Helicobacter pylori infection induced gastric cancer; advance in gastric stem cell research and the remaining challenges.

Helicobacter pylori infection is the major cause of gastric cancer, which remains an important health care challenge. Recent investigation in gastric stem cell or progenitor cell biology has uncovered valuable information in understanding the gastric gland renewal and maintenance of homeostasis, they also provide clues for further defining the mechanisms by which gastric cancer may originate and progress. Lgr5, Villin-promoter, TFF2-mRNA and Mist have recently been identified as gastric stem/progenitor cell markers; their identification enriched our understanding on the gastric stem cell pathobiology during chronic inflammation and metaplasia. In addition, advance in gastric cancer stem cell markers such as CD44, CD90, CD133, Musashi-1 reveal novel information on tumor cell behavior and disease progression implicated for therapeutics. However, two critical questions remain to be of considerable challenges for future exploration; one is how H. pylori or chronic inflammation affects gastric stem cell or their progenitors, which give rise to mucus-, acid-, pepsinogen-, and hormone-secreting cell lineages. Another one is how bacterial infection or inflammation induces oncogenic transformation and propagates into tumors. Focus on the interactions of H. pylori with gastric stem/progenitor cells and their microenvironment will be instrumental to decipher the initiation and origin of gastric cancer. Future studies in these areas will be critical to uncover molecular mechanisms of chronic inflammation-mediated oncogenic transformation and provide options for cancer prevention and intervention. We review recent progress and discuss future research directions in these important research fields.