Subcellular Localization and Quantification of Androgen Receptor in Hormone-Naïve Prostatic Adenocarcinoma and Clinical Correlation.
Wei Huang, Clifford Hoyt, Thomas Pier, David Fletcher-Holmes. University of Wisconsin-Madison; Cambridge Research and Instrumentation, Inc., Woburn, MA
Background: Androgen receptor (AR) is primarily located in the nucleus in an androgen-bound form and functions as a transcription factor. Recent studies have shown that AR shuttles between the nucleus and cytoplasm, and that cytoplasmic membrane AR initiates signal transduction. However, limited quantitative and clinical correlation studies of AR at subcellular levels are available.
Design: Two prostatic adenocarcinoma (PCa) outcome tissue microarrays (TMA) are constructed, each consisting of duplicate cores of PCa tissues from 183 PCa patients (174 hormone-naïve, 9 castration resistant) and 48 benign prostatic tissue (BPT). Two TMA slides with 4 cores representing each patient's PCa or BPT were stained using an immunofluorescent assay. The epithelial/membrane compartment was defined with mouse anti-e-cadherin monoclonal antibody (mAb) (Dako, 1:50) and visualized with Alexa Fluor 488. AR was detected with rat anti-AR mAb (Abcam, 1:200, with tyramide amplification) and visualized with Alexa Fluor 647. The nuclear compartment was defined and visualized with DAPI. VectraTM platform (CRI) was used to scan TMA slides, segment subcellular compartments and quantify AR in each compartment. AR expression levels in the nucleus (nAR), cytoplasm (cAR) and membrane (mAR) compartments from the 174 hormone-naïve patients were included for analysis and their correlation with Gleason scores, PCa pathological stages and recurrence status was studied. One-way Anova was used to compare means.
Results: AR was detected in all three compartments in both PCa and BPT: highest in nucleus, lowest in cytoplasm. AR levels in the three compartments were generally lower in PCa than BPT. Significantly lower nAR, cAR and mAR levels were only found in patients with cancer recurrence (CRecur) (p≤0.05) compared to recurrence-free (RF) patients. No significant differences of AR levels in any of the three compartments were found between RF patients and patients with biochemical recurrence (BRecur) or between BRecur patients and CRecur patients. Also, the mAR and nAR but not the cAR levels were significantly lower in the GS8 group compared to the GS6 and GS7 groups. The AR levels in all three compartments were not significantly correlated with PCa stages.
Conclusions: Our study confirms that AR is expressed not only in the nucleus but also in the cytoplasm and cytoplasmic membrane of prostatic epithelium. mAR and cAR could also be used as markers to predict PCa progression and outcome.
Category: Genitourinary (including renal tumors)
Monday, February 28, 2011 1:00 PM
Poster Session II # 158, Monday Afternoon