Expression of activator protein 2 in prostate cancer is related to tumor differentiation and cell proliferation

Objectives: Activator protein 2 (AP-2) is a DNA-binding transcription facto r that can activate the expression of p21 (waf1/cip1), which in turn causes growth arrest of cells through inhibition of cyclin-dependent kinases requ ired in G1-S progression. The aims of the present study were to analyze the expression of AP-2 in prostate cancer and to relate the results of AP-2 im munohistochemistry to other known prognostic factors and patient survival. Methods: AP-2 alpha was demonstrated by an immunohistochemical method in 21 5 prostate cancer cases, and the results of immunohistochemistry were relat ed to other known prognostic factors and patient survival. Results: The expression of AP-2 alpha in carcinomas was usually weak and cy toplasmic, similar to normal prostatic epithelium adjacent to tumors. In 6% of the tumors, the expression was strong, and in 15% no staining signal wa s detected. Nuclear expression was detected in 22% of cases. Low fraction o f AP-2-expressing cells was related to high mitotic index, Ki67 labeling an d high expression of p21 (waf1/cip1). Nuclear expression of AP-2 was relate d to high Gleason score, advanced T category, DNA aneuploidy and high S-pha se fraction. Nuclear expression was an indicator of unfavorable disease out come, but in multivariate analysis, expression of AP-2 had no prognostic va lue. Conclusions: Cytoplasmic expression of AP-2 alpha is reduced in poorly diff erentiated prostate carcinomas. The rare nuclear expression occurs in a sma ll proportion of tumors which are aneuploid, have a high T category and hig h Gleason score. The expression of AP-2 seems to have no prognostic value i n prostate cancer. Copyright (C) 2000 S. Karger AG, Basel.