H.pylori infection induces the emergence of CSC-like properties in gastric cancer cells.
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H.pylori activates the Wnt/β-catenin signaling pathway in a CagA-dependent manner.
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Wnt/β-catenin signaling activation is dependent upon the H. pylori-mediated phosphorylation of β-catenin at Ser675 and Ser552 in a c-met- and/or Akt-dependent manner.
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Wnt/β-catenin signaling activation is responsible for the H.pylori-induced CSC-like properties.
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H.pylori-activated Wnt/β-catenin signaling promotes the promoter activity of Nanog and Oct4 and upregulates their expression.
Abstract
Helicobacter pylori (H.pylori) infection is considered a major risk factor for gastric cancer. CagA behaves as a major bacterial oncoprotein playing a key role in H.pylori-induced tumorigenesis. Cancer stem cells (CSCs) are believed to possess the ability to initiate tumorigenesis and promote progression. Although studies have suggested that cancer cells can exhibit CSC-like properties in the tumor microenvironment, it remains unclear whether H.pylori infection could induce the emergence of CSC-like properties in gastric cancer cells and, the underlying mechanism. Here, gastric cancer cells were co-cultured with a CagA-positive H.pylori strain or a CagA isogenic mutant strain. We found that H.pylori-infected gastric cancer cells exhibited CSC-like properties, including an increased expression of CSC specific surface markers CD44 and Lgr5, as well as that of Nanog, Oct4 and c-myc, which are known pluripotency genes, and an increased capacity for self-renewal, whereas these properties were not observed in the CagA isogenic mutant strain-infected cells. Further studies revealed that H.pylori activated Wnt/β-catenin signaling pathway in a CagA-dependent manner and that the activation of this pathway was dependent upon CagA-positive H.pylori-mediated phosphorylation of β-catenin at the C-terminal Ser675 and Ser552 residues in a c-met- and/or Akt-dependent manner. We further demonstrated that this activation was responsible for H.pylori-induced CSC-like properties. Moreover, we found the promoter activity of Nanog and Oct4 were upregulated, and β-catenin was observed to bind to these promoters during H.pylori infection, while a Wnt/β-catenin inhibitor suppressed promoter activity and binding. Taken together, these results suggest that H.pylori upregulates Nanog and Oct4 via Wnt/β-catenin signaling pathway to promote CSC-like properties in gastric cancer cells.