Acurhagin-C, an ECD disintegrin, inhibits integrin alphavbeta3-mediated human endothelial cell functions by inducing apoptosis via caspase-3 activation.
OBJECTIVE
Acurhagin, a member of versatile metalloproteinase disintegrins from Agkistrodon acutus venom, has been identified as a platelet aggregation inhibitor, previously. Here, acurhagin-C, the C-terminal Glu-Cys-Asp (ECD)-containing fragment of acurhagin, was evaluated for its biological activities and potential applications in anti-angiogenic therapy.


METHODS
Human umbilical vein endothelial cells (HUVECs) were treated with acurhagin-C to assay effects on viability, apoptosis, adhesion, migration, invasion, proliferation and angiogenesis. The recognition site and signalling involved for the interactions of acurhagin-C with HUVEC were determined using flow cytometric, electrophoresis and immunoblotting analyses.


RESULTS
Acurhagin-C decreased viability and induced apoptosis in HUVEC. It also dose-dependently inhibited HUVEC adhesion to immobilized extracellular matrices fibronectin, collagen I and vitronectin with respective IC(50) values of approximately 0.6, 0.3 and 0.1 microM. Acurhagin-C prevented migration and invasion of HUVEC through vitronectin- and Matrigel-coated barriers respectively. Furthermore, acurhagin-C attenuated fibroblast growth factor-2-primed angiogenesis both in vitro and in vivo, and specifically blocked the binding of anti-alphavbeta3 monoclonal antibody 23C6 to HUVEC in an ECD-dependent manner. However, purified alphavbeta3 also dose-dependently bound to immobilized acurhagin and acurhagin-C with a saturable pattern. Interference with integrin alphavbeta3-mediated functions and promotion of caspase-3 activation by acurhagin-C affected morphology of HUVEC and induced apoptosis.


CONCLUSIONS
Acurhagin-C elicited endothelial anoikis via disruption of alphavbeta3/focal adhesion kinase/phosphatidylinositol 3-kinase/Akt survival cascade and subsequent initiation of the procaspase-3 apoptotic signalling pathway.
Wang
Wen-Jeng
WJ
Department of Nutrition and Health Sciences, Chang-Gung Institute of Technology, Kwei-Shan, Tao-Yuan, Taiwan. wjwang@gw.cgit.edu.tw
D023102:Anoikis / Q000187:drug effects; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000187:drug effects* / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D019483:Disintegrins / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000037:antagonists & inhibitors*; D010446:Peptide Fragments / Q000008:administration & dosage / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014471:Umbilical Veins / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D019483:Disintegrins; D039302:Integrin alphaVbeta3; D010446:Peptide Fragments; C552884:acurhagin-C protein, Agkistrodon acutus; D019869:Phosphatidylinositol 3-Kinases; D051416:Focal Adhesion Protein-Tyrosine Kinases; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3