21073 Background: Prostate cancer (PCa) is a leading cause of cancer death in North American men. The androgen receptor (AR) has an established role in the progression of this disease; however, it is unclear at what stage it intervenes. It is also uncertain whether the AR can be a useful prognostic marker for PCa. In this study, we assessed AR expression and sub-cellular localization in normal prostate as well as in androgen sensitive and insensitive PCa (AIPCa) tissues, and evaluated the ability of the AR to predict biochemical recurrence (BCR). Methods: We used tissue micro-arrays containing prostate tissue cores obtained from cancer-free patients (n=43), AIPCa patients (n=36), and patients with hormone-sensitive cancers (n=64) from which were collected both cancerous and normal adjacent tissue. Using immmunohistochemistry, we stained the tissue micro-arrays with a monoclonal antibody recognizing the AR. Two observers assessed the frequency and intensity of both cytoplasmic and nuclear AR staining. AR cytoplasmic (Ci) and nuclear (Ni) indices were calculated by multiplying nuclear staining frequency and nuclear staining intensity. Kaplan Meier, and Cox multivariate analyses were done using SPSS. Results: We found that AR Ci increased significantly in AIPCa although a modest but significant increase in PCa Ci was observed compared to normal tissues. In contrast, AR Ni was significantly lower in cancer-free patients as opposed to that seen in normal tissue adjacent to cancer. Similarly, cancerous tissue exhibited higher AR Ni than its adjacent normal tissue (p<0.05, Kruskal-Wallis). Kaplan Meier analyses revealed that low AR Ni was predictive of an early onset of BCR (before 3-years) in the sub-cohort of hormone-sensitive patients (LR=6.51, p=0.011). Futhermore, low AR Ni remained an independent predictor of early BCR in a Cox multivariate model controlling for age, pre-operative PSA, lymph node invasion, Gleason score and surgical margin status (HR=2.28, 95% CI=1.04 - 5, p<0.05). Conclusions: We conclude that increased nuclear AR activity could be a pre-malignant step in PCa progression whereas its role within cancer cells may be more complex, as low AR nuclear activity was associated with early onset of BCR. No significant financial relationships to disclose.
Androgen receptor CAG polymorphism and sporadic and early-onset prostate cancer among Mexican men
