Quantitative expression profile of PSGR in prostate cancer

PSGR is a novel member of the G-protein-coupled olfactory receptor family. Our initial report showed predominant expression of the PSGR in human prostate gland and significant alterations of PSGR expression in primary prostate cancer (CaP) specimens. The aim of this study was to provide in-depth evaluations of the expression profile of PSGR in prostatic epithelial cells of CaP patients and to evaluate the association of PSGR expression characteristics with clinico-pathologic features. In total, 220 RNA specimens, from laser capture microdissected paired benign and malignant prostatic epithelial cells of 110 CaP patients, were analyzed for PSGR expression by quantitative real-time PCR. The differential expression of PSGR between the prostatic epithelial cells of malignant and benign glands was statistically significant (P<0.0001). Comparison of PSGR expression between paired benign and tumor cells revealed prostate tumor cell-specific overexpression in 67.2% of tumor specimens (74 of 110), decreased expression in 20.9% of tumor specimens (23 of 110) and no difference of PSGR expression between tumor and normal cells in 11.8% of specimens (13 of 110). In representative cases, PSGR expression patterns were independently confirmed by in situ RNA hybridization. The PSGR overexpression associated with higher percentage of pathologic stage, pT3, and a higher level of preoperative serum PSA. CaP cells of African-American CaP patients exhibited about two-fold increase of PSGR expression in comparison to the Caucasian American CaP patients. Strikingly high-percentage CaP cells overexpress PSGR warrants further studies of PSGR expression alterations to define subsets of CaPs.