Chemoprevention of experimental bladder cancer

Abstract

The chemopreventive efficacy of several compounds was evaluated in the N-butyl-N-(4-hydroxybutyl)nitrosamine (OH-BBN)-induced urinary bladder cancer model using C57BL/6 x DBA/2F1 (BDF) male mice. Compounds were administered in a defined semipurified diet (AIN-76-A) either as single agents or in combination. As single agents and at the doses employed, 2-alpha-difluoromethylornithine (DFMO), piroxicam, oltipraz, and sodium molybdate effectively inhibited the incidence of transitional cell carcinoma (TCC). 4-Hydroxyphenyl retinamide (4-HPR) was ineffective. Body weight gain and survival was not affected by the doses of agents used. Combinations of two agents which increased efficacy were 4-HPR+DFMO, DFMO+piroxicam, 4-HPR+oltipraz, and DFMO+oltipraz. Three-agent combinations which showed enhanced efficacy against TCC induction were 4-HPR+Na molybdate+DFMO, 4-HPR+DFMO+piroxicam, and 4-HPR+DFMO+oltipraz. Although the three-agent combinations were, for the most part, no more effective than the two-agent combinations at the doses employed, all combination regimens significantly reduced bladder cancer incidence even when single agent administration did not.