Lower levels of nuclear beta-catenin predict for a poorer prognosis in localized prostate cancer.

Abstract

Beta-catenin in its role as a nuclear signaling molecule has been implicated in prostate carcinogenesis primarily through modulation of androgen receptor activity. We defined the pattern of beta-catenin protein expression in the nuclei of normal, hyperplastic and malignant human prostate tissue and determined whether differences in expression were associated with disease progression and prognosis. Five normal prostates, 26 benign prostatic hypertrophy specimens, 232 radical prostatectomy specimens from patients with clinically localized prostate cancer (PC) and 20 cases of advanced PC were assessed for beta-catenin expression using immunohistochemistry. Nuclear beta-catenin expression in localized PC was significantly lower than that in benign prostate tissue (p < 0.001) and significantly higher than that in advanced PC tissue (p < 0.001). In addition, lower levels of nuclear beta-catenin expression (< 10% of cancer cells) predicted for a shorter biochemical relapse-free survival in patients with localized PC (p = 0.008) and were inversely correlated with preoperative prostate-specific antigen (PSA) levels (p = 0.01). Analysis of the low-risk subgroup of patients with preoperative PSA levels < 10 ng/ml demonstrated that lower levels of nuclear beta-catenin expression (< 10% of cancer cells) again predicted for a poorer prognosis (p = 0.006). In conclusion, lower levels of nuclear beta-catenin expression are found in malignant compared to benign prostate tissue. In addition, lower nuclear beta-catenin expression is associated with a poorer prognosis in localized PC, in particular, in the low-risk subgroup of patients with preoperative PSA levels < 10 ng/ml. Thus, the level of nuclear beta-catenin expression may be of clinical utility as a preoperative prognostic marker in low-risk localized PC.