The Effect Of Benzo(a)Pyrene On Helicobacter Pylori CagA Expression And On Proliferation Of Gastric Epithelial Cells

Aims Gastric cancer is one of the most common malignant tumors worldwide. H.pylori is the major risk factor for gastric cancer. The risk for developing gastric cancer is 3-6 times higher among population infected with H.pylori than the uninfected subjects. Studies have shown that long-term consumption of grilled, fried food and smoking also are risk factors for gastric cancer. Evidence suggests a close link between the consumption of barbecue and fried foods with H.pylori infection. Benzo (a) pyrene (BaP), which is abundant in barbecue and fried foods, is a common environmental carcinogen. So the purpose of this study is to investigate the effect of BaP on the proliferation of H.pylori and CagA expression. Then we detect the proliferation of GES-1 cells after coculture with BaP and H.pylori.Methods H.pylori was inoculated on the medium with different concentration of BaP (0.2,0.5, 1.0 and 2.0 μmol/L), and set two control groups:BaP (0.0 μmol/L) and DMSO group. After 24,48, 72 hours, H.pylori proliferation was detected and then total RNA was extracted to determinate CagA expression by RT-PCR. H. pylori suspension was added to GES-1 cells at a multiplicity of infection (MOI) ranging from 20:1 to 400:1. Different concentrations of BaP 10μL (0.2,0.5,1.0 and 2.0 μmol/L) added to GES-1 cells. GES-1 cells co-cultured with H.pylori (MOI 20:1) and different concentrations of BaP. Using CCK-8 detect GES-1 cells proliferation.Results BaP promoted H.pylori proliferation. At 24 hours, BaP promoted H.pylori proliferation compared with the control group. There is a significant difference between 1.0 μmol/L and 2.0 μmol/L groups with control group. At 48 and 72 hours, all BaP groups promoted H.pylori proliferation compared with the control group (P<0.05). BaP upregulated H.pylori CagA mRNA expression at 24 and 48h, but not at 72 hours. H.pylori can promote the proliferation of GES-1 cells with different MOI. At MOI 20:1,50:1 and 100:1, H.pylori promoted GES-1 cells proliferation compared with the control group (P<0.05). When MOI was increased to 200:1, 400:1, GES-1 cells proliferation rate gradually declined, and the proliferation rate was inhibited at MOI 400:1. BaP promoted GES-1 cells proliferation in a dose-dependent manner. When H.pylori (MOI 20:1) was incubated with GES-1 cells in the presence of different concentrations of BaP, there was no dose-dependent change in the proliferation of GES-1 cells. But all BaP groups still has a significant difference compared with pure H.pylori group. In addition, in the BaP 0.2 and 0.5 μmol/L groups, GES-1 cells proliferation rate show a difference compared with BaP groups.Conclusion BaP promoted H.pylori proliferation and CagA mRNA expression in a dose- and time-dependent manners. BaP can synergically promote GES-1 cells proliferation with H.pylori. We speculate that BaP may increase the risk of H.pylori-realted gastric carcinogenesis.