Radiation-induced expression of platelet endothelial cell adhesion molecule-1 in cerebral endothelial cells

Background: Radiation-induced molecular changes on the endothelial surface of brain arteriovenous malformations (AVM) may be used as markers for specific vascular targeting agents. In this study, we examined the level of expression of platelet endothelial cell adhesion molecule-1 (PECAM-1) on brain endothelial cell surface a)er radiation treatment, with the aim of targeting the radiation-induced PECAM-1 on the AVM endothelium with prothrombotic agents to selectively occlude AVM vessels. Materials and Methods: Mouse cerebral endothelial cells (bEnd.3) were irradiated with 5, 15, or 25 Gy. Real-time quantitative polymerase chain reaction (PCR) and incell enzyme-linked immunosorbent assay (ELISA) were performed to quantify the temporal gene and surface PECAM-1 protein expression up to 168 hours post-irradiation. Two-tailed unpaired t-tests were used to determine statistical significance. Results: PECAM-1 gene expression was found to be significantly elevated post-irradiation in real-time quantitative PCR, with the maximum level of gene expression being evident at 120 hours post-irradiation representing an 11-fold increase in comparison to non-irradiated controls (p<0.001). In-cell ELISA detected a similar up-regulation for protein expression on the cell surface with delayed peak time. Conclusion: Ionising radiation can induce the up-regulation of PECAM-1 on brain endothelial cell surface. This protein may be a potential candidate for facilitating selective AVM vessel occlusion through the application of radiosurgery followed by vascular targeting.