Canstatin-N fragment inhibits in vitro endothelial cell proliferation and suppresses in vivo tumor growth

Type IV collagen is one of the components of vascular basement involved in regulation of angiogenesis. Canstatin, the non-collagenous 1 (NC1) domain of α2 chain of type IV collagen, was identified as an inhibitor of angiogenesis and tumor growth by Kamphaus et al. Our previous studies showed that canstatin-N, the N-terminal 1–89 amino acid fragment of canstatin, inhibited the neovascularization in a dose-dependent manner as tested by CAM assay. In the present study, we demonstrate that canstatin-N produced in Escherichia coli specifically inhibited in vitro the proliferation of human umbilical vein endothelial cells (ECV304) and significantly induced apoptosis. The apoptosis-inducing activity of canstatin-N was much stronger than that of canstatin, indicating that the apoptosis-inducing activity of canstatin is likely located within its N-terminal 1–89 amino acid fragment. Canstatin-N also suppressed in vivo growth of B16 murine melanoma in BALB/c mice at a dosage of 10 mg/kg/day. These results suggest that canstatin-N is a useful candidate molecule for inhibition of tumor growth. [Copyright &y& Elsevier]