Rosuvastatin attenuates oxidative stress and CaMKIIδ activation in isolated ventricular cardiomyocytes acutely exposed to Doxorubicin

Cardiotoxicity represents a major complication of cancer therapy with anthracyclines, whose main known compound is doxorubicin (DOX). Although the mechanisms of DOX-induced toxic cardiomyopathy (DICM) are not entirely understood, increased reactive oxygen species (ROS) and activated CaMKIIδ are known to contribute to impaired Ca handling in isolated cardiomyocytes. Recent clinical trials have shown that statins can attenuate DOX-mediated cardiotoxicity. We hypothesized that the preventive effect of statins is based on attenuation of DOX-related ROS-formation and CaMKIIδ activation.

Methods

Cytoplasmic ROS formation was examined in freshly isolated murine wildtype (WT) cardiomyocytes exposed to DOX at 10 µmol/L for 10 mins in the presence or absence of rosuvastatin (30 µmol/L). ROS were measured by confocal microscopy (CellRox Deep Red). Intracellular Ca handling was assessed by epifluorescence microscopy (Fura2-AM) and confocal microscopy (Fluo4-AM). Activation of CaMKIIδ and subsequent phosphorylation of CaMKIIδ-dependent target structures were assessed by western blot in tissue from DOX-perfused hearts. 

Results

DOX acutely increased intracellular ROS in WT cardiomyocytes by fourfold, which was significantly attenuated by concomitant application of rosuvastatin. This was associated with oxidation of CaMKIIδ in DOX-perfused hearts. Activation of CaMKIIδ resulted in impaired Ca handling (e.g. diastolic SR Ca loss) as a consequence of hyperphosphorylation at the CaMKIIδ-specific phosphorylation site serine 2814 of RyR2. As with reduced ROS formation, intracellular Ca handling was largely preserved upon concomitant DOX/rosuvastatin treatment, most likely as a consequence of attenuated serine 2814 hyperphosphorylation at RyR2. 

Conclusion

Our study shows that DOX-related ROS formation and CaMKIIδ activation can be attenuated upon concomitant application of rosuvastatin.