Endothelial cell surface ATP synthase-triggered caspase-apoptotic pathway is essential for k1-5-induced antiangiogenesis.
We have recently reported the identification of kringle 1-5 (K1-5) of plasminogen as a potent and specific inhibitor of angiogenesis and tumor growth. Here, we show that K1-5 bound to endothelial cell surface ATP synthase and triggered caspase-mediated endothelial cell apoptosis. Induction of endothelial apoptosis involved sequential activation of caspases-8, -9, and -3. Administration of neutralizing antibodies directed against the alpha- and beta-subunits of ATP synthase to endothelial cells attenuated activation of these caspases. Furthermore, inhibitors of caspases-3, -8, and -9 also remarkably blocked K1-5-induced endothelial cell apoptosis and antiangiogenic responses. In a mouse tumor model, we show that caspase-3 inhibitors abolished the antitumor activity of K1-5 by protecting the tumor vasculature undergoing apoptosis. These results suggest that the specificity of the antiendothelial effect of K1-5 is attributable, at least in part, to its interaction with the endothelial cell surface ATP synthase and that the caspase-mediated endothelial apoptosis is essential for the angiostatic activity of K1-5. Thus, our findings provide a mechanistic insight with respect to the angiostatic action and signaling pathway of K1-5 and angiostatin.
Veitonmäki
Niina
N
Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden.
Cao
Renhai
R
Wu
Lin-Hua
LH
Moser
Tammy L
TL
Li
Bo
B
Pizzo
Salvatore V
SV
Zhivotovsky
Boris
B
Cao
Yihai
Y
D025181:ATP Synthetase Complexes / Q000378:metabolism*; D020533:Angiogenesis Inhibitors / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002642:Chick Embryo; D003315:Cornea / Q000098:blood supply; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D005354:Fibrosarcoma / Q000098:blood supply* / Q000188:drug therapy* / Q000201:enzymology; D006801:Humans; D007527:Isoenzymes; D018082:Kringles; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D018919:Neovascularization, Physiologic / Q000187:drug effects; D010958:Plasminogen / Q000378:metabolism / Q000494:pharmacology*
D020533:Angiogenesis Inhibitors; D061945:Caspase Inhibitors; D007527:Isoenzymes; D010958:Plasminogen; D025181:ATP Synthetase Complexes; D020169:Caspases