Doxorubicin-induced skeletal muscle atrophy: Elucidating the underlying molecular pathways

Protective effects of Alamandine against doxorubicin-induced liver injury in rats

BACKGROUND

Doxorubicin (DOX), a common chemotherapeutic agent, is often associated with dose-limiting hepatotoxicity. Alamandine, a peptide of the renin-angiotensin system, has shown antioxidant and anti-inflammatory properties that may counteract these adverse effects.

OBJECTIVE

This study investigated the protective effects of alamandine on DOX-induced liver injury in rats.

METHODS

Male Wistar rats received DOX (3.75 mg/kg intraperitoneally) on days 14, 21, 28, and 35, reaching a cumulative dose of 15 mg/kg. Alamandine (50 µg/kg/day) was administered continuously via mini-osmotic pumps for 42 days. Liver toxicity was assessed through biochemical measurements of oxidative stress markers, inflammatory cytokines, and liver enzymes, as well as histological examination.

RESULTS

DOX administration significantly increased serum alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and malondialdehyde (MDA) levels while reducing superoxide dismutase (SOD) and catalase (CAT) activity. Histological analysis revealed hydropic degeneration and hepatocyte necrosis. Alamandine co-treatment restored SOD and CAT activity, reduced MDA and inflammatory markers, and normalized liver enzyme levels, indicating significant hepatoprotection. Furthermore, treatment with alamandine reduced the expression of pro-inflammatory cytokines IL-6, IL-1, and NF-κB induced by DOX, while p53 expression remained unchanged.

CONCLUSION

Alamandine effectively mitigates DOX-induced hepatotoxicity, demonstrating its therapeutic potential as an adjunctive agent in chemotherapy through its antioxidant and anti-inflammatory mechanisms.

Creatine Supplementation Mitigates Doxorubicin-Induced Skeletal Muscle Dysfunction but Not Cardiotoxicity

Creatine has demosntrated protective effects against muscle dysfunction, but its potential protection against doxorubicin-induced cardio and skeletal muscle toxicity remains poorly understood. We aimed to investigate the protective effects of creatine supplementation against doxorubicin-induced cardio and skeletal muscle myotoxicity. This study analyzed twenty male C57BL/6J mice, divided into three groups: Control (C; n = 6), Dox (n = 7) which received weekly doxorubicin injections (16 mg/kg i.p. in 20 days) and DoxCr (n = 7) with both doxorubicin and creatine supplementation (4%). Doxorubicin administration induced skeletal muscle atrophy in extensor digitorum longus (EDL) (-28%) and soleus muscles (-17%), accompanied by a decline in muscle strength. This atrophic response was concomitant with increased oxidative stress and elevated levels of IL-6. Cardiotoxic effects of doxorubicin were marked by a 15% reduction in cardiac mass and a significant 21% decrease in cardiomyocyte diameter, alongside a substantial 58% rise in IL-6 levels. On the opposite creatine supplementation mitigated doxorubicin-induced oxidative stress (elevated MDA and IL-6, and reduced GSH/GSSG ratio) and prevented skeletal muscle atrophy in both the EDL and soleus muscles, while also enhancing muscle strength. However, protective effects were not observed in cardiac muscle. Creatine protects skeletal, but not cardiac muscle against doxorubicin-induced toxicity, atrophy and strength loss.

Distinct Impact of Doxorubicin on Skeletal Muscle and Fat Metabolism in Mice: Without Dexrazoxane Effect

The chemotherapeutic agent doxorubicin (DOX) leads to the loss of skeletal muscle and adipose tissue mass, contributing to cancer cachexia. Experimental research on the molecular mechanisms of long-term DOX treatment is modest, and its effect on both skeletal muscle and adipose tissue has not been studied in an integrative manner. Dexrazoxane (DEXRA) is used to prevent DOX-induced cancer-therapy-related cardiovascular dysfunction (CTRCD), but its impact on skeletal muscle and adipose tissue remains elusive. Therefore, this study aimed to investigate the long-term effects of DOX on adipose tissue and skeletal muscle metabolism, and evaluate whether DEXRA can mitigate these effects. To this end, 10-week-old male C57BL6/J mice (n = 32) were divided into four groups: (1) DOX, (2) DOX-DEXRA combined, (3) DEXRA and (4) control. DOX (4 mg/kg weekly) and DEXRA (40 mg/kg weekly) were administered intraperitoneally over 6 weeks. Indirect calorimetry was used to assess metabolic parameters, followed by a molecular analysis and histological evaluation of skeletal muscle and adipose tissue. DOX treatment led to significant white adipose tissue (WAT) loss (74%) and moderate skeletal muscle loss (Gastrocnemius (GAS): 10%), along with decreased basal activity (53%) and energy expenditure (27%). A trend toward a reduced type IIa fiber cross-sectional area and a fast-to-slow fiber type switch in the Soleus muscle was observed. The WAT of DOX-treated mice displayed reduced Pparg (p < 0.0001), Cd36 (p < 0.0001) and Glut4 (p < 0.05) mRNA expression-markers of fat and glucose metabolism-compared to controls. In contrast, the GAS of DOX-treated mice showed increased Cd36 (p < 0.05) and Glut4 (p < 0.01), together with elevated Pdk4 (p < 0.001) mRNA expression-suggesting reduced carbohydrate oxidation-compared to controls. Additionally, DOX increased Murf1 (p < 0.05) and Atrogin1 (p < 0.05) mRNA expression-markers of protein degradation-compared to controls. In both the WAT and GAS of DOX-treated mice, Ppard mRNA expression remained unchanged. Overall, DEXRA failed to prevent these DOX-induced changes. Collectively, our results suggest that DOX induced varying degrees of wasting in adipose tissue and skeletal muscle, driven by distinct mechanisms. While DEXRA protected against DOX-induced CTRCD, it did not counteract its adverse effects on skeletal muscle and adipose tissue.

Tadalafil pretreatment attenuates doxorubicin-induced hepatorenal toxicity by modulating oxidative stress and inflammation in Wistar rats

Doxorubicin (DOX) is a widely used anticancer agent, but its clinical application is limited by significant off-target hepatorenal toxicity. Tadalafil (TAD), a selective phosphodiesterase-5 inhibitor used mainly for erectile dysfunction and pulmonary arterial hypertension, has shown potential in reducing oxidative stress. This study investigated TAD's chemoprotective effects and underlying mechanisms in DOX-induced hepatorenal toxicity in rats over 12 days. Eight groups of six rats each were orally pretreated with sterile water, silymarin (SIL), or TAD one hour before receiving intraperitoneal injections of 2.5 mg/kg DOX. On the 13th day, the rats were humanely sacrificed under inhaled halothane anesthesia, and serum was collected for hepatic and renal function tests, while liver and kidney tissues were analyzed for antioxidant enzyme activity, pro-inflammatory cytokines assay, and histopathological evaluation. DOX successfully induced hepatorenal toxicity, evidenced by significant increases (p<0.001, p<0.0001) in serum K+, urea, and creatinine levels, along with decreases in HCO3 -, TCa2+, and Cl-. Tissue analysis showed reduced SOD, CAT, GST, and GPx activities, with elevated MDA and GSH levels. TAD pretreatment significantly ameliorated these biochemical alterations (p<0.05, p<0.001, p<0.0001), suggesting its potential as an effective chemoprophylactic adjuvant in the development of DOX-induced hepatorenal toxicity.

The therapeutic effect of NRF2 activator, ezetimibe, in cardiac cachexia

INTRODUCTION

Heart failure (HF) is caused by functional and structural irregularity leading to impaired ejection or filling capacity of the heart. HF leads to chronic inflammatory conditions in the heart leads to weight loss, anorexia, and muscle atrophy known as cachexia. The present study was carried out to investigate the role of Ezetimibe, an NRF2 activator, in cardiac cachexia and to develop a treatment strategy for cardiac cachexia.

METHOD

Balb/c mice of either sex at 6-8 weeks of age were given 2 mg/kg of doxorubicin in 0.9% sodium chloride solution intraperitoneally (i.p.) for the alternate days for the first week and then once a week for the next 4 weeks. After induction of cardiac atrophy, treatment with Ezetimibe (1.5 mg/kg, p.o) was given for the next 4 weeks.

RESULT

In the cardiac cachectic animals, a significant decrease in body weight, food, and water intake was observed. Cardiac cachectic animals showed a significant increase in serum glucose, total cholesterol, LDL, triglyceride, VLDL, CK-MB, LDH, and CRP levels. Cardiac atrophic index, heart weight to body weight ratios (HW/BW), right ventricular weight to heart weight ratios (RV/HW), and left ventricular weight to heart weight ratios (LV/HW), were significantly decreased in cardiac cachectic animals. The weights of the skeletal muscles such as EDL, gastrocnemius, soleus, tibialis anterior, and quadriceps muscles, and the weight of adipose tissue such as subcutaneous, visceral, perirenal, and brown adipose tissue were significantly decreased in the cardiac cachectic group relative to the normal group. Treatment with ezetimibe improves body weight, food intake, and water intake. Ezetimibe decreases serum glucose, total cholesterol, LDL, triglyceride, VLDL, CK-MB, LDH and CRP levels. Cardiac atrophic markers such as HW/BW, RV/HW, and LV/HW were improved. The weight of skeletal muscles and adipose tissue was increased after treatment with ezetimibe.

CONCLUSION

Our data showed that the NRF2 activator, Ezetimibe produces a beneficial effect on cardiac cachexia in the doxorubicin-induced cardiac cachexia model. Ezetimibe was successful to reduce the levels of inflammatory cytokines, ameliorate the effects on cardiac muscle wasting, lipid levels, fat tissues, and skeletal muscles.

The effects of exercise and mitochondrial transplantation alone or in combination against Doxorubicin-induced skeletal muscle atrophy

Doxorubicin (DOX) is a chemotherapy drug used to treat various types of cancer, but it is associated with significant side effects such as skeletal muscle atrophy. Exercise has been found to prevent skeletal muscle atrophy through the modulation of mitochondrial pathways. Mitochondrial transplantation (MT) may mitigate toxicity, neurological disorders, kidney and liver injury, and skeletal muscle atrophy. The objective of this study was to evaluate the effects of MT, exercise, and MT with exercise on DOX-induced skeletal muscle atrophy. Male Sprague Dawley rats were randomly assigned to the following groups: control, DOX, MT with DOX, exercise with DOX, and exercise with MT and DOX. A 10-day treadmill running exercise and MT (6.5 µg/100 µL) to tibialis anterior (TA) muscle were administered prior to a single injection of DOX (20 mg/kg). Our data showed that exercise and MT with exercise led to an increase in cross-sectional area of the TA muscle. Exercise, MT and MT with exercise reduced inflammation and maintained mitochondrial enzyme activity. Additionally, exercise and MT have been shown to regulate mitochondrial fusion/fission. Our findings revealed that exercise and MT with exercise prevented oxidative damage. Furthermore, MT and MT with exercise decreased apoptosis and MT with exercise triggered mitochondrial biogenesis. These findings demonstrate the importance of exercise in the prevention of skeletal muscle atrophy and emphasize the significant benefits of MT with exercise. To the best of our knowledge, this is the first study to demonstrate the therapeutic effects of MT with exercise in DOX-induced skeletal muscle atrophy.

Brief Magnetic Field Exposure Stimulates Doxorubicin Uptake into Breast Cancer Cells in Association with TRPC1 Expression: A Precision Oncology Methodology to Enhance Chemotherapeutic Outcome

Background/Objectives: Doxorubicin (DOX) is commonly used as a chemotherapeutic agent for the treatment of breast cancer. Nonetheless, its systemic delivery via intravenous injection and toxicity towards healthy tissues commonly result in a broad range of detrimental side effects. Breast cancer severity was previously shown to be correlated with TRPC1 channel expression that conferred upon it enhanced vulnerability to pulsed electromagnetic field (PEMF) therapy. PEMF therapy was also previously shown to enhance breast cancer cell vulnerability to DOX in vitro and in vivo that correlated with TRPC1 expression and mitochondrial respiratory rates. Methods: DOX uptake was assessed by measuring its innate autofluorescence within murine 4T1 or human MCF7 breast cancer cells following magnetic exposure. Cellular vulnerability to doxorubicin uptake was assessed by monitoring mitochondrial activity and cellular DNA content. Results: Here, we demonstrate that 10 min of PEMF exposure could augment DOX uptake into 4T1 and MCF7 breast cancer cells. DOX uptake could be increased by TRPC1 overexpression, whereas inhibiting the activity of TRPC1 channels with SKF-96356 or genetic knockdown, precluded DOX uptake. PEMF exposure enhances DOX-mediated killing of breast cancer cells, reducing the IC50 value of DOX by half, whereas muscle cells, representative of collateral tissues, were less sensitive to PEMF-enhanced DOX-mediated cytotoxicity. Vesicular loading of DOX correlated with TRPC1 expression. Conclusions: This study presents a novel TRPC1-mediated mechanism through which PEMF therapy may enhance DOX cytotoxicity in breast cancer cells, paving the way for the development of localized non-invasive PEMF platforms to improve cancer outcomes with lower systemic levels of DOX.

Long-term effects of the chronic administration of doxorubicin on aged skeletal muscle: An exploratory study in mice

The widely used chemotherapeutic drug doxorubicin (DOX) has been associated with adverse effects on the skeletal muscle, which can persist for years after the end of the treatment. These adverse effects may be exacerbated in older patients, whose skeletal muscle might already be impaired by aging. Nonetheless, the mediators responsible for DOX-induced myotoxicity are still largely unidentified, particularly the ones involved in the long-term effects that negatively affect the quality of life of the patients. Therefore, this study aimed to investigate the long-term effects of the chronic administration of DOX on the soleus muscle of aged mice. For that and to mimic the clinical regimen, a dose of 1.5 mg kg-1 of DOX was administered two times per week for three consecutive weeks in a cumulative dose of 9 mg kg-1 to 19-month-old male mice, which were sacrificed two months after the last administration. Body wasting and the atrophy of the soleus muscle, as measured by a decrease in the cross-sectional area of the soleus muscle fibers, were identified as long-term effects of DOX administration. The atrophy observed was correlated with increased reactive oxygen species production and caspase-3 activity. An impaired skeletal muscle regeneration was also suggested due to the correlation between satellite cells activation and the soleus muscle fibers atrophy. Systemic inflammation, skeletal muscle energy metabolism and neuromuscular junction-related markers do not appear to be involved in the long-term DOX-induced skeletal muscle atrophy. The data provided by this study shed light on the mediators involved in the overlooked long-term DOX-induced myotoxicity, paving the way to the improvement of the quality of life and survival rates of older cancer patients.

Sorafenib induces cachexia by impeding transcriptional signaling of the SET1/MLL complex on muscle-specific genes

Chemotherapeutics used in cancer therapy are often linked to muscle wasting or cachexia. Insights into the molecular basis of chemotherapy-induced cachexia is essential to improve treatment strategies. Here, we demonstrated that Sorafenib-tyrosine kinase inhibitor (TKI) class of chemotherapeutic agents-induced cachexia. System-wide analyses revealed that Sorafenib alters the global transcriptional program and proteostasis in muscle cells. Mechanistically, Sorafenib treatment reduced active epigenetic mark H3K4 methylation on distinct muscle-specific genes by impeding chromatin association of SET1A-catalytic component of the SET1/MLL histone methyltransferase complex. This mechanism favored transcriptional disorientation that led to disrupted sarcomere assembly, calcium homeostasis and mitochondrial respiration. Consequently, the contractile ability of muscle cells was severely compromised. Interestingly, the other prominent TKIs Nilotinib and Imatinib did not exert similar effects on muscle cell physiology. Collectively, we identified an unanticipated transcriptional mechanism underlying Sorafenib-induced cachexia. Our findings hold the potential to strategize therapy regimens to minimize chemotherapy-induced cachexia.

Dexrazoxane prevents vascular toxicity in doxorubicin-treated mice

BACKGROUND

Doxorubicin (DOX) is used for breast cancer and lymphoma, but can cause cardiotoxicity, arterial stiffness, and endothelial dysfunction. We recently reported SERPINA3N as biomarker of cardiovascular toxicity in patients and mice. Dexrazoxane (DEXRA) is an FDA-approved drug that prevents DOX-induced cardiac toxicity in high-risk patients. However, the effect of DEXRA on vascular dysfunction during DOX treatment has not been documented. Therefore, here we investigated whether DEXRA protects against DOX-induced arterial stiffness, endothelial dysfunction, and SERPINA3N upregulation in tissue and plasma from mice.

METHODS

Male C57BL6/J mice were treated with DOX (4 mg/kg), DEXRA (40 mg/kg), a combination (DEXRA + DOX), or VEHICLE (0.9% NaCl) weekly i.p. for 6 weeks (n = 8 per group). Cardiovascular function was measured in vivo by ultrasound imaging at baseline, weeks 2 and 6. Vascular reactivity was analyzed ex vivo in the thoracic aorta at week 6 and molecular analysis was performed.

RESULTS

DEXRA prevented left ventricular ejection fraction decline by DOX (DEXRA + DOX: 62 ± 2% vs DOX: 51 ± 2%). Moreover, DEXRA prevented the increase in pulse wave velocity by DOX (DEXRA + DOX: 2.1 ± 0.2 m/s vs DOX: 4.5 ± 0.3 m/s) and preserved endothelium-dependent relaxation (DEXRA + DOX: 82 ± 3% vs DOX: 62 ± 3%). In contrast to DOX-treated mice, SERPINA3N did not increase in the DEXRA + DOX group.

CONCLUSION

Our results not only confirm the cardioprotective effects of DEXRA against DOX-induced cardiotoxicity but also add preservation of vascular endothelial cell function as an important mechanism. Moreover, the study demonstrates the potential of SERPINA3N as a biomarker for monitoring cardiovascular complications of DOX in high-risk patients.

Senescent cells inhibit mouse myoblast differentiation via the SASP-lipid 15d-PGJ2 mediated modification and control of HRas

Senescent cells are characterized by multiple features such as increased expression of senescence-associated β-galactosidase activity (SA β-gal) and cell cycle inhibitors such as p21 or p16. They accumulate with tissue damage and dysregulate tissue homeostasis. In the context of skeletal muscle, it is known that agents used for chemotherapy such as Doxorubicin (Doxo) cause buildup of senescent cells, leading to the inhibition of tissue regeneration. Senescent cells influence the neighboring cells via numerous secreted factors which form the senescence-associated secreted phenotype (SASP). Lipids are emerging as a key component of SASP that can control tissue homeostasis. Arachidonic acid-derived lipids have been shown to accumulate within senescent cells, specifically 15d-PGJ2, which is an electrophilic lipid produced by the non-enzymatic dehydration of the prostaglandin PGD2. This study shows that 15d-PGJ2 is also released by Doxo-induced senescent cells as an SASP factor. Treatment of skeletal muscle myoblasts with the conditioned medium from these senescent cells inhibits myoblast fusion during differentiation. Inhibition of L-PTGDS, the enzyme that synthesizes PGD2, diminishes the release of 15d-PGJ2 by senescent cells and restores muscle differentiation. We further show that this lipid post-translationally modifies Cys184 of HRas in C2C12 mouse skeletal myoblasts, causing a reduction in the localization of HRas to the Golgi, increased HRas binding to Ras Binding Domain (RBD) of RAF Kinase (RAF-RBD), and activation of cellular Mitogen Activated Protein (MAP) kinase-Extracellular Signal Regulated Kinase (Erk) signaling (but not the Akt signaling). Mutating C184 of HRas prevents the ability of 15d-PGJ2 to inhibit the differentiation of muscle cells and control the activity of HRas. This work shows that 15d-PGJ2 released from senescent cells could be targeted to restore muscle homeostasis after chemotherapy.

Effects of exercise and doxorubicin on acute diaphragm neuromuscular transmission failure

Doxorubicin (DOX) is a highly effective anthracycline antibiotic used to treat a wide variety of cancers including breast cancer, leukemia and lymphoma. Unfortunately, clinical use of DOX is limited due to adverse off-target effects resulting in fatigue, respiratory muscle weakness and dyspnea. The diaphragm is the primary muscle of inspiration and respiratory insufficiency is likely the result of both muscle weakness and neural impairment. However, the contribution of neuropathology to DOX-induced respiratory muscle dysfunction is unclear. We hypothesized that diaphragm weakness following acute DOX exposure is associated with neurotoxicity and that exercise preconditioning is sufficient to improve diaphragm muscle contractility by maintaining neuromuscular integrity. Adult female Sprague-Dawley rats were randomized into four experimental groups: 1) sedentary-saline, 2) sedentary-DOX, 3) exercise-saline or 4) exercise-DOX. Endurance exercise preconditioning consisted of treadmill running for 1 h/day at 30 m/min for 10 days. Twenty-four hours after the last bout of exercise, animals were treated with DOX (20 mg/kg, I.P.) or saline (equal volume). Our results demonstrate that 48-h following DOX administration diaphragm muscle specific force is reduced in sedentary-DOX rats in response to both phrenic nerve and direct diaphragm stimulation. Importantly, endurance exercise preconditioning in DOX-treated rats attenuated the decrease in diaphragm contractile function, reduced neuromuscular transmission failure and altered phrenic nerve morphology. These changes were associated with an exercise-induced reduction in circulating biomarkers of inflammation, nerve injury and reformation. Therefore, the results are consistent with exercise preconditioning as an effective way of reducing respiratory impairment via preservation of phrenic-diaphragm neuromuscular conduction.

Complex Interplay between DNA Damage and Autophagy in Disease and Therapy

Cancer, a multifactorial disease characterized by uncontrolled cellular proliferation, remains a global health challenge with significant morbidity and mortality. Genomic and molecular aberrations, coupled with environmental factors, contribute to its heterogeneity and complexity. Chemotherapeutic agents like doxorubicin (Dox) have shown efficacy against various cancers but are hindered by dose-dependent cytotoxicity, particularly on vital organs like the heart and brain. Autophagy, a cellular process involved in self-degradation and recycling, emerges as a promising therapeutic target in cancer therapy and neurodegenerative diseases. Dysregulation of autophagy contributes to cancer progression and drug resistance, while its modulation holds the potential to enhance treatment outcomes and mitigate adverse effects. Additionally, emerging evidence suggests a potential link between autophagy, DNA damage, and caretaker breast cancer genes BRCA1/2, highlighting the interplay between DNA repair mechanisms and cellular homeostasis. This review explores the intricate relationship between cancer, Dox-induced cytotoxicity, autophagy modulation, and the potential implications of autophagy in DNA damage repair pathways, particularly in the context of BRCA1/2 mutations.

Effects of heavy-load strength training during (neo-)adjuvant chemotherapy on muscle strength, muscle fiber size, myonuclei, and satellite cells in women with breast cancer

To investigate the effects of heavy-load strength training during (neo-)adjuvant chemotherapy in women with breast cancer on muscle strength, body composition, muscle fiber size, satellite cells, and myonuclei. Women with stage I-III breast cancer were randomly assigned to a strength training group (ST, n = 23) performing supervised heavy-load strength training twice a week during chemotherapy, or a usual care control group (CON, n = 17). Muscle strength and body composition were measured and biopsies from m. vastus lateralis collected before the first cycle of chemotherapy (T0) and after chemotherapy and training (T1). Muscle strength increased significantly more in ST than in CON in chest-press (ST: +10 ± 8%, p < .001, CON: -3 ± 5%, p = .023) and leg-press (ST: +11 ± 8%, p < .001, CON: +3 ± 6%, p = .137). Both groups reduced fat-free mass (ST: -4.9 ± 4.0%, p < .001, CON: -5.2 ± 4.9%, p = .004), and increased fat mass (ST: +15.3 ± 16.5%, p < .001, CON: +16.3 ± 19.8%, p = .015) with no significant differences between groups. No significant changes from T0 to T1 and no significant differences between groups were observed in muscle fiber size. For myonuclei per fiber a non-statistically significant increase in CON and a non-statistically significant decrease in ST in type I fibers tended (p = .053) to be different between groups. Satellite cells tended to decrease in ST (type I: -14 ± 36%, p = .097, type II: -9 ± 55%, p = .084), with no changes in CON and no differences between groups. Strength training during chemotherapy improved muscle strength but did not significantly affect body composition, muscle fiber size, numbers of satellite cells, and myonuclei compared to usual care.

Compound Z526 alleviates chemotherapy-induced cachectic muscle loss by ameliorating oxidative stress-driven protein metabolic imbalance and apoptosis

Chemotherapy is one of the primary and indispensable intervention against cancers though it is always accompanied by severe side effects especially cachexia. Cachexia is a fatal metabolic disorder syndrome, mainly characterized by muscle loss. Oxidative stress is the key factor that trigger cachectic muscle loss by inducing imbalance in protein metabolism and apoptosis. Here, we showed an oral compound (Z526) exhibited potent alleviating effects on C2C12 myotube atrophy induced by various chemotherapeutic agents in vitro as well as mice muscle loss and impaired grip force induced by oxaliplatin in vivo. Furthermore, Z526 also could ameliorate C2C12 myotube atrophy induced by the combination of chemotherapeutic agents with conditioned medium of various tumor cells in vitro as well as mice muscle atrophy of C26 tumor-bearing mice treated with oxaliplatin. The pharmacological effects of Z526 were based on its potency in reducing oxidative stress in cachectic myocytes and muscle tissues, which inhibited the activation of NF-κB and STAT3 to decrease Atrogin-1-mediated protein degradation, activated the AKT/mTOR signaling pathway to promote protein synthesis, regulated Bcl-2/BAX ratio to reduce Caspase-3-triggered apoptosis. Our work suggested Z526 to be an optional strategy for ameliorating cachexia muscle atrophy in the multimodality treatment of cancers.

Myogenic microRNAs as Therapeutic Targets for Skeletal Muscle Mass Wasting in Breast Cancer Models

Breast cancer is the type of cancer with the highest prevalence in women worldwide. Skeletal muscle atrophy is an important prognostic factor in women diagnosed with breast cancer. This atrophy stems from disrupted skeletal muscle homeostasis, triggered by diminished anabolic signalling and heightened inflammatory conditions, culminating in an upregulation of skeletal muscle proteolysis gene expression. The importance of delving into research on modulators of skeletal muscle atrophy, such as microRNAs (miRNAs), which play a crucial role in regulating cellular signalling pathways involved in skeletal muscle protein synthesis and degradation, has been recognised. This holds true for conditions of homeostasis as well as pathologies like cancer. However, the determination of specific miRNAs that modulate skeletal muscle atrophy in breast cancer conditions has not yet been explored. In this narrative review, we aim to identify miRNAs that could directly or indirectly influence skeletal muscle atrophy in breast cancer models to gain an updated perspective on potential therapeutic targets that could be modulated through resistance exercise training, aiming to mitigate the loss of skeletal muscle mass in breast cancer patients.

Electrical Pulse Stimulation Protects C2C12 Myotubes against Hydrogen Peroxide-Induced Cytotoxicity via Nrf2/Antioxidant Pathway

Skeletal muscle contraction evokes numerous biochemical alterations that underpin exercise benefits. This present study aimed to elucidate the mechanism for electrical pulse stimulation (EPS)-induced antioxidant adaptation in C2C12 myotubes. We found that EPS significantly upregulated Nrf2 and a broad array of downstream antioxidant enzymes involved in multiple antioxidant systems. These effects were completely abolished by pretreatment with a ROS scavenger, N-acetylcysteine. MitoSOX-Red, CM-H2DCFDA, and EPR spectroscopy revealed a significantly higher ROS level in mitochondria and cytosol in EPS cells compared to non-stimulated cells. Seahorse and Oroboros revealed that EPS significantly increased the maximal mitochondrial oxygen consumption rate, along with an upregulated protein expression of mitochondrial complexes I/V, mitofusin-1, and mitochondrial fission factor. A post-stimulation time-course experiment demonstrated that upregulated NQO1 and GSTA2 last at least 24 h following the cessation of EPS, whereas elevated ROS declines immediately. These findings suggest an antioxidant preconditioning effect in the EPS cells. A cell viability study suggested that the EPS cells displayed 11- and 36-fold higher survival rates compared to the control cells in response to 2 and 4 mM H2O2 treatment, respectively. In summary, we found that EPS upregulated a large group of antioxidant enzymes in C2C12 myotubes via a contraction-mitochondrial-ROS-Nrf2 pathway. This antioxidant adaptation protects cells against oxidative stress-associated cytotoxicity.

Liraglutide Pretreatment Does Not Improve Acute Doxorubicin-Induced Cardiotoxicity in Rats

Doxorubicin is an effective drug for cancer treatment; however, cardiotoxicity limits its use. Cardiotoxicity pathophysiology is multifactorial. GLP-1 analogues have been shown to reduce oxidative stress and inflammation. In this study, we evaluated the effect of pretreatment with liraglutide on doxorubicin-induced acute cardiotoxicity. A total of 60 male Wistar rats were allocated into four groups: Control (C), Doxorubicin (D), Liraglutide (L), and Doxorubicin + Liraglutide (DL). L and DL received subcutaneous injection of liraglutide 0.6 mg/kg daily, while C and D received saline for 2 weeks. Afterwards, D and DL received a single intraperitoneal injection of doxorubicin 20 mg/kg; C and L received an injection of saline. Forty-eight hours after doxorubicin administration, the rats were subjected to echocardiogram, isolated heart functional study, and euthanasia. Liraglutide-treated rats ingested significantly less food and gained less body weight than animals that did not receive the drug. Rats lost weight after doxorubicin injection. At echocardiogram and isolated heart study, doxorubicin-treated rats had systolic and diastolic function impairment. Myocardial catalase activity was statistically higher in doxorubicin-treated rats. Myocardial protein expression of tumor necrosis factor alpha (TNF-α), phosphorylated nuclear factor-κB (p-NFκB), troponin T, and B-cell lymphoma 2 (Bcl-2) was significantly lower, and the total NFκB/p-NFκB ratio and TLR-4 higher in doxorubicin-treated rats. Myocardial expression of OPA-1, MFN-2, DRP-1, and topoisomerase 2β did not differ between groups (p > 0.05). In conclusion, doxorubicin-induced cardiotoxicity is accompanied by decreased Bcl-2 and phosphorylated NFκB and increased catalase activity and TLR-4 expression. Liraglutide failed to improve acute doxorubicin-induced cardiotoxicity in rats.

Evaluation of skeletal muscle function in male rats with doxorubicin-induced myopathy following various exercise techniques: the significant role of glucose transporter 4

A common anthracycline antibiotic used to treat cancer patients is doxorubicin (DOX). One of the effects of DOX therapy is skeletal muscle fatigue. Our goal in this research was to study the beneficial effect of exercise on DOX-induced damaged muscle fibers and compare the effect of different exercise strategies (prophylactic, post- toxicity and combined) on DOX toxicity. Five groups were created from 40 male rats: group I, control group; group II, DOX was administered intraperitoneally for 2 weeks over 6 equal injections (each 2.5 mg/kg); group III, rats trained for 3 weeks before DOX; group IV, rats trained for 8 weeks after DOX; and group V, rats were trained for 3 weeks before DOX followed by 8 weeks after. Measures of oxidative damage (H2O2, catalase), inflammation (TNF-α), and glucose transporter 4 (GLUT4) expression on skeletal muscle were assessed. Also, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was estimated. Skeletal performance was evaluated by contraction time (CT), half relaxation time (1/2 RT), and force-frequency relationship by the end of this research. The current study demonstrated a detrimental effect of DOX on skeletal performance as evidenced by a significant increase in CT and 1/2 RT compared to control; in addition, H2O2, TNF-α, and HOMA-IR were significantly increased with a significant decrease in GLUT4 expression and catalase activity. Combined exercise therapy showed a remarkable improvement in skeletal muscle performance, compared to DOX, CT, and 1/2 RT which were significantly decreased; H2O2 and TNF-α were significantly decreased unlike catalase antioxidant activity that significantly increased; in addition, skeletal muscle glucose metabolism was significantly improved as GLUT4 expression significantly increased and HOMA-IR was significantly decreased. Exercise therapy showed significant improvement in all measured parameters relative to DOX. However, combined exercise therapy showed the best improvement relative to both pre-exercise and post-exercise groups.

Doxorubicin causes cachexia, sarcopenia, and frailty characteristics in mice

While chemotherapy treatment can be lifesaving, it also has adverse effects that negatively impact the quality of life. To investigate the effects of doxorubicin chemotherapy on body weight loss, strength and muscle mass loss, and physical function impairments, all key markers of cachexia, sarcopenia, and frailty. Seventeen C57/BL/6 mice were allocated into groups. 1) Control (n = 7): mice were exposed to intraperitoneal (i.p.) injections of saline solution. 2) Dox (n = 10): mice were exposed to doxorubicin chemotherapy cycles (total dose of 18 mg/kg divided over 15 days). The body weight loss and decreased food intake were monitored to assess cachexia. To assess sarcopenia, we measured muscle strength loss using a traction method and evaluated muscle atrophy through histology of the gastrocnemius muscle. To evaluate physical function impairments and assess frailty, we employed the open field test to measure exploratory capacity. Doxorubicin administration led to the development of cachexia, as evidenced by a significant body weight loss (13%) and a substantial decrease in food intake (34%) over a 15-day period. Furthermore, 90% of the mice treated with doxorubicin exhibited sarcopenia, characterized by a 20% reduction in traction strength (p<0,05), a 10% decrease in muscle mass, and a 33% reduction in locomotor activity. Importantly, all mice subjected to doxorubicin treatment were considered frail based on the evaluation of their overall condition and functional impairments. The proposed model holds significant characteristics of human chemotherapy treatment and can be useful to understand the intricate relationship between chemotherapy, cachexia, sarcopenia, and frailty.

A single chemotherapy administration induces muscle atrophy, mitochondrial alterations and apoptosis in breast cancer patients

BACKGROUND

Breast cancer patients are commonly treated with sequential administrations of epirubicin-cyclophosphamide (EC) and paclitaxel (TAX). The chronic effect of this treatment induces skeletal muscle alterations, but the specific effect of each chemotherapy agent is unknown. This study aimed to investigate the effect of EC or TAX administration on skeletal muscle homeostasis in breast cancer patients.

METHODS

Twenty early breast cancer patients undergoing EC followed by TAX chemotherapies were included. Two groups of 10 women were established and performed vastus lateralis skeletal muscle biopsies either before the first administration (pre) of EC (50 ± 14 years) or TAX (50 ± 16 years) and 4 days later (post). Mitochondrial respiratory capacity recording, reactive oxygen species production, western blotting and histological analyses were performed.

RESULTS

Decrease in muscle fibres cross-sectional area was only observed post-EC (-25%; P < 0.001), associated with a reduction in mitochondrial respiratory capacity for the complex I (CI)-linked substrate state (-32%; P = 0.001), oxidative phosphorylation (OXPHOS) by CI (-35%; P = 0.002), CI&CII (-26%; P = 0.022) and CII (-24%; P = 0.027). If H2 O2 production was unchanged post-EC, an increase was observed post-TAX for OXPHOS by CII (+25%; P = 0.022). We found a decrease in makers of mitochondrial content, as shown post-EC by a decrease in the protein levels of citrate synthase (-53%; P < 0.001) and VDAC (-39%; P < 0.001). Despite no changes in markers of mitochondrial fission, a decrease in the expression of a marker of mitochondrial inner-membrane fusion was found post-EC (OPA1; -60%; P < 0.001). We explored markers of mitophagy and found reductions post-EC in the protein levels of PINK1 (-63%; P < 0.001) and Parkin (-56%; P = 0.005), without changes post-TAX. An increasing trend in Bax protein level was found post-EC (+96%; P = 0.068) and post-TAX (+77%; P = 0.073), while the Bcl-2 level was decreased only post-EC (-52%; P = 0.007). If an increasing trend in TUNEL-positive signal was observed post-EC (+68%; P = 0.082), upregulation was highlighted post-TAX (+86%; P < 0.001), suggesting activation of the apoptosis process.

CONCLUSIONS

We demonstrated that a single administration of EC induced, in only 4 days, skeletal muscle atrophy and mitochondrial alterations in breast cancer patients. These alterations were characterized by reductions in mitochondrial function and content as well as impairment of mitochondrial dynamics and an increase in apoptosis. TAX administration did not worsen these alterations as this group had already received EC during the preceding weeks. However, it resulted in an increased apoptosis, likely in response to the increased H2 O2 production.

Formoterol reduces muscle wasting in mice undergoing doxorubicin chemotherapy

Background

Even though doxorubicin (DOX) chemotherapy promotes intense muscle wasting, this drug is still widely used in clinical practice due to its remarkable efficiency in managing cancer. On the other hand, intense muscle loss during the oncological treatment is considered a bad prognosis for the disease's evolution and the patient's quality of life. In this sense, strategies that can counteract the muscle wasting induced by DOX are essential. In this study, we evaluated the effectiveness of formoterol (FOR), a β2-adrenoceptor agonist, in managing muscle wasting caused by DOX.

Methods and results

To evaluate the effect of FOR on DOX-induced muscle wasting, mice were treated with DOX (2.5 mg/kg b.w., i.p. administration, twice a week), associated or not to FOR treatment (1 mg/kg b.w., s.c. administration, daily). Control mice received vehicle solution. A combination of FOR treatment with DOX protected against the loss of body weight (p<0.05), muscle mass (p<0.001), and grip force (p<0.001) promoted by chemotherapy. FOR also attenuated muscle wasting (p<0.01) in tumor-bearing mice on chemotherapy. The potential mechanism by which FOR prevented further DOX-induced muscle wasting occurred by regulating Akt/FoxO3a signaling and gene expression of atrogenes in skeletal muscle.

Conclusions

Collectively, our results suggest that FOR can be used as a pharmacological strategy for managing muscle wasting induced by DOX. This study provides new insights into the potential therapeutic use of FOR to improve the overall wellbeing of cancer patients undergoing DOX chemotherapy.

Adolescent and young adult Hodgkin lymphoma patients at risk for subcutaneous fat gain during early cancer treatment: a brief report

Computed tomography scans were assessed for subcutaneous fat area and density at thoracic vertebra 4 in 65 adolescent and young adult (AYA) patients with Hodgkin lymphoma. Subcutaneous fat was quantified over 3 timepoints; (1) baseline, (2) end of initial anthracycline treatment (EOT) and (3) 1 year. Fat area increased at EOT (62.3 ± 5.4 cm/m2 vs 53.5 ± 5.0 cm/m2, p < 0.01) and 1 year (65.8 ± 5.6 cm/m2 vs 53.5 ± 5.0 cm/m2, p < 0.01) compared to baseline. Fat density significantly decreased at EOT (-91.2 ± 1.4 HU vs -86.5 ± 1.4 HU, p < 0.01) and at 1 year (-90.3 ± 1.6 HU vs -86.5 ± 1.4 HU, p = 0.01) compared to baseline. Female, radiation receiving, and anthracycline dosage >250mg/m2subgroups experienced significant fat gain (p < 0.05 for all). Female AYA Hodgkin lymphoma patients receiving radiation, and/or high-dose anthracyclines may be at higher risk of subcutaneous fat gain during therapy.

Accelerated loss of lean body mass in head and neck cancer patients during cisplatin-based chemoradiation

BACKGROUND

This study investigated changes in body weight, lean body mass (LBM), fat mass (FM), muscle strength and functional performance during radiation treatment in head and neck cancer (HNSCC) patients. Secondly, it investigated the impact of cisplatin-based chemoradiation (CCRT) on LBM loss compared with radiation alone.

METHODS

48 patients (all tumor sites) received either 6 weeks of radiation alone (n = 16) with 66-68 Gy in 33-34 Fx, 5-6 Fx/week or CCRT, adding weekly cisplatin or carboplatin (n = 32). LBM and FM was evaluated using Dual-energy X-ray Absorptiometry bi-weekly from pre- to two weeks post-treatment. Maximal muscle strength (knee extension, leg - and chest press) and functional performance (stair climb, chair rise, and arm curl) were assessed pre- and post-treatment.

RESULTS

Body weight and LBM had declined significantly already week 2 into treatment and declined significantly further through week 4 and 6 before leveling off after week 6. Bi-weekly, from treatment start to week 2, 2-4, and 4-6, LBM declined 1.2 ± 0.4 kg (p = .002; 95% CI: 0.4;2.0), 2.0 ± 0.4 kg (p < .0001; 1.2;2.8) and 1.4 ± 0.4 kg (p = .001; 0.6;2.2). With a two-week delay, FM declined significantly from week 2-8. All measures of muscle strength declined significantly from pre- to post-treatment. Functional performance was unchanged. LBM loss from pre- to post-treatment was significantly associated with impaired muscle strength (R2 = 0.3-0.5). CCRT patients lost 3.1 ± 0.8 kg of LBM (p = .0001; 1.5;4.7) more from pre- to post-treatment compared with patients receiving radiation alone. Analyses adjusting for nimorazole, tumor stage, baseline BMI, mean radiation dose to constrictor muscles and oral cavity confirmed this.

CONCLUSION

Accelerated and substantial LBM loss was already initiated within the first two weeks of treatment - before the onset of radiation-induced mucositis. LBM loss was associated with muscle strength impairment. Patients receiving CCRT experienced significantly larger LBM loss than patients receiving radiation alone. Registered on clinincaltrials.gov (Identifier: NCT05890859).

Interleukin-1β triggers muscle-derived extracellular superoxide dismutase expression and protects muscles from doxorubicin-induced atrophy

Doxorubicin, a conventional chemotherapeutic agent prescribed for cancer, causes skeletal muscle atrophy and adversely affects mobility and strength. Given that doxorubicin-induced muscle atrophy is attributable primarily to oxidative stress, its effects could be mitigated by antioxidant-focused therapies; however, these protective therapeutic targets remain ambiguous. The aim of this study was to demonstrate that doxorubicin triggers severe muscle atrophy via upregulation of oxidative stress (4-hydroxynonenal and malondialdehyde) and atrogenes (atrogin-1/MAFbx and muscle RING finger-1) in association with decreased expression of the antioxidant enzyme extracellular superoxide dismutase (EcSOD), in cultured C2C12 myotubes and mouse skeletal muscle. Supplementation with EcSOD recombinant protein elevated EcSOD levels on the cellular membrane of cultured myotubes, consequently inhibiting doxorubicin-induced oxidative stress and myotube atrophy. Furthermore, doxorubicin treatment reduced interleukin-1β (IL-1β) mRNA expression in cultured myotubes and skeletal muscle, whereas transient IL-1β treatment increased EcSOD protein expression on the myotube membrane. Notably, transient IL-1β treatment of cultured myotubes and local administration in mouse skeletal muscle attenuated doxorubicin-induced muscle atrophy, which was associated with increased EcSOD expression. Collectively, these findings reveal that the regulation of skeletal muscle EcSOD via maintenance of IL-1β signalling is a potential therapeutic approach to counteract the muscle atrophy mediated by doxorubicin and oxidative stress. KEY POINTS: Doxorubicin, a commonly prescribed chemotherapeutic agent for patients with cancer, induces severe muscle atrophy owing to increased expression of oxidative stress; however, protective therapeutic targets are poorly understood. Doxorubicin induced muscle atrophy owing to increased expression of oxidative stress and atrogenes in association with decreased protein expression of extracellular superoxide dismutase (EcSOD) in cultured C2C12 myotubes and mouse skeletal muscle. Supplementation with EcSOD recombinant protein increased EcSOD levels on the cellular membrane of cultured myotubes, resulting in inhibition of doxorubicin-induced oxidative stress and myotube atrophy. Doxorubicin treatment decreased interleukin-1β (IL-1β) expression in cultured myotubes and skeletal muscle, whereas transient IL-1β treatment in vivo and in vitro increased EcSOD protein expression and attenuated doxorubicin-induced muscle atrophy. These findings reveal that regulation of skeletal muscle EcSOD via maintenance of IL-1β signalling is a possible therapeutic approach for muscle atrophy mediated by doxorubicin and oxidative stress.

Advances in research on cell models for skeletal muscle atrophy

Skeletal muscle, the largest organ in the human body, plays a crucial role in supporting and defending the body and is essential for movement. It also participates in regulating the processes of protein synthesis and degradation. Inhibition of protein synthesis and activation of degradation metabolism can both lead to the development of skeletal muscle atrophy, a pathological condition characterized by a decrease in muscle mass and fiber size. Many physiological and pathological conditions can cause a decline in muscle mass, but the underlying mechanisms of its pathogenesis remain incompletely understood, and the selection of treatment strategies and efficacy evaluations vary. Moreover, the early symptoms of this condition are often not apparent, making it easily overlooked in clinical practice. Therefore, it is necessary to develop and use cell models to understand the etiology and influencing factors of skeletal muscle atrophy. In this review, we summarize the methods used to construct skeletal muscle cell models, including hormone, inflammation, cachexia, genetic engineering, drug, and physicochemical models. We also analyze, compare, and evaluate the various construction and assessment methods.

Early skeletal muscle loss in adolescent and young adult cancer patients treated with anthracycline chemotherapy

BACKGROUND

Early skeletal muscle loss has been observed in adolescent and young adult (AYA) sarcoma patients undergoing treatment. Identification of individuals within the AYA populace that are at greatest risk of anthracycline-induced skeletal muscle loss is unknown. Moreover, investigations which seek out underlying causes of skeletal muscle degradation during chemotherapy are critical for understanding, preventing, and reducing chronic health conditions associated with poor skeletal muscle status.

METHODS

Computed tomography (CT) scans were used to investigate changes in skeletal muscle of 153 AYA sarcoma and Hodgkin lymphoma patients at thoracic vertebra 4 after anthracycline treatment. Images were examined at three time points during the first year of treatment. In parallel, we used translational juvenile mouse models to assess the impact of doxorubicin (DOX) in the soleus and gastrocnemius on muscle wasting.

RESULTS

Significant reductions in total skeletal muscle index and density were seen after chemotherapy in AYA cancer patients (p < 0.01 & p = 0.04, respectively). The severity of skeletal muscle loss varied by subgroup (i.e., cancer type, sex, and treatment). Murine models demonstrated a reduction in skeletal muscle fiber cross-sectional area, increased apoptosis and collagen volume for both the soleus and gastrocnemius after DOX treatment (all p < 0.05). After DOX, hindlimb skeletal muscle blood flow was significantly reduced (p < 0.01).

CONCLUSION

Significant skeletal muscle loss is experienced early during treatment in AYA cancer patients. Reductions in skeletal muscle blood flow may be a key contributing factor to anthracycline doxorubicin induced skeletal muscle loss.

Mitochondrial dysfunction and skeletal muscle atrophy: Causes, mechanisms, and treatment strategies

Skeletal muscle, which accounts for approximately 40% of total body weight, is one of the most dynamic and plastic tissues in the human body and plays a vital role in movement, posture and force production. More than just a component of the locomotor system, skeletal muscle functions as an endocrine organ capable of producing and secreting hundreds of bioactive molecules. Therefore, maintaining healthy skeletal muscles is crucial for supporting overall body health. Various pathological conditions, such as prolonged immobilization, cachexia, aging, drug-induced toxicity, and cardiovascular diseases (CVDs), can disrupt the balance between muscle protein synthesis and degradation, leading to skeletal muscle atrophy. Mitochondrial dysfunction is a major contributing mechanism to skeletal muscle atrophy, as it plays crucial roles in various biological processes, including energy production, metabolic flexibility, maintenance of redox homeostasis, and regulation of apoptosis. In this review, we critically examine recent knowledge regarding the causes of muscle atrophy (disuse, cachexia, aging, etc.) and its contribution to CVDs. Additionally, we highlight the mitochondrial signaling pathways involvement to skeletal muscle atrophy, such as the ubiquitin-proteasome system, autophagy and mitophagy, mitochondrial fission-fusion, and mitochondrial biogenesis. Furthermore, we discuss current strategies, including exercise, mitochondria-targeted antioxidants, in vivo transfection of PGC-1α, and the potential use of mitochondrial transplantation as a possible therapeutic approach.

Protective effect of grape seed extract and exercise training on tissues toxicities in doxorubicin-treated healthy rat

OBJECTIVE

The aim of the present study was to investigate the effects of Grape seed extract (GSE) and exercise training on Doxorubicin (Doxo)-induced cardio, hepato and myo toxicities in healthy rats.

METHODS

Thirty male Wistar rats were randomly divided into five groups and daily treated by intraperitoneal route during two months either with ethanol 10% (Control); Doxo (1.5 mg/kg); Doxo + exercise (1.5 mg/kg + swimming exercise for 30 min twice a week); Doxo + GSE (1.5 mg/kg + GSE 2.5 g/kg); Doxo + GSE + exercise (1.5 mg/kg + GSE 2.5 g/kg + swimming exercise for 30 min twice a week). At the end of the treatment, tissues were collected and processed for the determination of oxidative stress (OS), intracellular mediators, energy fuelling biomarkers, carbohydrate metabolism parameters and muscle histopathology.

RESULTS

Doxo provoked OS characterised by an increased lipoperoxidation (LPO) and protein carbonylation and decreased antioxidant enzyme activities. Doxo also affected intracellular mediators, disturbed carbohydrate metabolism and energy fuelling in skeletal muscle as assessed by down-regulated Electron Transport Chain (ETC) complex activities leading in fine to altered skeletal muscle structure and function.

CONCLUSION

Almost all Doxo-induced disturbances were partially corrected with GSE and exercise on their own and more efficiently with the combined treatment (GSE + exercise).

Tailoring renal-clearable zwitterionic cyclodextrin for colorectal cancer-selective drug delivery

Although cyclodextrin-based renal-clearable nanocarriers have a high potential for clinical translation in targeted cancer therapy, their designs remain to be optimized for tumour retention. Here we report on the design of a tailored structure for renal-clearable zwitterionic cyclodextrin for colorectal cancer-selective drug delivery. Twenty cyclodextrin derivatives with different charged moieties and spacers are synthesized and screened for colloidal stability. The resulting five candidates are evaluated for biodistribution and an optimized structure is identified. The optimized cyclodextrin shows a high tumour accumulation and is used for delivery of doxorubicin and ulixertinib. Higher tumour accumulation and tumour penetration facilitates tumour elimination. The improved antitumour efficacy is demonstrated in heterotopic and orthotopic colorectal cancer models.

A novel convex acoustic lens-attached ultrasound drug delivery system and its testing in a murine melanoma subcutaneous modelo

Target-specific drug release is indispensable to improve chemotherapeutic efficacy as it enhances drug uptake and penetration into tumors. Sono-responsive drug-loaded nano-/micro-particles are a promising solution for achieving target specificity by exposing them to ultrasound near tumors. However, the complicated synthetic processes and limited ultrasound (US) exposure conditions, such as limited control of ultrasound focal depth and acoustic power, prevent the practical application of this approach in clinical practice. Here, we propose a convex acoustic lens-attached US (CALUS) as a simple, economic, and efficient alternative of focused US for drug delivery system (DDS) application. The CALUS was characterized both numerically and experimentally using a hydrophone. In vitro, microbubbles (MBs) inside microfluidic channels were destroyed using the CALUS with various acoustic parameters (acoustic pressure [P], pulse repetition frequency [PRF], and duty cycle) and flow velocity. In vivo, tumor inhibition was evaluated using melanoma-bearing mice by characterizing tumor growth rate, animal weight, and intratumoral drug concentration with/without CALUS DDS. US beams were measured to be efficiently converged by CALUS, which was consistent with our simulation results. The acoustic parameters were optimized through the CALUS-induced MB destruction test (P = 2.34 MPa, PRF = 100 kHz, and duty cycle = 9%); this optimal parameter combination successfully induced MB destruction inside the microfluidic channel with an average flow velocity of up to 9.6 cm/s. The CALUS also enhanced the therapeutic effects of an antitumor drug (doxorubicin) in vivo in a murine melanoma model. The combination of the doxorubicin and the CALUS inhibited tumor growth by ∼55% more than doxorubicin alone, clearly indicating synergistic antitumor efficacy. Our tumor growth inhibition performance was better than other methods based on drug carriers, even without a time-consuming and complicated chemical synthesis process. This result suggests that our novel, simple, economic, and efficient target-specific DDS may offer a transition from preclinical research to clinical trials and a potential treatment approach for patient-centered healthcare.

Clofazimine-Mediated, Age-Related Changes in Skeletal Muscle Mitochondrial Metabolites

Mitochondrial health declines with age, and older patients can demonstrate dysfunction in mitochondrial-rich tissues, such as cardiac and skeletal muscle. Aged mitochondria may make older adults more susceptible to adverse drug reactions (ADRs). We assessed mitochondrial metabolic function by measuring two metabolites, l-carnitine and acetylcarnitine, to determine their effectiveness as candidate clinical biomarkers for age-related, drug-induced alterations in mitochondrial metabolism. To study age- and medication-related changes in mitochondrial metabolism, we administered the FDA-approved mitochondriotropic drug, clofazimine (CFZ), or vehicle for 8 weeks to young (4-week-old) and old (61-week-old) male C57BL/6J mice. At the end of treatment, whole blood and cardiac and skeletal muscle were analyzed for l-carnitine, acetylcarnitine, and CFZ levels; muscle function was measured via a treadmill test. No differences were found in blood or cardiac carnitine levels of CFZ-treated mice, but CFZ-treated mice displayed lost body mass and alterations in endurance and levels of skeletal muscle mitochondrial metabolites. These findings demonstrate the age-related susceptibility of the skeletal muscle to mitochondria drug toxicity. Since drug-induced alterations in mitochondrial metabolism in skeletal muscle were not reflected in the blood by l-carnitine or acetylcarnitine levels, drug-induced catabolism and changes in muscle function appear more relevant to stratifying individuals at increased risk for ADRs.

The Role of Natural Products in the Improvement of Cancer-Associated Cachexia

The enormous library of natural products and herbal medicine prescriptions presents endless research avenues. However, the lack of research evidence and trials on cancer-induced cachexia limit the therapeutic potential of natural products. Cancer-induced cachexia is a systemic wasting syndrome characterized by continuous body weight loss with skeletal muscle and adipose tissue atrophy. Cancer cachexia is a problem in itself and reduces the quality of life by lessening the treatment efficacy of anticancer drugs. This review summarizes single natural product extracts for cancer-induced cachexia, not compounds derived from natural products and herbal medicine prescriptions. This article also discusses the effect of natural products on cachexia induced by anticancer drugs and the role of AMPK in cancer-induced cachexia. The article included the mice model used in each experiment to encourage researchers to utilize animal models for research on cancer-induced cachexia in the future.

Molecular design, synthesis and anticancer activity of new thiopyrano[2,3-d]thiazoles based on 5-hydroxy-1,4-naphthoquinone (juglone)

A series of 11-substituted 9-hydroxy-3,5,10,11-tetrahydro-2H-benzo[6,7]thiochromeno[2,3-d][1,3]thiazole-2,5,10-triones 3.1-3.13 were synthesized via hetero-Diels-Alder reaction of 5-ene-4-thioxo-2-thiazolidinones and 5-hydroxy-1,4-naphthoquinone (juglone). The structure of newly synthesized compounds was established by means of spectral data and a single-crystal X-ray diffraction analysis. The synthesized compounds were tested on a panel of cell lines representing different types of cancer as well as normal and pseudonormal cells and peripheral human blood lymphocytes. Compound 3.10 was found to be the most active derivative, exhibiting a cytotoxic effect similar to doxorubicin's one (IC₅₀ ranged from 0.6 to 5.98 μM), but less toxic to normal and pseudonormal cells. All synthesized compounds were able to interact with DNA, although their anticancer activity did not correlate with the potency of interaction with DNA. The status of p53 in colorectal cancer cells correlated with the activity of the synthesized derivatives 3.1, 3.7, and 3.10. Compound 3.10 did not have an acute toxic effect on the body of С57BL/6 mice, unlike the well-known anticancer drug doxorubicin, which was used as a positive control. The injection of 3.10 (20 mg/kg) to mice had no effect on the counts of leukocytes, erythrocytes, platelets and hemoglobin level in their blood, in contrast to doxorubicin, which caused anemia and leukopenia, indicating bio-tolerance of 3.10in vivo.

Chemotherapy-Induced Molecular Changes in Skeletal Muscle

Paraneoplastic conditions such as cancer cachexia are often exacerbated by chemotherapy, which affects the patient’s quality of life as well as the response to therapy. The aim of this narrative review was to overview the body-composition-related changes and molecular effects of different chemotherapy agents used in cancer treatment on skeletal-muscle remodeling. A literature search was performed using the Web of Science, Scopus, and Science Direct databases and a total of 77 papers was retrieved. In general, the literature survey showed that the molecular changes induced by chemotherapy in skeletal muscle have been studied mainly in animal models and mostly in non-tumor-bearing rodents, whereas clinical studies have essentially assessed changes in body composition by computerized tomography. Data from preclinical studies showed that chemotherapy modulates several molecular pathways in skeletal muscle, including the ubiquitin–proteasome pathway, autophagy, IGF-1/PI3K/Akt/mTOR, IL-6/JAK/STAT, and NF-κB pathway; however, the newest chemotherapy agents are underexplored. In conclusion, chemotherapy exacerbates skeletal-muscle wasting in cancer patients; however, the incomplete characterization of the chemotherapy-related molecular effects on skeletal muscle makes the development of new preventive anti-wasting strategies difficult. Therefore, further investigation on molecular mechanisms and clinical studies are necessary.

Stimulation of soluble guanylate cyclase by vericiguat reduces skeletal muscle atrophy of mice following chemotherapy

Background: The chemotherapeutic doxorubicin (DOX) promotes severe skeletal muscle atrophy, which induces skeletal muscle weakness and fatigue. Soluble guanylate cyclase (sGC) contributes to a variety of pathophysiological processes, but whether it is involved in DOX-induced skeletal muscle atrophy is unclear. The present study aimed to stimulate sGC by vericiguat, a new oral sGC stimulator, to test its role in this process. Methods: Mice were randomly divided into four groups: control group, vericiguat group, DOX group, and DOX + vericiguat group. Exercise capacity was evaluated before the mice were sacrificed. Skeletal muscle atrophy was assessed by histopathological and molecular biological methods. Protein synthesis and degradation were monitored in mice and C2C12 cells. Results: In this study, a significant decrease in exercise capacity and cross-sectional area (CSA) of skeletal muscle fibers was found in mice following DOX treatment. Furthermore, DOX decreased sGC activity in mice and C2C12 cells, and a positive correlation was found between sGC activity and CSA of skeletal muscle fibers in skeletal muscle. DOX treatment also impaired protein synthesis, shown by puromycin detection, and activated ubiquitin-proteasome pathway. Following sGC stimulation, the CSA of muscle fibers was elevated, and exercise capacity was enhanced. Stimulation of sGC also increased protein synthesis and decreased ubiquitin-proteasome pathway. In terms of the underlying mechanisms, AKT/mTOR and FoxO1 pathways were impaired following DOX treatment, and stimulation of sGC restored the blunted pathways. Conclusion: These results unravel sGC stimulation can improve skeletal muscle atrophy and increase the exercise capacity of mice in response to DOX treatment by enhancing protein synthesis and inhibiting protein degradation. Stimulation of sGC may be a potential treatment of DOX-induced skeletal muscle dysfunction.

Nicotinamide Mononucleotide Administration Prevents Doxorubicin-Induced Cardiotoxicity and Loss in Physical Activity in Mice

Doxorubicin (Doxo) is a widely used antineoplastic drug with limited clinical application due to its deleterious dose-related side effects. We investigated whether nicotinamide mononucleotide (NMN) could protect against Doxo-induced cardiotoxicity and physical dysfunction in vivo. To assess the short- and long-term toxicity, two Doxo regimens were tested, acute and chronic. In the acute study, C57BL6/J (B6) mice were injected intraperitoneally (i.p.) once with Doxo (20 mg/kg) and NMN (180 mg/kg/day, i.p.) was administered daily for five days before and after the Doxo injection. In the chronic study, B6 mice received a cumulative dose of 20 mg/kg Doxo administered in fractionated doses for five days. NMN (500 mg/kg/day) was supplied in the mice's drinking water beginning five days before the first injection of Doxo and continuing for 60 days after. We found that NMN significantly increased tissue levels of NAD+ and its metabolites and improved survival and bodyweight loss in both experimental models. In addition, NMN protected against Doxo-induced cardiotoxicity and loss of physical function in acute and chronic studies, respectively. In the heart, NMN prevented Doxo-induced transcriptomic changes related to mitochondrial function, apoptosis, oxidative stress, inflammation and p53, and promyelocytic leukemia nuclear body pathways. Overall, our results suggest that NMN could prevent Doxo-induced toxicity in heart and skeletal muscle.

Obese mammary tumour-bearing mice are highly sensitive to doxorubicin-induced hepatotoxicity

BACKGROUND

Breast cancer is a major health burden for women, worldwide. Lifestyle-related risk factors, such as obesity and being overweight, have reached epidemic proportions and contributes to the development of breast cancer. Doxorubicin (DXR) is a chemotherapeutic drug commonly used to treat breast cancer, and although effective, may cause toxicity to other organs. The mechanisms and effects of DXR on hepatic tissue, and the contributing role of obesity, in breast cancer patients are poorly understood. The aim of this study was therefore to investigate the effects of DXR on hepatic tissue in an obese tumour-bearing mouse model.

METHODS

A diet-induced obesity (DIO) mouse model was established, where seventy-four three-week-old female C57BL6 mice were divided into two main groups, namely the high fat diet (containing 60% kcal fat) and standard diet (containing 10% kcal fat) groups. After eight weeks on their respective diets, the DIO phenotype was established, and the mice were further divided into tumour and non-tumour groups. Mice were subcutaneously inoculated with E0771 triple negative breast cancer cells in the fourth mammary gland and received three doses of 4 mg/kg DXR (cumulative dosage of 12 mg/kg) or vehicle treatments via intraperitoneal injection. The expression levels of markers involved in apoptosis and alanine aminotransferase (ALT) were compared by means of western blotting. To assess the pathology and morphology of hepatic tissue, haematoxylin and eosin staining was performed. The presence of fibrosis and lipid accumulation in hepatic tissues were assessed with Masson's trichrome and Oil Red O staining, respectively.

RESULTS

Microscopic examination of liver tissues showed significant changes in the high fat diet tumour-bearing mice treated with DXR, consisting of macrovesicular steatosis, hepatocyte ballooning and lobular inflammation, compared to the standard diet tumour-bearing mice treated with DXR and the control group (standard diet mice). These changes are the hallmarks of non-alcoholic fatty liver disease, associated with obesity.

CONCLUSION

The histopathological findings indicated that DXR caused significant hepatic parenchymal injury in the obese tumour-bearing mice. Hepatotoxicity is aggravated in obesity as an underlying co-morbidity. It has been shown that obesity is associated with poor clinical outcomes in patients receiving neo-adjuvant chemotherapy treatment regimens.

Physical Activity as the Best Supportive Care in Cancer: The Clinician's and the Researcher's Perspectives

Multidisciplinary supportive care, integrating the dimensions of exercise alongside oncological treatments, is now regarded as a new paradigm to improve patient survival and quality of life. Its impact is important on the factors that control tumor development, such as the immune system, inflammation, tissue perfusion, hypoxia, insulin resistance, metabolism, glucocorticoid levels, and cachexia. An increasing amount of research has been published in the last years on the effects of physical activity within the framework of oncology, marking the appearance of a new medical field, commonly known as "exercise oncology". This emerging research field is trying to determine the biological mechanisms by which, aerobic exercise affects the incidence of cancer, the progression and/or the appearance of metastases. We propose an overview of the current state of the art physical exercise interventions in the management of cancer patients, including a pragmatic perspective with tips for routine practice. We then develop the emerging mechanistic views about physical exercise and their potential clinical applications. Moving toward a more personalized, integrated, patient-centered, and multidisciplinary management, by trying to understand the different interactions between the cancer and the host, as well as the impact of the disease and the treatments on the different organs, this seems to be the most promising method to improve the care of cancer patients.

Chemotherapy impairs skeletal muscle mitochondrial homeostasis in early breast cancer patients

BACKGROUND

Chemotherapy is extensively used to treat breast cancer and is associated with skeletal muscle deconditioning, which is known to reduce patients' quality of life, treatment efficiency, and overall survival. To date, skeletal muscle mitochondrial alterations represent a major aspect explored in breast cancer patients; nevertheless, the cellular mechanisms remain relatively unknown. This study was dedicated to investigating overall skeletal muscle mitochondrial homeostasis in early breast cancer patients undergoing chemotherapy, including mitochondrial quantity, function, and dynamics.

METHODS

Women undergoing (neo)adjuvant anthracycline-cyclophosphamide and taxane-based chemotherapy participated in this study (56 ± 12 years). Two muscle biopsies were collected from the vastus lateralis muscle before the first and after the last chemotherapy administration. Mitochondrial respiratory capacity, reactive oxygen species production, and western blotting analyses were performed.

RESULTS

Among the 11 patients, we found a decrease in key markers of mitochondrial quantity, reaching -52.0% for citrate synthase protein levels (P = 0.02) and -38.2% for VDAC protein levels (P = 0.04). This mitochondrial content loss is likely explained by reduced mitochondrial biogenesis, as evidenced by a decrease in PGC-1α1 protein levels (-29.5%; P = 0.04). Mitochondrial dynamics were altered, as documented by a decrease in MFN2 protein expression (-33.4%; P = 0.01), a key marker of mitochondrial outer membrane fusion. Mitochondrial fission is a prerequisite for mitophagy activation, and no variation was found in either key markers of mitochondrial fission (Fis1 and DRP1) or mitophagy (Parkin, PINK1, and Mul1). Two contradictory hypotheses arise from these results: defective mitophagy, which probably increases the number of damaged and fragmented mitochondria, or a relative increase in mitophagy through elevated mitophagic potential (Parkin/VDAC ratio; +176.4%; P < 0.02). Despite no change in mitochondrial respiratory capacity and COX IV protein levels, we found an elevation in H₂ O₂ production (P < 0.05 for all substrate additions) without change in antioxidant enzymes. We investigated the apoptosis pathway and found an increase in the protein expression of the apoptosis initiation marker Bax (+72.0%; P = 0.04), without variation in the anti-apoptotic protein Bcl-2.

CONCLUSIONS

This study demonstrated major mitochondrial alterations subsequent to chemotherapy in early breast cancer patients: (i) a striking reduction in mitochondrial biogenesis, (ii) altered mitochondrial dynamics and potential mitophagy defects, (iii) exacerbated H₂ O₂ production, and (iv) increased initiation of apoptosis. All of these alterations likely explain, at least in part, the high prevalence of skeletal muscle and cardiorespiratory deconditioning classically observed in breast cancer patients.

Prolonged Endurance Exercise Adaptations Counteract Doxorubicin Chemotherapy-Induced Myotoxicity in Mice

Doxorubicin (DOX) is a potent chemotherapeutic agent widely used for various types of cancer; however, its accumulation causes myotoxicity and muscle atrophy. Endurance exercise (EXE) has emerged as a vaccine against DOX-induced myotoxicity. However, potential molecular mechanisms of EXE-mediated myocyte protection for the unfavorable muscle phenotype remain unelucidated. In addition, most studies have identified the short-term effects of DOX and EXE interventions, but studies on the prolonged EXE effects used as adjuvant therapy for chronic DOX treatment are lacking. Twelve-week-old adult male C57BL/6J mice were assigned to four groups: sedentary treated with saline (SED-SAL, n = 10), endurance exercise treated saline (EXE-SAL, n = 10), sedentary treated with doxorubicin (SED-DOX, n = 10), and endurance exercise treated with doxorubicin (EXE-DOX, n = 10). Mice were intraperitoneally injected with DOX (5 mg/kg) or saline five times biweekly for eight weeks, while a treadmill running exercise was performed. Body composition was assessed and then soleus muscle tissues were excised for histological and biochemical assays. Our data showed that DOX aggravated body composition, absolute soleus muscle mass, and distinct pathological features; also, TOP2B upregulation was linked to DOX-induced myotoxicity. We also demonstrated that EXE-DOX promoted mitochondrial biogenesis (e.g., citrate synthase). However, no alterations in satellite cell activation and myogenesis factors in response to DOX and EXE interventions were observed. Instead, SED-DOX promoted catabolic signaling cascades (AKT-FOXO3α-MuRF-1 axis), whereas EXE-DOX reversed its catabolic phenomenon. Moreover, EXE-DOX stimulated basal autophagy. We showed that the EXE-mediated catabolic paradigm shift is likely to rescue impaired muscle integrity. Thus, our study suggests that EXE can be recommended as an adjuvant therapy to ameliorate DOX-induced myotoxicity.

Exploring relationships between inspiratory muscle strength and functional capacity in childhood cancer survivors: a pilot study

Childhood cancer survivors (CCS) experience short- and long-term side effects from cancer treatment that often impair functional capacity. Inspiratory muscle weakness is a potential mechanism for reduced functional capacity. The objective of this pilot study was to examine the relationship between inspiratory muscle strength and functional capacity in 10 CCS. Inspiratory muscle strength was measured by maximal inspiratory pressure (MIP) while functional capacity was measured by the two-minute walk test (2MWT), the physiological cost index and hemodynamic response to exercise according to changes in heart rate, blood pressure and rate-pressure product (RPP). Overall, MIP and 2MWT distance were below predicted values. Hemodynamic responses to the 2MWT were consistent with little variation, except for elevated diastolic blood pressure (DBP) response. MIP had significant relationships with resting DBP (Spearman's rank correlation coefficient [r_s] = -0.70; p = 0.03) and DBP response (r_s = 0.72; p = 0.02). Time since completion of cancer treatment had a significant positive relationship with RPP response (r_s = 0.67; p = 0.03). Inspiratory muscle weakness in childhood cancer could be an indicator of skeletal muscle dysfunction and should be considered when symptoms of dyspnea or poor functional capacity arise. Inspiratory muscle strength was found to be related to changes in blood pressure in CCS. Future studies should further investigate these relationships and the impact of inspiratory muscle training on hemodynamics and functional capacity in CCS.

Current insights into cellular senescence and myotoxicity induced by doxorubicin

Doxorubicin is an anti-neoplasmic drug that prevents DNA replication but induces senescence and cellular toxicity. Intensive research has focused on strategies to alleviate the doxorubicin-induced skeletal myotoxicity. The aim of the present review is to critically discuss the relevant scientific evidence about the role of exercise and growth factor administration and offer novel insights about newly developed-tools to combat the adverse drug reactions of doxorubicin treatment on skeletal muscle. In the first part, we discuss current data and mechanistic details on the impact of doxorubicin on skeletal myotoxicity. We next, review key aspects about the role of regular exercise and the impact of growth factors either administered pharmacologically or via genetic interventions. Future strategies such as combination of exercise and growth factor administration remain to be established to combat the pharmacologically-induced myotoxicity.

Cardiomyocyte Atrophy, an Underestimated Contributor in Doxorubicin-Induced Cardiotoxicity

Left ventricular (LV) mass loss is prevalent in doxorubicin (DOX)-induced cardiotoxicity and is responsible for the progressive decline of cardiac function. Comparing with the well-studied role of cell death, the part of cardiomyocyte atrophy (CMA) playing in the LV mass loss is underestimated and the knowledge of the underlying mechanism is still limited. In this review, we summarized the recent advances in the DOX-induced CMA. We found that the CMA caused by DOX is associated with the upregulation of FOXOs and “atrogenes,” the activation of transient receptor potential canonical 3-NADPH oxidase 2 (TRPC3-Nox2) axis, and the suppression of IGF-1-PI3K signaling pathway. The imbalance of anabolic and catabolic process may be the common final pathway of these mechanisms. At last, we provided some strategies that have been demonstrated to alleviate the DOX-induced CMA in animal models.

Overview of Methods to Quantify Invasiveness of Surgical Approaches in Orthopedic Surgery-A Scoping Review

BACKGROUND

There is a trend toward minimally invasive and more automated procedures in orthopedic surgery. An important aspect in the further development of these techniques is the quantitative assessment of the surgical approach. The aim of this scoping review is to deliver a structured overview on the currently used methods for quantitative analysis of a surgical approaches' invasiveness in orthopedic procedures. The compiled metrics presented in the herein study can serve as the basis for digitization of surgery and advanced computational methods that focus on optimizing surgical procedures.

METHODS

We performed a blinded literature search in November 2020. In-vivo and ex-vivo studies that quantitatively assess the invasiveness of the surgical approach were included with a special focus on radiological methods. We excluded studies using exclusively one or multiple of the following parameters: risk of reoperation, risk of dislocation, risk of infection, risk of patient-reported nerve injury, rate of thromboembolic event, function, length of stay, blood loss, pain, operation time.

RESULTS

The final selection included 51 articles. In the included papers, approaches to 8 different anatomical structures were investigated, the majority of which examined procedures of the hip (57%) and the spine (29%). The different modalities to measure the invasiveness were categorized into three major groups "biological" (23 papers), "radiological" (25), "measured in-situ" (14) and their use "in-vivo" or "ex-vivo" was analyzed. Additionally, we explain the basic principles of each modality and match it to the anatomical structures it has been used on.

DISCUSSION

An ideal metric used to quantify the invasiveness of a surgical approach should be accurate, cost-effective, non-invasive, comprehensive and integratable into the clinical workflow. We find that the radiological methods best meet such criteria. However, radiological metrics can be more prone to confounders such as coexisting pathologies than in-situ measurements but are non-invasive and possible to perform in-vivo. Additionally, radiological metrics require substantial expertise and are not cost-effective. Owed to their high accuracy and low invasiveness, radiological methods are, in our opinion, the best suited for computational applications optimizing surgical procedures. The key to quantify a surgical approach's invasiveness lies in the integration of multiple metrics.

miR-27b-3p Attenuates Muscle Atrophy by Targeting Cbl-b in Skeletal Muscles

As it is well known, muscle atrophy is a process in which protein degradation increases and protein synthesis decreases. This process is regulated by a variety of links. Among them, microRNAs play an essential role in this process, which has attracted widespread attention. In this paper, we find that miR-27b-3p and Cbl-b genes are significantly differentially expressed in the induced atrophy model. The dual-luciferase experiment and Western blot analysis confirmed that miR-27b-3p could regulate the expression of Cbl-b. In C2C12-differentiated myotubes, the overexpression of the Cbl-b gene showed that Cbl-b could upregulate the expression of MuRF-1 and Atrogin-1, which are related marker genes of muscle atrophy, at both the mRNA and protein levels, indicating that the Cbl-b gene can specifically affect muscle atrophy. The knockdown of the Cbl-b gene after C2C12-differentiated myotubes induced atrophy treatment can downregulate the expression of muscle-atrophy-related genes, indicating that manual intervention to downregulate the expression of Cbl-b has a certain alleviating effect on muscle atrophy. These data suggest that miR-27b-3p can regulate the expression of the Cbl-b gene and then exert a particular influence on muscle atrophy through the Cbl-b gene.

Muscle wasting in cancer: opportunities and challenges for exercise in clinical cancer trials

BACKGROUND

Low muscle in cancer is associated with an increase in treatment-related toxicities and is a predictor of cancer-related and all-cause mortality. The mechanisms of cancer-related muscle loss are multifactorial, including anorexia, hypogonadism, anaemia, inflammation, malnutrition, and aberrations in skeletal muscle protein turnover and metabolism.

METHODS

In this narrative review, we summarise relevant literature to (i) review the factors influencing skeletal muscle mass regulation, (ii) provide an overview of how cancer/treatments negatively impact these, (iii) review factors beyond muscle signalling that can impact the ability to participate in and respond to an exercise intervention to counteract muscle loss in cancer, and (iv) provide perspectives on critical areas of future research.

RESULTS

Despite the well-known benefits of exercise, there remains a paucity of clinical evidence supporting the impact of exercise in cancer-related muscle loss. There are numerous challenges to reversing muscle loss with exercise in clinical cancer settings, ranging from the impact of cancer/treatments on the molecular regulation of muscle mass, to clinical challenges in responsiveness to an exercise intervention. For example, tumour-related/treatment-related factors (e.g. nausea, pain, anaemia, and neutropenia), presence of comorbidities (e.g. diabetes, arthritis, and chronic obstructive pulmonary disease), injuries, disease progression and bone metastases, concomitant medications (e.g., metformin), can negatively affect an individual's ability to exercise safely and limit subsequent adaptation.

CONCLUSIONS

This review identifies numerous gaps and oppportunities in the area of low muscle and muscle loss in cancer. Collaborative efforts between preclinical and clinical researchers are imperative to both understanding the mechanisms of atrophy, and develop appropriate therapeutic interventions.

Cardiotoxicity in pediatric lymphoma survivors

INTRODUCTION

Over the past five decades, the diagnosis and management of children with various malignancies have improved tremendously. As a result, an increasing number of children are long-term cancer survivors. With improved survival, however, has come an increased risk of treatment-related cardiovascular complications that can appear decades later.

AREAS COVERED

This review discusses the pathophysiology, epidemiology and effects of treatment-related cardiovascular complications from anthracyclines and radiotherapy in pediatric lymphoma survivors. There is a paucity of evidence-based recommendations for screening for and treatment of cancer therapy-induced cardiovascular complications. We discuss current preventive measures and strategies for their treatment.

EXPERT OPINION

Significant cardiac adverse effects occur due to radiation and chemotherapy received by patients treated for lymphoma. Higher lifetime cumulative doses, female sex, longer follow-up, younger age, and preexisting cardiovascular disease are associated with a higher incidence of cardiotoxicity. With deeper understanding of the mechanisms of these adverse cardiac effects and identification of driver mutations causing these effects, personalized cancer therapy to limit cardiotoxic effects while ensuring an adequate anti-neoplastic effect would be ideal. In the meantime, expanding the use of cardioprotective agents with the best evidence such as dexrazoxane should be encouraged and further studied.