Decreased concentrations of prostate-specific antigen and human glandular kallikrein 2 in malignant versus nonmalignant prostatic tissue

Objectives. To study quantitatively the relative expression of human glandu lar kallikrein 2 (hK2) and prostate-specific antigen (PSA) in paired (from the same patient) cancerous and noncancerous prostatic tissue to evaluate w hether these proteins are overexpressed or underexpressed in cancer. Methods. We studied 14 patients who underwent radical retropubic prostatect omy for prostate cancer. Cancerous and adjacent normal tissues were excised and then extracted to prepare cytosolic extracts. The extracts were analyz ed for total protein, and for hK2 and PSA using sensitive and specific immu nofluorometric procedures. Results. PSA was present in the prostatic extracts at about 50 to 100 times higher amounts than hK2. The correlation between PSA and hK2 values was go od. Both prostate kallikreins were expressed more in noncancerous than in c ancerous prostatic tissue. Conclusions. Our results demonstrated that both PSA and hK2 are down-regula ted in prostate cancer compared with noncancerous tissue. The degree of dow n-regulation was higher for PSA than for hK2. The mechanism and physiologic consequences of this down-regulation are unknown. UROLOGY 56: 527-532, 200 0. (C) 2000, Elsevier Science Inc.