Volume 43, Number 5, 200836th annual meeting of the European Radiation Research Society
|Number of page(s)||1|
|Section||Poster Presentation - Normal Tissue Damage|
|Published online||03 September 2008|
Role of plasminogen activator inhibitor type-1 in radiation-induced endothelial cell apoptosis.
IRSN, BP 17, 92265 Fontenay-aux-Roses cedex, France
2 Laboratoire CRRET-UMR7149, Université Paris Xll -Val de Marne, IUT de Créteil, 61 avenue du Général de Gaulle, 94010 CRETEIL CEDEX, France
3 IRSN, BP 17, 92262 Fontenay-aux-Roses, France
4 Rouen University ospital, 1 rue de Germont, 76 031 Rouen, France
Normal tissue toxicity still remains a dose-limiting factor in clinical radiation therapy. Intestinal radiation toxicity is characterized by mucosal injury, inflammation, vascular activation followed by development of progressive vascular fibrosis/sclerosis and radiation enteritis. The endothelium is known to play a critical role in radiation-induced intestinal injury. Previous studies showed that endothelial cell (EC) apoptosis plays a central role in early radiation-induced intestinal injury. Recently, we demonstrated that plasminogen activator inhibitor type 1 (PAI-1) is an essential mediator of late intestinal radiation toxicity. PAI-1 knockout mice (PAI-1 -/-) are protected against intestinal radiation-induced damage with increased survival and better intestinal function compared with wild type mice (Wt). However, it is not clear whether PAI-1 plays a role in acute radiation-induced intestinal damages. We hypothesized that PAI-1 could contribute to the radiosensitivity of the endothelium in acute phases of radiation enteropathy. In vitro, irradiation stimulates PAI-1 expression (mRNA and protein) in EC 4 hours to 48 hours after irradiation. Moreover, FACS analyses (Sub-G1 and AnnexinV) and caspase assay showed that apoptosis is rapidly induced 4h to 24h after irradiation. These results suggest that PAI-1 could play a key role in radiation-induced EC cell death. To prove that PAI-1 is involved, molecular modulation of PAI-1 expression was performed using an expression vector and a RNA interference strategy. In EC overexpressing PAI-1 (pCMV PAI-1), radiation-induced apoptosis is increased 6h after 10Gy irradiation compared with EC transfected with a control vector. 48 hours after PAI-1 siRNA transfection, PAI-1 mRNA and protein levels are decreased by 85%. Sub-G1 and Annexin V flow cytometry analyses showed that radiation-induced apoptosis is decreased in siRNA-PAI-1 transfected EC. These preliminary results show that PAI-1 plays a role in the radiosensitivity of EC. To prove the relevance of our in vitro results, radiation-induced EC apoptosis in vivo was monitored in a model radiation enteropathy. After exposure of an intestinal segment to 19 Gy radiation, acute intestinal radiation injury are assessed in Wt and PAI-1 -/- mice 4 hours to 3 days after irradiation. Radiation injury score (RIS) is monitored and radiation-induced EC apoptosis is followed by double immunolabelling TUNEL or caspase-3 / CD31. RIS is reduced in PAI-1 -/- mice compared to Wt mice suggesting that acute EC apoptosis is reduced in PAI-1 -/- mice. This current and ongoing work should allow to determine the putative role of PAI-1 in radiation-induced endothelial cells apoptosis and consequently in intestinal radiation injury.
Key words: radiation enteritis / PAI-1
© EDP Sciences, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.