Prostate carcinoma in transgenic Lewis rats - a tumor model for evaluation of immunological treatments.

Transgenic rodent models of prostate cancer have served as valuable preclinical models to evaluate novel treatments and understand malignant disease progression. In particular, a transgenic rat autochthonous model of prostate cancer using the SV40 large T antigen expressed under a prostate-specific probasin promoter was previously developed as a model of androgen-dependent prostate cancer (TRAP). In the current report, we backcrossed this strain to the Lewis strain, an inbred rat strain better characterized for immunological analyses. We demonstrate that Lewis transgenic rats (Lew-TRAP) developed prostate adenocarcinomas with 100% penetrance by 25 weeks of age. Tumors were predominantly androgen-dependent, as castration prevented tumor growth in the majority of animals. Finally, we demonstrate that Lew-TRAP rats could be immunized with a DNA vaccine encoding a human prostate tumor antigen (prostatic acid phosphatase) with the development of Lewis strain-specific T-cell responses. We propose that this Lew-TRAP strain, and prostate tumor cell lines derived from this strain, can be used as a future prostate cancer immunotherapy model.