FREQUENT P53 MUTATIONS AND OCCASIONAL LOSS OF CHROMOSOME-4 IN INVASIVE BLADDER-CARCINOMA INDUCED BY N-BUTYL-N-(4-HYDROXYBUTYL)NITROSAMINE IN B6D2F(1) MICE

B6D2F(1) mice (45/group) were treated with N-butyl-N-(4-hydroxybutyl)n itrosamine (BBN) or uracil as follows: Group 1 received 0.05% BBN in d rinking water for the entire experiment, Group 2 received 5 mg of BBN by gastric gavage in 0.1 mL of 20% ethanol twice per week for 10 wk, G roup 3 received a 2.5% uracil-containing diet for the entire experimen t, and Group 4 was controls (received 0.1 mt of 20% ethanol by gavage twice per week for 10 wk). The surviving mice in Group 1 were killed a fter week 26 and those in the other groups after week 30. By week 15, three of 11 Group 1 and one of 15 Group 2 mice had bladder carcinoma. By 26 and 30 wk, respectively, invasive carcinomas were observed in 33 of 34 and six of 21 mice in Groups 1 and 2 and renal pelvic carcinoma s in 11 of 34 and three of 21 mice in Groups 1 and 2. Four of 19 uraci l-treated mice had bladder nodular hyperplasia. By polymerase chain re action-single-strand conformation polymorphism and sequence analyses, 16 of 20 and two of five bladder carcinomas from Groups 1 and 2, respe ctively, showed mutations in the p53 gene. Ha-ras mutation was present in one case. Loss of heterozygosity analysis with simple-sequence len gth polymorphism markers for chromosome 4 showed that 10 of 21, two of 15, and nine of 13 mice in Groups 1-3, respectively, had heterozygous or homozygous deletions. B6D2F(1) mice are therefore susceptible to t he urothelial carcinogenic effects of BBN and develop frequent p53 mut ations and chromosome 4 deletions. Chromosome 4 deletions were also se en with uracil. (C) 1998 Wiley-Liss, Inc.