CDX1 confers intestinal phenotype on gastric epithelial cells via induction of stemness-associated reprogramming factors SALL4 and KLF5

Intestinal metaplasia of the stomach, a mucosal change characterized by the conversion of gastric epithelium into an intestinal phenotype, is a precancerous lesion from which intestinal-type gastric adenocarcinoma arises. Chronic infection with Helicobacter pylori is a major cause of gastric intestinal metaplasia, and aberrant induction by H. pylori of the intestine-specific caudal-related homeobox (CDX) transcription factors, CDX1 and CDX2, plays a key role in this metaplastic change. As such, a critical issue arises as to how these factors govern the cell- and tissue-type switching. In this study, we explored genes directly activated by CDX1 in gastric epithelial cells and identified stemness-associated reprogramming factors SALL4 and KLF5. Indeed, SALL4 and KLF5 were aberrantly expressed in the CDX1⁺ intestinal metaplasia of the stomach in both humans and mice. In cultured gastric epithelial cells, sustained expression of CDX1 gave rise to the induction of early intestinal-stemness markers, followed by the expression of intestinal-differentiation markers. Furthermore, the induction of these markers was suppressed by inhibiting either SALL4 or KLF5 expression, indicating that CDX1-induced SALL4 and KLF5 converted gastric epithelial cells into tissue stem-like progenitor cells, which then transdifferentiated into intestinal epithelial cells. Our study places the stemness-related reprogramming factors as critical components of CDX1-directed transcriptional circuitries that promote intestinal metaplasia. Requirement of a transit through dedifferentiated stem/progenitor-like cells, which share properties in common with cancer stem cells, may underlie predisposition of intestinal metaplasia to neoplastic transformation.