Cancer cachexia and skeletal muscle atrophy in clinical studies: what do we really know?

Impact of sarcopenia on outcomes of bladder cancer undergoing radical cystectomy: A systematic review and meta-analysis

OBJECTIVE

To provide synthesized evidence on the association between sarcopenia and risk of mortality, recurrence and postoperative complications in patients with bladder cancer and undergoing radical cystectomy (RC).

METHODS

Only studies with observational design that investigated the association between sarcopenia and outcomes of interest among patients with bladder cancer undergoing RC were included. The outcomes of interest were mortality, recurrence, and postoperative complications. The systematic search was conducted using three large databases, that is, PubMed, EMBASE, and Scopus. A random effects model was used for the analysis and pooled effect sizes were reported as odds ratio (OR) or hazards ratio (HR) along with 95% confidence intervals (CIs).

RESULTS

A total of 21 studies with 4997 patients were included. Compared to non-sarcopenic subjects, those with sarcopenia had increased risk of all-cause mortality (HR 1.45, 95% CI: 1.32, 1.61), cancer-specific mortality (HR 1.74, 95% CI: 1.49, 2.03) and a lower recurrence free survival (HR 1.84, 95% CI: 1.30, 2.62). Patients with sarcopenia also had higher risk of developing complications within 90 days postoperatively (OR 1.77, 95% CI: 1.23, 2.55).

CONCLUSION

Sarcopenia among patients with bladder cancer and managed using RC is associated with adverse survival outcomes and an increased risk of postoperative complications.

Oncostatin M signaling drives cancer-associated skeletal muscle wasting

Progressive weakness and muscle loss are associated with multiple chronic conditions, including muscular dystrophy and cancer. Cancer-associated cachexia, characterized by dramatic weight loss and fatigue, leads to reduced quality of life and poor survival. Inflammatory cytokines have been implicated in muscle atrophy; however, available anticytokine therapies failed to prevent muscle wasting in cancer patients. Here, we show that oncostatin M (OSM) is a potent inducer of muscle atrophy. OSM triggers cellular atrophy in primary myotubes using the JAK/STAT3 pathway. Identification of OSM targets by RNA sequencing reveals the induction of various muscle atrophy-related genes, including Atrogin1. OSM overexpression in mice causes muscle wasting, whereas muscle-specific deletion of the OSM receptor (OSMR) and the neutralization of circulating OSM preserves muscle mass and function in tumor-bearing mice. Our results indicate that activated OSM/OSMR signaling drives muscle atrophy, and the therapeutic targeting of this pathway may be useful in preventing muscle wasting.

Transcriptomic signature of cancer cachexia by integration of machine learning, literature mining and meta-analysis

BACKGROUND

Cancer cachexia is a severe metabolic syndrome marked by skeletal muscle atrophy. A successful clinical intervention for cancer cachexia is currently lacking. The study of cachexia mechanisms is largely based on preclinical animal models and the availability of high-throughput transcriptomic datasets of cachectic mouse muscles is increasing through the extensive use of next generation sequencing technologies.

METHODS

Cachectic mouse muscle transcriptomic datasets of ten different studies were combined and mined by seven attribute weighting models, which analysed both categorical variables and numerical variables. The transcriptomic signature of cancer cachexia was identified by attribute weighting algorithms and was used to evaluate the performance of eleven pattern discovery models. The signature was employed to find the best combination of drugs (drug repurposing) for developing cancer cachexia treatment strategies, as well as to evaluate currently used cachexia drugs by literature mining.

RESULTS

Attribute weighting algorithms ranked 26 genes as the transcriptomic signature of muscle from mice with cancer cachexia. Deep Learning and Random Forest models performed better in differentiating cancer cachexia cases based on muscle transcriptomic data. Literature mining revealed that a combination of melatonin and infliximab has negative interactions with 2 key genes (Rorc and Fbxo32) upregulated in the transcriptomic signature of cancer cachexia in muscle.

CONCLUSIONS

The integration of machine learning, meta-analysis and literature mining was found to be an efficient approach to identifying a robust transcriptomic signature for cancer cachexia, with implications for improving clinical diagnosis and management of this condition.

Cancer-associated muscle weakness - From triggers to molecular mechanisms

Skeletal muscle weakness is a debilitating consequence of many malignancies. Muscle weakness has a negative impact on both patient wellbeing and outcome in a range of cancer types and can be the result of loss of muscle mass (i.e. muscle atrophy, cachexia) and occur independently of muscle atrophy or cachexia. There are multiple cancer specific triggers that can initiate the progression of muscle weakness, including the malignancy itself and the tumour environment, as well as chemotherapy, radiotherapy and malnutrition. This can induce weakness via different routes: 1) impaired intrinsic capacity (i.e., contractile dysfunction and intramuscular impairments in excitation-contraction coupling or crossbridge cycling), 2) neuromuscular disconnection and/or 3) muscle atrophy. The mechanisms that underlie these pathways are a complex interplay of inflammation, autophagy, disrupted protein synthesis/degradation, and mitochondrial dysfunction. The current lack of therapies to treat cancer-associated muscle weakness highlight the critical need for novel interventions (both pharmacological and non-pharmacological) and mechanistic insight. Moreover, most research in the field has placed emphasis on directly improving muscle mass to improve muscle strength. However, accumulating evidence suggests that loss of muscle function precedes atrophy. This review primarily focuses on cancer-associated muscle weakness, independent of cachexia, and provides a solid background on the underlying mechanisms, methodology, current interventions, gaps in knowledge, and limitations of research in the field. Moreover, we have performed a mini-systematic review of recent research into the mechanisms behind muscle weakness in specific cancer types, along with the main pathways implicated.

Licochalcone A and B enhance muscle proliferation and differentiation by regulating Myostatin

BACKGROUND

Myostatin (MSTN) inhibition has demonstrated promise for the treatment of diseases associated with muscle loss. In a previous study, we discovered that Glycyrrhiza uralensis (G. uralensis) crude water extract (CWE) inhibits MSTN expression while promoting myogenesis. Furthermore, three specific compounds of G. uralensis, namely liquiritigenin, tetrahydroxymethoxychalcone, and Licochalcone B (Lic B), were found to promote myoblast proliferation and differentiation, as well as accelerate the regeneration of injured muscle tissue.

PURPOSE

The purpose of this study was to build on our previous findings on G. uralensis and demonstrate the potential of its two components, Licochalcone A (Lic A) and Lic B, in muscle mass regulation (by inhibiting MSTN), aging and muscle formation.

METHODS

G. uralensis, Lic A, and Lic B were evaluated thoroughly using in silico, in vitro and in vivo approaches. In silico analyses included molecular docking, and dynamics simulations of these compounds with MSTN. Protein-protein docking was carried out for MSTN, as well as for the docked complex of MSTN-Lic with its receptor, activin type IIB receptor (ACVRIIB). Subsequent in vitro studies used C2C12 cell lines and primary mouse muscle stem cells to acess the cell proliferation and differentiation of normal and aged cells, levels of MSTN, Atrogin 1, and MuRF1, and plasma MSTN concentrations, employing techniques such as western blotting, immunohistochemistry, immunocytochemistry, cell proliferation and differentiation assays, and real-time RT-PCR. Furthermore, in vivo experiments using mouse models focused on measuring muscle fiber diameters.

RESULTS

CWE of G. uralensis and two of its components, namely Lic A and B, promote myoblast proliferation and differentiation by inhibiting MSTN and reducing Atrogin1 and MuRF1 expressions and MSTN protein concentration in serum. In silico interaction analysis revealed that Lic A (binding energy -6.9 Kcal/mol) and B (binding energy -5.9 Kcal/mol) bind to MSTN and reduce binding between it and ACVRIIB, thereby inhibiting downstream signaling. The experimental analysis, which involved both in vitro and in vivo studies, demonstrated that the levels of MSTN, Atrogin 1, and MuRF1 were decreased when G. uralensis CWE, Lic A, or Lic B were administered into mice or treated in the mouse primary muscle satellite cells (MSCs) and C2C12 myoblasts. The diameters of muscle fibers increased in orally treated mice, and the differentiation and proliferation of C2C12 cells were enhanced. G. uralensis CWE, Lic A, and Lic B also promoted cell proliferation in aged cells, suggesting that they may have anti-muslce aging properties. They also reduced the expression and phosphorylation of SMAD2 and SMAD3 (MSTN downstream effectors), adding to the evidence that MSTN is inhibited.

CONCLUSION

These findings suggest that CWE and its active constituents Lic A and Lic B have anti-mauscle aging potential. They also have the potential to be used as natural inhibitors of MSTN and as therapeutic options for disorders associated with muscle atrophy.

A triple-masked, two-center, randomized parallel clinical trial to assess the superiority of eight weeks of grape seed flour supplementation against placebo for weight loss attenuation during perioperative period in patients with cachexia associated with colorectal cancer: a study protocol

Background

Progressive, involuntary weight and lean mass loss in cancer are linked to cachexia, a prevalent syndrome in gastrointestinal malignancies that impacts quality of life, survival and postoperative complications. Its pathophysiology is complex and believed to involve proinflammatory cytokine-mediated systemic inflammation resulting from tumor-host interaction, oxidative stress, abnormal metabolism and neuroendocrine changes. Therapeutic options for cachexia remain extremely limited, highlighting the need for clinical research targeting new interventions. Thus, this study primarily assesses the effects of grape-seed flour (GSF), rich in polyphenols and fibers, for attenuating perioperative weight loss in colorectal cancer.

Methods

This is a dual-center, triple-masked, placebo-controlled, parallel-group, phase II, randomized clinical trial designed to investigate GSF supplementation in subjects with pre- or cachexia associated with colorectal cancer during the perioperative period. Eighty-two participants will receive 8g of GSF or cornstarch (control) for 8 weeks. Assessments are scheduled around surgery: pre-intervention (4 weeks prior), day before, first week after, and post-intervention (4 weeks later). The primary endpoint is the difference in body weight mean change from baseline to week 8. The secondary endpoints describe the harms from 8-week supplementation and assess its superiority to improve body composition, post-surgical complications, quality of life, anorexia, fatigue, gastrointestinal symptoms, and handgrip strength. The study will also explore its effects on gut bacteria activity and composition, systemic inflammation, and muscle metabolism.

Discussion

The current trial addresses a gap within the field of cancer cachexia, specifically focusing on the potential role of a nutritional intervention during the acute treatment phase. GSF is expected to modulate inflammation and oxidative stress, both involved in muscle and intestinal dysfunction. The research findings hold substantial implications for enhancing the understanding about cachexia pathophysiology and may offer a new clinical approach to managing cachexia at a critical point in treatment, directly impacting clinical outcomes.

Trial registration

The Brazilian Registry of Clinical Trials (ReBEC), RBR-5p6nv8b; UTN: U1111-1285-9594. Prospectively registered on February 07, 2023.

Metabolic signatures and potential biomarkers for the diagnosis and treatment of colon cancer cachexia

Cancer cachexia (CAC) is a debilitating condition that often arises from noncachexia cancer (NCAC), with distinct metabolic characteristics and medical treatments. However, the metabolic changes and underlying molecular mechanisms during cachexia progression remain poorly understood. Understanding the progression of CAC is crucial for developing diagnostic approaches to distinguish between CAC and NCAC stages, facilitating appropriate treatment for cancer patients. In this study, we establish a mouse model of colon CAC and categorize the mice into three groups: CAC, NCAC and normal control (NOR). By performing nuclear magnetic resonance (NMR)-based metabolomic profiling on mouse sera, we elucidate the metabolic properties of these groups. Our findings unveil significant differences in the metabolic profiles among the CAC, NCAC and NOR groups, highlighting significant impairments in energy metabolism and amino acid metabolism during cachexia progression. Additionally, we observe the elevated serum levels of lysine and acetate during the transition from the NCAC to CAC stages. Using multivariate ROC analysis, we identify lysine and acetate as potential biomarkers for distinguishing between CAC and NCAC stages. These biomarkers hold promise for the diagnosis of CAC from noncachexia cancer. Our study provides novel insights into the metabolic mechanisms underlying cachexia progression and offers valuable avenues for the diagnosis and treatment of CAC in clinical settings.

Unravelling the Role of Cancer Cell-Derived Extracellular Vesicles in Muscle Atrophy, Lipolysis, and Cancer-Associated Cachexia

Cancer-associated cachexia is a metabolic syndrome that causes significant reduction in whole-body weight due to excessive loss of muscle mass accompanied by loss of fat mass. Reduced food intake and several metabolic abnormalities, such as increased energy expenditure, excessive catabolism, and inflammation, are known to drive cachexia. It is well documented that cancer cells secrete EVs in abundance which can be easily taken up by the recipient cell. The cargo biomolecules carried by the EVs have the potential to alter the signalling pathways and function of the recipient cells. EV cargo includes proteins, nucleic acids, lipids, and metabolites. Tumour-secreted EVs have been found to alter the metabolic and biological functions of adipose and muscle tissue, which aids in the development of the cachexia phenotype. To date, no medical intervention or FDA-approved drug exists that can completely reverse cachexia. Therefore, understanding how cancer-derived EVs contribute to the onset and progression of cancer-associated cachexia may help with the identification of new biomarkers as well as provide access to novel treatment alternatives. The goal of this review article is to discuss the most recent research on cancer-derived EVs and their function in cellular crosstalk that promotes catabolism in muscle and adipose tissue during cancer-induced cachexia.

The impact of sarcopenia on prognosis of patients with pancreatic cancer: A systematic review and meta-analysis

OBJECTIVE

To summarize recent findings on the association of low skeletal muscle mass and muscle quality with overall survival and recurrence-free survival in patients with pancreatic cancer.

METHODS

A systematic search was conducted using Medline (via PubMed), Embase and Scopus databases for observational studies reporting on the overall survival and recurrence-free survival. Pooled effect sizes were reported as hazards ratio along with 95% confidence intervals.

RESULTS

A total of 34 studies were included. Low skeletal muscle index (indicating muscle mass) was associated with poor overall survival (hazards ratio: 1.50; 95% confidence interval: 1.34, 1.67) and lower recurrence-free survival (hazards ratio: 1.28, 95% confidence interval: 1.15, 1.43). Low skeletal muscle attenuation (indicating muscle quality) was associated with poor overall survival (hazards ratio: 1.32; 95% confidence interval: 1.05, 1.66). Recurrence-free survival was similar in patients with low and normal/high skeletal muscle attenuation (hazards ratio: 1.12, 95% confidence interval: 0.89, 1.40).

CONCLUSION

Both low skeletal muscle mass and poor muscle quality are associated with poor long-term survival. Low skeletal muscle index, but not low skeletal muscle attenuation, are associated with poor recurrence-free survival.

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.

Muscle wasting: emerging pathways and potential drug targets

Muscle wasting is a serious comorbidity associated with many disorders, including cancer, kidney disease, heart failure, and aging. Progressive loss of skeletal muscle mass negatively influences prognosis and survival, and is often accompanied by frailty and poor quality of life. Clinical trials testing therapeutics against muscle wasting have yielded limited success. Some therapies improved muscle mass in patients without appreciable differences in physical performance. This review article discusses emerging pathways that regulate muscle atrophy, including oncostatin M (OSM) and ectodysplasin A2 (EDA2) receptor (EDA2R) signaling, outcomes of recent clinical trials, and potential drug targets for future therapies.

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.

Tryptophan Modulation in Cancer-Associated Cachexia Mouse Models

Cancer cachexia is a multifactorial syndrome that interferes with treatment and reduces the quality of life and survival of patients. Currently, there is no effective treatment or biomarkers, and pathophysiology is not clear. Our group reported alterations on tryptophan metabolites in cachectic patients, so we aim to investigate the role of tryptophan using two cancer-associated cachexia syngeneic murine models, melanoma B16F10, and pancreatic adenocarcinoma that is KPC-based. Injected mice showed signs of cancer-associated cachexia as reduction in body weight and raised spleen weight, MCP1, and carbonilated proteins in plasma. CRP and Myostatin also increased in B16F10 mice. Skeletal muscle showed a decrease in quadriceps weight and cross-sectional area (especially in B16F10). Higher expression of atrophy genes, mainly Atrogin1, was also observed. Plasmatic tryptophan levels in B16F10 tumor-bearing mice decreased even at early steps of tumorigenesis. In KPC-injected mice, tryptophan fluctuated but were also reduced and in cachectic patients were significantly lower. Treatment with 1-methyl-tryptophan, an inhibitor of tryptophan degradation, in the murine models resulted in the restoration of plasmatic tryptophan levels and an improvement on splenomegaly and carbonilated proteins levels, while changes in plasmatic inflammatory markers were mild. After the treatment, CCR2 expression in monocytes diminished and lymphocytes, Tregs, and CD8+, were activated (seen by increased in CD127 and CD25 expression, respectively). These immune cell changes pointed to an improvement in systemic inflammation. While treatment with 1-MT did not show benefits in terms of muscle wasting and atrophy in our experimental setting, muscle functionality was not affected and central nuclei fibers appeared, being a feature of regeneration. Therefore, tryptophan metabolism pathway is a promising target for inflammation modulation in cancer-associated cachexia.

Mitochondrial dysfunction: roles in skeletal muscle atrophy

Mitochondria play important roles in maintaining cellular homeostasis and skeletal muscle health, and damage to mitochondria can lead to a series of pathophysiological changes. Mitochondrial dysfunction can lead to skeletal muscle atrophy, and its molecular mechanism leading to skeletal muscle atrophy is complex. Understanding the pathogenesis of mitochondrial dysfunction is useful for the prevention and treatment of skeletal muscle atrophy, and finding drugs and methods to target and modulate mitochondrial function are urgent tasks in the prevention and treatment of skeletal muscle atrophy. In this review, we first discussed the roles of normal mitochondria in skeletal muscle. Importantly, we described the effect of mitochondrial dysfunction on skeletal muscle atrophy and the molecular mechanisms involved. Furthermore, the regulatory roles of different signaling pathways (AMPK-SIRT1-PGC-1α, IGF-1-PI3K-Akt-mTOR, FoxOs, JAK-STAT3, TGF-β-Smad2/3 and NF-κB pathways, etc.) and the roles of mitochondrial factors were investigated in mitochondrial dysfunction. Next, we analyzed the manifestations of mitochondrial dysfunction in muscle atrophy caused by different diseases. Finally, we summarized the preventive and therapeutic effects of targeted regulation of mitochondrial function on skeletal muscle atrophy, including drug therapy, exercise and diet, gene therapy, stem cell therapy and physical therapy. This review is of great significance for the holistic understanding of the important role of mitochondria in skeletal muscle, which is helpful for researchers to further understanding the molecular regulatory mechanism of skeletal muscle atrophy, and has an important inspiring role for the development of therapeutic strategies for muscle atrophy targeting mitochondria in the future.

Impairment of aryl hydrocarbon receptor signalling promotes hepatic disorders in cancer cachexia

BACKGROUND

The aryl hydrocarbon receptor (AHR) is expressed in the intestine and liver, where it has pleiotropic functions and target genes. This study aims to explore the potential implication of AHR in cancer cachexia, an inflammatory and metabolic syndrome contributing to cancer death. Specifically, we tested the hypothesis that targeting AHR can alleviate cachectic features, particularly through the gut-liver axis.

METHODS

AHR pathways were explored in multiple tissues from four experimental mouse models of cancer cachexia (C26, BaF3, MC38 and APCMin/+ ) and from non-cachectic mice (sham-injected mice and non-cachexia-inducing [NC26] tumour-bearing mice), as well as in liver biopsies from cancer patients. Cachectic mice were treated with an AHR agonist (6-formylindolo(3,2-b)carbazole [FICZ]) or an antibody neutralizing interleukin-6 (IL-6). Key mechanisms were validated in vitro on HepG2 cells.

RESULTS

AHR activation, reflected by the expression of Cyp1a1 and Cyp1a2, two major AHR target genes, was deeply reduced in all models (C26 and BaF3, P < 0.001; MC38 and APCMin/+ , P < 0.05) independently of anorexia. This reduction occurred early in the liver (P < 0.001; before the onset of cachexia), compared to the ileum and skeletal muscle (P < 0.01; pre-cachexia stage), and was intrinsically related to cachexia (C26 vs. NC26, P < 0.001). We demonstrate a differential modulation of AHR activation in the liver (through the IL-6/hypoxia-inducing factor 1α pathway) compared to the ileum (attributed to the decreased levels of indolic AHR ligands, P < 0.001), and the muscle. In cachectic mice, FICZ treatment reduced hepatic inflammation: expression of cytokines (Ccl2, P = 0.005; Cxcl2, P = 0.018; Il1b, P = 0.088) with similar trends at the protein levels, expression of genes involved in the acute-phase response (Apcs, P = 0.040; Saa1, P = 0.002; Saa2, P = 0.039; Alb, P = 0.003), macrophage activation (Cd68, P = 0.038) and extracellular matrix remodelling (Fga, P = 0.008; Pcolce, P = 0.025; Timp1, P = 0.003). We observed a decrease in blood glucose in cachectic mice (P < 0.0001), which was also improved by FICZ treatment (P = 0.026) through hepatic transcriptional promotion of a key marker of gluconeogenesis, namely, G6pc (C26 vs. C26 + FICZ, P = 0.029). Strikingly, these benefits on glycaemic disorders occurred independently of an amelioration of the gut barrier dysfunction. In cancer patients, the hepatic expression of G6pc was correlated to Cyp1a1 (Spearman's ρ = 0.52, P = 0.089) and Cyp1a2 (Spearman's ρ = 0.67, P = 0.020).

CONCLUSIONS

With this set of studies, we demonstrate that impairment of AHR signalling contributes to hepatic inflammatory and metabolic disorders characterizing cancer cachexia, paving the way for innovative therapeutic strategies in this context.

EDA2R-NIK signalling promotes muscle atrophy linked to cancer cachexia

Skeletal muscle atrophy is a hallmark of the cachexia syndrome that is associated with poor survival and reduced quality of life in patients with cancer¹. Muscle atrophy involves excessive protein catabolism and loss of muscle mass and strength². An effective therapy against muscle wasting is currently lacking because mechanisms driving the atrophy process remain incompletely understood. Our gene expression analysis in muscle tissues indicated upregulation of ectodysplasin A2 receptor (EDA2R) in tumour-bearing mice and patients with cachectic cancer. Here we show that activation of EDA2R signalling promotes skeletal muscle atrophy. Stimulation of primary myotubes with the EDA2R ligand EDA-A2 triggered pronounced cellular atrophy by induction of the expression of muscle atrophy-related genes Atrogin1 and MuRF1. EDA-A2-driven myotube atrophy involved activation of the non-canonical NFĸB pathway and was dependent on NFκB-inducing kinase (NIK) activity. Whereas EDA-A2 overexpression promoted muscle wasting in mice, deletion of either EDA2R or muscle NIK protected tumour-bearing mice from loss of muscle mass and function. Tumour-induced oncostatin M (OSM) upregulated muscle EDA2R expression, and muscle-specific oncostatin M receptor (OSMR)-knockout mice were resistant to tumour-induced muscle wasting. Our results demonstrate that EDA2R-NIK signalling mediates cancer-associated muscle atrophy in an OSM-OSMR-dependent manner. Thus, therapeutic targeting of these pathways may be beneficial in prevention of muscle loss.

Clinical and Prognostic Relevance of Cardiac Wasting in Patients With Advanced Cancer

BACKGROUND

Body wasting in patients with cancer can affect the heart.

OBJECTIVES

The frequency, extent, and clinical and prognostic importance of cardiac wasting in cancer patients is unknown.

METHODS

This study prospectively enrolled 300 patients with mostly advanced, active cancer but without significant cardiovascular disease or infection. These patients were compared with 60 healthy control subjects and 60 patients with chronic heart failure (ejection fraction <40%) of similar age and sex distribution.

RESULTS

Cancer patients presented with lower left ventricular (LV) mass than healthy control subjects or heart failure patients (assessed by transthoracic echocardiography: 177 ± 47 g vs 203 ± 64 g vs 300 ± 71 g, respectively; P < 0.001). LV mass was lowest in cancer patients with cachexia (153 ± 42 g; P < 0.001). Importantly, the presence of low LV mass was independent of previous cardiotoxic anticancer therapy. In 90 cancer patients with a second echocardiogram after 122 ± 71 days, LV mass had declined by 9.3% ± 1.4% (P < 0.001). In cancer patients with cardiac wasting during follow-up, stroke volume decreased (P < 0.001) and resting heart rate increased over time (P = 0.001). During follow-up of on average 16 months, 149 patients died (1-year all-cause mortality 43%; 95% CI: 37%-49%). LV mass and LV mass adjusted for height squared were independent prognostic markers (both P < 0.05). Adjustment of LV mass for body surface area masked the observed survival impact. LV mass below the prognostically relevant cutpoints in cancer was associated with reduced overall functional status and lower physical performance.

CONCLUSIONS

Low LV mass is associated with poor functional status and increased all-cause mortality in cancer. These findings provide clinical evidence of cardiac wasting-associated cardiomyopathy in cancer.

Kanserde Kaşeksi ve Beslenme

ABSTRACT Cachexia results from different combinations of metabolic variables and decreased food intake, including increased energy expenditure, excessive catabolism, and inflammations. Anorexia, asthenia, sarcopenia and anemia are clinical features of cachexia, and are effective in reducing the quality of life. The prevalence of cachexia in cancer patients is estimated to be 35%. There are 2 factors that cause the development of cachexia in cancer. The first is the disruption of the anabolic process. All types of cachexia are associated with anorexia, decreased oral intake, lack of movement, and accompanying endocrine changes. Factors such as early satiety, taste and tissue disorders, pain, psychological reasons, gastrointestinal system disorders, dry mouth are factors that contribute to weight loss by reducing oral intake. Secondly, it is the catabolic process caused by the tumor-derived factors and metabolic changes. Enteral and parenteral nutrition support improves the patient's nutritional status by increasing appetite and energy intake. A multidisciplinary team effort is required in prevention of cancer cachexia. The purpose of this review is to interpret the role of nutrition in cancer cachexia. Keywords: Cancer, cachexia, nutrition ÖZET Kaşeksi, artan enerji harcaması, aşırı katabolizma ve inflamasyonlar dahil olmak üzere, metabolik değişkenler ve azalan gıda alımının farklı kombinasyonları sonucu olarak ortaya çıkmaktadır. Anoreksiya, asteni, sarkopeni ve anemi kaşeksinin klinik özelliklerinden olup yaşam kalitesinin azalmasında etkili olmaktadır. Kanser hastalarında kaşeksi prevalansının %35 olduğu tahmin edilmektir. Kanserde kaşeksi gelişimine sebep olan 2 faktör bulunmaktadır; Birincisi anabolik sürecin bozulmasıdır. Bütün kaşeksi türlerinde anoreksiyle oral alımda azalma, hareket eksikliği ve eşlik eden endokrin değişimler mevcuttur. Erken doyma, tat ve doku rahatsızlıkları, ağrı, psikolojik sebepler, gastrointestinal sistem bozukluları, ağız kuruluğu gibi etmenler oral alımı azaltarak kilo kaybına katkı sağlayan faktörlerdir. İkinci olarak da tümör kaynaklı faktörler ve metabolik değişimlerin sebep olduğu katabolik süreçtir. Enteral ve parenteral beslenme desteği, iştah ve enerji alımında artış sağlayarak hastanın beslenme durumunda gelişme sağlamaktadır. Kanser kaşeksisinin önlenmesinde multidisipliner bir ekip çalışması gereklidir. Bu derlemenin amacı kanser kaşeksisinde beslenmenin rolünü yorumlamaktır. Anahtar kelimeler: Kanser, kaşeksi, beslenme

Abdominal fat and muscle distributions in different stages of colorectal cancer

BACKGROUND

The purpose of this study is to explore the difference of abdominal fat and muscle composition, especially subcutaneous and visceral adipose tissue, in different stages of colorectal cancer (CRC).

MATERIALS AND METHODS

Patients were divided into 4 groups: healthy controls (patients without colorectal polyp), polyp group (patients with colorectal polyp), cancer group (CRC patients without cachexia), and cachexia group (CRC patients with cachexia). Skeletal muscle (SM), subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and intermuscular adipose tissue (IMAT) were assessed at the third lumbar level on computed tomography images obtained within 30 days before colonoscopy or surgery. One-way ANOVA and linear regression were used to analyze the difference of abdominal fat and muscle composition in different stages of CRC.

RESULTS

A total of 1513 patients were divided into healthy controls, polyp group, cancer group, and cachexia group, respectively. In the development of CRC from normal mucosa to polyp and cancer, the VAT area of the polyp group was significantly higher than that of the healthy controls both in male (156.32 ± 69.71 cm² vs. 141.97 ± 79.40 cm², P = 0.014) and female patients (108.69 ± 53.95 cm² vs. 96.28 ± 46.70 cm², P = 0.044). However, no significant differences were observed of SAT area between polyp group and healthy controls in both sexes. SAT area decreased significantly in the male cancer group compared with the polyp group (111.16 ± 46.98 cm² vs. 126.40 ± 43.52 cm², P = 0.001), while no such change was observed in female patients. When compared with healthy controls, the SM, IMAT, SAT, and VAT areas of cachexia group was significantly decreased by 9.25 cm² (95% CI: 5.39-13.11 cm², P < 0.001), 1.93 cm² (95% CI: 0.54-3.32 cm², P = 0.001), 28.84 cm² (95% CI: 17.84-39.83 cm², P < 0.001), and 31.31 cm² (95% CI: 18.12-44.51 cm², P < 0.001) after adjusting for age and gender.

CONCLUSION

Abdominal fat and muscle composition, especially SAT and VAT, was differently distributed in different stages of CRC. It is necessary to pay attention to the different roles of subcutaneous and visceral adipose tissue in the development of CRC.

The protective effect of cannabinoids against colorectal cancer cachexia through modulation of inflammation and immune responses

Cancer cachexia is a multifactorial disorder characterized by weight loss and muscle wasting, and there are currently no FDA-approved medications. In the present study, upregulation of six cytokines was observed in serum samples from patients with colorectal cancer (CRC) and in mouse models. A negative correlation between the levels of the six cytokines and body mass index in CRC patients was seen. Gene Ontology analysis revealed that these cytokines were involved in regulating T cell proliferation. The infiltration of CD8⁺ T cells was found to be associated with muscle atrophy in mice with CRC. Adoptive transfer of CD8⁺ T cells isolated from CRC mice resulted in muscle wasting in recipients. The Genotype-Tissue Expression database showed that negative correlations between the expression of cachexia markers and cannabinoid receptor 2 (CB2) in human skeletal muscle tissues. Pharmacological treatment with Δ⁹-tetrahydrocannabinol (Δ⁹-THC), a selective CB2 agonist or overexpression of CB2 attenuated CRC-associated muscle atrophy. In contrast, knockout of CB2 with a CRISPR/Cas9-based strategy or depletion of CD8⁺ T cells in CRC mice abolished the Δ⁹-THC-mediated effects. This study demonstrates that cannabinoids ameliorate CD8⁺ T cell infiltration in CRC-associated skeletal muscle atrophy via a CB2-mediated pathway. Serum levels of the six-cytokine signature might serve as a potential biomarker to detect the therapeutic effects of cannabinoids in CRC-associated cachexia.

The elusive role of myostatin signaling for muscle regeneration and maintenance of muscle and bone homeostasis

Skeletal muscle is one of the leading frameworks of the musculo-skeletal system, which works in synergy with the bones. Long skeletal muscles provide stability and mobility to the human body and are primarily composed of proteins. Conversely, improper functioning of various skeletal muscles leads to diseases and disorders, namely, age-related muscle disorder called sarcopenia, a group of genetic muscle disorders such as muscular dystrophies, and severe muscle wasting in cancer known as cachexia. However, skeletal muscle has an excellent ability to undergo hypertrophy and enhanced functioning during sustained exercise over time. Indeed, these processes of skeletal muscle regeneration/hypertrophy, as well as degeneration and atrophy, involve an interplay of various signaling pathways. Myostatin is one such chemokine/myokine with a significant contribution to muscle regeneration or atrophy in multiple conditions. In this review, we try to put together the role and regulation of myostatin as a function of muscle regeneration extrapolated to multiple aspects of its molecular functions.

Triceps skinfold-albumin index significantly predicts the prognosis of cancer cachexia: A multicentre cohort study

BACKGROUND

The fat mass and nutritional status play important roles in the onset and progression of cancer cachexia. The present study evaluated the joint prognostic value of the fat mass, as indicated by the triceps skinfold thickness (TSF), and the serum albumin level, for mortality in patients with cancer cachexia.

METHODS

We performed a multicentre cohort study including 5134 patients with cancer cachexia from January 2013 to April 2019. The sum of the TSF (mm) and serum albumin (g/L) was defined as the triceps skinfold-albumin index (TA). Harrell's C index, a time-dependent receiver operating characteristic (ROC) curve analysis and the area under the curve (AUC) were used to evaluate the prognostic performance of the TA and other indices. Optimal stratification was used to identify the thresholds to define a low TA, and the association of the TA with all-cause mortality was evaluated using Kaplan-Meier analysis and Cox proportional hazard regression models.

RESULTS

The study enrolled 2408 women and 2726 men with a median age of 58.6 years and a median follow-up of 44 months. A total of 607 women (TA < 49.9) and 817 men (TA < 45.6) were classified as having a low TA. The TA showed better discrimination performance (C index = 0.621, 95% confidence interval [CI] = 0.607-0.636) to predict mortality in patients with cancer cachexia than the handgrip strength, the nutritional risk index, the prognostic nutritional index, the controlling nutritional status index, the systemic immune-inflammation index, the modified Glasgow prognostic score, and the TSF or albumin alone in the study population (all P < 0.05). The 1-, 3- and 5-year time-dependent ROC analyses (AUC = 0.647, 0.625 and 0.630, respectively) showed that the TA had the highest prognostic value among all indices investigated (all P < 0.05). Univariate analysis showed that a lower TA was associated with an increased death hazard (hazard ratio [HR] = 1.859, 95% CI = 1.677-2.062), regardless of the sex and cancer type. Multivariable survival analysis showed that a lower TA was independently associated with an increased death hazard (HR = 1.381, 95% CI = 1.223-1.560). This association was significantly strengthened in patients who did not receive curative chemotherapy (HR = 1.491, 95% CI = 1.298-1.713), those who had higher serum total protein levels (HR = 1.469, 95% CI = 1.284-1.681) and those with better physical performance (HR = 1.453, 95% CI = 1.271-1.662).

CONCLUSIONS

This study defined and evaluated a new prognostic index, the TA, which may improve the selection of intervention strategies to optimize the survival of patients with cancer cachexia.

Development and validation of an online dynamic nomogram system for predicting cancer cachexia among inpatients: a real-world cohort study in China

BACKGROUND

Early recognition of cachexia is essential for ensuring the prompt intervention and treatment of cancer patients. However, the diagnosis of cancer cachexia (CC) usually is delayed. This study aimed to establish an accurate and high-efficiency diagnostic system for CC.

METHODS

A total of 4834 cancer inpatients were enrolled in the INSCOC project from July 2013 to June 2020. All cancer patients in the study were randomly assigned to a development cohort (n=3384, 70%) and a validation cohort (n=1450, 30%). The least absolute shrinkage and selection operator (LASSO) method and multivariable logistic regression were used to identify the independent predictors for developing the dynamic nomogram. Discrimination and calibration were adopted to evaluate the ability of nomogram. A decision curve analysis (DCA) was used to evaluate clinical use.

RESULTS

We combined 5 independent predictive factors (age, NRS2002, PG-SGA, QOL by the QLQ-C30, and cancer categories) to establish the online dynamic nomogram system. The C-index, sensitivity, and specificity of the nomo-system to predict CC was 0.925 (95%CI, 0.916-0.934, P < 0.001), 0.826, and 0.862 in the development set, while the values were 0.923 (95%CI, 0.909-0.937, P < 0.001), 0.854, and 0.829 in the validation set. In addition, the calibration curves of the diagnostic nomogram also presented good agreement with the actual situation. DCA showed that the model is clinically useful and can increase the clinical benefit in cancer patients.

CONCLUSIONS

This study developed an online dynamic nomogram system with outstanding accuracy to help clinicians and dieticians estimate the probability of cachexia. This simple-to-use online nomogram can increase the clinical benefit in cancer patients and is expected to be widely adopted.

Phytochemicals: A potential therapeutic intervention for the prevention and treatment of cachexia

Cachexia, a multifactorial and often irreversible wasting syndrome, is often associated with the final phase of several chronic disorders. Although cachexia is characterized by skeletal muscle wasting and adipose tissue loss, it is a syndrome affecting different organs, which ultimately results in systemic complications and impaired quality of life. The pathogenesis and underlying molecular mechanisms of cachexia are not fully understood, and currently there are no effective standard treatments or approved drug therapies to completely reverse cachexia. Moreover, adequate nutritional interventions alone cannot significantly improve cachexia. Other approaches to ameliorate cachexia are urgently needed, and thus, the role of medicinal plants has received considerable importance in this respect due to their beneficial health properties. Increasing evidence indicates great potential of medicinal plants and their phytochemicals as an alternative and promising treatment strategy to reduce the symptoms of many diseases including cachexia. This article reviews the current status of cachexia, the molecular mechanisms of primary events driving cachexia, and state-of-the-art knowledge that reports the preventive and therapeutic activities of multiple families of phytochemical compounds and their pharmacological mode of action, which may hold promise as an alternative treatment modality for the management of cachexia. Based on our review of various in vitro and in vivo models of cachexia, we would conclude that phytochemicals may have therapeutic potential to attenuate cachexia, although clinical trials are required to unequivocally confirm this premise.

Targeting cancer cachexia: Molecular mechanisms and clinical study

Cancer cachexia is a complex systemic catabolism syndrome characterized by muscle wasting. It affects multiple distant organs and their crosstalk with cancer constitute cancer cachexia environment. During the occurrence and progression of cancer cachexia, interactions of aberrant organs with cancer cells or other organs in a cancer cachexia environment initiate a cascade of stress reactions and destroy multiple organs including the liver, heart, pancreas, intestine, brain, bone, and spleen in metabolism, neural, and immune homeostasis. The role of involved organs turned from inhibiting tumor growth into promoting cancer cachexia in cancer progression. In this review, we depicted the complicated relationship of cancer cachexia with the metabolism, neural, and immune homeostasis imbalance in multiple organs in a cancer cachexia environment and summarized the treatment progress in recent years. And we discussed the molecular mechanism and clinical study of cancer cachexia from the perspective of multiple organs metabolic, neurological, and immunological abnormalities. Updated understanding of cancer cachexia might facilitate the exploration of biomarkers and novel therapeutic targets of cancer cachexia.

The inflammatory response, a mixed blessing for muscle homeostasis and plasticity

Skeletal muscle makes up almost half the body weight of heathy individuals and is involved in several vital functions, including breathing, thermogenesis, metabolism, and locomotion. Skeletal muscle exhibits enormous plasticity with its capacity to adapt to stimuli such as changes in mechanical loading, nutritional interventions, or environmental factors (oxidative stress, inflammation, and endocrine changes). Satellite cells and timely recruited inflammatory cells are key actors in muscle homeostasis, injury, and repair processes. Conversely, uncontrolled recruitment of inflammatory cells or chronic inflammatory processes leads to muscle atrophy, fibrosis and, ultimately, impairment of muscle function. Muscle atrophy and loss of function are reported to occur either in physiological situations such as aging, cast immobilization, and prolonged bed rest, as well as in many pathological situations, including cancers, muscular dystrophies, and several other chronic illnesses. In this review, we highlight recent discoveries with respect to the molecular mechanisms leading to muscle atrophy caused by modified mechanical loading, aging, and diseases. We also summarize current perspectives suggesting that the inflammatory process in muscle homeostasis and repair is a double-edged sword. Lastly, we review recent therapeutic approaches for treating muscle wasting disorders, with a focus on the RANK/RANKL/OPG pathway and its involvement in muscle inflammation, protection and regeneration processes.

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.

PD-1 Alleviates Cisplatin-Induced Muscle Atrophy by Regulating Inflammation and Oxidative Stress

Skeletal muscle atrophy is an important characteristic of cachexia, which can be induced by chemotherapy and significantly contributes to functional muscle impairment. Inflammation and oxidative stress are believed to play important roles in the muscle atrophy observed in cachexia, but whether programmed cell death protein 1 (PD-1) is affected by this condition remains unclear. PD-1 is a membrane protein that is expressed on the surface of many immune cells and plays an important role in adaptive immune responses and autoimmunity. Thus, we investigated the role and underlying mechanism of PD-1 in cisplatin-induced muscle atrophy in mice. We found that PD-1 knockout dramatically contributed to skeletal muscle atrophy. Mechanistically, we found that E3 ubiquitin-protein ligases were significantly increased in PD-1 knockout mice after cisplatin treatment. In addition, we found that PD-1 knockout significantly exacerbated cisplatin-induced skeletal muscle inflammation and oxidative stress. Moreover, we found that there were significant increases in ferroptosis-related and autophagy-related genes in PD-1 knockout mice after cisplatin treatment. These data indicate that PD-1 plays an important role in cisplatin-induced skeletal muscle atrophy.

The evolving view of thermogenic fat and its implications in cancer and metabolic diseases

The incidence of metabolism-related diseases like obesity and type 2 diabetes mellitus has reached pandemic levels worldwide and increased gradually. Most of them are listed on the table of high-risk factors for malignancy, and metabolic disorders systematically or locally contribute to cancer progression and poor prognosis of patients. Importantly, adipose tissue is fundamental to the occurrence and development of these metabolic disorders. White adipose tissue stores excessive energy, while thermogenic fat including brown and beige adipose tissue dissipates energy to generate heat. In addition to thermogenesis, beige and brown adipocytes also function as dynamic secretory cells and a metabolic sink of nutrients, like glucose, fatty acids, and amino acids. Accordingly, strategies that activate and expand thermogenic adipose tissue offer therapeutic promise to combat overweight, diabetes, and other metabolic disorders through increasing energy expenditure and enhancing glucose tolerance. With a better understanding of its origins and biological functions and the advances in imaging techniques detecting thermogenesis, the roles of thermogenic adipose tissue in tumors have been revealed gradually. On the one hand, enhanced browning of subcutaneous fatty tissue results in weight loss and cancer-associated cachexia. On the other hand, locally activated thermogenic adipocytes in the tumor microenvironment accelerate cancer progression by offering fuel sources and is likely to develop resistance to chemotherapy. Here, we enumerate current knowledge about the significant advances made in the origin and physiological functions of thermogenic fat. In addition, we discuss the multiple roles of thermogenic adipocytes in different tumors. Ultimately, we summarize imaging technologies for identifying thermogenic adipose tissue and pharmacologic agents via modulating thermogenesis in preclinical experiments and clinical trials.

Identifying cancer cachexia in patients without weight loss information: machine learning approaches to address a real-world challenge

BACKGROUND

Diagnosing cancer cachexia relies extensively on the patient-reported historic weight, and failure to accurately recall this information can lead to severe underestimation of cancer cachexia.

OBJECTIVES

The present study aimed to develop inexpensive tools to facilitate the identification of cancer cachexia in patients without weight loss information.

METHODS

This multicenter cohort study included 12774 patients with cancer. Cachexia was retrospectively diagnosed using Fearon's framework. Baseline clinical features, excluding weight loss, were modeled to mimic a situation where the patient is unable to recall their weight history. Multiple machine learning (ML) models were trained using 75% of the study cohort to predict cancer cachexia, with the remaining 25% of the cohort used to assess model performance.

RESULTS

The study enrolled 6730 males and 6044 females (median age = 57.5 years). Cachexia was diagnosed in 5261 (41.2%) patients and most diagnoses were made based on the weight loss criterion. A 15-variable logistic regression (LR) model mainly comprising cancer types, gastrointestinal symptoms, tumor stage and serum biochemistry indices was selected among the various ML models. The LR model showed good performance for predicting cachexia in the validation data (area under the curve = 0.763, 95% confidence interval=[0.747, 0.780]). The calibration curve of the model demonstrated good agreement between predictions and actual observations (accuracy = 0.714, Kappa = 0.396, sensitivity = 0.580, specificity = 0.808, positive predictive value = 0.679, negative predictive value = 0.733). Subgroup analyses showed that the model was feasible in patients with different cancer types. The model was deployed as an online calculator and a nomogram, and was exported as predictive model markup language to permit flexible, individualized risk calculation.

CONCLUSIONS

We developed a ML model that can facilitate the identification of cancer cachexia in patients without weight loss information, which might improve decision-making and lead to the development of novel management strategies in cancer care.

Inflammation: Roles in Skeletal Muscle Atrophy

Various diseases can cause skeletal muscle atrophy, usually accompanied by inflammation, mitochondrial dysfunction, apoptosis, decreased protein synthesis, and enhanced proteolysis. The underlying mechanism of inflammation in skeletal muscle atrophy is extremely complex and has not been fully elucidated, thus hindering the development of effective therapeutic drugs and preventive measures for skeletal muscle atrophy. In this review, we elaborate on protein degradation pathways, including the ubiquitin-proteasome system (UPS), the autophagy-lysosome pathway (ALP), the calpain and caspase pathways, the insulin growth factor 1/Akt protein synthesis pathway, myostatin, and muscle satellite cells, in the process of muscle atrophy. Under an inflammatory environment, various pro-inflammatory cytokines directly act on nuclear factor-κB, p38MAPK, and JAK/STAT pathways through the corresponding receptors, and then are involved in muscle atrophy. Inflammation can also indirectly trigger skeletal muscle atrophy by changing the metabolic state of other tissues or cells. This paper explores the changes in the hypothalamic-pituitary-adrenal axis and fat metabolism under inflammatory conditions as well as their effects on skeletal muscle. Moreover, this paper also reviews various signaling pathways related to muscle atrophy under inflammatory conditions, such as cachexia, sepsis, type 2 diabetes mellitus, obesity, chronic obstructive pulmonary disease, chronic kidney disease, and nerve injury. Finally, this paper summarizes anti-amyotrophic drugs and their therapeutic targets for inflammation in recent years. Overall, inflammation is a key factor causing skeletal muscle atrophy, and anti-inflammation might be an effective strategy for the treatment of skeletal muscle atrophy. Various inflammatory factors and their downstream pathways are considered promising targets for the treatment and prevention of skeletal muscle atrophy.

The Molecular Basis and Therapeutic Potential of Leukemia Inhibitory Factor in Cancer Cachexia

Simple Summary

The mechanism of cancer cachexia is linked to a variety of factors, and inflammatory factors are thought to play a key role. We summarize the main roles of LIF in the development of cancer cachexia, including promoting fat loss, inducing skeletal muscle atrophy and causing anorexia nervosa. The main aim of this review is to increase the understanding of the effects of LIF in cachexia and to provide new insights into the treatment of cancer cachexia.

Abstract

Cachexia is a chronic metabolic syndrome that is characterized by sustained weight and muscle mass loss and anorexia. Cachexia can be secondary to a variety of diseases and affects the prognosis of patients significantly. The increase in inflammatory cytokines in plasma is deeply related to the occurrence of cachexia. As a member of the IL-6 cytokine family, leukemia inhibitory factor (LIF) exerts multiple biological functions. LIF is over-expressed in the cancer cells and stromal cells of various tumors, promoting the malignant development of tumors via the autocrine and paracrine systems. Intriguingly, increasing studies have confirmed that LIF contributes to the progression of cachexia, especially in patients with metastatic tumors. This review combines all of the evidence to summarize the mechanism of LIF-induced cachexia from the following four aspects: (i) LIF and cancer-associated cachexia, (ii) LIF and alterations of adipose tissue in cachexia, (iii) LIF and anorexia nervosa in cachexia, and (iv) LIF and muscle atrophy in cachexia. Considering the complex mechanisms in cachexia, we also focus on the interactions between LIF and other key cytokines in cachexia and existing therapeutics targeting LIF.

Pectoralis major muscle atrophy is associated with mitochondrial energy wasting in cachectic patients with gastrointestinal cancer

BACKGROUND

Cancer cachexia is a multifactorial syndrome characterized by involuntary and pathological weight loss, mainly due to skeletal muscle wasting, resulting in a decrease in patients' quality of life, response to cancer treatments, and survival. Our objective was to investigate skeletal muscle alterations in cachectic cancer patients.

METHODS

This is a prospective study of patients managed for pancreatic or colorectal cancer with an indication for systemic chemotherapy (METERMUCADIG - NCT02573974). One lumbar CT image was used to determine body composition. Patients were divided into three groups [8 noncachectic (NC), 18 with mild cachexia (MC), and 19 with severe cachexia (SC)] based on the severity of weight loss and muscle mass. For each patient, a pectoralis major muscle biopsy was collected at the time of implantable chamber placement. We used high-resolution oxygraphy to measure mitochondrial muscle oxygen consumption on permeabilized muscle fibres. We also performed optical and electron microscopy analyses, as well as gene and protein expression analyses.

RESULTS

Forty-five patients were included. Patients were 67% male, aged 67 years (interquartile range, 59-77). Twenty-three (51%) and 22 (49%) patients were managed for pancreatic and colorectal cancer, respectively. Our results show a positive correlation between median myofibres area and skeletal muscle index (P = 0.0007). Cancer cachexia was associated with a decrease in MAFbx protein expression (P < 0.01), a marker of proteolysis through the ubiquitin-proteasome pathway. Mitochondrial oxygen consumption related to energy wasting was significantly increased (SC vs. NC, P = 0.028) and mitochondrial area tended to increase (SC vs. MC, P = 0.056) in SC patients. On the contrary, mitochondria content and networks remain unaltered in cachectic cancer patients. Finally, our results show no dysfunction in lipid storage and endoplasmic reticulum homeostasis.

CONCLUSIONS

This clinical protocol brings unique data that provide new insight to mechanisms underlying muscle wasting in cancer cachexia. We report for the first time an increase in mitochondrial energy wasting in the skeletal muscle of severe cachectic cancer patients. Additional clinical studies are essential to further the exploring and understanding of these alterations.

Inflammation and Wasting of Skeletal Muscles in Kras-p53-Mutant Mice with Intraepithelial Neoplasia and Pancreatic Cancer-When Does Cachexia Start?

Skeletal muscle wasting critically impairs the survival and quality of life in patients with pancreatic ductal adenocarcinoma (PDAC). To identify the local factors initiating muscle wasting, we studied inflammation, fiber cross-sectional area (CSA), composition, amino acid metabolism and capillarization, as well as the integrity of neuromuscular junctions (NMJ, pre-/postsynaptic co-staining) and mitochondria (electron microscopy) in the hindlimb muscle of LSL-KrasG12D/+; LSL-TrP53R172H/+; Pdx1-Cre mice with intraepithelial-neoplasia (PanIN) 1-3 and PDAC, compared to wild-type mice (WT). Significant decreases in fiber CSA occurred with PDAC but not with PanIN 1-3, compared to WT: These were found in the gastrocnemius (type 2x: −20.0%) and soleus (type 2a: −21.0%, type 1: −14.2%) muscle with accentuation in the male soleus (type 2a: −24.8%, type 1: −17.4%) and female gastrocnemius muscle (−29.6%). Significantly higher densities of endomysial CD68+ and cyclooxygenase-2+ (COX2+) cells were detected in mice with PDAC, compared to WT mice. Surprisingly, CD68+ and COX2+ cell densities were also higher in mice with PanIN 1-3 in both muscles. Significant positive correlations existed between muscular and hepatic CD68+ or COX2+ cell densities. Moreover, in the gastrocnemius muscle, suppressor-of-cytokine-3 (SOCS3) expressions was upregulated >2.7-fold with PanIN 1A-3 and PDAC. The intracellular pools of proteinogenic amino acids and glutathione significantly increased with PanIN 1A-3 compared to WT. Capillarization, NMJ, and mitochondrial ultrastructure remained unchanged with PanIN or PDAC. In conclusion, the onset of fiber atrophy coincides with the manifestation of PDAC and high-grade local (and hepatic) inflammatory infiltration without compromised microcirculation, innervation or mitochondria. Surprisingly, muscular and hepatic inflammation, SOCS3 upregulation and (proteolytic) increases in free amino acids and glutathione were already detectable in mice with precancerous PanINs. Studies of initial local triggers and defense mechanisms regarding cachexia are warranted for targeted anti-inflammatory prevention.

Chest computed tomography-derived muscle mass and quality indicators, in-hospital outcomes, and costs in older inpatients

BACKGROUND

Muscle mass and muscle quality assessed by computed tomography (CT) have been associated with poor prognosis in oncology and surgery patients, but the relevant evidence was limited in older patients. We hypothesized that muscle mass and muscle quality indicators derived from opportunistic chest CT images at the 12th thorax vertebra level (T12) could predict in-hospital death, length of hospital stay (hospital LOS), and hospital costs among older patients in acute care wards.

METHODS

We conducted a prospective cohort study. Older patients admitted to the acute geriatric wards of a teaching hospital were continuously recruited. Chest CT images were analysed using SliceOmatic software. The skeletal muscle area, skeletal muscle radiodensity, and intermuscular adipose tissue (IMAT) at the T12 level were measured. Skeletal muscle index (SMI) was calculated using skeletal muscle area divided by body height squared.

RESULTS

We included 1135 older patients with a median age of 80 years (interquartile range, 73 to 85 years), 498 (44%) were women, 148 (13%) patients died during hospitalization. The SMI and SMD were negatively correlated to age (ρ = -0.11, P < 0.001, ρ = -0.30, P < 0.001, respectively), whereas the IMAT was positively correlated to age (ρ = 0.27, P < 0.001). Compared with survivors, dead patients had significantly lower SMI in men (P < 0.001) but not in women (P = 0.760). After adjusting for sex and other potential confounders, the SMI [increased per 1 cm² /m² , odds ratio (OR) 0.96, 95% confidence interval (CI) 0.93 to 0.99] and SMD (increased per 1 Hounsfield unit, OR 0.93, 95% CI 0.90 to 0.96) were negatively and independently associated with in-hospital death, whereas the IMAT (increased per 1 cm² , OR 1.09, 95% CI 1.05 to 1.14) was independently and positively associated with in-hospital death. None of the SMI, SMD, or IMAT was significantly related to long hospital LOS or increased hospital costs.

CONCLUSIONS

Chest CT-derived muscle mass indicator (T12 SMI) and muscle quality indicators (T12 SMD and T12 IMAT) may serve as prognostic factors for predicting in-hospital death among older inpatients. Opportunistic chest CT images might be an overlooked resource for measuring muscle mass and muscle quality and for predicting short-term prognosis in older inpatients.

Exercise-Based Interventions to Counteract Skeletal Muscle Mass Loss in People with Cancer: Can We Overcome the Odds?

Addressing skeletal muscle mass loss is an important focus in oncology research to improve clinical outcomes, including cancer treatment tolerability and survival. Exercise is likely a necessary component of muscle-mass-preserving interventions for people with cancer. However, randomized controlled trials with exercise that include people with cancer with increased susceptibility to more rapid and severe muscle mass loss are limited. The aim of the current review is to highlight features of cancer-related skeletal muscle mass loss, discuss the impact in patients most at risk, and describe the possible role of exercise as a management strategy. We present current gaps within the exercise oncology literature and offer several recommendations for future studies to support research translation, including (1) utilizing accurate and reliable body composition techniques to assess changes in skeletal muscle mass, (2) incorporating comprehensive assessments of patient health status to allow personalized exercise prescription, (3) coupling exercise with robust nutritional recommendations to maximize the impact on skeletal muscle outcomes, and (4) considering key exercise intervention features that may improve exercise efficacy and adherence. Ultimately, the driving forces behind skeletal muscle mass loss are complex and may impede exercise tolerability and efficacy. Our recommendations are intended to foster the design of high-quality patient-centred research studies to determine whether exercise can counteract muscle mass loss in people with cancer and, as such, improve knowledge on this topic.

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.

Bile Acid Dysregulation Is Intrinsically Related to Cachexia in Tumor-Bearing Mice

Simple Summary

Cancer cachexia is considered a multi-organ syndrome. An improved understanding of how circulating molecules can affect tissues and mediate their crosstalk in the pathogenesis of cancer cachexia is emerging. Considering the various actions of bile acids on host metabolism and immunity, they could represent innovative targets in cancer cachexia. In this study, we investigated how bile acids could contribute to this syndrome by assessing the bile flow, by comparing the impact on bile acid pathways of cachexia-inducing and non-cachexia-inducing cell sublines, and by investigating the effects of ursodeoxycholic acid, a choleretic compound, in cachectic mice. Altogether, our analyses strengthen the importance of bile acids and their receptors as key players in the metabolic disorders associated with cancer, thereby laying the foundation for new therapeutic opportunities.

Abstract

Bile acids exert diverse actions on host metabolism and immunity through bile acid-activated receptors, including Takeda G protein-coupled receptor 5 (TGR5). We have recently evidenced an alteration in bile acids in cancer cachexia, an inflammatory and metabolic syndrome contributing to cancer death. This current study aims to further explore the links emerging between bile acids and cancer cachexia. First, we showed that bile flow is reduced in cachectic mice. Next, comparing mice inoculated with cachexia-inducing and with non-cachexia-inducing C26 colon carcinoma cells, we demonstrated that alterations in the bile acid pathways and profile are directly associated with cachexia. Finally, we performed an interventional study using ursodeoxycholic acid (UDCA), a compound commonly used in hepatobiliary disorders, to induce bile acid secretion and decrease inflammation. We found that UDCA does not improve hepatic inflammation and worsens muscle atrophy in cachectic mice. This exacerbation of the cachectic phenotype upon UDCA was accompanied by a decreased TGR5 activity, suggesting that TGR5 agonists, known to reduce inflammation in several pathological conditions, could potentially counteract cachectic features. This work brings to light major evidence sustaining the emerging links between bile acids and cancer cachexia and reinforces the interest in studying bile acid-activated receptors in this context.

Associations of low hand grip strength with 1 year mortality of cancer cachexia: a multicentre observational study

BACKGROUNDS

Hand grip strength (HGS) is one of diagnose criteria factors of sarcopenia and is associated with the survival of patients with cancer. However, few studies have addressed the association of HGS and 1 year mortality of patients with cancer cachexia.

METHODS

This cohort study included 8466 patients with malignant solid tumour from 40 clinical centres throughout China. Cachexia was diagnosed using the 2011 International cancer cachexia consensus. The hazard ratio (HR) of all cancer cachexia mortality was calculated using Cox proportional hazard regression models. Kaplan-Meier curves were generated to evaluate the association between HGS and the 1 year mortality of patients with cancer cachexia. The interaction analysis was used to explore the combined effect of low HGS and other factors on the overall survival of patients with cancer cachexia.

RESULTS

Among all participants, 1434 (16.9%) patients with cancer were diagnosed with cachexia according to the 2011 International cancer cachexia consensus with a mean (SD) age of 57.75 (12.97) years, among which there were 871 (60.7%) male patients. The HGS optimal cut-off points of male and female patients were 19.87 and 14.3 kg, respectively. Patients with cancer cachexia had lower HGS than those patients without cachexia (P < 0.05). In the multivariable Cox analysis, low HGS was an independent risk factor of cachexia [HR: 1.491, 95% confidence interval (CI): 1.257-1.769] after adjusting other factors. In addition, all of cancer cachexia patients with lower HGS had unfavourable 1 year survival (P < 0.001). In a subset analysis, low HGS was an independent prognosis factor of male patients with cancer cachexia (HR: 1.623, 95% CI: 1.308-2.014, P < 0.001), but not in female patients (HR: 1.947, 95% CI: 0.956-3.963, P = 0.0662), and low HGS was associated with poor 1 year survival of digestive system, respiratory system, and other cancer cachexia patients (all P < 0.05). Low HGS has combined effects with high neutrophil-to-lymphocyte ratio or low albumin on unfavourable overall survival of patients with cancer cachexia.

CONCLUSIONS

Low HGS was associated with poor 1 year survival of patients with cancer cachexia.

Mirtazapine in Cancer-Associated Anorexia and Cachexia: A Double-Blind Placebo-Controlled Randomized Trial

CONTEXT

Few pharmacological interventions are available for cancer-associated anorexia and cachexia. Mirtazapine has been suggested for use in cancer-associated anorexia and cachexia.

OBJECTIVES

This study was conducted to assess the efficacy and tolerability of mirtazapine in cancer-associated anorexia and cachexia.

METHODS

A double-blind placebo-controlled randomized trial. The study included 120 incurable solid tumour patients with anorexia (appetite loss ≥4 on 0 - 10 scale, 10 = maximum appetite loss), cachexia (>5% body weight loss over 6 months or >2% plus body mass index <20) and depression score ≤3 on 0-6 scale (6 = extreme feelings of depression). Patients were 1:1 randomized to receive mirtazapine 15mg daily at night for 8 weeks or placebo. The primary endpoint was change in appetite from baseline to day 28. Other outcomes included changes in quality-of-life, fatigue, depressive symptoms, body weight, lean body mass, handgrip strength, inflammatory markers, adverse events and survival.

RESULTS

48 (80%) patients in the mirtazapine arm and 52 (87%) in the placebo were assessable for the 1ry endpoint. Appetite score increased significantly with mirtazapine as well as with placebo (P < 0.0001 each). The increase in appetite score did not differ significantly between the two arms in the per-protocol and intention-to-treat analysis (P = 0.472 and 0.462, respectively). Mirtazapine was associated with significantly less increase in depressive symptoms and higher prevalence of somnolence. The change in other outcomes did not differ significantly between mirtazapine and placebo.

CONCLUSION

Mirtazapine 15mg at night for 28 days is no better than placebo in improving the appetite of incurable solid tumor patients with cancer-associated anorexia and cachexia.

Skeletal Muscle Deconditioning in Breast Cancer Patients Undergoing Chemotherapy: Current Knowledge and Insights From Other Cancers

Breast cancer represents the most commonly diagnosed cancer while neoadjuvant and adjuvant chemotherapies are extensively used in order to reduce tumor development and improve disease-free survival. However, chemotherapy also leads to severe off-target side-effects resulting, together with the tumor itself, in major skeletal muscle deconditioning. This review first focuses on recent advances in both macroscopic changes and cellular mechanisms implicated in skeletal muscle deconditioning of breast cancer patients, particularly as a consequence of the chemotherapy treatment. To date, only six clinical studies used muscle biopsies in breast cancer patients and highlighted several important aspects of muscle deconditioning such as a decrease in muscle fibers cross-sectional area, a dysregulation of protein turnover balance and mitochondrial alterations. However, in comparison with the knowledge accumulated through decades of intensive research with many different animal and human models of muscle atrophy, more studies are necessary to obtain a comprehensive understanding of the cellular processes implicated in breast cancer-mediated muscle deconditioning. This understanding is indeed essential to ultimately lead to the implementation of efficient preventive strategies such as exercise, nutrition or pharmacological treatments. We therefore also discuss potential mechanisms implicated in muscle deconditioning by drawing a parallel with other cancer cachexia models of muscle wasting, both at the pre-clinical and clinical levels.

Out of Control: The Role of the Ubiquitin Proteasome System in Skeletal Muscle during Inflammation

The majority of critically ill intensive care unit (ICU) patients with severe sepsis develop ICU-acquired weakness (ICUAW) characterized by loss of muscle mass, reduction in myofiber size and decreased muscle strength leading to persisting physical impairment. This phenotype results from a dysregulated protein homeostasis with increased protein degradation and decreased protein synthesis, eventually causing a decrease in muscle structural proteins. The ubiquitin proteasome system (UPS) is the predominant protein-degrading system in muscle that is activated during diverse muscle atrophy conditions, e.g., inflammation. The specificity of UPS-mediated protein degradation is assured by E3 ubiquitin ligases, such as atrogin-1 and MuRF1, which target structural and contractile proteins, proteins involved in energy metabolism and transcription factors for UPS-dependent degradation. Although the regulation of activity and function of E3 ubiquitin ligases in inflammation-induced muscle atrophy is well perceived, the contribution of the proteasome to muscle atrophy during inflammation is still elusive. During inflammation, a shift from standard- to immunoproteasome was described; however, to which extent this contributes to muscle wasting and whether this changes targeting of specific muscular proteins is not well described. This review summarizes the function of the main proinflammatory cytokines and acute phase response proteins and their signaling pathways in inflammation-induced muscle atrophy with a focus on UPS-mediated protein degradation in muscle during sepsis. The regulation and target-specificity of the main E3 ubiquitin ligases in muscle atrophy and their mode of action on myofibrillar proteins will be reported. The function of the standard- and immunoproteasome in inflammation-induced muscle atrophy will be described and the effects of proteasome-inhibitors as treatment strategies will be discussed.

Phosphorylation of Dynamin-Related Protein 1 (DRP1) Regulates Mitochondrial Dynamics and Skeletal Muscle Wasting in Cancer Cachexia

Background

Cancer-associated cachexia (CAC) is a syndrome characterized by skeletal muscle atrophy, and the underlying mechanisms are still unclear. Recent research studies have shed light on a noteworthy link between mitochondrial dynamics and muscle physiology. In the present study, we investigate the role of dynamin-related protein 1 (DRP1), a pivotal factor of mitochondrial dynamics, in myotube atrophy during cancer-associated cachexia.

Methods

Seventy-six surgical patients, including gastrointestinal tumor and benign disease, were enrolled in the study and divided to three groups: control, non-cachexia, and cancer-associated cachexia. Demographic data were collected. Their rectus abdominis samples were acquired intraoperatively. Muscle fiber size, markers of ubiquitin proteasome system (UPS), mitochondrial ultrastructure, and markers of mitochondrial function and dynamics were assayed. A cachexia model in vitro was established via coculturing a C2C12 myotube with media from C26 colon cancer cells. A specific DRP1 inhibitor, Mdivi-1, and a lentivirus of DRP1 knockdown/overexpression were used to regulate the expression of DRP1. Muscle diameter, mitochondrial morphology, mass, reactive oxygen species (ROS), membrane potential, and markers of UPS, mitochondrial function, and dynamics were determined.

Results

Patients of cachexia suffered from a conspicuous worsened nutrition status and muscle loss compared to patients of other groups. Severe mitochondrial swelling and enlarged area were observed, and partial alterations in mitochondrial function were found in muscle. Analysis of mitochondrial dynamics indicated an upregulation of phosphorylated DRP1 at the ser616 site. In vitro, cancer media resulted in the atrophy of myotube. This was accompanied with a prominent unbalance of mitochondrial dynamics, as well as enhanced mitochondrial ROS and decreased mitochondrial function and membrane potential. However, certain concentrations of Mdivi-1 and DRP1 knockdown rebalanced the mitochondrial dynamics, mitigating this negative phenotype caused by cachexia. Moreover, overexpression of DRP1 aggravated these phenomena.

Conclusion

In clinical patients, cachexia induces abnormal mitochondrial changes and possible fission activation for the atrophied muscle. Our cachexia model in vitro further demonstrates that unbalanced mitochondrial dynamics contributes to this atrophy and mitochondrial impairment, and rebuilding the balance by regulating of DRP1 could ameliorate these alterations.

Muscle-nerve communication and the molecular assessment of human skeletal muscle denervation with aging

Muscle fiber denervation is a major contributor to the decline in physical function observed with aging. Denervation can occur through breakdown of the neuromuscular junctions (NMJ) itself, affecting only that particular fiber, or through the death of a motor neuron, which can lead to a loss of all the muscle fibers in that motor unit. In this review, we discuss the muscle-nerve relationship, where signaling from both the motor neuron and the muscle fiber is required for maximal preservation of neuromuscular function in old age. Physical activity is likely to be the most important single factor that can contribute to this preservation. Furthermore, we propose that inactivity is not an innocent bystander, but plays an active role in denervation through the production of signals hostile to neuron survival. Investigating denervation in human muscle tissue samples is challenging due to the shared protein profile of regenerating and denervated muscle fibers. In this review, we provide a detailed overview of the key traits observed in immunohistochemical preparations of muscle biopsies from healthy, young, and elderly individuals. Overall, a combination of assessing tissue samples, circulating biomarkers, and electrophysiological assessments in humans will prove fruitful in the quest to gain more understanding of denervation of skeletal muscle. In addition, cell culture models represent a valuable tool in the search for key signaling factors exchanged between muscle and nerve, and which exercise has the capacity to alter.

Mitochondrial Dysfunction Is a Common Denominator Linking Skeletal Muscle Wasting Due to Disease, Aging, and Prolonged Inactivity

Skeletal muscle is the most abundant tissue in the body and is required for numerous vital functions, including breathing and locomotion. Notably, deterioration of skeletal muscle mass is also highly correlated to mortality in patients suffering from chronic diseases (e.g., cancer). Numerous conditions can promote skeletal muscle wasting, including several chronic diseases, cancer chemotherapy, aging, and prolonged inactivity. Although the mechanisms responsible for this loss of muscle mass is multifactorial, mitochondrial dysfunction is predicted to be a major contributor to muscle wasting in various conditions. This systematic review will highlight the biochemical pathways that have been shown to link mitochondrial dysfunction to skeletal muscle wasting. Importantly, we will discuss the experimental evidence that connects mitochondrial dysfunction to muscle wasting in specific diseases (i.e., cancer and sepsis), aging, cancer chemotherapy, and prolonged muscle inactivity (e.g., limb immobilization). Finally, in hopes of stimulating future research, we conclude with a discussion of important future directions for research in the field of muscle wasting.

Exercise-A Panacea of Metabolic Dysregulation in Cancer: Physiological and Molecular Insights

Metabolic dysfunction is a comorbidity of many types of cancers. Disruption of glucose metabolism is of concern, as it is associated with higher cancer recurrence rates and reduced survival. Current evidence suggests many health benefits from exercise during and after cancer treatment, yet only a limited number of studies have addressed the effect of exercise on cancer-associated disruption of metabolism. In this review, we draw on studies in cells, rodents, and humans to describe the metabolic dysfunctions observed in cancer and the tissues involved. We discuss how the known effects of acute exercise and exercise training observed in healthy subjects could have a positive outcome on mechanisms in people with cancer, namely: insulin resistance, hyperlipidemia, mitochondrial dysfunction, inflammation, and cachexia. Finally, we compile the current limited knowledge of how exercise corrects metabolic control in cancer and identify unanswered questions for future research.

Translational research on Myology and Mobility Medicine: 2021 semi-virtual PDM3 from Thermae of Euganean Hills, May 26 - 29, 2021

On 19-21 November 2020, the meeting of the 30 years of the Padova Muscle Days was virtually held while the SARS-CoV-2 epidemic was hitting the world after a seemingly quiet summer. During the 2020-2021 winter, the epidemic is still active, despite the start of vaccinations. The organizers hope to hold the 2021 Padua Days on Myology and Mobility Medicine in a semi-virtual form (2021 S-V PDM3) from May 26 to May 29 at the Thermae of Euganean Hills, Padova, Italy. Here the program and the Collection of Abstracts are presented. Despite numerous world problems, the number of submitted/selected presentations (lectures and oral presentations) has increased, prompting the organizers to extend the program to four dense days.

Development and progression of cancer cachexia: Perspectives from bench to bedside

Cancer cachexia (CC) is a devastating syndrome characterized by weight loss, reduced fat mass and muscle mass that affects approximately 80% of cancer patients and is responsible for 22%–30% of cancer-associated deaths. Understanding underlying mechanisms for the development of CC are crucial to advance therapies to treat CC and improve cancer outcomes. CC is a multi-organ syndrome that results in extensive skeletal muscle and adipose tissue wasting; however, CC can impair other organs such as the liver, heart, brain, and bone as well. A considerable amount of CC research focuses on changes that occur within the muscle, but cancer-related impairments in other organ systems are understudied. Furthermore, metabolic changes in organ systems other than muscle may contribute to CC. Therefore, the purpose of this review is to address degenerative mechanisms which occur during CC from a whole-body perspective. Outlining the information known about metabolic changes that occur in response to cancer is necessary to develop and enhance therapies to treat CC. As much of the current evidences in CC are from pre-clinical models we should note the majority of the data reviewed here are from pre-clinical models.

Cancer cachexia and skeletal muscle atrophy in clinical studies: what do we really know?

Research investigators have shown a growing interest in investigating alterations underlying skeletal muscle wasting in patients with cancer. However, skeletal muscle dysfunctions associated with cancer cachexia have mainly been studied in preclinical models. In the present review, we summarize the results of clinical studies in which skeletal muscle biopsies were collected from cachectic vs. non-cachectic cancer patients. Most of these studies suggest the presence of significant physiological alterations in skeletal muscle from cachectic cancer patients. We suggest a hypothesis, which connects structural and metabolic parameters that may, at least in part, be responsible for the skeletal muscle atrophy characteristic of cancer cachexia. Finally, we discuss the importance of a better standardization of the diagnostic criteria for cancer cachexia, as well as the requirement for additional clinical studies to improve the robustness of these conclusions.

Exercise as a therapy for cancer-induced muscle wasting

Cancer cachexia is a progressive disorder characterized by body weight, fat, and muscle loss. Cachexia induces metabolic disruptions that can be analogous and distinct from those observed in cancer, obscuring both diagnosis and treatment options. Inflammation, hypogonadism, and physical inactivity are widely investigated as systemic mediators of cancer-induced muscle wasting. At the cellular level, dysregulation of protein turnover and energy metabolism can negatively impact muscle mass and function. Exercise is well known for its anti-inflammatory effects and potent stimulation of anabolic signaling. Emerging evidence suggests the potential for exercise to rescue muscle's sensitivity to anabolic stimuli, reduce wasting through protein synthesis modulation, myokine release, and subsequent downregulation of proteolytic factors. To date, there is no recommendation for exercise in the management of cachexia. Given its complex nature, a multimodal approach incorporating exercise offers promising potential for cancer cachexia treatment. This review's primary objective is to summarize the growing body of research examining exercise regulation of cancer cachexia. Furthermore, we will provide evidence for exercise interactions with established systemic and cellular regulators of cancer-induced muscle wasting.