Carcinogenicity of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP)in the rat prostate and induction of invasive carcinomas by subsequent treatment with testosterone propionate

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) at 400 ppm in the di et for 52 weeks was found to induce noninvasive microscopic carcinomas in t he ventral prostate of the treated rats, in addition to colon and mammary c arcinomas. The current experimental data demonstrate that only a 20-week pe riod of PhIP treatment is sufficient for induction of ventral carcinomas an d that long-term pharmacological dosing with testosterone propionate which applied through a Silastic tube embedded in the subcutis after PhIP treatme nt can induce invasive carcinomas in the anterior prostate and seminal vesi cles. Thus, PhIP may provide the basis for a good two stage carcinogenesis model for investigation of prostate carcinogenesis. (C) 1999 Elsevier Scien ce Ireland Ltd. All rights reserved.