Plumbagin protects H9c2 cardiomyocytes against TBHP-induced cytotoxicity by alleviating ROS-induced apoptosis and modulating autophagy

Plumbagin (PLB) has been previously reported to alleviate myocardial ischemia/reperfusion injury in vivo. In the present study, the potential of plumbagin to protect against hydrogen peroxide-induced injury in cardiomyocytes was analyzed. Specifically, the cytoprotective effects of PLB were evaluated in H9c2 cardiomyocytes, in which oxidative stress was induced by tertiary butyl hydrogen peroxide (TBHP; 75 mu M) treatment. After the cardiomyocytes were treated with different concentrations of PLB, cell viability, creatine kinase (CK) activity and lactate dehydrogenase (LDH) release were determined. The apoptosis rate and reactive oxygen species (ROS) levels were evaluated by flow cytometry. Western blot analyses of cleaved caspase-3, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase enzyme 4 (NOX4), and phosphorylated (p)-p38 mitogen-activated protein kinase (MAPK) were performed. PLB pretreatment (5, 10 or 20 mu M) restored TBHP-treated H9c2 cell viability (P<0.01). Additionally, PLB significantly decreased CK (P<0.01) and LDH activity (P<0.01). TBHP induced apoptosis and oxidative stress in cardiomyocytes, whereas PLB pretreatment significantly reduced the TBHP-induced apoptosis rate (P<0.01) and ROS levels (P<0.01). Furthermore, PLB resulted in a decrease in the expression of cleaved caspase-3, NOX4, and p-p38 MAPK in TBHP-treated H9c2 cells. The active marker of autophagosomes, LC3-II/LC3-I, was increased following treatment with PLB, indicating the induction of autophagy. The present study revealed the protective role of PLB against TBHP-induced cardiomyocyte injury via the alleviation of ROS-mediated apoptosis and induction of autophagy.