The heterocyclic amines IQ and MeIQx show no promotive effect in a short-term in vivo liver carcinogenesis assay

The food-derived heterocyclic amines 2-amino-3-methylimidazo4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo4,5-f]quinoxaline(MeIQx) are carcinogenic in rodents as well as in non-humanprimates (IQ). Using a shortterm liver carcinogenesis modelthe compounds were found to be only weak initiators. It is alsopossible that these amines are involved in other phases of thecarcinogenesis process. In an attempt to study the promotiveeffects of IQ and MeIQx, these heterocyclic amines were repeatedlygiven by gavage, over a period of 10 days, to Wistar rats previouslyinitiated with diethylnitrosamine (DEN) and subjected to a partialhepatectomy. The rats were killed 1 month after DEN administrationand their livers examined for glutathione-S-transferase positive(GST-P) foci. The positive control, 2-acetylaminofluorene, significantlyincreased the development of GST-P foci in the DEN-treated ratscompared to the negative control, saline. However, neither theIQ- nor the MeIQx-treated groups differed from the controlsand thus these amines do not promote the growth of DEN-initiatedGST-P liver foci in this model.