Downregulated miRNA-26a-5p induces the apoptosis of endothelial cells in coronary heart disease by inhibiting PI3K/AKT pathway

R. Jing, Q.-Q. Zhong, T.-Y. Long, W. Pan, Z.-X. Qian

Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Changsha, China. qianzhx@foxmail.com

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• Cardiology

OBJECTIVE: Multiple microRNAs (miRNAs) are abnormally expressed in endothelial cells during the occurrence of coronary artery disease (CAD). Previous researches have demonstrated that miRNA-26a-5p participates in regulating the proliferation of vascular smooth muscle cells and angiogenesis. The aim of this study was to clarify the role of miRNA-26a-5p in regulating cellular performances of endothelial cells in the progression of CAD.
PATIENTS AND METHODS: In vivo CAD model was successfully established by feeding high-fat diet in 8-week-old female ApoE/LDLR-/- mice. CAD mice were administered with miRNA-26a-5p NC or miRNA-26a-5p inhibitor, respectively. Meanwhile, coronary endothelial cells were isolated from CAD mice and normal controls. Relative levels of miRNA-26a-5p, the gene of phosphate and tension homology deleted on chromosome ten (PTEN) and vascular endothelial growth factor (VEGF) in CAD patients and coronary endothelial cells isolated from CAD mice were examined. The regulatory effect of miRNA-26a-5p on atherosclerosis-related genes in primary endothelial cells and HUVECs were detected as well. Moreover, the viability and apoptosis of primary endothelial cells with miRNA-26a-5p knockdown were assessed by cell counting kit-8 (CCK-8) assay and flow cytometry, respectively. Dual-luciferase reporter gene assay was conducted to identify the relationship between miRNA-26a-5p and PTEN. Furthermore, the regulatory role of miRNA-26a-5p in phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway was examined in endothelial cells.
RESULTS: MiRNA-26a-5p and VEGF were significantly downregulated in CAD patients and primary endothelial cells isolated from CAD mice. However, PTEN was significantly upregulated. CAD mice administrated with miRNA-26a-5p inhibitor exhibited remarkably upregulated ET-1, TxA2, and ANG II, as well as downregulated eNOS and PGI2. Conversely, transfection of miRNA-26a-5p mimics in HUVECs obtained the opposite trends. PTEN was identified as the direct target gene of miRNA-26a-5p. Moreover, significantly reduced viability and enhanced apoptotic rate were observed in endothelial cells isolated from CAD mice administrated with miRNA-26a-5p inhibitor. In addition, the protein level of p-AKT in endothelial cells with miRNA-26a-5p knockdown was significantly down-regulated.
CONCLUSIONS: MiRNA-26a-5p influences the proliferative and apoptotic abilities of endothelial cells isolated from CAD mice by targeting PTEN to activate PI3K/AKT pathway.

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