Elevation of dipeptidylpeptidase IV activities in the prostate peripheral zone and prostatic secretions of men with prostate cancer: Possible prostate cancer disease marker

Purpose: Dipeptidylpeptidase IV (DPIV) is a multifunctional type II plasma membrane glycoprotein with serine-type exopeptidase activity that is secreted by the prostate and increased in prostate cancer. We determined whether changes in DPIV activities in prostatic tissue zones and expressed secretions were associated with the presence of cancer. Materials and Methods: Expressed prostatic secretion (EPS), and biopsy of the transition (TZ) and peripheral (PZ) zones were collected from men undergoing ultrasound guided prostate biopsy. DPIV activities were measured by glypro-p-nitroanalide hydrolysis. Results: DPIV activities were significantly higher in TZ than in PZ tissues in men with no evidence of malignancy. However, activities in EPS were negatively associated with TZ volume and positively associated with PZ volume. Mean and median DPIV activities in EPS from men with biopsy determined cancer were significantly higher than in men with no evidence of malignancy. DPIV activities in TZ and PZ biopsies were higher in men with cancer but most markedly in the PZ. Conclusions: These data indicate that secreted DPIV originates from the TZ and PZ. Increased DPIV activities in cancer are strongly associated with the PZ, which is the zone most commonly involved with cancer. Measuring DPIV levels in expressed EPS or post-digital rectal prostate examination urine may be useful for evaluating men for prostate cancer.