Prostate-specific membrane antigen is produced in tumor-associated neovasculature

Prostate-specific membrane antigen (PSMA), a type II transmembrane protein, was originally thought to be strictly expressed in prostatic tissue, but r ecent studies have demonstrated PSMA protein expression in nonprostatic tum or neovasculature as well. Using immunohistochemistry, reverse transcriptio n-PCR assays, and in situ hybridization, we have demonstrated PSMA mRNA tra nscripts and protein expression in the endothelium of tumor-associated neov asculature of multiple nonprostatic solid malignancies. In addition, we fou nd no PSMA mRNA or protein expression in the vascular endothelial cells of corresponding benign tissue examples. Our findings expand the possible ther apeutic role of PSMA and establish it as a unique biomarker specifically pr oduced and expressed by tumor-associated neovasculature but not produced or expressed by normal vessels.