Endorepellin, a Novel Inhibitor of Angiogenesis Derived from the C Terminus of Perlecan

Abstract

Perlecan, a ubiquitous basement membrane heparan sulfate proteoglycan, plays key roles in blood vessel growth and structural integrity. We discovered that the C terminus of perlecan potently inhibited four aspects of angiogenesis: endothelial cell migration, collagen-induced endothelial tube morphogenesis, and blood vessel growth in the chorioallantoic membrane and in Matrigel plug assays. The C terminus of perlecan was active at nanomolar concentrations and blocked endothelial cell adhesion to fibronectin and type I collagen, without directly binding to either protein; henceforth we have named it "endorepellin." We also found that endothelial cells possess a significant number of high affinity (K d of 11 nM) binding sites for endorepellin and that endorepellin binds endostatin and counteracts its anti-angiogenic effects. Thus, endorepellin represents a novel anti-angiogenic product, which may retard tumor neovascularization and hence tumor growth in vivo.

Vasculostatin, a proteolytic fragment of Brain Angiogenesis Inhibitor 1, is an antiangiogenic and antitumorigenic factor

“…It was previously shown that some proteolytic fragments of larger proteins can have angiostatic functions. These include cleavage products of extracellular matrix proteins such as endostatin, a C-terminal fragment of collagen XVIII; tumstatin, a fragment of the noncollagenase 1 (NCI) domain of the a3 chain of type IV collagen; endorepellin, a C-terminal domain of the heparan sulfate proteoglycan perlecan; and angiostatin and K1-5, both fragments of plasminogen (O'Reilly et al, 1994(O'Reilly et al, , 1997Cao et al, 1999;Maeshima et al, 2000;Mongiat et al, 2003). Vasostatin, a fragment derived from calreticullin, and PEX-c, the C-terminal cleavage product of MMP-2, also have antiangiogenic functions (Brooks et al, 1998;Pike et al, 1998).…”

The bone morphogenetic protein 1/Tolloid-like metalloproteinases

“…The perlecan carboxyl-terminal domain, domain V, is responsible for most of the molecule's ability to bind cells and, when cleaved, corresponds to a fragment designated endorepellin, with angiostatic activity (Mongiat et al, 2003). Endorepellin comprises EGF-like repeats and laminin-like globular (LG) motifs.…”

Endorepellin-evoked Autophagy Contributes to Angiostasis

“…Endorepellin and Torin 1 Inhibit ex Vivo AngiogenesisGiven its well established angiostatic activity (34,43,47), we hypothesized that endorepellin could evoke autophagy and inhibit angiogenesis via a common pathway. To this end, we utilized an ex vivo model, the aortic ring assay (54).…”

“…In contrast, the C-terminal domain V of perlecan, known as endorepellin, exhibits angiostatic properties (34). Endorepellin is found in vivo, where it is proteolytically processed from perlecan (14) via matrix metalloproteinases, a family of enzymes involved in a multitude of biological processes (35)(36)(37)(38)(39).…”

“…As its name implies, endorepellin is an inhibitor of endothelial cell migration and capillary morphogenesis, thus preventing the formation of new blood vessels (34). These functional properties result from a "dual receptor antagonism" through its binding to VEGFR2 and ␣2␤1 integrin (43)…”