Prostaglandins & other Lipid Mediators 76 (2005) 19–34 Enhanced 15-HPETE production during oxidant stress induces apoptosis of endothelial cells Lorraine M. Sordillo a,∗ , James A. Weaver b , Yu-Zhang Cao b , Chris Corl a , Matt J. Sylte b , Isis K. Mullarky b a Large Animal Clinical Sciences, D202 Veterinary Medical Center, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824-1314, USA b Department of Veterinary Science, The Pennsylvania State University, University Park, PA, USA Received 3 July 2004; received in revised form 15 October 2004; accepted 20 October 2004 Available online 8 March 2005 Abstract Oxidant stress plays an important role in the etiology of vascular diseases by increasing rates of endothelial cell apoptosis, but few data exist on the mechanisms involved. Using a unique model of oxidative stress based on selenium deficiency (-Se), the effects of altered eicosanoid production on bovine aortic endothelial cells (BAEC) apoptosis was evaluated. Oxidant stress sig- nificantly increased the immediate oxygenation product of arachidonic acid metabolized by the 15-lipoxygenase pathway, 15-hydroxyperoxyeicosatetraenoic acid (15-HPETE). Treatment of -Se BAEC with TNF/cyclohexamide (CHX) exhibited elevated levels of apoptosis, which was signifi- cantly reduced by the addition of a specific 15-lipoxygenase inhibitor PD146176. Furthermore, the addition of 15-HPETE to PD146176-treated BAEC, partially restored TNF/CHX-induced apopto- sis. Increased exposure to 15-HPETE induced apoptosis, as determined by internucleosomal DNA fragmentation, chromatin condensation, caspase-3 activation, and caspase-9 activation, which sug- gests mitochondrial dysfunction. The expression of Bcl-2 protein also was decreased in -Se BAEC. Addition of a caspase-9 inhibitor (LEHD-fmk) completely blocked 15-HPETE-induced chromatin condensation in -Se BAEC, suggesting that 15-HPETE-induced apoptosis is caspase-9 dependent. Increased apoptosis of BAEC as a result of oxidant stress and subsequent production of 15-HPETE may play a critical role in a variety of inflammatory based diseases. © 2005 Elsevier Inc. All rights reserved. Keywords: Endothelial cell; Oxidant stress; Selenium; 15-Lipoxygenase; Apoptosis ∗ Corresponding author. Tel.: +1 517 432 8821; fax: +1 517 432 8823. E-mail address: sordillo@msu.edu (L.M. Sordillo). 1098-8823/$ – see front matter © 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.prostaglandins.2004.10.007