[Studies for proteolysis in malignant tumours (author's transl)]

It's well known that increased proteolytic activity in plasma as well as in interstitial fluids is often associated with malignant tumours. There are numerous reports that cell cultures of malignant origin contain plasminogen activators responsible for an increased proteolysis. Our studies showed that patients with a carcinoma excrete in their urine a significant higher amount of an acid-stable inhibitor than healthy patients. This urine inhibitor is a split product (MW: 30,000) of the Inter-alpha-trypsin inhibitor (MW: 180,000). We conclude that the increased amount of acid-stable split products is the result of increased proteolysis in patients with malignant tumours. In contrast to other authors we do not think that the activation of plasmin by plasminogen is responsible for the proteolytic cleavage of ITI. Otherwise proteolysis by Cathepsin G and granulocytic Elastase would be reasonable. So enhanced proteolysis seems to be a sign of general enzymatic change associated with transformation.