Oxidative DNA Damage And Repair In Chronic Atrophic Gastritis And Gastric Cancer

Background:Increased production of reactive oxygen species, which cause oxidative DNA damage, is considered to be related to gastric carcino genesis. However the same reactive oxygen species will cause different oxidative DNA damage from person to person due to different level of antioxidant enzymes. Up to now8-Hydroxy-2-deoxy-guanosine (8-OHdG) is a useful marker of DNA damage induced by oxidative stress. Human8-oxoguanine glycosylase (hOGGl) is the key component responsible for the removal of8-OHdG. MnSOD is one of antioxidant enzymes located in the mitochondrial matrix, which can scavenge ROS, prevent their formation. The aim of the present research was to detect the8-OHdG, and the expression of hOGGland MnSOD, in human gastric mucosa tissues of patients with chronic atrophic gastritis (CAG) and gastric carcinoma (GC) comparing with control group.Methods:In total,88patients (male/female45/43, mean age54years) consisted of28normal controls (NC group),30chronic atrophic gastritis patients (CAG group) and30gastric carcinoma patients (GC group) who were diagnosed with gastroscopy and pathology in2010. The level of8-OHdG in gastric biopsy specimens was assessed with Immunohistochemistry. Biopsies from68patients (male/female33/35, mean age51.5 years) consisted of32NC,26CAG,10GC. The expression level of hOGGland MnSOD in gastric biopsy specimens was assessed with Western blot.Results:Apparent difference was observed at the percentage and intensity of cells8-OHdG staining in tissues of controls, CAG group, and GC group. The8-OHdG staining in CAG and GC mucosa was stronger than control (P<0.01). hOGG1were expressed to a lower degree in GC and CAG, when compared to the control group (both P＜0.01). And the level of GC was even lower than CAG (P＜O.05). MnSOD were expressed to a greater degree in GC group, when compared to the control (P<0.05). No difference was observed between control and CAG group.Conclusion:According to the high expression of8-OHdG in GC, severe oxidative damage of DNA was found in atrophic gastritis and gastric cancer. Patients with chronic atrophic gastritis who express8-OHdG highly should be monitored carefully for the potentially occurrence of GC. The lower lever of hOGGl in CAG and GC with higher level of8-OHdG implies that hOGGl is closely related to oxidative DNA damage, and maybe lead to gastric mucosa lesions and carcinoma.