Correlation between tumor proliferation and tumor tissue level of urokinase-type plasminogen activator

Natural and engineered plasmin inhibitors: applications and design strategies

The serine protease plasmin is ubiquitously expressed throughout the human body in the form of the zymogen plasminogen. Conversion to active plasmin occurs through enzymatic cleavage by plasminogen activators. The plasminogen activator/plasmin system has a well-established function in the removal of intravascular fibrin deposition through fibrinolysis and the inhibition of plasmin activity; this has found widespread clinical use in reducing perioperative bleeding. Increasing evidence also suggests diverse, although currently less defined, roles for plasmin in a number of physiological and pathological processes relating to extracellular matrix degradation, cell migration and tissue remodelling. In particular, dysregulation of plasmin has been linked to cancer invasion/metastasis and various chronic inflammatory conditions; this has prompted efforts to develop inhibitors of this protease. Although a number of plasmin inhibitors exist, they commonly suffer from poor potency and/or specificity of inhibition that either results in reduced efficacy or prevents clinical use. Consequently, there is a need for further development of high-affinity plasmin inhibitors that maintain selectivity over other serine proteases. This review summarises clearly defined and potential applications for plasmin inhibition. The properties of naturally occurring and engineered plasmin inhibitors are discussed in the context of current knowledge regarding plasmin structure, specificity and function. This includes design strategies to obtain the potency and specificity of inhibition in addition to controlled temporal and spatial distribution tailored for the intended use.

Tumor-associated proteolytic factors uPA and PAI-1 in endometrial carcinoma

The levels of plasminogen activator urokinase (uPA) and of its inhibitor (PAI-1) were measured by use of ELISA in the cytosol of tissue homogenates obtained from endometrial carcinomas and the marginal, tumor-free endometrium of postmenopausal patients (n = 64). Significantly higher median levels of uPA and PAI-1 were found in malignant endometrium (uPA 1.89 ng/mg, PAI-1 3.04 ng/mg) compared to tumor-free endometrium (uPA 0.84 ng/mg, PAI-1 1.01 ng/mg). Concerning uPA, no significant differences were found in dependence on histomorphological prognostic factors (staging, grading), but the median level of PAI-1 was significantly higher in G2/G3 carcinomas compared to G1 tumors (5.08 ng/mg vs 2.19 ng/mg). Because of the good prognosis of operated patients with endometrial carcinomas, the prognostic value of uPA and PAI-1 can only be decided by a larger number of patients and a long observation time.

Arginase activity determination. A marker of large bowel mucosa proliferation

Arginase activity of the intestinal mucosa was tested as a proliferative marker in the adenoma-carcinoma sequence. The enzyme activity was determined by an end-point colorimetric method with L-arginine as substrate. Arginase activity was evaluated in 430 biopsy samples of large bowel mucosa, polyps and cancer tissue. The activities (U/g protein, mean +/- SE; n) were: normal mucosa 83.2 +/- 7.3; 25, adenomas 199.4 +/- 19.1; 40, carcinomas 1269.7 +/- 174.9; 40, inflammatory bowel disease 1210.7 +/- 247.1; 34. The arginase activity differs significantly in the adenoma-carcinoma sequence according to the Duncan's test (p < 0.05).