Circulating microRNA-126 in patients with coronary artery disease: correlation with LDL cholesterol

Background: Coronary artery disease (CAD) is a major problem worldwide. Atherosclerosis and thrombosis underlying CAD involve multiple cell types. New and useful diagnostic markers are required. MicroRNAs (miRNAs) are a class of noncoding RNAs that posttranscriptionally regulate the gene expressions involved in various cellular processes. Endothelial dysfunction is implicated in early processes of athero-thrombosis. Thus, it was hypothesized that the level of vascular endothelium-enriched miRNAs would be altered in plasma samples of CAD patients. Methods: Vascular endothelium-enriched miRNA (miR-126) level was analyzed in plasma from 31 patients with CAD and 36 patients without CAD (qRT-PCR analysis). Results: MiR-126 was not significantly down-regulated or up-regulated in CAD patients. Interestingly, the level of miR-126 was significantly decreased in patients with CAD and high low-density lipoprotein (LDL) cholesterol level. In contrast, the level of miR-126 was significantly increased when LDL cholesterol was high in patients who had risk factors for CAD but did not have angiographically significant CAD. Conclusion: MiR-126 was not significantly down-regulated or up-regulated in CAD patients and was not suitable for discriminating CAD patients from patients without CAD. The oppositely-directed relationship between miR-126 and LDL cholesterol in patients with or without CAD may have significant implications for identifying a potential role of miR-126 in cholesterol metabolism.