Friend or Foe: A Cancer Suppressor MicroRNA-34 Potentially Plays an Adverse Role in Vascular Diseases by Regulating Cell Apoptosis and Extracellular Matrix Degradation.

BACKGROUND MicroRNAs (miRNAs) have emerged as central regulators of many processes. MiRNA-34 (miR-34) functions as a well-known tumor suppressor. The aim of this study was to investigate the mechanisms underlying how miR-34 participates in vascular disorders. MATERIAL AND METHODS Three miR-34 family members (miR-34a, miR-34b, and miR-34c) were overexpressed or silenced in human vascular smooth muscle cells (VSMCs) and umbilical vein endothelial cells (UVECs), respectively, before the proliferation and apoptosis of cells were detected by using Cell Counting Kit-8 assay and Annexin V- fluorescein isothiocyanate/propidium iodide flow cytometry. The protein expression of apoptosis biomarkers was detected by western blot. Dual-luciferase reporter assay was performed to determine the candidate target of miR-34, and enzyme-linked immune sorbent assay was used to evaluate the effect of miR-34 on the expression of the target gene. RESULTS Overexpression of miR-34 family members repressed proliferation and promoted apoptosis of VSMCs and UVECs, whereas miR-34 knockdown led to the opposite results. In addition, miR-34a inhibited the expression of alpha-1 antitrypsin (AAT), a serine protease inhibitor that suppresses the degradation of extracellular matrix, through a miR-34-binding site within the 3'-UTR of AAT. CONCLUSIONS MiR-34 promoted apoptosis of VSMC and UVEC cells by inhibiting AAT expression. This finding provides an update on the understanding of the clinical value of miR-34, which might assist to uncover novel and effective therapeutic strategies for the treatment of vascular diseases.