Doxorubicin-induced oxidative stress differentially regulates proteolytic signaling in cardiac and skeletal muscle

Abstract

Doxorubicin (DOX) is a highly effective antineoplastic agent used in cancer treatment. Unfortunately, clinical use of DOX is limited due to the development of dose-dependent toxicity to cardiac and respiratory (i.e., diaphragm) muscles. After administration, DOX preferentially localizes to the inner mitochondrial membrane, where it promotes cellular toxicity via enhanced mitochondrial reactive oxygen species (ROS) production. Although recent evidence suggests that amelioration of mitochondrial ROS emission preserves cardiorespiratory muscle function following DOX treatment, the mechanisms responsible for this protection remain unknown. Therefore, we tested the hypothesis that DOX-induced mitochondrial ROS production is required to stimulate pathological signaling by the autophagy/lysosomal system (ALS), the ubiquitin-proteasome pathway (UPP), and the unfolded protein response (UPR). Cause and effect were determined by administration of the mitochondria-targeted peptide SS-31 to DOX-treated animals. Interestingly, while SS-31 abrogated aberrant ROS emission in cardiorespiratory muscles of DOX-treated animals, our results revealed muscle-specific regulation of effector pathways. In the heart, SS-31 prevented DOX-induced proteolytic signaling through the ALS and UPP. In contrast, ALS signaling was inhibited by SS-31 in the diaphragm, but the UPP was not affected. UPR signaling was activated in both muscles at eukaryotic translation initiation factor 2α (eIF2α) S51 in the heart and diaphragm of DOX-treated animals and was attenuated with SS-31 treatment in both tissues. However, downstream signaling of eIF2α (activating transcription factor 4 and CCAAT/enhancer-binding protein homologous protein) was diminished in the heart but upregulated in the diaphragm with DOX. Collectively, these results show that DOX-induced ROS production plays distinct roles in the regulation of cardiac and diaphragm muscle proteolysis.

Prevention of Doxorubicin-Induced Autophagy Attenuates Oxidative Stress and Skeletal Muscle Dysfunction

“…However, the signaling pathways responsible for DOX-induced soleus muscle dysfunction remain unclear. Our laboratory and others have reported the significant upregulation of several proteins required for elevated protein breakdown via autophagy acutely following DOX administration [12,14,[41][42][43]. These initial findings suggest a role for enhanced autophagy signaling in the development of DOX-induced skeletal muscle weakness, and our results confirm that the upregulation of autophagy by DOX contributes to increased muscle proteolysis and contractile dysfunction.…”

“…With regard to muscle wasting, activation of the UPR has been shown to contribute to cancer cachexia-induced skeletal muscle atrophy, primarily through the induction of eIF2α phosphorylation and splicing of XBP1 [45]. Activation of eIF2α induces the expression of the transcription factor ATF4, which leads to the activation of several genes involved in the adaptation to cellular stress [12,33]. Indeed, ATF4 has been shown to regulate starvation-induced skeletal muscle atrophy and promote the expression of autophagy genes [46].…”

“…This increase in DOX-induced mitochondrial ROS production is associated with enhanced cytosolic and myofibrillar protein degradation in skeletal muscle, causing disruption to muscle contraction and fiber atrophy [10]. Specifically, oxidative damage to skeletal muscle acts as an upstream trigger to stimulate muscle breakdown through activation of key proteolytic systems [7,9,11,12].…”

The Impact of Immune Cells on the Skeletal Muscle Microenvironment During Cancer Cachexia

“…However, muscle contractions induced by neuromuscular electrical stimulation was recently shown to improve muscle mass in breast cancer patients receiving chemotherapy ( Guigni et al, 2019 ; Toth et al, 2020 ). Both resistance ( Bredahl et al, 2020 ) and endurance ( Smuder, 2019 ; Huertas et al, 2020 ; Montalvo et al, 2020 ) exercise have shown promise in mitigating chemotherapy-induced skeletal muscle toxicities in preclinical rats. Additionally, resistance ( Hardee et al, 2016 , 2018 ) and endurance ( Puppa et al, 2012 ; Vanderveen et al, 2020 ) exercise can improve muscle mass and function in cachectic mice.…”

“…Our understanding of chemotherapy’s deleterious off-target effects on skeletal muscle has improved over the last decade highlighting a key role for metabolic and DNA/cell stress ( Gilliam et al, 2009 ; Barreto et al, 2016b ; Morton et al, 2019 ; Sougiannis et al, 2019 ). Targeting the generation of mitochondrial reactive oxygen species (ROS), by exercise or antioxidants, has shown promise in mitigating Doxorubicin (DOX)-induced skeletal muscle dysfunction ( Smuder, 2019 ; Montalvo et al, 2020 ), and targeting the activation of MAPKs with ACVR2B/Fc and MEK1 inhibitors has been proposed to alleviate 5-FU induced mitochondrial dysfunction ( Barreto et al, 2016b , 2017 ). Inflammatory signaling has been demonstrated to regulate chemotherapy-induced E3 ligase activation through modulating TNF-α ( Gilliam et al, 2009 ).…”