Identification and characterization of prostein, a novel prostate-specificprotein

In this report, me describe the application of a systematic, genome-based a pproach to identify prostein, a novel prostate-specific protein expressed i n normal and malignant prostate tissues. Characterization of the prostein g ene shows that prostein cDNA encodes a 553-amino acid protein. The protein is predicted to be a type IIIa plasma membrane protein with a cleavable sig nal peptide and 11 transmembrane-spanning regions. The prostein gene is loc ated on chromosome 1 at the WI-9641. locus between q32 and q42. Prostein mR NA is shown to be uniquely expressed in normal and cancerous prostate tissu es using Northern blot, cDNA microarray, and real-time PCR analyses. Furthe rmore, prostein mRNA expression does not appear to be prostate tumor grade related and is restricted exclusively to prostate cell lines. Immunuhistoch emical staining using a mouse monoclonal antibody generated against prostei n demonstrates that this protein is specifically detected in prostate tissu es both at the plasma membrane and in the cytoplasm, Prostein expression is androgen responsive because treatment of LNCaP cells with androgen up-regu lates prostein message and protein expression levels. These results validat e prostein as a prostate-specific marker with potential utility in the diag nosis and treatment of prostate cancer.