Colon tumor promotion: Is it a selection process? Effects of cholate, phytate, and food restriction in rats on proliferation and apoptosis in normal and aberrant crypts

Promotion would suppose the selection of initiated cells. We tested the selection of aberrant crypt cells by cholic acid, a colon cancer promoter, and the effect of protectors, phytate and food restriction. After an azoxymethane injection, rats were allocated to a control diet, or to supplements of cholic acid, sodium phytate, or to a 50% food restriction. The proliferation and apoptosis of 1200 crypts were assessed, after immune-staining for BrdU. Cholic acid increased the proliferation of aberrant crypts but not of normal crypts. Phytate and food restriction decreased the proliferation of normal crypts, but not of aberrant crypts. Apoptosis was not affected by diets. Results support the hypothesis that cholic acid can select initiated cells in the colon. (C) 1997 Elsevier Science Ireland Ltd.