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Binding of tissue‐type plasminogen activator to human melanoma cells
Author(s) -
Bizik Jozef,
Stephens Ross W.,
Grofova Marta,
Vaheri Antti
Publication year - 1993
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240510312
Subject(s) - plasmin , tissue plasminogen activator , chemistry , plasminogen activator , cell , biochemistry , microbiology and biotechnology , biology , endocrinology , enzyme
We have shown (Bizik et al., Cell Regul 1:895–905, 1990) that tPA can activate plasminogen on the surface of human melanoma cells in the presence of α 2 ‐macroglobulin (α 2 M) secretion. In the present study, we investigated the binding of tPA on the surface of Bowes melanoma cells, selected since they lacked production of PAI‐1 and α 2 M. Elution of tPA from the cell layers indicated that polylysine (5 μg/ml) and tranexamic acid (10 mM), an analog of lysine, were the most efficient agents for disrupting the interaction between tPA and cell surface component(s). Using a panel of monoclonal antibodies against individual domains of tPA revealed that an antibody directed to the kringle‐2 domain of tPA interfered most significantly with cell‐surface plasmin generation. As tPA is a glycoprotein, interactions between the tPA sugar moieties and cell surface were also tested by the use of a series of monosaccharides. N‐acetyl‐ D ‐glucosamine (100 mM) was the most potent sugar to release tPA from melanoma cells, but the results indicated that the oligosaccharides of tPA play only a supportive role in the binding of tPA to the cell surface. Quantitative comparison of the cell surface localized tPA, which was eluted by tranexamic acid, with the total cellular tPA showed that cell surface bound tPA could represent up to 10%. We conclude that tPA interacts with the melanoma cell surface in a similar manner as has been described for binding of tPA to fibrin and to the putative endothelial cell surface receptor. © 1993 Wiley‐Liss, Inc.

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