Effects of the Helicobacter pylori Virulence Factor CagA and Ammonium Ion on Mucins in AGS Cells

PURPOSE: To investigate the effects of Helicobacter pylori (H. pylori)-CagA and the urease metabolite [Formula: see text] on mucin expression in AGS cells. MATERIALS AND METHODS: AGS cells were transfected with CagA and/or treated with different concentrations of NH(4)CL. Mucin gene and protein expression was assessed by qPCR and immunofluorescence assays, respectively. RESULTS: CagA significantly upregulated MUC5AC, MUC2, and MUC5B expression in AGS cells, but did not affect E-cadherin and MUC6 expression. MUC5AC, MUC6, and MUC2 expression in AGS cells increased with increasing [Formula: see text] concentrations until reaching a peak level at 15 mM. MUC5B mRNA expression in AGS cells ([Formula: see text] concentration of 15 mM) was significantly higher than that at 0, 5, and 10 mM [Formula: see text]. No changes in E-cadherin expression in AGS cells treated with [Formula: see text] were noted, except at 20 mM. The expression of MUC5AC, MUC2, and MUC6 mRNA in CagA-transfected AGS cells at an [Formula: see text] concentration of 15 mM was significantly higher than that at 0 mM, and decreased at higher concentrations. The expression of MUC5B mRNA increased with increases in [Formula: see text] concentration, and was significantly higher compared to that in untreated cells. No significant change in the expression of E-cadherin mRNA in CagA-transfected AGS cells was observed. Immunofluorescence assays confirmed the observed changes. CONCLUSION: H. pylori may affect the expression of MUC5AC, MUC2, MUC5B, and MUC6 in AGS cells via CagA and/or [Formula: see text], but not E-cadherin.