Recombinant Mouse Canstatin Inhibits Chicken Embryo Chorioallantoic Membrane Angiogenesis and Endothelial Cell Proliferation

Human canstatin, a 24 kD fragment of the α2 chain of type IV collagen, has been proved to be one of the most effective inhibitors of angiogenesis and tumor growth. To investigate in vivo antiangiogenesis activity and in vitro effects on endothelial cell proliferation of recombinant mouse canstatin, the cDNA of mouse canstatin was introduced into an expression vector pQE40 to construct a prokaryotic expression vector pQE-mCan. The recombinant mouse canstatin efficiently expressed in E. coli M15 after IPTG induc- tion was monitored by SDS-PAGE and by Western blotting with an anti-hexahistidine tag antibody. The expressed mouse canstatin, mainly as inclusion bodies, accounted for approximately 35% of the total bacte- rial proteins. The inclusion bodies were washed, lysed and purified by the nickel affinity chromatography to a purity of approximately 93%. The refolded mouse canstatin was tested on the chicken embryo chorioallan- toic membranes (CAM), and a large number of newly formed blood vessels were significantly regressed. In addition, recombinant mouse canstatin potently inhibited endothelial cell proliferation with no inhibition on non-endothelial cells. Taken together, these findings demonstrate that the recombinant mouse canstatin ef- fectively inhibited angiogenesis of the chicken embryo in a dose-dependent manner and specially suppressed in vitro the proliferation of human umbilical vein endothelial cells.