Persistent Hedgehog overexpression induces mouse prostate tumorigenesis. (A) Histopathological analysis with hematoxylin-eosin stain showing characteristics of progressive tumor formation through stages of PIN and CaP in a pCX-shh-IG-injected prostate at day 90 as compared to sham (0.9%NaCl) and vehicle (pCX-IG) injection controls. The lower pictures are higher magnifications corresponding to the tissue sections shown in the upper pictures. (B) Tumor formation induced by Hedgehog overexpression (arrowheads in (b) indicate tumor mass), as compared to vehicle control (arrowhead in (a)). The prostate gland displayed GFP signals at day 90 after pCX-shh-IG injection (arrowhead-indicated in (c) and (d), also magnified in the inlets). (C) The pCX-shh-IG-injected prostate tissue sections were stained strongly for Hedgehog protein in PIN and CaP, in contrast to those of the sham and vehicle controls. Scale bars: 50 μm in upper (d) of panel A; 10 μm in lower (d) of panel A and in (d) of panel C. CaP: prostate cancer; HE: hematoxylin-eosin stain; PIN: prostatic intraepithelial neoplasia; HGPIN: high grade prostatic intraepithelial neoplasia.