Novel method of generating prostate‐specific Cre–LoxP gene switching via intraductal delivery of adenovirus

BACKGROUND In order to facilitate elucidation of oncogene or tumor suppressor gene function on initiation and progression of prostate cancer, it would be advantageous to develop an effective method to generate spatially and temporally controlled gene modification in murine prostates. METHODS Adenovirus expressing Cre‐recombinase (Adeno‐Cre) was intraductally injected into the prostate of ROSA26 reporter mice. Immmunohistochemical and X‐gal staining were performed on prostate tissue sections harvested from mice at various time points following viral injection to confirm expression and activity of Cre‐recombinase, respectively. RESULTS Adenovirus was intraductally delivered to the anterior lobe of the mouse prostate. Using this method of intraductal injection, we were able to precisely obtain Adeno‐Cre infection to a majority of epithelial cells but not in the stromal cells or other organs. We further demonstrated that Adeno‐Cre infected epithelial cells not only expressed Cre‐recombinase enzyme but more importantly, Cre‐recombinase activity was revealed through positive X‐gal staining in Rosa26 reporter mice, thus, confirming epithelial‐specific Cre–loxP recombination in Adeno‐Cre infected prostate tissue sections. CONCLUSIONS This novel method of direct genetic delivery into adult murine prostates could provide an alternative to the more expensive and time‐consuming transgenic/knockout approaches. The latter also have other limitations such as the availability of cell‐type specific or temporally‐regulated promoters, and the complication of genetic background differences, which can potentially be complemented by the technology we describe here. © 2005 Wiley‐Liss, Inc.