Molecular expression of PSMA mRNA and protein in primary renal tumors

Human prostate-specific membrane antigen (PSMA), a 100-kDa integral transme mbrane glycoprotein, is considered to be a highly specific marker of the pr ostate gland, and has successfully been used as a marker of circulating pro static epithelial cells. Extended PSMA homology has been demonstrated with a cDNA found in rat cerebral and renal tissues. In this study, we aimed to evaluate the expression of PSMA mRNA in a variety of human renal cancer tis sues (n = 20) and cell tines (n = 12). Using reverse transcriptase-polymera se chain reaction, DNA sequencing, blottings, and specific anti-PSMA labell ing with CYT 351 antibody, we identified PSMA mRNA and protein in normal an d in neoplastic renal tissue. The sequence of the polymerase-chain-reaction products is identical to that of PSMA cDNA derived from prostate tissue. I mmunological staining with the CYT 351 reveals that PSMA is expressed mainl y in tubular cells. Since PSMA does not appear to be restricted to prostati c tissue, this novel biomarker may prove useful in the staging of renal can cer and in the search for the hematogenous spread of renal cells. Int. J. C ancer 80:799-803, 1999. (C) 1999 Wiley-Liss, Inc.