Normal and Neoplastic Human Cells Molecular Species of Plasminogen Activators Secreted by Updated Version

size quantitative differences between normal and malignant cells in terms of rates of enzyme synthesis and release. There have been relatively few reports that have dealt specifically with the question of whether neoplastic transformation is as sociated with qualitative differences in the type of plasminogen activator that is synthesized. This is an important consideration since it is well established that human plasminogen activators exist in several molecular forms that can be distinguished definitively on the basis of their biochemical characteristics and their immunochemical relationship to UK2 and circumstantially on the basis of the biological source from which they are obtained, e.g. , ‘‘tissue activator' ‘(7), ‘‘vascular activator' ‘(1, 2), ‘‘UK' ‘, etc. This matter has recently been the subject of comprehensive and informative reviews (3, 4). To examine this matter further, we have studied the plasmin ogen activators released by a variety of normal and tumor derived cell cultures using antibodies to umokinase,a sensitive radioenzymatic assay (14) for plasminogen-dependent fibnin olysis, and a zymographic technique (6) for detecting and defining plasminogen activators separated by electrophoresis in polyacrylamide gel slabs containing the detergent SDS. In this paper, we draw attention to a particular set of plas minogen activators that were secreted by cells derived from melanomas, certain other malignant neoplasms, embryonic tissues, and 2 samples of normal adult tissue. These enzymes differed in molecular weight and in susceptibility to inhibition by antibody to human urinary UK, from plasminogen activators secreted by cells derived from other neoplasms, and from most other normal adult tissues. Human Tissues and Cell Culture. Human tissue samples were obtained at the time of elective surgery, endoscopy, organ procurement, from cadaver transplant donors, or from therapeutic termination of pregnancy and cultured as explants or disrupted single-cell suspensions. Tissue culture techniques and the criteria used to decide whether cultures were repre sentative of the tissues in question have been described in detail previously (20). Early-passage human embryo fibroblasts were obtained from an 8-week fetus (crown-rump length, 3.5 cm) after disruption by mincing with scissors and digestion with trypsin. All cells used in this study were derived from cultures estab lished in this laboratory with the exception of the following melanoma cell lines which were generously provided by the persons indicated: 2 The abbreviations used are: UK, urokinasa; SOS. sodium dodecyl sulfate. MARCH1980 933 ABSTRACT A survey of 56 normal and neoplastic tissues has shown that plasminogen activators were released …