Small RNA Biomarkers Come of Age⁎

Small RNA Biomarkers Come of Age⁎: MicroRNAs (miRNAs) are endogenous, 21- to 23-nucleotide- long RNA molecules that post-transcriptionally regulate target genes. miRNAs interact specifically with certain mRNAs by repressing their translation or inducing their degradation (1). Current estimates are that miRNAs thereby regulate the levels of the majority of mammalian proteins (2). Research in recent years has assigned miRNAs a key regulatory role in various physiological processes. Also, a growing number of miRNAs has been implicated in the pathogenesis of several diseases, including cardiac disease (3). With respect to the latter, miRNAs have been implicated in cardiac hypertrophy (4,5), fibrosis (6), and vascular disease (7). Intriguingly, miRNAs also appear to represent valid therapeutic targets, because modulation of their expression in vivo (for example, with antisense RNA molecules) has been shown to effectively modulate cardiovascular disease in various animal models (4,6,8–10). Most recently, miRNAs have received much attention regarding their suitability as biomarkers for disease. Following pioneering work from the cancer field (11,12), also several cardiovascular studies have found marked deregulation of miRNAs in various types of clinical specimens (for review, see ref. 13).