Protective effect of microRNA-30b on hypoxia/reoxygenation-induced apoptosis in H9C2 cardiomyocytes

• We investigate the protective role of miR-30b and H/R induced apoptosis.
• H/R treatment is used to simulate I/R injury.
• MiR-30b could down-regulate cell apoptosis.
• Ras–PI3K–Akt pathway is involved in the apoptosis process.
• MiR-30b could be a new therapy for heart disease.

We examined the protective role of microRNA-30b (miR-30b) in ischemia–reperfusion (I/R)-induced injury in rat H9C2 cardiomyocytes. H9C2 cells were subjected to hypoxia–reoxygenation (H/R) treatment to simulate ischemia–reperfusion (I/R) injury. H9C2 cells were divided into: vehicle control (VC) group; scrambled inhibitors (INC) group; scrambled mimics (MNC) group; H/R + VC group; H/R + INC group; H/R + mimics group. H/R induced apoptosis was detected by flow cytometry and the pathways involved in miR-30b-mediated protection were examined by analyzing the expression of miR-30b, Bcl-2, Bax, Caspase-3, KRAS, p-AKT and total AKT in H9C2 cells. Overexpression of miR-30b mimic (H/R + mimics group) significantly increased Bcl-2 and Bcl-2/Bax levels and decreased Bax and Caspase-3 levels, compared with the H/R + VC group (all P < 0.05). Consistent with this, the apoptosis rate was significantly decreased in the H/R + mimics group (P < 0.05) compared with the H/R + VC group. Western blot analysis revealed that overexpression of miR-30b mimic resulted in significantly increase in AKT activation and decreased KRAS, compared to the H/R + VC group (both P < 0.05). In conclusion, the H/R induced apoptosis decreased miR-30b expression, but over-expression of miR-30b inhibited H/R induced apoptosis. The observed miR-30b-mediated protection against H/R induced apoptosis involved the upregulation of Ras–PI3K–Akt pathway.