Androgen receptor as a potential sign of prostate cancer metastasis

BACKGROUND Androgen receptor (AR) expression and its modulation through the carcinogenesis process have been investigated in several studies with conflicting results. MATERIALS AND METHODS In situ hybridization and immunocytochemistry were used to examine AR expression in prostatic needle core biopsies of benign, high grade prostatic intraepithelial neoplasia (HGPIN) and prostatic adenocarcinoma. RESULTS A significant increase in AR mRNA levels was found in the cancerous prostatic cells when compared with the benign tissue biopsies. AR abundance in HGPIN was found to be almost half-way between that observed in benign and in cancerous tissue. In the benign prostatic epithelium, the immunocytochemistry data show that AR is exclusively expressed in the nuclei of epithelial cells. However, in 72% of examined cancer biopsies, AR was expressed in both the cytoplasm and nuclei. After examination of medical records of 100 patients diagnosed with prostate cancer, it was found that the AR was expressed in both cellular compartments of cancer cells in 81% of cases when cancer was found to have metastasized outside the prostate. In contrast, when the cancer was organ-confined, AR was localized in both the nuclei and cytoplasm in only 66% of cases. Moreover, when the AR was expressed in the cytoplasm of cancerous cells, consecutive serial sections immunostained with the mitochondrial marker suggest that AR is localized in the mitochondria. CONCLUSIONS AR mRNA expression is significantly higher in prostate cancer when compared to benign prostatic tissue. Prostate 69: 1704–1711, 2009. © 2009 Wiley-Liss, Inc.