Cloning and characterization of the prostate-specific membrane antigen promoter
Prostate-specific membrane antigen (PSMA) is a protein that is expressed predominantly in normal prostate epithelial cells and in most adenocarcinomas of the prostate (Cap) and in virtually all Cap metastases. In this article we describe the cloning of a 2-kb human genomic DNA fragment containing the 5' upstream untranslated region of the PSMA gene and present evidence that it provides promoter activity. When the DNA fragment was cloned into transient expression vectors to examine promoter activity, the vectors were functional in promoting expression in several prostate and nonprostate cell lines in transient transfection assays. A 614-bp fragment derived from the 3' end of the 2-kb fragment may represent the minimal PSMA promoter as determined by deletion mutagenesis. The 2-kb fragment compared with the 614-bp fragment provided higher expression levels when using prostate-derived cell lines (DU 145 and LNCaP). The increased transcription using the 2-kb fragment was not as great in non-prostate cell lines. Little or no transcription over basal levels was seen with a 232-bp promoter fragment. When the concentration of dihydrotestosterone was depleted or supplemented in the growth medium, no significant effect was seen on PSMA-promoted transient expression in LNCaP cells, a prostate cell line.