Analysis of loss of heterozygosity in neoplastic nodules induced by diethylnitrosamine in the resistant BFF1 rat strain

Loss of heterozygosity (LOH) at specific chromosomal regions is a frequent event in poorly differentiated human hepatocellular carcinomas (HCCs), but rare in mouse HCCs. This behavior could depend on interspecies differences in mechanisms of hepatocarcinogenesis or in developmental stage of lesions, To verify if LOH is involved in rat hepatocarcinogenesis, we studied LOH f requency in slowly growing neoplastic nodules induced by Solt-Farber model in diethylnitrosamine-initiated BFF1 rats. We analyzed, with microsatellite s, markers at 67 rat loci dispersed over all chromosomes, corresponding to regions homologous to those lost in human HCCs or containing hepatocellular susceptibility (Hcs) or resistance (Hcr) loci in rat and mouse. In agreeme nt with previous findings with mouse HCCs, but at variance with human HCCs, no detectable LOH was found at any locus in rats, suggesting rare LOH invo lvement in neoplastic nodules, with low tendency to progress to full malign ancy, of BFF1 rats.