Background: Doxorubicin (Dox) can induce endotheliotoxicity and damage the vascular endothelium (VE). The most principle mechanism might be excess reactive oxygen species (ROS) generation. Nevertheless, the characteristics of ROS generation, downstream mechanisms, and target organelles in Dox-induced endotheliotoxicity have yet to be elucidated. Methods and Results: In order to explore the related problems, the VE injury models were established in mice and human umbilical vein endothelial cells (HUVECs) by Dox-induced endotheliotoxicity. Results showed that the activities of lactate dehydrogenase (LDH) and creatine kinase of mice’s serum increased after injected Dox. The thoracic aortic strips’ endothelium-dependent dilation was significantly impaired, seen noticeable inflammatory changes, and brown TUNEL-positive staining in microscopy. After Dox-treated, HUVECs viability lowered, LDH and caspase-3 activities, and apoptotic cells increased. Both intracellular/mitochondrial ROS generation significantly increased, and intracellular ROS generation lagged behind mitochondria. HUVECs treated with Dox plus ciclosporin A (CsA) could basically terminate ROS burst, but plus edaravone (Eda) could only delay or inhibit, but could not completely cancel ROS burst. Meanwhile, the expression of endothelial nitric oxide synthase (eNOS) decreased, especially phosphorylation of eNOS significantly. Then nitric oxide content decreased, the mitochondrial function was impaired, mitochondrial membrane potential (MMP) impeded, mitochondrial swelled, mitochondrial permeability transition pore (mPTP) was opened, and cytochrome C was released from mitochondria into the cytosol. Conclusion: Dox produces excess ROS in the mitochondria, thereby weakens the MMP, opens mPTP, activates the ROS-induced ROS release mechanism, induces ROS burst, and leads to mitochondrial dysfunction, which in turn damages VE. Therefore, interrupting any step of the cycles, as mentioned above can end the related vicious cycle and prevent the occurrence and development of injury.

Reports indicate that the mechanism of doxorubicin (Dox)-induced cardiotoxicity is very complex, involving multiple regulatory cell death forms. Furthermore, the clinical intervention effect is not ideal. Iron dependence, abnormal lipid metabolism, and excess reactive oxygen species generation, three characteristics of ferroptosis, are potential therapeutic intervention targets. Here, we confirmed in vitro and in vivo that at least autophagy, apoptosis, and ferroptosis are involved in Dox cardiotoxicity-induced damage. When the neonatal rat cardiomyocytes and H9C2 cells or C57BL/6 mice were subjected to Dox-induced cardiotoxicity, epigallocatechin-3-gallate pretreatment could effectively decrease iron accumulation, inhibit oxidative stress and abnormal lipid metabolism, and thereby alleviate Dox cardiotoxicity-induced ferroptosis and protect the myocardium according to multiple functional, enzymatic, and morphological indices. The underlying mechanism was verified to involve the upregulation and activation of AMP-activated protein kinase α2, which promoted adaptive autophagy, increased energy supply, and maintained mitochondrial function. We believe that epigallocatechin-3-gallate is a candidate phytochemical against Dox-induced cardiotoxicity.

Doxorubicin (Dox) induces cardiotoxicity, thereby limiting its clinical application for chemotherapy of cancer. The mechanism of cardiotoxicity includes the production of excess intracellular ROS. 14-3-3s have been found to protect the myocardium against various types of injury. Curcumin (Cur) is a polyphenolic compound that is derived from turmeric and has multiple bioactivities, including anti-oxidative and radical-scavenging activities that exert cytoprotection. We hypothesize that the cardioprotective effects of Cur are exerted by regulating 14-3-3γ. To test the hypothesis, Dox-induced cardiotoxicity was used to establish an in vivo myocardial injury model in mice (in vivo) and primary cardiomyocytes (in intro). The effects of Cur were assessed by determining the heart rate and ECG's ST segments, as well as lactate dehydrogenase (LDH) and creatine kinase (CK) activities in the serum, caspase-3 activity, apoptosis rate, and histopathological changes of the myocardium (in vivo). In addition, cell viability, LDH, SOD, CAT, GPx, and caspase-3 activities, levels of ROS, MDA, and MMP, mPTP opening, and the apoptosis rate (in vitro) were evaluated. The expression of 14-3-3γ and Bcl-2 as well as the phosphorylation levels of Bad (S112) were determined by western blot analysis. Our results showed that Dox-induced injury to the myocardium was decreased by Cur treatment via upregulating the protein expression of 14-3-3γ in total protein and Bcl-2 expression on mitochondria, activating Bad (S112) phosphorylation, reducing the heart rate and ST segment, and reducing LDH and CK activities in the serum, thereby causing a reduction in caspase-3 activity, the apoptosis rate, and histopathological changes of the myocardium (in vivo). Furthermore, Dox treatment increased cell viability and MMP levels, decreased LDH and caspase-3 activity, ROS levels, mPTP opening, and the apoptosis rate (in vitro). However, the cardioprotective effects of Cur were attenuated by pAD/14-3-3γ-shRNA, an adenovirus that caused a knock-down of intracellular 14-3-3γ expression. In conclusion, this is the first study to demonstrate that Cur protected the myocardium against Dox-induced injury via upregulating 14-3-3γ expression, thereby promoting the translocation of Bcl-2 to mitochondria, suppressing oxidative stress, and improving mitochondrial function.

We previously demonstrated that iron overload induces liver damage by causing the formation of reactive oxygen species (ROS). Taurine is a potent free radical scavenger that attenuates the damage caused by excessive oxygen free radicals. Therefore, the aim of the present study was to investigate whether taurine could reduce the hepatotoxicity of iron overload with regard to ROS production. Mice were intraperitoneally injected with iron 5 days/week for 13 weeks to achieve iron overload. It was found that iron overload resulted in liver dysfunction, increased apoptosis and elevated oxidative stress. Taurine supplementation increased liver taurine levels by 40% and led to improved liver function, as well as a reduction in apoptosis, ROS formation and mitochondrial swelling and an attenuation in the loss of the mitochondrial membrane potential. Treatment with taurine mediated a reduction in oxidative stress in iron‑overloaded mice, attenuated liver lipid peroxidation, elevated antioxidant enzyme activities and maintained reduced glutathione levels. These results indicate that taurine reduces iron‑induced hepatic oxidative stress, preserves liver function and inhibits hepatocyte apoptosis. Therefore, taurine may be a potential therapeutic drug to reduce liver damage caused by iron overload.