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 factor that can activate the expression of p21 (waf1/cip1), which in turn causes growth arrest of cells through inhibition of cyclin-dependent kinases required 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 immunohistochemistry to other known prognostic factors and patient survival.
METHODS: AP-2alpha was demonstrated by an immunohistochemical method in 215 prostate cancer cases, and the results of immunohistochemistry were related to other known prognostic factors and patient survival.
RESULTS: The expression of AP-2alpha in carcinomas was usually weak and cytoplasmic, similar to normal prostatic epithelium adjacent to tumors. In 6% of the tumors, the expression was strong, and in 15% no staining signal was detected. Nuclear expression was detected in 22% of cases. Low fraction of AP-2-expressing cells was related to high mitotic index, Ki67 labeling and high expression of p21 (waf1/cip1). Nuclear expression of AP-2 was related to high Gleason score, advanced T category, DNA aneuploidy and high S-phase fraction. Nuclear expression was an indicator of unfavorable disease outcome, but in multivariate analysis, expression of AP-2 had no prognostic value.
CONCLUSIONS: Cytoplasmic expression of AP-2alpha is reduced in poorly differentiated prostate carcinomas. The rare nuclear expression occurs in a small proportion of tumors which are aneuploid, have a high T category and high Gleason score. The expression of AP-2 seems to have no prognostic value in prostate cancer.