p16 Is upregulated in proliferative inflammatory atrophy of the prostate

• Published in: The Prostate 2005-09, Vol.65 (1), p.73-82
• Main Authors: Faith, Dennis, Han, Steven, Lee, Daniel K., Friedl, Andreas, Hicks, Jessica L., De Marzo, Angelo M., Jarrard, David F.
• Format: Article
• Language: English
• Subjects: Aged; Atrophy; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p16 - analysis; Fluorescent Antibody Technique; Humans; Immunohistochemistry; inflammation; Inflammation - pathology; Ki-67 Antigen - analysis; Male; Middle Aged; p16; Prostate - chemistry; Prostate - pathology; prostate atrophy; Up-Regulation
• ISSN: 0270-4137; 1097-0045
• DOI: 10.1002/pros.20258

BACKGROUND Proliferative inflammatory atrophy (PIA) of the prostate is a common histological finding that has been postulated to be associated with prostate cancer. We examine PIA lesions for the expression of p16/CDKN2, a cyclin‐dependent kinase inhibitor frequently altered in prostate cancer. METHODS Within tissues from two independent patient populations (“Test Set” and “Validation Set”) undergoing radical prostatectomy, PIA lesions were identified and subjected to immunohistochemical staining for p16. Atrophic epithelial cells and regional normal epithelium were scored for the extent of p16 staining. In the Test Set, staining was also performed for the proliferation marker Ki‐67. Double label immunofluorescence was employed to co‐localize staining for p16 and Ki‐67. RESULTS p16 expression was elevated in PIA in both data sets compared to normal epithelium (mean percent of cells staining positive in PIA = 11.1%–16.2%; mean percent of cells staining positive in normal = 0.6%–1.3%) (P = 0.0001). As expected from prior studies, the mean Ki‐67 index was higher in PIA lesions (mean 8.2% staining positive) versus normal epithelium (mean 1.9% staining positive) (P = 0.0001), and the extent of staining for p16 correlated with Ki‐67 (r = 0.7, P