Immunohistochemical detection of 8-hydroxy-2'-deoxyguanosine in gallbladder epithelium of patients with pancreaticobiliary maljunction.

Abstract

Pancreaticobiliary maljunction, an anomalous union of the pancreatic duct with the common bile duct, is a risk factor for biliary carcinoma. We hypothesized that, in patients with pancreaticobiliary maljunction, persistent regurgitation of pancreatic juice into the biliary tract induces oxidative DNA damage. We assessed the expression of an oxidative DNA base-modified product, 8-hydroxy-2'-deoxyguanosine, in gallbladder epithelium. Eleven noncancerous gallbladders from patients with pancreaticobiliary maljunction, 12 gallbladder carcinomas from patients without pancreaticobiliary maljunction and 14 noncancerous gallbladders from patients without pancreaticobiliary maljunction (control) were studied. Immunohistochemistry was performed for 4-hydroxy-2-nonenal-modified protein (as a marker for lipid peroxidation), 8-hydroxy-2'-deoxyguanosine and p53 gene product. Stronger cytoplasmic staining of 4-hydroxy-2-nonenal-modified protein was observed in the gallbladder epithelium from patients with pancreaticobiliary maljunction than in epithelium from gallbladder cancer patients or from control subjects with normal gallbladders. Clear, strong nuclear staining of 8-hydroxy-2'-deoxyguanosine was observed in the gallbladder epithelial cells from patients with pancreaticobiliary maljunction. Densitometric quantitation revealed significantly higher expression of 8-hydroxy-2'-deoxyguanosine in gallbladder epithelial cells from patients with pancreaticobiliary maljunction (index 27.3 +/- 3.1) than in cells from patients with gallbladder carcinoma (11.4 +/- 1.5; P < 0.05) or from control subjects with normal gallbladder (6.4 +/- 1.0; P < 0.05). Positivity of p53 was 27% in gallbladder epithelium associated with pancreaticobiliary maljunction, 75% in gallbladder carcinoma epithelium and 0% in control epithelium. These results suggest that reactive oxygen species are produced in the gallbladder of patients with pancreaticobiliary maljunction and that oxidative DNA injury is related to carcinogenesis in these patients.