Background: The importance of matrix metalloproteinases in angiogenesis, tumor growth, and metastasis is well known. However, little is known about the role of matrix metalloproteinases in the formation of hemangiomas and about the possible therapeutic use of matrix metalloproteinase inhibitors in aggressive vascular tumors.
Purpose: To study the role of matrix metalloproteinase in vascular tumors, we tested the antineoplastic activity of a synthetic inhibitor of matrix metalloproteinases, batimastat, on an experimental model of hemangioma, formed by murine endothelioma cells transformed by polyoma middle-T oncogene (eEnd.1).
Methods: The effect of batimastat was studied in vivo on the formation of hemorrhaging, cavernous hemangiomas by eEnd.1 endothelioma cells injected subcutaneously in nude mice and on the angiogenic response induced by an endothelioma cell supernatant embedded in a pellet of reconstituted basement membrane (Matrigel). The effect of batimastat was investigated in vitro on endothelial cell proliferation, motility, and invasion of a layer of Matrigel.
Results: Daily treatment with batimastat (30, 3, and 0.3 mg/kg at the site of eEnd.1 cell injection) inhibited tumor growth, with increased doubling time. The carboxamide derivative of batimastat, BB-374, a poor inhibitor of matrix metalloproteinase activity, was less active in reducing hemangioma growth. Histologic analysis of treated tumors indicated a reduction in the size of blood-filled spaces and in hemorrhage. Batimastat also inhibited the angiogenic response induced by cultured eEnd.1 endothelioma cell supernatant embedded in a pellet of Matrigel. Batimastat significantly inhibited endothelial cell invasion in vitro through a layer of Matrigel, but it showed no direct cytotoxic activity.
Conclusions: Batimastat reduces in vivo growth of experimental hemangiomas, most probably by blocking endothelial cell recruitment by the transformed cells or by interfering with cell organization in vascular structures.
Implications: These results confirm the importance of matrix metalloproteinase in endothelial cell recruitment that occurs in angiogenesis and in the formation of vascular tumors and suggest a therapeutic potential for synthetic matrix metalloproteinase inhibitors.