Reduction of H2O2 and DDP sensitivity of ESCC cells by high-level expression of DNA repair enzyme hOGG1

Abstract

Objective To explore the effect of high-level expression of DNA repair enzyme human 8-oxoguanine DNA glycosylase (hOGG1) on H2O2 and cisplatin (DDP) sensitivity of esophageal squamous cell carcinoma (ESCC) EC9706 cells. Methods Recombinant adenovirus pAd-CMV5-DEST-hOGG1 was transferred into EC 9706 cells to establish the EC9706 cell model with high-level expression of hOGG1 protein. EC9706 cells infected with the recombinant adenovirus (EC9706-hOGG1) or adenovirus vector (EC9706-LACZ), or non-transfected EC9706 cells (EC9706) were acted by H2O2 and DDP, respectively. The survival rate of the three kinds of cells was compared by using methyl thiazol tetrazolium (MTT) and trypan blue experiments. The comparison of the oxidative damage of the three kinds of ceils was performed by using 8-oxoG immunohistochemistry. The apoptosis index were assayed by the TUNEL staining and flow cytometry (FCM). Results The higher survival rate and the lower 8-oxoG oxidative damage and the lower apoptosis index of the EC9706 cells with high-lever high hOGGlexpression were than ones of the two control groups;Detected by FCM,after 1000 μmol/L H2O2 inducing apoptosis 1.5 hour, cell apoptosis rate of EC9706-hOGG1 ( 5.50％ ) was downregulated markedly than EC9706-LACZ ( 12. 54％ ) and EC9706 cells (13.48％). After three groups treat with 10 mg/L DDP 1.5 h,the apoptois rate in groups EC9706-hOGG1 ,EC9706-LACZ and EC9706 was 3.95％, 11.59％ and 11.48％. There was significant difference between group EC9706-hOGG1 and other control groups. Conclusion The high-level expression of hOGG1 protein of EC 9706 cells may reduce H2O2 and cisplatin sensitivity to EC 9706 cells. Key words: Esophageal squamous cell carcinoma; hOGG1 ; H2O2 ; Cisplatin