Preventive effect of JTE-522, a selective cyclooxygenase-2 inhibitor, on DEN-induced hepatocarcinogenesis in rats

Abstract

Background Chemopreventive effect of a selective cyclooxygenase-2 (COX-2) inhibitor JTE-522 on diethylnitrosamine (DEN)-induced hepatocarcinogenesis was evaluated in Wistar rats. Methods Animals in the control group (G1) were injected with phosphate buffered saline (PBS), those in hepatocellular carcinoma (HCC) group (G2) were injected with DEN with regular foods for 14 weeks, and those in the treatment groups were injected with DEN for 14 weeks fed with JTE-522 for 7 (G3) and 14 weeks (G4), respectively. Proliferation and precancerous lesions were evaluated by expression levels of proliferating cell nuclear antigen (PCNA) and glutathione S-transferase-P (GST-P), respectively by immunohistochemistry and Western blot analysis. Apoptosis and oxidative stress were evaluated by TdT-mediated dUTP-biotin nick-end labeling (TUNEL) and 8-hydroxy-2’-deoxyguanosine (8-OHdG) staining, respectively. Results After 14 weeks of the treatment, HCC was developed in G2, G3, and G4 showing no significant differences in gross appearance and histology of the liver among the three groups. There were no significant differences in the expression levels of PCNA and numbers of TUNEL and 8-OHdG positive cells in the liver among the three groups. However, GST-P positive area was significantly suppressed in G3 and G4 compared to G2. Conclusion Our data revealed that JTE-522 had a modest inhibitory effect on hepatocarcinogenesis in rats in a manner independent of induction of apoptosis and inhibition of oxidative stress.