Human glandular kallikrein 2 expression in prostate adenocarcinoma and lymph node metastases

Objectives. To describe the expression of a potential new tumor marker, hum an glandular kallikrein 2 (hK2), in primary adenocarcinoma and lymph node m etastases that may be useful as an adjunct to prostate-specific antigen (PS A) in the diagnosis and monitoring of prostate cancer. Methods, We evaluated 151 radical prostatectomy specimens removed at Mayo C linic with node-positive adenocarcinoma to compare cytoplasmic expression o f hK2, pro-hK2, and PSA in benign tissue, prostate adenocarcinoma, and lymp h node metastases. Monoclonal antibodies for mature hK2 (hK2-G586), pro-hK2 (pro-hK2-G464), and PSA (PSA-773) were used. A polyclonal antibody for PSA was also used. Immunoreactivity in each case was tested to determine wheth er cancer recurrence could be predicted. Results. Intense epithelial cytoplasmic immunoreactivity was observed in ev ery case for hK2-G586, pro-hK2-G464, PSA-773, and polyclonal PSA (100% of c ases, respectively). The intensity and extent of hK2 expression was greater in lymph node metastases than in primary cancer; furthermore, the expressi on in primary cancer was greater than in benign epithelium. Pro-hK2 was exp ressed in a greater percentage of cells in primary cancer than in benign ti ssue; furthermore, pro-hK2 was expressed to a greater extent in primary can cer than in lymph node metastases. In marked contrast to mature hK2, monocl onal PSA immunoreactivity was expressed to a higher extent in primary cance r than in lymph node metastases. Polyclonal PSA showed an incremental incre ase in expression from benign tissue to primary cancer and a further increa se in expression in lymph node metastases. Conclusions. hK2 was expressed in every cancer, and the expression incremen tally increased from benign epithelium to primary cancer and lymph node met astases. Pro-hK2 was expressed to the greatest extent in primary cancer. Mo noclonal PSA displayed inverse immunoreactivity compared with hK2, Polyclon al PSA showed incremental increases, suggesting that both hK2 and PSA were being detected. Tissue expression of hK2 appears to be regulated independen tly of PSA in benign epithelium, adenocarcinoma, and lymph node metastases, UROLOGY 53: 939-944, 1999. (C) 1999, Elsevier Science Inc. All rights rese rved.