Overexpression of PHGPx inhibits hydroperoxide-induced oxidation, NF kappaB activation and apoptosis and affects oxLDL-mediated proliferation of rabbit aortic smooth muscle cells

Rabbit abdominal aortic smooth muscle cells (SMC) were stably transfected w ith the cDNA of porcine phospholipid hydroperoxide glutathione peroxidase ( PHGPx) by means of a retroviral gene transfer technique, to create a model for studying cellular processes relevant to atherogenesis. The transfected cells (SMC/PHGPx) had approximately 4-fold higher PHGPx activity when cultu red in the presence of selenite whereas the parental cells did not show any significant increase in PHGPx or total GPx activity upon selenium suppleme ntation. In situ functionality of PHGPx was validated by inhibition of lino leic acid hydroperoxide-induced toxicity, dihydrorhodamine oxidation, NF ka ppa B activation and apoptosis. SMC grown in 1% FCS responded to oxidized L DL (oxLDL) with a marked proliferation, as measured by [H-3]thymidine incor poration, irrespective of selenium supplementation. In SMC/PHGPx grown with or without selenite under control conditions or exposed to native LDL, thy midine incorporation was generally depressed. Also, oxLDL-induced prolifera tion was lower in SMC/PHGPx compared to untransfected SMC up to 24 h of inc ubation. After 40 h, however, selenite supplementation restored maximum pro liferation response to oxLDL in SMC/PHGPx. The results suggest a proliferat ive effect of endogenous hydroperoxides in SMC. They further reveal that hy droperoxy lipids of oxLDL contribute to the induction of proliferation, but also suggest involvement of hydroxy lipids in the response to oxLDL. (C) 2 000 Elsevier Science Ireland Ltd. All rights reserved.