IQ (2-amino-3-methylimidazo[4,5-f]quinoline)-induced aberrant crypt foci and colorectal tumour development in rats fed two different carbohydrate diets.

Abstract

In most aberrant crypt foci (ACF) and colorectal tumour studies, chemical carcinogens not normally found in food have been used as initiators. In the present study the food-related compound, IQ (2-amino-3-methylimidazo[4,5-f]quinoline), has been used. A diet high in refined carbohydrates has been associated with enhanced development of ACF and colorectal cancer in humans. The present study was designed as an integrated part of our earlier published ACF study and follows the animals until tumour development. The aim of the study was to investigate (1) the effect of a refined carbohydrate-rich diet on the development of IQ-induced ACF over time and (2) possible correlation between early and late ACF and/or colorectal tumour development. The study showed that a feeding regimen with continuous doses of 0.03% IQ in the diet for 14 weeks, followed by 32 weeks without IQ was able to induce tumours in the rat colon, liver, skin and Zymbal gland. The data demonstrate that a sucrose-rich diet enhance ACF development. A correlation between the outcome of early and late ACF was seen. However, as the tumour incidence of this study was very low it was not possible to obtain a meaningful correlation between ACF development and colorectal tumour incidence.