Chronic CagA‐positive Helicobacter pylori infection with MNNG stimulation synergistically induces mesenchymal and cancer stem cell‐like properties in gastric mucosal epithelial cells

Abstract A CagA‐positive Helicobacter pylori ( H. pylori ) infection can cause malignant transformation of human gastric mucosal epithelial cells, and N‐methyl‐N’‐nitro‐N‐nitrosoguanidine (MNNG) is a chemical carcinogen that induces gastric carcinogenesis. Whether this environmental chemocarcinogen may synergistically enhance the risk of H. pylori ‐infected gastric cancer remains unclear. In this study, we adopted a chronic CagA‐positive H. pylori infection with or without MNNG coinduction to establish a cellular model in GES‐1 cells and an animal model in C57BL/6J mice. The proliferation, cell phenotype, apoptosis, epithelial‐mesenchymal transition (EMT), stemness and tumorigenicity of gastric mucosal epithelial cells were analyzed in vitro and in vivo. The results showed that chronic H. pylori ‐infected GES‐1 cells displayed inhibited apoptosis, abnormal proliferation, enhanced invasion, and migration, increased EMT/mesenchymal phenotype, colony formation and stem cell‐like properties, and enhanced tumorsphere‐formatting efficiency as well as CD44 expression, a known gastric cancer stem cell (CSC) marker. MNNG synergistically promoted the above actions of chronic H. pylori infection. Further studies in chronic H. pylori ‐infected C57BL/6J mice models showed that an increased incidence of premalignant lesions in the gastric mucosa tissue of the H. pylori ‐infected mice had occurred, the mouse gastric mucosa cells exhibited similar mesenchymal and CSC‐like properties in the above GES‐1 cells, and precancerous lesions and EMT/CSC‐like phenotypes were reinforced by the synergistic action of MNNG stimulation. H. pylori infection and/or MNNG induction were capable of causing enhanced expression and activation of Wnt2 and β‐catenin, indicating that the Wnt/β‐catenin pathway is involved in the actions of H. pylori and MNNG. Taken together, these findings suggest that chronic CagA‐positive H. pylori infection with MNNG stimulation synergistically induces mesenchymal and CSC‐like properties of gastric mucosal epithelial cells.