Immunohistochemical localization and analysis of kallikrein-related peptidase 7 and 11 expression in paired cancer and benign foci in prostate cancer patients.

Kallikrein-related peptidases 7 and 11 (KLK7/KLK11) share a high degree of structural similarity with PSA (KLK3) and other KLKs. The aim of this study was to evaluate differences in KLK7/ KLK11 expression in paired cancer/benign prostate foci and to determine possible associations with clinicopathological parameters. Seventy archived paraffin-embedded tissue samples obtained from radical prostatectomy were stained for KLK7, KLK11, PSA and PSMA and expression was evaluated semiquantitatively. The results showed statistically significant differences for all studied proteins between BPH and CaP foci. Both KLK7 (P=0.026) and KLK11 (P<0.001) expressions were decreased in prostate cancer cells compared to normal/benign prostate cells. Positive correlations were found for both KLK7 (Rs=0.74, P<0.001) and KLK11 (Rs=0.35, P=0.003) between CaP and BPH. We found a statistically significant upregulation of KLK11 in advanced cases compared to localized ones (P=0.026). For the first time, we report lower expression of KLK11 in CaP compared to BPH and slight upregulation of KLK11 in advanced tumors compared to localized ones. Our observations support the diagnostic potential of KLK7/KLK11 for early prostate cancers but further studies on larger cohorts are needed in order to validate the clinical value of these biomarkers and clarify their biological role in prostate development and tumorigenesis.