Circulating MicroRNAs As Potential Biomarkers of Coronary Artery Disease

A therosclerotic coronary artery disease (CAD) continues to be an important socioeconomic problem and the leading cause of death in the Western world.Several cellular components, including endothelial, inflammatory, and smooth muscle cells of the arterial wall, participate in the generation of an atherosclerotic plaque, 1 the growth of which is responsible for a progressive narrowing of the lumen of the affected coronary vessel and the ensuing decrease in oxygenrich blood flow to downstream heart muscle, which may then be acutely or chronically damaged.Progression of CAD is highly variable and is driven by both environmental factors and genetic determinants.The genetic risk is thought to be attributable to an unfavorable combination of genetic variations in multiple genes that have not yet been completely characterized.However, major independent risk factors for CAD are known to include familiarity, high blood cholesterol levels, hypertension, smoking, diabetes, and obesity.Innovative early and reliable biomarkers and therapeutic targets for CAD would thus be acclaimed.MicroRNAs (also known as miRs or miRNAs) are approximately 20-to 25-nt-long noncoding RNAs that negatively regulate gene expression by binding to sites in the 3Ј untranslated region of targeted messenger RNAs. 2 These small RNAs have been found to be involved in almost every biological process, from cellular differentiation and proliferation 3,4 to cell death and apoptosis, 5,6 from synaptic plasticity 7 to immunity 8 and cardiovascular development 9 ; in addition, changes in miRNA levels and activity have been linked to human pathologies, including cancer 10 and cardiovascular diseases.11,12 Recently, miRNAs were found to be present in the circulating bloodstream, [13][14][15] together with other types of noncoding RNA, DNA, and mRNA.16 In fact, despite the high sensibility of all ribonucleic acids to RNase activity, it was discovered that plasma and serum miRNAs possess robust stability even after cycles of freezing/thawing.14,15 Moreover, circulating miRNAs were found to vary significantly duringThe opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.