Effects of 13-cis retinoic acid on dibutyl-nitrosamine-induced cell kinetic changes in mouse urinary bladder epithelium.

The effect of 13-cis-retinoic acid on cell proliferation in normal urothelium and during early stages in N-nitrosodibutylamine (DBN) induced malignant transformation was studied in male hairless mice. The retinoic acid was administered orally, and the parameters studied were (a) variations in total cell number, (b) labelling index (LI), (c) mitotic rate (MR), (d) the proportions of DNA-synthesizing cells in the diploid and tetraploid fractions, and (e) morphological changes. 13-cis-retinoic acid caused no effect on these parameters in normal urothelium, nor did it prevent the changes caused by DBN in the urothelium prior to malignant development.