PROMOTION OF CHOLANGIOCARCINOMAS BY CLONORCHIS-SINENSIS INFECTION IN HAMSTERS AFTER INDUCTION BY DIMETHYLNITROSAMINE

Clonorchis sinensis (CS) infection of hamsters exposed to dimethylnitr osamine (DMN) results in development of cholangiocarcinomas (CHCAs). H amsters administered 0.0015% DMN for 4 weeks before or simultaneously with infection by metacercariae of CS infection developed CHCA associa ted with marked papillary and adenomatous hyperplasia of bile ducts. O n the other hand, CHCAs did not develop in hamsters that were infected with CS for 5 weeks, treated with the drug, praziquantel and one week later administered DMN. CS infection alone produced oval cell and bil e duct hyperplasia, but not CHCA. These results suggest that stimulati on of bile duct proliferation by CS infection in hamster may act as a promoter on DMN initiated ''bipolar'' liver stem cells or that initiat ion by DMN occurs at the level of the bile duct committed cell.