Plasminogen activator content of human colon tumors and normal mucosae: separation of enzymes and partial purification.

Plasminogen activator content was determined quantitatively in extracts of 23 pairs of surgically removed colon tumors and adjacent normal mucosa specimens. The activator content averaged 4.4 times higher in the tumor samples than in the corresponding normal tissue. Polyps removed with the adenocarcinomas gave values intermediate between those for tumors and those for the normal mucosae. The enzyme content of the group of tumors that showed invasive propagation or metastatic spread was significantly higher (P < 0.05) than was the enzyme content of the group not manifesting these conditions. Activator activity of the tumor extracts was completely inhibited by rabbit antibody formed against human urokinse. The activity of the normal mucosae was variably inhibited, suggesting the presence of several kinds of activator in normal tissues. The activator from the normal tissues could be separated into a completely refractory fraction and a completely inhibitable fraction by means of an affinity column made of Sepharose-linked, rabbit antiurokinase antibody. The activator, eluted from this column with 1 M acetic acid in 0.5 M NaCl (pH 2.2), was highly purified and had an isoelectric point of 8.6, as does authentic urokinase. The details of the isoelectric profile of the two, however, differed. The data are discussed in relation to earlier studies on the fibrinolytic system in colon cancer.