Modeling prostate cancer in mice: something old, something new, something premalignant, something metastatic
BACKGROUND Genetically engineered mouse models play important roles in analyses of prostate development and pathobiology. While constitutive genetic gain- and loss-of-function models have contributed significantly to our understanding of molecular events driving these processes, the availability of a tightly regulated inducible expression system could extend the utility of transgenic approaches. Here, we describe the development of a Tet-regulatory system that employs Hoxb13 transcriptional control elements to direct reverse tetracycline transactivator (rtTA) expression in the prostate. METHODS Using recombineering technology, the rtTA gene was placed under Hoxb13 cis-regulatory transcriptional control in the context of a 218-kb bacterial artificial chromosome. F(1) offspring carrying the Hoxb13-rtTA transgene were bred to a Tetracycline operator-Histone 2B-Green Fluorescent Protein (TetO-H2BGFP) responder line. Detailed reporter gene expression analyses, including doxycycline (Dox) induction and withdrawal kinetics, were performed in Hoxb13-rtTA|TetO-H2BGFP double transgenic adult mice and embryos. RESULTS Dox-dependent GFP expression was observed exclusively in the prostate and distal colon epithelia of double transgenic mice. Reporter gene mRNA was detected in the prostate within 6 hr of Dox exposure, and was extinguished within 24 hr after Dox withdrawal. Furthermore, Dox-induced reporter gene expression persisted after castration. CONCLUSIONS The Hoxb13-rtTA transgenic system provides a powerful tool for conditional Tet operator-driven transgene expression in the normal prostate and during disease progression. Used in conjunction with other prostate pathology models, these mice will enable precise, temporally controlled analyses of gene function and can provide opportunities for detailed analyses of molecular events underlying prostate diseases.