MicroRNA-155 affects oxidative damage through regulating autophagy in endothelial cells

MicroRNA-155 (miRNA-155) is a typical multifunctional miRNA, which serves a crucial role in the regulation of numerous vessel cells. However, its effects on dysfunctional endothelial cells have not been completely elucidated. In order to investigate the signaling pathway of miRNA-155-induced cell injury, H₂O₂ was used to establish an oxidative stress cell model, and miR-155 was transfected into H₂O₂-treated cells. The CCK8 assay was then employed to examine the effect of miR-155 on the cell proliferations of H₂O_2-treated cells, and the expressions of Microtubule Associated Protein 1 Light Chain 3 (LC3) and Sequestosome 1 (P62) were detected to examine the effect of miR-155 on the autophagy of Human umbilical vein endothelial cells, and then the formation of intracellular autophagosomes was observed. The results indicated that endothelial cell proliferation was promoted, and oxidant-induced injury was decreased when the expression of miR-155 was inhibited. In addition, the results also demonstrated that when the miR-155 inhibitor was used, the expression of LC3 was increased and the expression of P62 was decreased. This suggests that modulated miR-155 can prevent oxidative damage in endothelial cells, by regulating the level of autophagy. Furthermore, the present study also demonstrated that miR-155 regulated autophagy via promotion of the expression of the autophagy-related gene, Autophagy Related 5 (ATG5). In conclusion, the attenuated expression of miR-155 can decrease oxidant-induced injury and promote cell proliferation via upregulating autophagy, which subsequently affects the expression of ATG5. The present study provides a novel insight into microRNAs as potential therapeutics for the treatment of heart disease.