PurposeTo investigate the effects of Helicobacter pylori (H. pylori)-CagA and the urease metabolite on mucin expression in AGS cells.Materials and MethodsAGS cells were transfected with CagA and/or treated with different concentrations of NH4CL. Mucin gene and protein expression was assessed by qPCR and immunofluorescence assays, respectively.ResultsCagA 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 concentrations until reaching a peak level at 15 mM. MUC5B mRNA expression in AGS cells ( concentration of 15 mM) was significantly higher than that at 0, 5, and 10 mM . No changes in E-cadherin expression in AGS cells treated with were noted, except at 20 mM. The expression of MUC5AC, MUC2, and MUC6 mRNA in CagA-transfected AGS cells at an 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 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.ConclusionH. pylori may affect the expression of MUC5AC, MUC2, MUC5B, and MUC6 in AGS cells via CagA and/or , but not E-cadherin.