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 an chored glycoprotein (M-r=50-60 kDa) on the surface of various cell types. T his receptor can be bound by or cleaved by urokinase. The cleaved receptor, soluble urokinase-type plasminogen activator receptor (suPAR), with an M-r =35 kDa has no known physiological function and can be identified circulati ng in the blood of normal individuals. Although no function has been charac terized, the soluble receptor has been reported to be of clinical significa nce. The objective of this study is to characterize novel serum markers tha t can be used for the early detection of prostate cancer and to predict pat ient prognosis. Thirty-nine patients at the University of Yaounde I, Yaound e, Cameroon, West Africa were examined for prostatic disorders. Of these, 4 6% were diagnosed with benign prostate hyperplasia (BPH), while 44% of the patients were diagnosed via biopsy with prostate cancer and graded accordin gly. Here we show that serum from patients with BPH or prostate cancer cont ains elevated levels of suPAR. To examine the significance of suPAR as a di agnostic factor, we used a suPAR ELISA kit and compared these results with serum levels of prostate specific antigen (PSA), the current diagnostic mar ker for prostate cancer. PSA and serum suPAR levels in BPH and cancer patie nts were greatly elevated in the majority of patients, while others had und etectable levels of either. Serum levels of suPAR were high in cancer patie nts as well as, although to a lesser degree, in patients with BPH. Cancer p atients who died during the follow-up period were found to have consistentl y higher serum suPAR levels than correlating serum PSA levels. These prelim inary findings are the first evaluating serum suPAR levels as a possible di agnostic marker for the early detection of prostate cancer and for the pred iction of patient prognosis.