title: Enhanced plasminogen activator production of Syrian hamster embryo cells transformed by chemicals or the c-Ha-ras oncogene: type of plasminogen activators involved and their contribution to the transformed phenotype.
abstract: The plasminogen activator (PA) activity produced by Syrian hamster embryo (SHE) cells in different stages of neoplastic conversion was analysed. PA activity was characterized immunologically and by SDS-PAGE. Normal SHE cells had a very low PA activity. Although activity of either the tissue type of PA (t-PA) or the urokinase type (u-PA) or both were found to be increased in most immortal or transformed SHE cells, there was no correlation between enhanced production of a particular PA type and the development of the immortal or transformed phenotype. However, within a group of cell lines clonally derived from a culture of immortal cells, a positive correlation was found between extracellular t-PA, but not u-PA, activity and cellular growth rate. For the Syrian hamster PA species, crossreacting with anti-human u-PA, a mol. wt of 39 kd was observed. For the Syrian hamster PA species, crossreacting with anti-human t-PA, multiple species were found with mol. wts of 98, 72 and 59 kd respectively. Evidence was obtained that the 72-kd species represents the intact enzyme, the 59-kd species a partial digestion product thereof and the 98 kd species, which often appears as a doublet, a complex of either of these species with an inhibitor, likely to be secreted by the same cells. Finally, our data suggest a novel mechanism for the enhancement of t-PA activity of transformed cells, namely by a decrease in the effective extracellular amount of putative inhibitor.
authors.affiliation: Department of Radiation Genetics and Chemical Mutagenesis, Sylvius Laboratories, State University of Leiden, The Netherlands.
authors.forename: A J
authors.initials: AJ
authors.lastname: de Kok
authors.forename: H
authors.initials: H
authors.lastname: Sips
authors.forename: G T
authors.initials: GT
authors.lastname: Chang
authors.forename: J H
authors.initials: JH
authors.lastname: Verheijen
mesh_terms: D000818:Animals; D000906:Antibodies; D001564:Benzo(a)pyrene / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D006224:Cricetinae; D004622:Embryo, Mammalian; D004792:Enzyme Precursors / Q000096:biosynthesis*; D005038:Ethylnitrosourea / Q000494:pharmacology; D011905:Genes, ras; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007531:Isoflurophate / Q000494:pharmacology; D008647:Mesocricetus; D010641:Phenotype; D010960:Plasminogen Activators / Q000096:biosynthesis*; D010959:Tissue Plasminogen Activator / Q000096:biosynthesis*; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis*
chemical_list: D000906:Antibodies; D002273:Carcinogens; D004792:Enzyme Precursors; D007328:Insulin; D007531:Isoflurophate; D001564:Benzo(a)pyrene; D010960:Plasminogen Activators; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator; D005038:Ethylnitrosourea