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

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.