In vitro detection of differential and cell-specific hepatobiliary toxicity induced by geldanamycin and 17-allylaminogeldanamycin in rats

The differential toxicity of two anticancer agents is described using the in vitro rat liver slice culture model. Liver slices from F-344 rats were cultured for 5days in Waymouth’s-based medium with exposure to a range of geldanamycin (GEL) or 17-allylaminogeldanamycin (17-AAG) concentrations. GEL induced concentration-dependent reduction of alkaline phosphatase and of γ-glutamyl transferase levels, which are indicators of biliary epithelial cell(s) (BEC) viability, and exhibited hepatocellular toxicity at higher concentrations. Histologically, BEC cell injury was evident at the lowest GEL concentration (0.1μM) and progressed to overt bile duct necrosis at 5μM, a level at which hepatocellular damage was also more prominent. Slices exposed to the same concentrations were more sensitive to toxic effects of GEL than of 17-AAG. 17-AAG at the lowest concentration had more slice biomarker retention than GEL, and histological analysis revealed minimal toxic effect on BEC. With increasing concentration, BEC were progressively lost, and BEC proliferation was completely inhibited at 5μM 17-AAG. Hepatocellular injury was evident only at high dose exposures. This is believed to be the first use of an in vitro liver tissue model to accurately predict the differential and concentration-dependent toxicities of these compounds.