Heparanase neutralizes the anticoagulation properties of heparin and low-molecular-weight heparin.
BACKGROUND
Heparanase is a mammalian endo-D-glucuronidase that cleaves heparan sulfate (HS) in the extracellular matrix and cell surface. It is preferentially expressed by cells of the immune system and tumor cells. Heparanase overexpression in experimental tumor models results in increased angiogenesis and metastasis. Heparin and low-molecular weight heparin (LMWH) inhibit HS degradation by heparanase.


OBJECTIVE
To investigate whether heparanase cleaves heparin and LMWH, and elucidate its effect on blood coagulation.


METHODS
Heparin and LMWH were incubated with recombinant heparanase and subjected to measurements of molecular size (size exclusion chromatography) and anticoagulant activity (plasma APTT-activated thromboplastin time, and anti-Xa activity). APTT was also measured in plasma samples of transgenic mice overexpressing heparanase, in comparison with control mice.


RESULTS
Incubation of heparin and LMWH with heparanase resulted in degradation of these substrates, as revealed by a significant decrease in their molecular weight. This was correlated with a marked suppression of the anticoagulant activity of heparin and LMWH, as indicated by a decreased effect on APTT and anti-Xa activity, respectively, when human plasma was added. Transgenic mice overexpressing heparanase exhibited a significantly shorter APTT than control mice.


CONCLUSIONS
Heparanase is capable of degrading heparin and LMWH, so that its overexpression by tumor cells may contribute to heparin resistance, commonly occurring in cancer patients. In view of the complexity of the currently available heparanase activity assays, we propose an indirect approach to quantify heparanase activity by measuring the decrease in plasma APTT or anti-Xa activity exerted by the enzyme under the defined conditions.
Nasser
N J
NJ
The Bruce Rappaport Faculty of Medicine, Cancer and Vascular Biology Research Center, Technion, Israel.
Sarig
G
G
Brenner
B
B
Nevo
E
E
Goldshmidt
O
O
Zcharia
E
E
Li
J P
JP
Vlodavsky
I
I
D000818:Animals; D000925:Anticoagulants / Q000378:metabolism* / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects; D065427:Factor Xa Inhibitors; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism / Q000494:pharmacology; D006495:Heparin, Low-Molecular-Weight / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010314:Partial Thromboplastin Time; D011994:Recombinant Proteins / Q000378:metabolism; D000099175:Heparanase
D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D005966:Glucuronidase; D006493:Heparin; D006495:Heparin, Low-Molecular-Weight; D011994:Recombinant Proteins; D000099175:Heparanase