Tumor angiogenesis

Angiogenesis requires the migration, differentiation and proliferation of endothelial cells. Tumor growth is angiogenesis-dependent and angiogenesis is directly or indirectly induced by the tumor. Induction of angiogenesis is, therefore, an important stage in carcinogenesis and in the development of metastasis. Numerous angiogenic factors have been identified, most of which are mitogenic for endothelial cells and only some of which are responsible for tube formation. Pharmacologic compounds such as heparin, heparin fragments and corticosteroids have been shown to be anti angiogenic substances. Recently two new inhibitors of angiogenesis, a cartilage-derived inhibitor and platelet factor 4 have been described.