Atorvastatin inhibits expression of minichromosome maintenance proteins in vascular smooth muscle cells.
3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been reported to inhibit vascular smooth muscle cell growth, a key event in the pathogenesis of proliferative vascular diseases. The mechanism by which HMG-CoA reductase inhibitors exert their antiproliferative activity is not fully understood, especially their effect on DNA replication. We therefore investigated the effects of atorvastatin on minichromosome maintenance (MCM) protein 6 and 7 expression in vascular smooth muscle cells, two proteins essential for initiation of DNA replication. Stimulation of quiescent rat aortic vascular smooth muscle cells with fetal bovine serum induced MCM6 and MCM7 protein and mRNA expression, which was potently attenuated by atorvastatin in a dose-dependent fashion. Mevalonate completely abrogated the inhibitory effect on serum-induced MCM6 and MCM7 expression, demonstrating that biosynthesis of isoprenoids was likely the specific pathway blocked by atorvastatin. Transient transfection experiments revealed that atorvastatin inhibited MCM6 and MCM7 promoter activity, implicating a transcriptional mechanism. The MCM6 and MCM7 promoters contain several E2F sites critical for their transcriptional activation. Activity of a luciferase reporter plasmid containing four E2F elements was also strongly inhibited by atorvastatin. The inhibitory effect of atorvastatin on MCM6 and MCM7 was reversed by adenoviral-mediated overexpression of E2F, indicating that their downregulation by atorvastatin involves an E2F-dependent mechanism. These findings demonstrate that MCM proteins play an essential role during the proliferation of vascular smooth muscle cells and may provide a novel therapeutic target for proliferative vascular diseases. Inhibition of MCM6 and MCM7 expression by blocking E2F function may contribute importantly to the inhibition of vascular smooth muscle cell DNA synthesis by atorvastatin.
Bruemmer
Dennis
D
Division of Endocrinology, Diabetes and Hypertension and The Gonda (Goldschmied) Diabetes Center, David Geffen School of Medicine, University of California, Warren Hall, Suite 24-130, 900 Veteran Avenue, Los Angeles, CA 90095, USA.
Yin
Fen
F
Liu
Joey
J
Kiyono
Tohru
T
Fleck
Eckart
E
Van Herle
Andre
A
Graf
Kristof
K
Law
Ronald E
RE
D017502:Adenovirus E2 Proteins / Q000235:genetics / Q000502:physiology; D000818:Animals; D000069059:Atorvastatin; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D005822:Genetic Vectors / Q000235:genetics; D006538:Heptanoic Acids / Q000494:pharmacology*; D015151:Immunoblotting; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D011758:Pyrroles / Q000494:pharmacology*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
D017502:Adenovirus E2 Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D006538:Heptanoic Acids; D009687:Nuclear Proteins; D011758:Pyrroles; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D016160:Retinoblastoma Protein; D000069059:Atorvastatin; D008156:Luciferases