CONTENT AND CHARACTERIZATION OF PLASMINOGEN ACTIVATORS IN HUMAN-LUNG TUMORS AND NORMAL LUNG-TISSUE

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 40  (3) , 841-848
Abstract
The plasminogen activator content of surgically removed lung cancers and of adjacent normal lung tissue was determined quantitatively. Optimum conditions for the quantitative extraction were worked out using a modification of the technique described by Nagy et al. which utilizes a buffered solution of the non-ionic detergent Triton X-100. Plasminogen activator was significantly elevated in the tumors (2.5- to 4.3-fold over the normal lung) although individual variations between tumors were extremely large. No significant correlation was found between the histopathological character of the tumors and the activator content, or between invasiveness and activator content. Using rabbit antibody formed against purified urokinase as an inhibitor of activator action, lung tumors apparently contain a urokinase-like enzyme as the predominant plasminogen activator, while the activator content of the adjacent normal lung tissue consists of some urokinase-like enzyme, but mostly of an enzyme which is not inhibited by the antibody. The urokinase-like activator was purified approximately 22,000-fold from lung tumors by 2 affinity chromatographic procedures and was compared with purified urokinase with a MW of 55,000. On all criteria used, the lung tumor activator was identical to urokinase.