Characterization of prostatic epithelial cell lines derived from transgenic adenocarcinoma of the mouse prostate (TRAMP) model

To develop a syngeneic transplantable system to study immunotherapeutic approaches for the treatment of prostate cancer, three cell lines were established from a heterogeneous 32 week tumor of the transgenic adenocarcinoma mouse prostate (TRAMP) model. TRAMP is a transgenic line of C57BL/6 mice harboring a construct comprised of the minimal -426/+28 rat probasin promoter driving prostate-specific epithelial expression of the SV40 large T antigen. TRAMP males develop histological prostatic intraepithelial neoplasia by 8-12 weeks of age that progress to adenocarcinoma with distant metastases by 24-30 weeks of age. The three cell lines (TRAMP-C1, TRAMP-C2, and TRAMP-C3) express cytokeratin, E-cadherin, and androgen receptor by immunohistochemical analysis and do not appear to have a mutated p53. Although TRAMP-C1 and TRAMP-C2 are tumorigenic when grafted into syngeneic C57BL/6 hosts, TRAMP-C3 grows readily in vitro but does not form tumors. The T antigen oncoprotein is not expressed by the cell lines in vitro or in vivo. The rationale for establishing multiple cell lines was to isolate cells representing various stages of cellular transformation and progression to androgen-independent metastatic disease that could be manipulated in vitro and, in combination with the TRAMP model, provide a system to investigate therapeutic interventions, such as immunotherapy prior to clinical trials.