Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.2.2.7 (heparinase)
 1,270 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Imatinib mesylate (Gleevec) inhibits the BCR-ABL tyrosine kinase in chronic granulocytic leukemia. Previous studies have demonstrated that imatinib mesylate also inhibits the survival and functions of normal mast cells by interfering with the receptor tyrosine kinase for stem cell factor (SCF), c-kit, which is expressed by mast cells. Because mast cells extensively surround many types of cancer and contain powerful anticoagulants such as heparin, we investigated the effects of imatinib mesylate on blood clotting and tumor growth within subcutaneous implants of a mammary adenocarcinoma cell line (4T1) in BALB/c mice. After 5 days of oral treatment with 10 mg/kg of the drug, the average mass of the tumors in treated mice (198 +/- 42 mg, n = 5) was significantly (p < 0.05) greater than the average mass of the tumors from untreated (control) mice (60 +/- 23 mg, n = 5). Moreover, the tumors in the treated mice were frequently surrounded by large lakes of clotted blood that were not evident in tumors from the control mice. Accelerated growth and blood clotting were also observed in tumor-bearing mice treated with heparinase I enzyme to destroy endogenous mast cell heparin and in NDST-2 knockout mice in which there is a targeted disruption in the gene coding for mast cell heparin synthesis. We conclude that imatinib mesylate accelerated the growth and peri-tumoral blood clotting of implants of mammary adenocarcinoma in mice. These results suggest that imatinib mesylate may have significant effects on mast cells infiltrating tumors, in addition to its other biologic activities. Our results also indicate that the mechanism of this effect may be related to the anticoagulant properties of mast cell heparin.
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PMID:Acceleration of tumor growth and peri-tumoral blood clotting by imatinib mesylate (Gleevec). 1286 22

An unexplained paradox of malignant melanoma is the apparent failure of the blood within the tumor to clot despite the presence of multiple factors that should promote blood clotting. Here we present histochemical evidence that human and murine melanomas are extensively infiltrated by abundant mast cells. Because mast cells contain the natural anticoagulant heparin, the present studies were aimed at defining the role of mast cell heparin in preventing the blood from clotting within B16 melanoma grafts in C57BL/6 J mice. Mice bearing B16 melanoma grafts were treated with non-specific or specific inhibitors of mast cell heparin (protamine or heparinase, respectively). After the drug treatment there was histologic and functional evidence of selective thrombosis of the blood vessels within the protamine and heparinase treated melanoma grafts. A similar, high degree of thrombosis was also observed in B16 tumors grown in transgenic NDST-2 knockout mice bearing a targeted disruption in the gene coding for mast cell heparin synthesis. The tumors grown in the protamine-treated animals were significantly smaller than the tumors from control (untreated mice). By contrast, the tumors treated with heparinase or grown in the NDST-2 knockout mice were significantly larger than the tumors from control (untreated) mice. We conclude that the intrinsic procoagulant properties of malignant melanoma are neutralized in vivo by the anticoagulant properties of endogenous heparin produced by mast cells that naturally infiltrate the tumor. Our results also suggest that thrombosis and hemostasis within melanoma may play a complex role in modulating the growth of the tumor.
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PMID:Inhibition of thrombosis in melanoma allografts in mice by endogenous mast cell heparin. 1288 84