Age-dependent histopathological findings in the prostate of probasin/SV40 T antigen transgenic rats: lack of influence of carcinogen or testosterone treatment.

Sequential changes in the phenotype of prostatic lesions and the impact of additional carcinogen treatment or castration on development and progression of prostate cancers were examined in probasin/simian virus 40 (SV40) T antigen transgenic (TG) rats. Non-invasive prostate adenocarcinomas were evident in all lobes at 15 weeks of age. Invasive tumors were limited to the anterior lobe at this time point and were found in all lobes in an age-dependent manner thereafter. No metastasis was apparent at any age. Additional carcinogen treatment or castration did not enhance progression or generate selective growth of hormone-independent prostate cancer cells. These results suggest that our TG rats are suitable for clarification of mechanisms in early stages of prostate carcinogenesis, that is, from prostatic intraepithelial neoplasia (PIN) to non-invasive and then invasive lesions.