of a CagA-negative Helicobacter pylori strain, GD13, on nonhomologous end joining-mediated repair of proximal DNA double-strand breaks in GCV6 cells

Abstract

Mammalian cells infected with Helicobacter pylori show an accumulation of DNA double-strand breaks (DSBs). Previous studies have shown that the virulence factor CagA of H. pylori induces genomic instability in host cells. Most DSBs in infected cells are repaired by nonhomologous end-joining (NHEJ) pathways. Indeed, impairment of NHEJ-mediated DSB repair may lead to genetic alterations and contribute to the development of gastric cancer. Nonetheless, the impacts of H. pylori and its virulence factor, CagA, on the efficacy of NHEJ are poorly defined. This study aimed to reveal the effect of GD13, a CagA-H. pylori strain isolated in Vietnam, on the NHEJ-mediated repair of DSBs in host cells. For this purpose, we utilized GCV6 cells with an NHEJ-reporter substrate, which has been proven to be an appropriate model for evaluating the repair efficiency of NHEJ in H. pylori-infected cells. The level of interleukin-8 released into the cell culture supernatant was measured by ELISA. Our findings suggest that the reference CagA+ 26695 strain impaired the NHEJ-mediated repair of double-strand breaks (DSBs), whereas the GD13 strain has not exhibited any discernible effect thus far. In addition, H. pylori strain GD13 triggered a lower level of interleukin-8 secretion in GCV6 cells than did the CagA-positive strain 26695.