Expression pattern of miR-21, miR-25 and PTEN in peripheral blood mononuclear cells of patients with significant or insignificant coronary stenosis.

Coronary artery disease (CAD) is primarily caused by atherosclerosis, which is a series of chronic inflammatory processes leading to the initiation and progression of vascular endothelial cell injury enhancing plaque formation. As critical components of the immune system, peripheral blood mononuclear cells (PBMCs) actively cross-talk with pathophysiological conditions induced by endothelial cell injury, reflecting in altered PBMC expression pattern. This study explored PBMC expression levels of miR-21, miR-25 and PTEN in patients with angiographically proven significant coronary stenosis (the CAD group), patients with insignificant coronary stenosis (the ICAD group) and healthy subjects, and assessed potentials of PBMC expressions in discriminating groups of study subjects. In-silico analysis was also performed to obtain insights into CAD-related pathways and biological processes that may be influenced by altered miRNA expressions. A reduced level of PBMC miR-21 was observed in the ICAD group compared to the CAD group (P: 0.004) or healthy controls (P: 0.0001). PBMC miR-21 level was negatively correlated with the PTEN expression (Spearman r: -0.43, P: 3.9e-09). The PTEN expression was increased in the CAD or ICAD group compared to the control group (CAD vs. controls P: 0.0003, ICAD vs. controls P: 0.03). A stepwise increase in PBMC miR-25 levels was observed from healthy controls to ICADs and CAD patients (Kruskal-Wallis P: 7.68e-12). PBMC gene expressions had reasonable power to discriminate between pairs of study groups. PBMC miR-21 levels were able to discriminate ICADs from both CADs and controls and miR-25 levels had potentials to differentiate among all pairs of study groups (i.e. CADs-ICADs, CADs-controls, CADs-all other subjects, ICADs-controls). PBMC PTEN expression was able to discriminate patients with CAD or ICAD from control subjects. Overrepresentation enrichment analysis of experimentally validated targets of miR-21 and miR-25 highlighted key biological processes and pathways, such as "angiogenesis" and "leukocyte cell-cell adhesion", that may be influenced by dysregulation of PBMC miR-21 and miR-25. In conclusion, these findings suggest that patients with insignificant coronary stenosis may have a distinct PBMC miRNA expression profile than those with significant stenosis or healthy controls.