The p53 homologue p63 encodes for different isotypes able to either transac
tivate p53 reporter genes (TAP63) or act as p53-dominant-nebatives (Delta N
p63). p63 is expressed in the basal cells of many epithelial organs and its
germline inactivation in the mouse results in agenesis of organs such as s
kin appendages and the breast. Here, we show that prostate basal cells, but
not secretory or neuroendocrine cells, express p63, In addition, prostate
basal cells in culture predominantly express the Delta Np63 alpha isotype,
In contrast, p63 protein is not detected in human prostate adenocarcinomas.
Finally, and most importantly, p63(-/-) mice do not develop the prostate.
These results indicate that p63 is required for prostate development and su
pport the hypothesis that basal cells represent and/or include prostate ste
m cells. Furthermore, our results show that p63 immunohistochemistry may be
a valuable tool in the differential diagnosis of benign versus malignant p
rostatic lesions.