Prostate-specific antigen synthesis and secretion by human placenta: A physiological kallikrein source during pregnancy

Prostate-specific antigen (PSA), a kallikrein-like serine protease until re cently thought to be prostate specific, has been demonstrated in various no nprostatic tissues and body fluids. PSA has been also found in human endome trium and amniotic fluids, even if the significance of this novel expressio n is unclear. In this study, we have demonstrated by multiple techniques th at human placental tissue, obtained at delivery from normal full-term pregn ancies, synthesizes and secretes PSA. RT-PCR showed the presence of PSA mes senger ribonucleic acid; biochemical, chromatographic, and immunological st udies revealed the expression of both free and complexed PSA forms; immunoe lectron microscopy indicated the syncytiotrophoblast as the site of PSA syn thesis and secretion. Moreover, in vitro experiments demonstrated that PSA production and secretion are up-regulated by 17 beta-estradiol, a pregnancy -related steroid hormone. These results suggest that human placenta is a so urce of the PSA present in amniotic fluid and maternal serum during pregnan cy.