Inhibition of miR-23a attenuates doxorubicin-induced mitochondria-dependent cardiomyocyte apoptosis by targeting the PGC-1α/Drp1 pathway.

Background And Purpose: Doxorubicin (Dox)-induced cardiotoxicity limits its clinical use. A number of microRNAs (miRs) have been found essential in Dox-induced cardiotoxicity. The aim of the present study was to elucidate the effects of miR-23a on Dox-induced cardiomyocyte apoptosis and underlying mechanisms.

Experimental Approach: Dox-induced cardiotoxicity model was established in primary neonatal rat ventricular myocytes (NRVMs). MTT assay, Live/Dead staining was employed to examine the viability and cell death of NRVMs. Mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were measured. Protein levels of mitochondria biogenesis and fission/fusion associated factors including peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), dynamin-related protein-1 (Drp1) and mitofusin 2 (Mfn2) were detected. Meanwhile, apoptosis-related cytochrome c (Cyt c) and caspase-3 expression were examined by western blot. PGC-1α siRNA was employed to validate the role of miR-23a in Dox-induced cardiotoxicity.

Key Results: MiR-23a expression was significantly increased by Dox concentration-dependently. Inhibition of miR-23a markedly increased viability and MMP, reduced cell death and ROS production of NRVMs. MiR-23a mimic significantly inhibited expression of its target PGC-1α. MiR-23a inhibitor significantly diminished phosphorylation of Drp1 without affecting Mfn2 expression. Protein expression of Cyt c and cleaved caspase-3 were markedly inhibited by miR-23a inhibitor. The protective effects of miR-23a inhibitor were reversed by PGC-1α siRNA.

Conclusions And Implications: Increased miR-23a promoted mitochondrial injury in the Dox-induced cellular model. Inhibition of miR-23a attenuated cardiomyocyte damage by directly targeting PGC-1α/p-Drp1, thereby inhibiting mitochondria-dependent apoptosis. These findings may provide a new potential target for the treatment of Dox-induced cardiotoxicity.