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REGULATION OF EXPRESSION OF THE COMPONENTS OF PLASMINOGEN ACTIVATION SYSTEM IN THE LEUKEMIC CELLS
In present research the abilities of leukemic cell lines K562, U937 and THP-1 to modulate expression of the components of plasminogen activation system under the influences of tumor promoter, phorbol myristate acetate (PMA), and antiproliferative agents, tumor necrosis factor a (TNF-a) and interferon-a (IFN-a) were studied. PMA was found to cause the significant increase in urokinase receptor (uPAR) and urokinase (uPA) molecules expression in both permeabilized and non-permeabilized cells of the investigated lines. TNF-a stimulated expression of uPA and plasminogen activator inhibitor type-1 (PAI-1) molecules in permeabilized THP-1 cells, and promoted the decrease in surface level of uPAR molecules in THP-1 cells. IFN-a did not influence the cell surface levels of the components of plasminogen activation system, but markedly stimulated the intracellular expression of PAI-1 in U937 and THP-1 cells. At the same time IFN-a decreased a rate of uPAR molecules expression in permeabilized THP-1 cells. The data suggest, that influence of TNF-a and IFN-a on the expression of the components of plasminogen activator system can represent a link in the mechanisms of antitumor activities of investigated cytokines and can mediate their inhibitory action on several functions of leukemic cells.
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