miR-93-3p alleviates lipopolysaccharide-induced inflammation and apoptosis in H9c2 cardiomyocytes by inhibiting toll-like receptor 4

Background: miR-93 is recently recognized to perform anti-inflammatory action in the pathological process of cardiomyocytes dysfunction. However, it remains unclear whether miR-93-3p involves in lipopolysaccharide (LPS)-induced inflammation and apoptosis in H9c2 cells. The present study aimed to investigate the functions of miR-93-3p and its target, toll-like receptor 4 (TLR4), in LPS-stimulated cardiomyocytes. Material and methods: Cell viability was analyzed by CCK-8 assay. AnnexinV-FITC/PI staining and lactate dehydrogenase (LDH) assay were used to evaluate the cell death. The mRNA and protein levels were assayed by RT-qPCR and western blotting, respectively. The targeted gene was predicted by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay. Results: LDH stimulation resulted in the suppression of cell viability and the increase in apoptosis rate, inflammatory cytokines and LDH levels, while inhibition of TLR4 with TAK-242 or overexpression of miR-93-3p dramatically blocked LPS-induced inflammation and apoptosis in cardiomyocytes. Intriguingly, bioinformatics analysis and experimental data suggested that TLR4 was a direct target of miR-93-3p, which could inhibit TLR4 expression by transfected with miR-93-3p mimics or elevate the expression of TLR4 by transfected with miR-93-3p inhibitors. Overexpression of TLR4 carried out an opposite effect to miR-93-3p and positively regulated LPS-induced inflammation and apoptosis in cardiomyocytes. Conclusion: miR-93-3p showed the protective effects against LPS-induced inflammation and apoptosis in cardiomyocytes by inhibiting TLR4 expression.