Discovery of PSMA in the prostate of the common marmoset (Callithrix jacchus)

Background: Prostate-specific membrane antigen (PSMA) is a biomarker and therapeutic target of high relevance in prostate cancer. Although upregulated PSMA expression is a well-documented feature of prostatic neoplasia in both humans and canids, to date humans are the only species known to express PSMA basally in the prostate. Thus, traditional laboratory animal species have limited utility for studying PSMA biology in the prostate or for predicting efficacy or toxicity of PSMA-targeted agents. Methods: PSMA expression in human, macaque, and marmoset prostates was determined by immunohistochemistry, employing an antibody with validated cross-species reactivity in a PSMA-positive control tissue; kidney. Results: We newly discover that the common marmoset endogenously expresses PSMA in non-diseased prostate, similar to humans, and thus may be a valuable preclinical model for researchers studying PSMA.