Cathepsin B levels in urine from bladder cancer patients

There is accumulating evidence that cysteine proteinase activity plays an i mportant role in cancer cell invasion and metastasis. Previously we demonst rated that cathepsin B (CB) plasma activity is increased in patients with t ransitional bladder cancer (TCC). In this work we have attempted to determi ne whether urine CB protein levels could be used as tumor marker in bladder cancer patients. Urine CB levels were evaluated employing a dot blot metho d, in 30 patients with TCC, 21 patients successfully treated from TCC witho ut evidence of disease at the moment of urine collection (NED) and in 30 he althy volunteers. The median value (Md) of the control group was 3.8 mu g C B/ml. Significantly higher urine CB Values (Md: 5.9 mu g/ml) were found in the TCC group. A high CB value was also found in the NED group (5.0 mu g/ml ). Urine CB values over the 5.2 mu g/ml (cut-off point) were observed in 63 % of TCC patients, 48% of NED and 8% of the control group. Only 4% NED pati ents had CB values over 13.0 mu g/ml while 33% of TCC patients surpassed th is value. Thus, urine CB might be a potential marker for transitional bladd er cancer diagnosis.