Use of Precision-Cut Liver Slices to Evaluate Species Differences in 2-Acetylaminofluorene-Induced Unscheduled DNA Synthesis

Abstract

Precision-cut liver slices were prepared from male Sprague–Dawley rats (pretreated with or without Aroclor 1254), male Dunkin–Hartley guinea pigs, male cynomolgus monkeys, and humans. Liver slices were cultured for 24 hr using a dynamic organ culture system in medium containing [3H]thymidine and 2-acetylaminofluorene (2-AAF), aflatoxin B1(AFB1), or 6-aminochrysene (6-AC). The liver slices were then harvested and processed for autoradiographic evaluation of unscheduled DNA synthesis (UDS). All three genotoxins induced UDS in liver slices from untreated and Aroclor 1254-treated rats. In human liver slices 2-AAF produced a concentration-dependent induction of UDS and at the highest concentration examined 2-AAF also induced UDS in guinea pig liver slices. However, 2-AAF did not induce UDS in cynomolgus monkey liver slices, although both AFB1and 6-AC induced UDS in liver slices from this species as well as from guinea pigs and humans. The inability of 2-AAF to induce UDS in cynomolgus monkey liver slices appears to be at least partially due to the absence of hepatic CYP1A2 in this species. Precision-cut liver slices appear to be a useful alternative to primary hepatocyte cultures for studies of xenobiotic-induced genotoxicity employing the UDS technique. As shown by this study they may also be employed to evaluate species differences in xenobiotic-induced genotoxicity.