Abstract WMP120: Radiosurgery Induces Novel Protein Changes on the Endothelium of Arteriovenous Malformations: Potential for Therapeutic Targets
Introduction: Brain arteriovenous malformations (AVMs) are a significant cause of hemorrhagic stroke. Almost one third are untreatable using current methods. We aim to use stereotactic radiosurgery as a priming tool to elicit novel protein expression on irradiated AVM vessels and targeting with thrombotic antibody-conjugates to induce rapid thrombosis and vessel closure.
Hypothesis: Radiosurgery induces novel protein changes on the AVM endothelium that are potential therapeutic targets.
Methods: A model arteriovenous fistula (AVF) formed in rats was irradiated by GammaKnife (20Gy) or sham-irradiated. After 24h, animals were perfused with EZ-link Sulfo-NHS-LC Biotin to label surface-accessible proteins. Biotinylated AVFs were dissected, pooled (n=4/group) and protein extracted. Biotin-labelled proteins were enriched on streptavidin-agarose beads before LC-MS/MS using SWATH acquisition label-free mass spectrometry.
Results: At 24h post-irradiation, 280 surface-associated proteins were identified in sham and irradiated extracts. Of these, 56 were up-regulated in irradiated AVMs (greater than 1.5-fold change vs sham). Radiation increased fibrinogen α/β (1.5-fold), platelet factor 4 (16-fold) and plasminogen (2-fold), suggesting enhanced adhesion of blood-borne molecules to the vessel wall. Twenty-eight mitochondrial proteins increased, including manganese superoxide dismutase (2-fold), which may reflect radiation-induced changes in subcellular localization or cell lysis causing intracellular molecule release and entrapment. Troponin I (cardiac) and tropomyosin 1α, actin-associated proteins externalized under stress, increased 14- and 4-fold. Secreted and membrane proteins were also identified (e.g. clusterin, 1.5-fold; CD93, 5-fold; Ras-related Rab18, 1.8-fold).
Conclusions: Using in vivo biotin labelling, we have identified a series of novel surface-accessible proteins induced by radiosurgery that are potential therapeutic targets. Externalization of intracellular proteins may provide unique radiation-stimulated candidates for vascular targeting in AVMs.
Author Disclosures: L.S. McRobb: None. V.S. Lee: None. S.G. Thomas: None. M. Wiedmann: None. J.V. Amal Raj: None. Z. Zhao: None. M. Grace: None. V. Moutrie: None. M. McKay: None. M. Molloy: None. M.A. Stoodley: None.
- © 2016 by American Heart Association, Inc.