RESUMO
The loss of strength in combination with constant fatigue is a burden on cancer patients undergoing chemotherapy. Doxorubicin, a standard chemotherapy drug used in the clinic, causes skeletal muscle dysfunction and increases mitochondrial H2O2 We hypothesized that the combined effect of cancer and chemotherapy in an immunocompetent breast cancer mouse model (E0771) would compromise skeletal muscle mitochondrial respiratory function, leading to an increase in H2O2-emitting potential and impaired muscle function. Here, we demonstrate that cancer chemotherapy decreases mitochondrial respiratory capacity supported with complex I (pyruvate/glutamate/malate) and complex II (succinate) substrates. Mitochondrial H2O2-emitting potential was altered in skeletal muscle, and global protein oxidation was elevated with cancer chemotherapy. Muscle contractile function was impaired following exposure to cancer chemotherapy. Genetically engineering the overexpression of catalase in mitochondria of muscle attenuated mitochondrial H2O2 emission and protein oxidation, preserving mitochondrial and whole muscle function despite cancer chemotherapy. These findings suggest mitochondrial oxidants as a mediator of cancer chemotherapy-induced skeletal muscle dysfunction.
Assuntos
Antineoplásicos/farmacologia , Catalase/efeitos dos fármacos , Doxorrubicina/farmacologia , Mitocôndrias Musculares/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Animais , Neoplasias da Mama/tratamento farmacológico , Catalase/genética , Catalase/metabolismo , Modelos Animais de Doenças , Complexo I de Transporte de Elétrons/efeitos dos fármacos , Complexo I de Transporte de Elétrons/metabolismo , Complexo II de Transporte de Elétrons/efeitos dos fármacos , Complexo II de Transporte de Elétrons/metabolismo , Feminino , Peróxido de Hidrogênio/metabolismo , Camundongos , Camundongos Transgênicos , Mitocôndrias Musculares/enzimologia , Mitocôndrias Musculares/metabolismo , Contração Muscular/efeitos dos fármacos , Músculo Esquelético/fisiopatologia , Oxirredução/efeitos dos fármacos , Proteínas/efeitos dos fármacos , Proteínas/metabolismoRESUMO
Cellular proteins rely on reversible redox reactions to establish and maintain biological structure and function. How redox catabolic (NAD+/NADH) and anabolic (NADP+/NADPH) processes integrate during metabolism to maintain cellular redox homoeostasis, however, is unknown. The present work identifies a continuously cycling mitochondrial membrane potential (ΔΨm)-dependent redox circuit between the pyruvate dehydrogenase complex (PDHC) and nicotinamide nucleotide transhydrogenase (NNT). PDHC is shown to produce H2O2 in relation to reducing pressure within the complex. The H2O2 produced, however, is effectively masked by a continuously cycling redox circuit that links, via glutathione/thioredoxin, to NNT, which catalyses the regeneration of NADPH from NADH at the expense of ΔΨm. The net effect is an automatic fine-tuning of NNT-mediated energy expenditure to metabolic balance at the level of PDHC. In mitochondria, genetic or pharmacological disruptions in the PDHC-NNT redox circuit negate counterbalance changes in energy expenditure. At the whole animal level, mice lacking functional NNT (C57BL/6J) are characterized by lower energy-expenditure rates, consistent with their well-known susceptibility to diet-induced obesity. These findings suggest the integration of redox sensing of metabolic balance with compensatory changes in energy expenditure provides a potential mechanism by which cellular redox homoeostasis is maintained and body weight is defended during periods of positive and negative energy balance.
Assuntos
Peróxido de Hidrogênio/metabolismo , Potencial da Membrana Mitocondrial/fisiologia , Mitocôndrias Musculares/enzimologia , NADP Trans-Hidrogenase Específica para A ou B/metabolismo , NADP/metabolismo , Complexo Piruvato Desidrogenase/metabolismo , Animais , Inibidores Enzimáticos/farmacologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Mitocôndrias Musculares/genética , Proteínas Mitocondriais/antagonistas & inibidores , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , NADP/genética , NADP Trans-Hidrogenase Específica para A ou B/antagonistas & inibidores , NADP Trans-Hidrogenase Específica para A ou B/genética , Oxirredução/efeitos dos fármacos , Complexo Piruvato Desidrogenase/antagonistas & inibidores , Complexo Piruvato Desidrogenase/genéticaRESUMO
Doxorubicin, a commonly prescribed chemotherapeutic agent, causes skeletal muscle wasting in cancer patients undergoing treatment and increases mitochondrial reactive oxygen species (ROS) production. ROS stimulate protein degradation in muscle by activating proteolytic systems that include caspase-3 and the ubiquitin-proteasome pathway. We hypothesized that doxorubicin causes skeletal muscle catabolism through ROS, causing upregulation of E3 ubiquitin ligases and caspase-3. We tested this hypothesis by exposing differentiated C2C12 myotubes to doxorubicin (0.2 µM). Doxorubicin decreased myotube width 48 h following exposure, along with a 40-50% reduction in myosin and sarcomeric actin. Cytosolic oxidant activity was elevated in myotubes 2 h following doxorubicin exposure. This increase in oxidants was followed by an increase in the E3 ubiquitin ligase atrogin-1/muscle atrophy F-box (MAFbx) and caspase-3. Treating myotubes with SS31 (opposes mitochondrial ROS) inhibited expression of ROS-sensitive atrogin-1/MAFbx and protected against doxorubicin-stimulated catabolism. These findings suggest doxorubicin acts via mitochondrial ROS to stimulate myotube atrophy.
Assuntos
Doxorrubicina/farmacologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Linhagem Celular , Humanos , Metabolismo/efeitos dos fármacos , Metabolismo/fisiologia , Fibras Musculares Esqueléticas/citologiaRESUMO
The prevalence and economic burden of obesity and type 2 diabetes is a driving force for the discovery of molecular targets to improve insulin sensitivity and glycemic control. Here, we review several transgenic mouse models that identify promising targets, ranging from proteins involved in the insulin signaling pathway, alterations of genes affecting energy metabolism, and transcriptional metabolic regulators. Despite the diverse endpoints in each model, a common thread that emerges is the necessity for maintenance of energy balance, suggesting pharmacotherapy must target the development of drugs that decrease energy intake, accelerate energy expenditure in a well controlled manner, or augment natural compensatory responses to positive energy balance.
Assuntos
Modelos Animais de Doenças , Doenças Metabólicas/metabolismo , Camundongos Transgênicos , Animais , Dieta , Ingestão de Energia , Metabolismo Energético , Humanos , CamundongosRESUMO
Doxorubicin, a common chemotherapeutic agent, causes respiratory muscle weakness in both patients and rodents. Tumor necrosis factor-α (TNF), a proinflammatory cytokine that depresses diaphragm force, is elevated following doxorubicin chemotherapy. TNF-induced diaphragm weakness is mediated through TNF type 1 receptor (TNFR1). These findings lead us to hypothesize that TNF/TNFR1 signaling mediates doxorubicin-induced diaphragm muscle weakness. We tested this hypothesis by treating C57BL/6 mice with a clinical dose of doxorubicin (20 mg/kg) via intravenous injection. Three days later, we measured contractile properties of muscle fiber bundles isolated from the diaphragm. We tested the involvement of TNF/TNFR1 signaling using pharmaceutical and genetic interventions. Etanercept, a soluble TNF receptor, and TNFR1 deficiency protected against the depression in diaphragm-specific force caused by doxorubicin. Doxorubicin stimulated an increase in TNFR1 mRNA and protein (P < 0.05) in the diaphragm, along with colocalization of TNFR1 to the plasma membrane. These results suggest that doxorubicin increases diaphragm sensitivity to TNF by upregulating TNFR1, thereby causing respiratory muscle weakness.
Assuntos
Diafragma/efeitos dos fármacos , Diafragma/fisiopatologia , Doxorrubicina/efeitos adversos , Debilidade Muscular/induzido quimicamente , Debilidade Muscular/fisiopatologia , Receptores Tipo I de Fatores de Necrose Tumoral/fisiologia , Fator de Necrose Tumoral alfa/fisiologia , Animais , Antineoplásicos/efeitos adversos , Sequência de Bases , Primers do DNA/genética , Etanercepte , Imunoglobulina G/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Debilidade Muscular/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores do Fator de Necrose Tumoral , Receptores Tipo I de Fatores de Necrose Tumoral/deficiência , Receptores Tipo I de Fatores de Necrose Tumoral/genética , Transdução de Sinais/efeitos dos fármacos , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Fator de Necrose Tumoral alfa/genética , Regulação para Cima/efeitos dos fármacosRESUMO
Doxorubicin is a chemotherapeutic agent prescribed for a variety of tumors. While undergoing treatment, patients exhibit frequent symptoms that suggest respiratory muscle weakness. Cancer patients can receive doxorubicin chemotherapy through either intravenous (IV) or intraperitoneal (IP) injections. We hypothesized that respiratory muscle function would be depressed in a murine model of chemotherapy. We tested this hypothesis by treating C57BL/6 mice with a clinical dose of doxorubicin (20 mg/kg) via IV or IP injection. Three days later we measured contractile properties of muscle fiber bundles isolated from the diaphragm. Doxorubicin consistently depressed diaphragm force with both methods of administration (P < 0.01). Doxorubicin IP exaggerated the depression in diaphragm force and stimulated tissue inflammation and muscle fiber injury. These results suggest that clinically relevant doses of doxorubicin cause respiratory muscle weakness and that the loss of function depends, in part, on the route of administration.
Assuntos
Antibióticos Antineoplásicos/toxicidade , Diafragma/efeitos dos fármacos , Modelos Animais de Doenças , Doxorrubicina/toxicidade , Debilidade Muscular/induzido quimicamente , Paralisia Respiratória/induzido quimicamente , Animais , Diafragma/patologia , Diafragma/fisiopatologia , Injeções Intraperitoneais/efeitos adversos , Injeções Intravenosas/efeitos adversos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Debilidade Muscular/patologia , Debilidade Muscular/fisiopatologia , Paralisia Respiratória/patologia , Paralisia Respiratória/fisiopatologiaRESUMO
Sphingomyelinase (SMase) hydrolyzes membrane sphingomyelin into ceramide, which increases oxidants in nonmuscle cells. Serum SMase activity is elevated in sepsis and heart failure, conditions where muscle oxidants are increased, maximal muscle force is diminished, and fatigue is accelerated. We tested the hypotheses that exogenous SMase and accumulation of ceramide in muscle increases oxidants in muscle cells, depresses specific force of unfatigued muscle, and accelerates the fatigue process. We also anticipated that the antioxidant N-acetylcysteine (NAC) would prevent SMase effects on muscle function. We studied the responses of C2C12 myotubes and mouse diaphragm to SMase treatment in vitro. We observed that SMase caused a 2.8-fold increase in total ceramide levels in myotubes. Exogenous ceramide and SMase elevated oxidant activity in C2C12 myotubes by 15-35% (P < 0.05) and in diaphragm muscle fiber bundles by 58-120% (P < 0.05). The SMase-induced increase in diaphragm oxidant activity was prevented by NAC. Exogenous ceramide depressed diaphragm force by 55% (P < 0.05), while SMase depressed maximal force by 30% (P < 0.05) and accelerated fatigue--effects opposed by treatment with NAC. In conclusion, our findings suggest that SMase stimulates a ceramide-oxidant signaling pathway that results in muscle weakness and fatigue.
Assuntos
Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Oxidantes/fisiologia , Esfingomielina Fosfodiesterase/fisiologia , Acetilcisteína/farmacologia , Animais , Antioxidantes/farmacologia , Proteínas de Bactérias/farmacologia , Linhagem Celular , Ceramidas/metabolismo , Citosol/metabolismo , Diafragma/fisiologia , Técnicas In Vitro , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Contração Muscular , Fibras Musculares Esqueléticas/metabolismo , Espécies Reativas de Nitrogênio/metabolismo , Transdução de Sinais , Esfingomielina Fosfodiesterase/farmacologiaRESUMO
Fatiguing exercise promotes oxidation of intracellular thiols, notably glutathione. Interventions that oppose or reverse thiol oxidation can inhibit fatigue. The reduced cysteine donor l-2-oxothiazolidine-4-carboxylate (OTC) supports glutathione synthesis and is approved for use in humans but has not been evaluated for effects on skeletal muscle. We tested the hypotheses that OTC would 1) increase reduced glutathione (GSH) levels and decrease oxidized glutathione, and 2) inhibit functional indexes of fatigue. Diaphragm fiber bundles from adult male ICR mice were incubated for 1 or 2 h at 37 degrees C with buffer (control, C) or OTC (10 mM). N-acetylcysteine (NAC; 10 mM) was used as a positive control. We measured GSH metabolites and fatigue characteristics. We found that muscle GSH content was increased after 1-h incubation with OTC or NAC but was not altered after 2-h incubation. One-hour treatment with OTC or NAC slowed the decline in force with repetitive stimulation [mean (SD) fatigue index at 300 s: OTC = 34 +/- 6% vs. C = 50 +/- 8%, P < 0.05; NAC = 55 +/- 4% vs. C = 65 +/- 8%, P < 0.05] as did the 2-h OTC treatment (OTC = 38 +/- 9% vs. C = 51 +/- 9%, P < 0.05). These results demonstrate that OTC modulates the muscle GSH pool and opposes fatigue under the current experimental conditions.
Assuntos
Antioxidantes/farmacologia , Diafragma/efeitos dos fármacos , Fadiga/prevenção & controle , Dissulfeto de Glutationa/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ácido Pirrolidonocarboxílico/farmacologia , Tiazolidinas/farmacologia , Acetilcisteína/farmacologia , Animais , Diafragma/metabolismo , Diafragma/fisiopatologia , Sequestradores de Radicais Livres/farmacologia , Técnicas In Vitro , Masculino , Camundongos , Camundongos Endogâmicos ICR , OxirreduçãoRESUMO
Although nicotinamide nucleotide transhydrogenase (NNT)-deficient C57BL/6J (6J) mice are known to be highly susceptible to diet-induced metabolic disease, this notion stems primarily from comparisons of 6J mice to other inbred strains. To date, very few studies have directly compared metabolic disease susceptibility between NNT-deficient 6J mice and NNT-competent C57BL/6 substrains. In this study, comprehensive profiling of the metabolic response to a high-fat/high-sucrose diet (HFD) were compared across time in 6J and C57BL/6NJ (6N) mice. Given that increased peroxide exposure drives insulin resistance, coupled with the fact that NNT regulates peroxide detoxification, it was hypothesized that 6J mice would experience greater derangements in redox homeostasis/metabolic disease upon HFD exposure. Contrary to this, both lines were found to be highly susceptible to diet-induced metabolic disease, as evidenced by impairments in glucose tolerance as early as 24 h into the HFD. Moreover, various markers of the metabolic syndrome, as well as peroxide stress, were actually blunted, rather than exacerbated, in the 6J mice, likely reflecting compensatory increases in alterative redox-buffering pathways. Together, these data provide evidence that the susceptibility to HFD-induced metabolic disease is similar in the 6J and 6N substrains. Given the numerous genetic variances in the 6J stain, including loss of NNT function, these findings suggest that the 6N substrain is the more logical and representative genetic background model for metabolic studies.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Animais , Desoxiglucose/metabolismo , Suscetibilidade a Doenças , Peróxido de Hidrogênio/metabolismo , Resistência à Insulina/fisiologia , Doenças Metabólicas/etiologia , Doenças Metabólicas/metabolismo , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismoRESUMO
In insulin-sensitive skeletal muscle, the expression of constitutively active Ca(2+)/calmodulin-dependent protein kinase kinase α (caCaMKKα) stimulates glucose uptake independent of insulin signaling (i.e., Akt and Akt-dependent TBC1D1/TBC1D4 phosphorylation). Our objectives were to determine whether caCaMKKα could stimulate glucose uptake additively with insulin in insulin-sensitive muscle, in the basal state in insulin-resistant muscle, and if so, to determine whether the effects were associated with altered TBC1D1/TBC1D4 phosphorylation. Mice were fed a control or high-fat diet (60% kcal) for 12 weeks to induce insulin resistance. Muscles were transfected with empty vector or caCaMKKα plasmids using in vivo electroporation. After 2 weeks, caCaMKKα protein was robustly expressed. In insulin-sensitive muscle, caCaMKKα increased basal in vivo [(3)H]-2-deoxyglucose uptake approximately twofold, insulin increased glucose uptake approximately twofold, and caCaMKKα plus insulin increased glucose uptake approximately fourfold. caCaMKKα did not increase basal TBC1D1 (Ser(237), Thr(590), Ser(660), pan-Thr/Ser) or TBC1D4 (Ser(588), Thr(642), pan-Thr/Ser) phosphorylation. In insulin-resistant muscle, caCaMKKα increased basal glucose uptake approximately twofold, and attenuated high-fat diet-induced basal TBC1D1 (Thr(590), pan-Thr/Ser) and TBC1D4 (Ser(588), Thr(642), pan-Thr/Ser) phosphorylation. In cell-free assays, CaMKKα increased TBC1D1 (Thr(590), pan-Thr/Ser) and TBC1D4 (Ser(588), pan-Thr/Ser) phosphorylation. Collectively, these results demonstrate that caCaMKKα stimulates glucose uptake additively with insulin, and in insulin-resistant muscle, and alters the phosphorylation of TBC1D1/TBC1D4.
Assuntos
Quinase da Proteína Quinase Dependente de Cálcio-Calmodulina/metabolismo , Glucose/metabolismo , Resistência à Insulina/fisiologia , Músculo Esquelético/metabolismo , Animais , Quinase da Proteína Quinase Dependente de Cálcio-Calmodulina/genética , Proteínas Ativadoras de GTPase/genética , Proteínas Ativadoras de GTPase/metabolismo , Glucose/farmacologia , Insulina/metabolismo , Camundongos , Músculo Esquelético/efeitos dos fármacos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fosforilação/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacosRESUMO
Considerable debate exists about whether alterations in mitochondrial respiratory capacity and/or content play a causal role in the development of insulin resistance during obesity. The current study was undertaken to determine whether such alterations are present during the initial stages of insulin resistance in humans. Young (â¼23 years) insulin-sensitive lean and insulin-resistant obese men and women were studied. Insulin resistance was confirmed through an intravenous glucose tolerance test. Measures of mitochondrial respiratory capacity and content as well as H(2)O(2) emitting potential and the cellular redox environment were performed in permeabilized myofibers and primary myotubes prepared from vastus lateralis muscle biopsy specimens. No differences in mitochondrial respiratory function or content were observed between lean and obese subjects, despite elevations in H(2)O(2) emission rates and reductions in cellular glutathione. These findings were apparent in permeabilized myofibers as well as in primary myotubes. The results suggest that reductions in mitochondrial respiratory capacity and content are not required for the initial manifestation of peripheral insulin resistance.
Assuntos
Resistência à Insulina/fisiologia , Mitocôndrias Musculares/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Obesidade/metabolismo , Adolescente , Adulto , Glicemia/metabolismo , Feminino , Humanos , Peróxido de Hidrogênio/metabolismo , Insulina/sangue , Masculino , Músculo Esquelético/metabolismo , OxirreduçãoRESUMO
The combined loss of muscle strength and constant fatigue are disabling symptoms for cancer patients undergoing chemotherapy. Doxorubicin, a standard chemotherapy drug used in the clinic, causes skeletal muscle dysfunction and premature fatigue along with an increase in reactive oxygen species (ROS). As mitochondria represent a primary source of oxidant generation in muscle, we hypothesized that doxorubicin could negatively affect mitochondria by inhibiting respiratory capacity, leading to an increase in H2O2-emitting potential. Here we demonstrate a biphasic response of skeletal muscle mitochondria to a single doxorubicin injection (20mg/kg). Initially at 2h doxorubicin inhibits both complex I- and II-supported respiration and increases H2O2 emission, both of which are partially restored after 24h. The relationship between oxygen consumption and membrane potential (ΔΨ) is shifted to the right at 24h, indicating elevated reducing pressure within the electron transport system (ETS). Respiratory capacity is further decreased at a later time point (72 h) along with H2O2-emitting potential and an increased sensitivity to mitochondrial permeability transition pore (mPTP) opening. These novel findings suggest a role for skeletal muscle mitochondria as a potential underlying cause of doxorubicin-induced muscle dysfunction.
Assuntos
Antibióticos Antineoplásicos/farmacologia , Doxorrubicina/farmacologia , Metabolismo Energético/efeitos dos fármacos , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Animais , Peróxido de Hidrogênio/metabolismo , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias Musculares/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Oxirredução , Consumo de Oxigênio , Ratos Sprague-DawleyRESUMO
Once regarded as a "by-product" of aerobic metabolism, the production of superoxide/H2O2 is now understood to be a highly specialized and extensively regulated process responsible for exerting control over a vast number of thiol-containing proteins, collectively referred to as the redox-sensitive proteome. Although disruptions within this process, secondary to elevated peroxide exposure, have been linked to disease, the sources and mechanisms regulating increased peroxide burden remain poorly defined and as such are difficult to target using pharmacotherapy. Here we identify the pyruvate dehydrogenase complex (PDC) as a key source of H2O2 within skeletal muscle mitochondria under conditions of depressed glutathione redox buffering integrity. Treatment of permeabilized myofibers with varying concentrations of the glutathione-depleting agent 1-chloro-2,4-dinitrobenzene led to a dose-dependent increase in pyruvate-supported JH2O2 emission (the flux of H2O2 diffusing out of the mitochondrial matrix into the surrounding assay medium), with emission rates eventually rising to exceed those of all substrate combinations tested. This striking sensitivity to glutathione depletion was observed in permeabilized fibers prepared from multiple species and was specific to PDC. Physiological oxidation of the cellular glutathione pool after high-fat feeding in rodents was found to elevate PDC JH2O2 emission, as well as increasing the sensitivity of the complex to GSH depletion. These findings reveal PDC as a potential major site of H2O2 production that is extremely sensitive to mitochondrial glutathione redox status.
Assuntos
Glutationa/química , Peróxido de Hidrogênio/química , Mitocôndrias Musculares/metabolismo , Complexo Piruvato Desidrogenase/metabolismo , Superóxidos/química , Adulto , Animais , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias Musculares/enzimologia , NAD/biossíntese , NAD/química , Oxirredução , Ratos , Ratos Sprague-Dawley , RespiraçãoRESUMO
SIGNIFICANCE: Fatigue is one of the most common symptoms of cancer and its treatment, manifested in the clinic through weakness and exercise intolerance. These side effects not only compromise patient's quality of life (QOL), but also diminish physical activity, resulting in limited treatment and increased morbidity. RECENT ADVANCES: Oxidative stress, mediated by cancer or chemotherapeutic agents, is an underlying mechanism of the drug-induced toxicity. Nontargeted tissues, such as striated muscle, are severely affected by oxidative stress during chemotherapy, leading to toxicity and dysfunction. CRITICAL ISSUES: These findings highlight the importance of investigating clinically applicable interventions to alleviate the debilitating side effects. This article discusses the clinically available chemotherapy drugs that cause fatigue and oxidative stress in cancer patients, with an in-depth focus on the anthracycline doxorubicin. Doxorubicin, an effective anticancer drug, is a primary example of how chemotherapeutic agents disrupt striated muscle function through oxidative stress. FUTURE DIRECTIONS: Further research investigating antioxidants could provide relief for cancer patients from debilitating muscle weakness, leading to improved quality of life.
Assuntos
Antineoplásicos/efeitos adversos , Fadiga Muscular/efeitos dos fármacos , Debilidade Muscular/induzido quimicamente , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Humanos , Debilidade Muscular/metabolismoRESUMO
Cancer patients receiving doxorubicin chemotherapy experience both muscle weakness and fatigue. One postulated mediator of the muscle dysfunction is an increase in tumor necrosis factor-alpha (TNF), a proinflammatory cytokine that mediates limb muscle contractile dysfunction through the TNF receptor subtype 1 (TNFR1). Our main hypothesis was that systemic doxorubicin administration would cause muscle weakness and fatigue. Systemic doxorubicin administration (20 mg/kg) depressed maximal force of the extensor digitorum longus (EDL; P < 0.01), accelerated EDL fatigue (P < 0.01), and elevated serum TNF levels (P < 0.05) 72 h postinjection. Genetic TNFR1 deficiency prevented the fall in specific force caused by systemic doxorubicin, without protecting against fatigue (P < 0.01). These results demonstrate that clinical doxorubicin concentrations disrupt limb muscle function in a TNFR1-dependent manner.