Neuregulin-1 protects cardiomyocytes against doxorubicin-induced apoptosis required Akt activation

Objective To explore the effects and possible mechanisms of neuregulin-1 protecting against doxorubicin induced cardiomyocyte injury. Methods Neonatal rat ventricular myocytes(NRVMs) were separated from two-day-old SD rats. NRVMs were subjected to various treatments, in order to both induce apoptosis and determine the effects of NRG-1 on the process. After treated with different concentration of neuregulin-1(NRG-1, 10-1 000 ng/ml), DOX(1 μmol/L) or the inhibitor of PI3K LY294002 (10 μmol/L). Activation of apoptosis was determined by observing increases in the protein levels of classic apoptosis markers (including cleaved caspase 3, cytochrome c, Bcl-2, BAX and terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining). The activation of Akt was detected by means of western blot analysis. Results Compared to DOX group, p-Akt[(0.83±0.21)% vs (2.02±0.13)%, P<0.05], protein expression and the cell viability of cardiomyocytes was significantly increased[(58.45±6.24)% vs (96.32±5.42)%, P<0.05], Cleaved caspase3[(2.92±0.34)% vs (1.34±0.25)%, P<0.05], cytochrome C[(1.92±0.21)% vs (0.87±0.13)%, P<0.05], protein expression were markedly reduced in NRG-1(1 000 ng/ml) group. Compared to DOX+ NRG-1 group, pretreatment with phosphoinositole-3-kinase inhibitor LY294002 significantly reduced the p-Akt protein expression[(2.02±0.13)% vs(0.91±0.14), P<0.05], increased the apoptotic rate[(1.76±0.28)% vs (5.43±0.31)%, P<0.05], down-regulated the ratio of Bcl-2/Bax[(0.91±0.19)% vs (0.48±0.15)%, P<0.05]. Conclusion NRG-1 is a potent inhibitor of doxorubicin-induced apoptosis, which acts through the PI3K-Akt pathway. NRG-1 is a novel therapeutic drug which may be effective in preventing further damage from occurring in DOX-induced damaged myocardium. Key words: Neuregulin; Doxorubicin; Myocyte, cardiac; Aapoptosis