Inhibition of endothelial cell survival and angiogenesis by protein kinase A.
Receptors for the provisional ECM are important regulators of angiogenesis. One of these receptors, integrin alpha5beta1, plays a critical role in tumor- and growth factor-induced angiogenesis, because antagonists of this integrin potently inhibit angiogenesis and tumor growth. Here we show that the integrin alpha5beta1 promotes endothelial cell survival during angiogenesis in vivo by suppressing the activity of protein kinase A (PKA). Antagonists of integrin alpha5beta1 activate PKA, which then leads to the activation of caspase-8 and induction of apoptosis. Direct activation of PKA by cAMP or by expression of the PKA catalytic subunit also induces endothelial cell apoptosis, resulting in angiogenesis inhibition in vivo. Our studies indicate that ligation of integrin alpha5beta1 during angiogenesis suppresses an apoptotic program that is dependent on PKA. These studies also indicate that induction of endothelial cell apoptosis in vivo by genetic or pharmacological activation of PKA may be a useful strategy to inhibit angiogenesis.
Kim
Semi
S
University of California, San Diego Comprehensive Cancer Center, La Jolla, California 92093, USA.
Bakre
Manjiri
M
Yin
Hong
H
Varner
Judith A
JA
D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000502:physiology; D002470:Cell Survival; D002645:Chickens; D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology*; D004789:Enzyme Activation; D005353:Fibronectins / Q000502:physiology; D006801:Humans; D039081:Integrin alpha5beta1 / Q000502:physiology; D018919:Neovascularization, Physiologic; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism
D020533:Angiogenesis Inhibitors; D005353:Fibronectins; D039081:Integrin alpha5beta1; D019253:Proto-Oncogene Proteins c-bcl-2; D017868:Cyclic AMP-Dependent Protein Kinases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases