A novel androgen-regulated gene, PMEPA1, located on chromosome 20q13 exhibits high level expression in prostate

Biologic effects of androgen on target cells are mediated in part by transcriptional regulation of androgen-regulated genes (ARGs) by androgen receptor. Using serial analysis of gene expression (SAGE), we have identified a comprehensive repertoire of ARGs in LNCaP cells. One of the SAGE-derived tags exhibiting homology to an expressed sequence tag was maximally induced in response to synthetic androgen R1881 treatment. The open reading frame of the androgen-induced RNA (PMEPA1) was characterized as a 759-bp nucleotide sequence coding for a 252-amino-acid protein. The analysis of PMEPA1 protein sequence indicated the existence of a type Ib transmembrane domain between residues 9 and 25. Analysis of multiple-tissue Northern blots revealed the highest level of PMEPA1 expression in prostate tissue. PMEPA1 expression was predominately detected in glandular epithelial cells of prostate by in situ hybridization analysis. The expression of PMEPA1 in LNCaP cells was induced by androgen in a time- and dose-specific manner. Evaluation of PMEPA1 expression in androgen-dependent/independent tumors of the CWR22 xenograft model revealed that PMEPA1 was overexpressed in three of four androgen-independent tumor tissues. These observations define PMEPA1 as a novel androgen-regulated gene exhibiting abundant expression in prostate tissue. The increased expression of PMEPA1 in relapsed tumors of the CWR22 model suggests activation of androgen signaling in hormone refractory disease. PMEPA1, along with other highly androgen-induced prostate-specific genes, has potential to serve as an androgen signaling read-out biomarker in prostate tissue.