Ezrin Expression in Prostate Cancer and Benign Prostatic Tissue

The membrane-linking protein ezrin is highly expressed in several types of human cancers and correlations between its immunoreactivity and histopathological data as well as patient outcome have previously been shown. However, such studies have not yet been done on human prostate cancer. This study assesses ezrin protein expression in a series of clinical specimens. Immunohistochemical analysis was used to characterize patterns of ezrin expression in prostatic carcinoma and benign epithelium in 103 radical prostatectomy specimens. Ezrin immunoreactivity (IR) was scored 0 to 3 (absent, weak, moderate or strong staining). Agreement between three independent observers was calculated. Ezrin IR in prostate cancers was moderate or strong in 70% of specimens while negative or only weakly positive in benign epithelium. Interobserver agreement of IR score was substantial (mean weighted kappa 0.70, range 0.67–0.73). Ezrin expression correlated with Gleason score (p = 0.016) and seminal vesicle invasion (p = 0.006) but not with extraprostatic extension or margin status. No correlation with biochemical recurrence after prostatectomy was found (p = 0.19). Urothelial and squamous metaplasia invariably showed moderate or strong ezrin expression. Epithelium of seminal vesicles and ejaculatory ducts was always intensely positive. Ezrin was expressed in the majority of prostate cancers and correlated with adverse prognostic factors. Interestingly, high levels of ezrin IR were observed in benign metaplastic epithelium and in seminal vesicles.