Critical promoter region for statin-induced human endothelial nitric oxide synthase (eNOS) transcription in EA.hy926 cells

Aim: statins have many anti-atherogenic effects apart from reducing the serum level of low density lipoprotein cholesterol (ldl-c). for instance,statins can enhance the expression of endothelial nitric oxide synthase (enos),at least partly by upregulating its transcription. although it has been reported that -786 t/c polymorphism of the promoter region has an important influence on statininduced transcription of the human enos gene,much remains unclear about statin-induced enos transcription. we tried to identify other statin-responsive promoter regions. methods: a human endothelial cell line (ea.hy926 cells) was treated with pitavastatin,atorvastatin,or fluvastatin,after which enos mrna levels were assessed by quantitative real-time rt-pcr. ea.hy926 cells were also transiently transfected with luciferase reporter genes driven by various lengths of the human enos promoter and were treated with statins before luciferase activity was measured. results: statin treatment increased enos mrna levels in ea.hy926 cells. in addition,cells transfected with the reporter gene driven by the enos promoter fragment starting from position -740 exhibited a pitavastatin-induced increase of luciferase activity,which was not observed in cells transfected with the reporter gene driven by the fragment starting from -727. similar results were also obtained with atorvastatin and fluvastatin. conclusions: statins enhanced enos expression in ea.hy926 cells,at least partly by inducing its transcription. although a statin-responsive sequence that could function even in a heterologous promoter was not precisely identified,the region of the human enos promoter around position -730 seems to be critical for statin-induced transcriptional activation.