CHANGES IN LIVER FATTY-ACID-BINDING PROTEIN IN RAT ENZYME-ALTERED FOCI

The level of liver fatty acid-binding protein (L-FABP) was analyzed in enzyme-altered foci (EAF) positive for GST-P, or after classification of foci into different subclasses by haematoxylin and eosin staining. Rats were treated with either an initiating single dose of diethylnit rosamine (DEN) followed by no treatment, treatment with phenobarbital, PCB, nafenopin or repeated injections of DEN, or alternatively non-tr eated or treated with nafenopin alone. Changes in the level of L-FABP were detected in the majority of EAF and both L-FABP-positive and -neg ative foci were seen. However, in rats initiated with DEN, EAF were al most exclusively L-FABP-negative. The fraction of L-FABP-negative foci increased with increasing foci size, while the time of treatment or: the dose of the promoter did not seem to have any effect. It was also found that treatment with DEN gave a higher fraction of L-FABP-negativ e foci as compared to treatment with phenobarbital or PCB, indicating a specific effect of DEN. These data together with previously publishe d findings suggest that L-FABP expression in EAF is determined by the initiating carcinogenic regimen and that it might be possible to use t he expression of L-FABP in tumours to differentiate initiating chemica ls. (C) 1998 Elsevier Science Ireland Ltd.