Expression of soluble urokinase plasminogen activator receptor may be related to outcome in prostate cancer patients.

The urokinase-type plasminogen activator receptor (uPAR) exists as a GPI anchored glycoprotein (Mr=50-60 kDa) on the surface of various cell types. This receptor can be bound by or cleaved by urokinase. The cleaved receptor, soluble urokinase-type plasminogen activator receptor (suPAR), with an Mr=35 kDa has no known physiological function and can be identified circulating in the blood of normal individuals. Although no function has been characterized, the soluble receptor has been reported to be of clinical significance. The objective of this study is to characterize novel serum markers that can be used for the early detection of prostate cancer and to predict patient prognosis. Thirty-nine patients at the University of Yaounde I, Yaounde, Cameroon, West Africa were examined for prostatic disorders. Of these, 46% were diagnosed with benign prostate hyperplasia (BPH), while 44% of the patients were diagnosed via biopsy with prostate cancer and graded accordingly. Here we show that serum from patients with BPH or prostate cancer contains elevated levels of suPAR. To examine the significance of suPAR as a diagnostic factor, we used a suPAR ELISA kit and compared these results with serum levels of prostate specific antigen (PSA), the current diagnostic marker for prostate cancer. PSA and serum suPAR levels in BPH and cancer patients were greatly elevated in the majority of patients, while others had undetectable levels of either. Serum levels of suPAR were high in cancer patients as well as, although to a lesser degree, in patients with BPH. Cancer patients who died during the follow-up period were found to have consistently higher serum suPAR levels than correlating serum PSA levels. These preliminary findings are the first evaluating serum suPAR levels as a possible diagnostic marker for the early detection of prostate cancer and for the prediction of patient prognosis.