Circulating <i>miR-200c</i> is up-regulated in paediatric patients with familial hypercholesterolaemia and correlates with <i>miR-33a/b</i> levels: implication of a ZEB1-dependent mechanism

Abstract

Hypercholesterolaemia provokes reactive oxygen species (ROS) increase and is a major risk factor for cardiovascular disease (CVD) development. We previously showed that circulating <i>miR-33a/b</i> expression levels were up-regulated in children with familial hypercholesterolaemia (FH). <i>miR-33a/b</i> control cholesterol homoeostasis and recently <i>miR-33b</i> has been demonstrated to directly target the transcription factor zinc finger E-box-binding homeobox 1 (ZEB1). The latter acts in a negative feedback loop with the <i>miR-200</i> family. Our previous studies showed that the ROS-dependent <i>miR-200c</i> up-regulation induces endothelial dysfunction and provokes a ZEB1-dependent apoptosis and senescence. In the present study, we aimed to verify whether circulating <i>miR-200c</i> was induced in FH children, and whether a correlation existed with <i>miR-33a/b</i> Total RNA was extracted from plasma of 28 FH children and 25 age-matched healthy subjects (HS) and <i>miR-200c</i> levels were measured. We found that <i>miR-200c</i> was up-regulated in FH compared with HS (4.00 ± 0.48-fold increase, <i>P</i><0.05) and exhibited a positive correlation with <i>miR-33a/b. miR-200c</i> did not correlate with plasma lipids, but correlated with C-reactive protein (CRP) plasma levels and glycaemia (GLI). Ordinary least squares (OLS) regression analysis revealed that <i>miR-200c</i> was significantly affected by GLI and by <i>miR-33a</i> (<i>P</i><0.01; <i>P</i><0.001 respectively). Moreover, we found that <i>miR-33</i> overexpression, in different cell lines, decreased ZEB1 expression and up-regulated both the intracellular and the extracellular <i>miR-200c</i> expression levels. In conclusion, circulating <i>miR-200c</i> is up-regulated in FH, probably due to oxidative stress and inflammation and via a <i>miR-33a/b</i>-ZEB1-dependent mechanism. The present study could provide the first evidence to point to the use of <i>miR-33a/b</i> and <i>miR-200c</i>, as early biomarkers of CVD, in paediatric FH.