Enhancement of DHPN induced hepatocellular, cholangiocellular and pancreatic carcinogenesis by Opisthorchis viverrini infestation in Syrian golden hamsters.

Infection with 100 Opisthorchis viverrini (OP) metacercariae prior to two injections of dihydroxy-di-n-propyl nitrosamine (DHPN) (1000 mg/kg body weight) brought about significant enhancement of resultant preneoplastic lesion development in Syrian hamster liver and pancreas tissue. Thus combined treatment with carcinogen and parasite was associated with pancreatic atypical (dysplastic) foci, hepatocellular nodules, cholangiofibrosis and cholangiocarcinomas. No such lesions were observed in carcinogen alone, parasite alone or untreated control groups. In addition, parasite induced hyperplastic gall bladder epithelium was found to include areas of putative preneoplastic cells only in the DHPN-OP combined group. The results strongly suggest that pancreatitis and biliary cirrhosis associated with liver fluke infestation are responsible for the observed enhancement of carcinogenesis, and that the resultant increased proliferation plays a major role in tumorigenesis.