Glandular kallikreins and prostate-specific antigen are expressed in the human endometrium

Glandular or tissue kallikrein and prostate-specific antigen (PSA) are members of the human kallikrein (KLK) multigene family of enzymes. Various components of the glandular kallikrein-kinin system (kallikrein, low molecular weight kininogen, bradykinin) have been recently shown to be present or active in the human endometrium. We have used the reverse transcriptase-polymerase chain reaction (RT-PCR) with universal KLK primers to demonstrate kallikrein gene expression in this tissue. On Southern blot analysis with gene-specific oligonucleotide probes, we have detected expression of the three human KLK genes--KLK1 (kallikrein), KLK2 (or hGK1) and KLK3 (PSA). The expression of KLK1 and KLK3 was further confirmed by sequence analysis of three different endometrial PCR products. These findings confirm the presence of a local kallikrein-kinin system in the human endometrium. The significance of the novel expression of KLK2 and KLK3 (PSA), previously thought to be prostate-specific genes, in the endometrium is unclear. This family of enzymes must now be considered potential local regulators of uterine function.