Moderate exercise in mice improves cancer plus chemotherapy-induced muscle wasting and mitochondrial alterations

Voluntary wheel running ameliorates select paclitaxel chemotherapy-induced sickness behaviors and associated melanocortin signaling

While chemotherapy remains a common cancer treatment, it is associated with debilitating side effects (e.g., anorexia, weight loss, and fatigue) that adversely affect patient quality of life and increase mortality. However, the mechanisms underlying taxane chemotherapy-induced side effects, and effective treatments to ameliorate them, are not well-established. Here, we tested the longitudinal relationship between a clinically-relevant paclitaxel regimen, inflammation, and sickness behaviors (loss of body mass, anorexia, fever, and fatigue) in adult, female mice. Furthermore, we sought to identify the extent to which voluntary exercise (wheel running) attenuates paclitaxel-induced sickness behaviors and underlying central pathways. Body mass and food intake decreased following six doses of chemotherapy treatment relative to vehicle controls, lasting less than 5 days after the last dose. Paclitaxel treatment also transiently decreased locomotion (open field test), voluntary wheel running, home-cage locomotion, and core body temperature without affecting motor coordination (rotarod task). Circulating interleukin (IL)-6 and hypothalamic Il1b gene expression remained elevated in chemotherapy-treated mice at least 3 days after the last dose. Exercise intervention did not ameliorate fatigue or inflammation, but hastened recovery from paclitaxel-induced weight loss. Body mass recovery was associated with the wheel running-induced recovery of body composition, paclitaxel-induced alterations to hypothalamic melanocortin signaling, and associated peripheral circulating hormones (ghrelin and leptin). The present findings demonstrate the benefits of exercise on faster recovery from paclitaxel-induced body mass loss and deficits in melanocortin signaling and suggests the development of therapies targeting the melanocortin pathway to reduce paclitaxel-induced weight loss.

Exercise Training as Therapeutic Approach in Cancer Cachexia: A Review of Potential Anti-inflammatory Effect on Muscle Wasting

Cachexia is a multifactorial inflammatory syndrome with high prevalence in cancer patients. It is characterized by a metabolic chaos culminating in drastic reduction in body weight, mainly due to skeletal muscle and fat depletion. Currently, there is not a standard intervention for cachexia, but it is believed that a dynamic approach should be applied early in the course of the disease to maintain or slow the loss of physical function. The present review sought to explain the different clinical and experimental applications of different models of exercise and their contribution to a better prognosis of the disease. Here the advances in knowledge about the application of physical training in experimental models are elucidated, tests that contribute substantially to elucidate the cellular and biochemical mechanisms of exercise in different ways, as well as clinical trials that present not only the impacts of exercise in front cachexia but also the challenges of its application in clinical practice.

Molecular Basis for the Therapeutic Effects of Exercise on Mitochondrial Defects

Mitochondrial dysfunction is common to many organ system disorders, including skeletal muscle. Aging muscle and diseases of muscle are often accompanied by defective mitochondrial ATP production. This manuscript will focus on the pre-clinical evidence supporting the use of regular exercise to improve defective mitochondrial metabolism and function in skeletal muscle, through the stimulation of mitochondrial turnover. Examples from aging muscle, muscle-specific mutations and cancer cachexia will be discussed. We will also examine the effects of exercise on the important mitochondrial regulators PGC-1α, and Parkin, and summarize the effects of exercise to reverse mitochondrial dysfunction (e.g., ROS production, apoptotic susceptibility, cardiolipin synthesis) in muscle pathology. This paper will illustrate the breadth and benefits of exercise to serve as "mitochondrial medicine" with age and disease.

A Pound of Flesh: What Cachexia Is and What It Is Not

Body weight loss, mostly due to the wasting of skeletal muscle and adipose tissue, is the hallmark of the so-called cachexia syndrome. Cachexia is associated with several acute and chronic disease states such as cancer, chronic obstructive pulmonary disease (COPD), heart and kidney failure, and acquired and autoimmune diseases and also pharmacological treatments such as chemotherapy. The clinical relevance of cachexia and its impact on patients’ quality of life has been neglected for decades. Only recently did the international community agree upon a definition of the term cachexia, and we are still awaiting the standardization of markers and tests for the diagnosis and staging of cancer-related cachexia. In this review, we discuss cachexia, considering the evolving use of the term for diagnostic purposes and the implications it has for clinical biomarkers, to provide a comprehensive overview of its biology and clinical management. Advances and tools developed so far for the in vitro testing of cachexia and drug screening will be described. We will also evaluate the nomenclature of different forms of muscle wasting and degeneration and discuss features that distinguish cachexia from other forms of muscle wasting in the context of different conditions.

Understanding the common mechanisms of heart and skeletal muscle wasting in cancer cachexia

Cachexia is a severe complication of cancer that adversely affects the course of the disease, with currently no effective treatments. It is characterized by a progressive atrophy of skeletal muscle and adipose tissue, resulting in weight loss, a reduced quality of life, and a shortened life expectancy. Although the cachectic condition primarily affects the skeletal muscle, a tissue that accounts for ~40% of total body weight, cachexia is considered a multi-organ disease that involves different tissues and organs, among which the cardiac muscle stands out for its relevance. Patients with cancer often experience severe cardiac abnormalities and manifest symptoms that are indicative of chronic heart failure, including fatigue, shortness of breath, and impaired exercise tolerance. Furthermore, cardiovascular complications are among the major causes of death in cancer patients who experienced cachexia. The lack of effective treatments for cancer cachexia underscores the need to improve our understanding of the underlying mechanisms. Increasing evidence links the wasting of the cardiac and skeletal muscles to metabolic alterations, primarily increased energy expenditure, and to increased proteolysis, ensuing from activation of the major proteolytic machineries of the cell, including ubiquitin-dependent proteolysis and autophagy. This review aims at providing an overview of the key mechanisms of cancer cachexia, with a major focus on those that are shared by the skeletal and cardiac muscles.

Pathophysiological mechanisms explaining poor clinical outcome of older cancer patients with low skeletal muscle mass

Low skeletal muscle mass is highly prevalent in older cancer patients and affects 5% to 89% depending on the type and stage of cancer. Low skeletal muscle mass is associated with poor clinical outcomes such as post-operative complications, chemotherapy toxicity and mortality in older cancer patients. Little is known about the mediating pathophysiological mechanisms. In this review, we summarize proposed pathophysiological mechanisms underlying the association between low skeletal muscle mass and poor clinical outcomes in older cancer patients including a) systemic inflammation; b) insulin-dependent glucose handling; c) mitochondrial function; d) protein status and; e) pharmacokinetics of anticancer drugs. The mechanisms of altered myokine balance negatively affecting the innate and adaptive immune system, and altered pharmacokinetics of anticancer drugs leading to a relative overdosage of anticancer drugs are best-substantiated. The effects of glucose intolerance and circulating mitochondrial DNA as a consequence of low skeletal muscle mass are topics of interest for future research. Restoring myokine balance through physical exercise, exercise mimetics, neuro-muscular activation and adapting anticancer drug dosing on skeletal muscle mass could be targeted approaches to improve clinical outcomes in older cancer patients with low skeletal muscle mass.

Nutraceuticals and Exercise against Muscle Wasting during Cancer Cachexia

Cancer cachexia (CC) is a debilitating multifactorial syndrome, involving progressive deterioration and functional impairment of skeletal muscles. It affects about 80% of patients with advanced cancer and causes premature death. No causal therapy is available against CC. In the last few decades, our understanding of the mechanisms contributing to muscle wasting during cancer has markedly increased. Both inflammation and oxidative stress (OS) alter anabolic and catabolic signaling pathways mostly culminating with muscle depletion. Several preclinical studies have emphasized the beneficial roles of several classes of nutraceuticals and modes of physical exercise, but their efficacy in CC patients remains scant. The route of nutraceutical administration is critical to increase its bioavailability and achieve the desired anti-cachexia effects. Accumulating evidence suggests that a single therapy may not be enough, and a bimodal intervention (nutraceuticals plus exercise) may be a more effective treatment for CC. This review focuses on the current state of the field on the role of inflammation and OS in the pathogenesis of muscle atrophy during CC, and how nutraceuticals and physical activity may act synergistically to limit muscle wasting and dysfunction.

Marked Increased Production of Acute Phase Reactants by Skeletal Muscle during Cancer Cachexia

Simple Summary

Muscle wasting during cancer is recognized as an independent predictor of mortality. The aim of this study was to characterize the changes in the muscle secretome associated with cancer cachexia to gain a better understanding of the mechanisms involved and to identify secreted proteins which may reflect this wasting process. Our study demonstrated that skeletal muscle is a source of several acute phase reactants during cancer cachexia that may hold the key to a cachexia-specific signature. Future work will have to determine whether some of these acute phase reactants contribute to and/or reflect the muscle atrophy caused by cancer, therefore representing potential therapeutic targets and/or biomarkers of cancer cachexia.

Abstract

Loss of skeletal muscle mass in cancer cachexia is recognized as a predictor of mortality. This study aimed to characterize the changes in the muscle secretome associated with cancer cachexia to gain a better understanding of the mechanisms involved and to identify secreted proteins which may reflect this wasting process. The changes in the muscle proteome of the C26 model were investigated by label-free proteomic analysis followed by a bioinformatic analysis in order to identify potentially secreted proteins. Multiple reaction monitoring and Western blotting were used to verify the presence of candidate proteins in the circulation. Our results revealed a marked increased muscular production of several acute phase reactants (APR: Haptoglobin, Serine protease inhibitor A3N, Complement C3, Serum amyloid A-1 protein) which are released in the circulation during C26 cancer cachexia. This was confirmed in other models of cancer cachexia as well as in cancer patients. Glucocorticoids and proinflammatory cytokines are responsible for an increased production of APR by muscle cells. Finally, their muscular expressions are strongly positively correlated with body weight loss as well as the muscular induction of atrogens. Our study demonstrates therefore a marked increased production of APR by the muscle in cancer cachexia.

The Etiology and Impact of Muscle Wasting in Metastatic Cancer

Metastasis arises when cancer cells disseminate from their site of origin and invade distant organs. While cancer cells rarely colonize muscle, they often induce a debilitating muscle-wasting condition known as cachexia that compromises feeding, breathing, and cardiac function in metastatic cancer patients. In fact, nearly 80% of metastatic cancer patients experience a spectrum of muscle-wasting states, which deteriorates the quality of life and overall survival of cancer patients. Muscle wasting in cancer results from increased muscle catabolism induced by circulating tumor factors and a systemic metabolic dysfunction. In addition, muscle loss can be exacerbated by the exposure to antineoplastic therapies and the process of aging. With no approved therapies to alleviate cachexia, muscle health, therefore, becomes a key determinant of prognosis, treatment response, and survival in metastatic cancer patients. This review will discuss the current understanding of cancer-associated cachexia and highlight promising therapeutic strategies to treat muscle wasting in the context of metastatic cancers.

The Redox Balance: A Target for Interventions Against Muscle Wasting in Cancer Cachexia?

Significance: The management of cancer patients is frequently complicated by the occurrence of a complex syndrome known as cachexia. It is mainly characterized by muscle wasting, a condition that associates with enhanced protein breakdown and with negative energy balance. While the mechanisms underlying cachexia have been only partially elucidated, understanding the pathogenesis of muscle wasting in cancer hosts is mandatory to design new targeted therapeutic strategies. Indeed, most of cancer patients will experience cachexia during the course of their disease, and about 25% of cancer-related deaths are due to this syndrome, rather than to the tumor itself. Recent Advances: Compelling evidence suggests that an altered redox homeostasis likely contributes to cancer-induced muscle protein depletion, directly or indirectly activating the intracellular degradative pathways. In addition, oxidative stress impinges on both mitochondrial number and function; the other way round, altered mitochondria lead to enhanced redox imbalance, creating a vicious loop that eventually results in negative energy metabolism. Critical Issues: The present review focuses on the possibility that pharmacological and nonpharmacological strategies able to restore a physiologic redox balance could be useful components of treatment schedules aimed at counteracting cancer-induced muscle wasting. Future Directions: Exercise and the use of exercise mimetic drugs represent the most promising approaches capable of reinforcing the muscle antioxidant defenses of cancer patients. The results from ongoing and new clinical trials are needed to validate the preclinical studies and provide effective therapies for cancer cachexia. Antioxid. Redox Signal. 33, 542-558.

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

Progressive weight loss combined with skeletal muscle atrophy, termed cachexia, is a common comorbidity associated with cancer that results in adverse consequences for the patient related to decreased chemotherapy responsiveness and increased mortality. Cachexia's complexity has provided a barrier for developing successful therapies to prevent or treat the condition, since a large number of systemic disruptions that can regulate muscle mass are often present. Furthermore, considerable effort has focused on investigating how tumor derived factors and inflammatory mediators directly signal skeletal muscle to disrupt protein turnover regulation. Currently, there is developing appreciation for understanding how cancer alters skeletal muscle's complex microenvironment and the tightly regulated interactions between multiple cell types. Skeletal muscle microenvironment interactions have established functions in muscle response to regeneration from injury, growth, aging, overload-induced hypertrophy, and exercise. This review explores the growing body of evidence for immune cell modulation of the skeletal muscle microenvironment during cancer-induced muscle wasting. Emphasis is placed on the regulatory network that integrates physiological responses between immune cells with other muscle cell types including satellite cells, fibroblast cells, and endothelial cells to regulate myofiber size and plasticity. The overall goal of this review is to provide an understanding of how different cell types that constitute the muscle microenvironment and their signaling mediators contribute to cancer and chemotherapy-induced muscle wasting.

Muscle NAD+ depletion and Serpina3n as molecular determinants of murine cancer cachexia-the effects of blocking myostatin and activins

Objective

Cancer cachexia and muscle loss are associated with increased morbidity and mortality. In preclinical animal models, blocking activin receptor (ACVR) ligands has improved survival and prevented muscle wasting in cancer cachexia without an effect on tumour growth. However, the underlying mechanisms are poorly understood. This study aimed to identify cancer cachexia and soluble ACVR (sACVR) administration-evoked changes in muscle proteome.

Methods

Healthy and C26 tumour-bearing (TB) mice were treated with recombinant sACVR. The sACVR or PBS control were administered either prior to the tumour formation or by continued administration before and after tumour formation. Muscles were analysed by quantitative proteomics with further examination of mitochondria and nicotinamide adenine dinucleotide (NAD⁺) metabolism. To complement the first prophylactic experiment, sACVR (or PBS) was injected as a treatment after tumour cell inoculation.

Results

Muscle proteomics in TB cachectic mice revealed downregulated signatures for mitochondrial oxidative phosphorylation (OXPHOS) and increased acute phase response (APR). These were accompanied by muscle NAD⁺ deficiency, alterations in NAD⁺ biosynthesis including downregulation of nicotinamide riboside kinase 2 (Nrk2), and decreased muscle protein synthesis. The disturbances in NAD⁺ metabolism and protein synthesis were rescued by treatment with sACVR. Across the whole proteome and APR, in particular, Serpina3n represented the most upregulated protein and the strongest predictor of cachexia. However, the increase in Serpina3n expression was associated with increased inflammation rather than decreased muscle mass and/or protein synthesis.

Conclusions

We present evidence implicating disturbed muscle mitochondrial OXPHOS proteome and NAD⁺ homeostasis in experimental cancer cachexia. Treatment of TB mice with a blocker of activin receptor ligands restores depleted muscle NAD⁺ and Nrk2, as well as decreased muscle protein synthesis. These results indicate putative new treatment therapies for cachexia and that although acute phase protein Serpina3n may serve as a predictor of cachexia, it more likely reflects a condition of elevated inflammation.

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Cachectic muscle proteome shows decreased OXPHOS and increased acute phase response.

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Cancer cachexia is characterized by lowered muscle Nrk2 expression and NAD⁺ levels.

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Blocking activin receptor 2B ligands rescues muscle NAD⁺ homeostasis in cachexia.

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Blocking activin receptor 2B ligands prevents affected protein synthesis in cachexia.

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Serpina3n predicts cachexia and cancer-induced APR independently from muscle atrophy.

Interleukin-4 administration improves muscle function, adult myogenesis, and lifespan of colon carcinoma-bearing mice

BACKGROUND

Anorexia, body wasting, inflammation, muscle, and adipose tissue loss are hallmarks of cancer cachexia, a syndrome that affects the majority of cancer patients, impairing their ability to endure chemotherapeutic therapies and reducing their lifespan. In the last 10 years, alterations of protein turnover and impairment of adult myogenesis have been proposed as major contributing factors.

METHODS

Muscle stem cells, including satellite cells, mesoangioblasts, and fibroadipogenic progenitors, were isolated and characterized from C26 colon carcinoma-bearing (C26) mice. Circulating levels of interleukin-4/13 (IL4/IL13) were analysed by ELISA, and the effects of IL4 on muscle mass and function, protein synthesis, muscle regeneration, and myogenic progenitor cell number were analysed at both functional (treadmill and grip test) and molecular levels (qRT-PCR, immunofluorescence analysis, surface sensing of translation, and western blot). The Kaplan-Meier test was used to analyse the survival curve of IL4-treated and IL4-untreated C26 mice.

RESULTS

The administration of IL4 to C26 mice rescued muscle mass by increasing protein synthesis. The IL4 treatment improved performances and prolonged survival of C26 mice. IL4 administration re-established both number and function of satellite cells and fibroadipogenic progenitors without affecting mesoangioblasts in C26 mice, rescuing myogenesis. Upon IL4 treatment, a high number of cytotoxic lymphocytes and type II macrophages were observed with a subsequent increase in necrotic areas of C26 tumours.

CONCLUSIONS

The results here presented shed new light on IL4 signalling during muscle wasting and early stages of muscle regeneration that explain the beneficial effect observed in IL4-treated C26 mice. These findings might aid to develop therapeutic approaches to improve mobility and quality of life in cachectic patients.

Human Cachexia Induces Changes in Mitochondria, Autophagy and Apoptosis in the Skeletal Muscle

Cachexia is a wasting syndrome characterized by the continuous loss of skeletal muscle mass due to imbalance between protein synthesis and degradation, which is related with poor prognosis and compromised quality of life. Dysfunctional mitochondria are associated with lower muscle strength and muscle atrophy in cancer patients, yet poorly described in human cachexia. We herein investigated mitochondrial morphology, autophagy and apoptosis in the skeletal muscle of patients with gastrointestinal cancer-associated cachexia (CC), as compared with a weight-stable cancer group (WSC). CC showed prominent weight loss and increased circulating levels of serum C-reactive protein, lower body mass index and decreased circulating hemoglobin, when compared to WSC. Electron microscopy analysis revealed an increase in intermyofibrillar mitochondrial area in CC, as compared to WSC. Relative gene expression of Fission 1, a protein related to mitochondrial fission, was increased in CC, as compared to WSC. LC3 II, autophagy-related (ATG) 5 and 7 essential proteins for autophagosome formation, presented higher content in the cachectic group. Protein levels of phosphorylated p53 (Ser46), activated caspase 8 (Asp384) and 9 (Asp315) were also increased in the skeletal muscle of CC. Overall, our results demonstrate that human cancer-associated cachexia leads to exacerbated muscle-stress response that may culminate in muscle loss, which is in part due to disruption of mitochondrial morphology, dysfunctional autophagy and increased apoptosis. To the best of our knowledge, this is the first report showing quantitative morphological alterations in skeletal muscle mitochondria in cachectic patients.

Autophagy Exacerbates Muscle Wasting in Cancer Cachexia and Impairs Mitochondrial Function

Cancer cachexia is a multifactorial syndrome characterized by anorexia, weight loss and muscle wasting that impairs patients' quality of life and survival. Aim of this work was to evaluate the impact of either autophagy inhibition (knocking down beclin-1) or promotion (overexpressing TP53INP2/DOR) on cancer-induced muscle wasting. In C26 tumor-bearing mice, stress-induced autophagy inhibition was unable to rescue the loss of muscle mass and worsened muscle morphology. Treating C26-bearing mice with formoterol, a selective β2-agonist, muscle sparing was paralleled by reduced static autophagy markers, although the flux was maintained. Conversely, the stimulation of muscle autophagy exacerbated muscle atrophy in tumor-bearing mice. TP53INP2 further promoted atrogene expression and suppressed mitochondrial dynamics-related genes. Excessive autophagy might impair mitochondrial function through mitophagy. Consistently, tumor-induced mitochondrial dysfunction was detected by reduced ex vivo muscle fiber respiration. Overall, the results evoke a central role for muscle autophagy in cancer-induced muscle wasting.

Colon 26 adenocarcinoma (C26)-induced cancer cachexia impairs skeletal muscle mitochondrial function and content

The present study aimed to determine the impact of colon 26 adenocarcinoma (C26)-induced cancer cachexia on skeletal muscle mitochondrial respiration and content. Twelve male CD2F1 mice were injected with C26-cells (tumor bearing (TB) group), whereas 12 age-matched mice received PBS vehicle injection (non-tumor bearing (N-TB) group). Mitochondrial respiration was studied in saponin-permeabilized soleus myofibers. TB mice showed lower body weight (~ 20%) as well as lower soleus, gastrocnemius-plantaris complex and tibialis anterior masses versus N-TB mice (p < 0.05). Soleus maximal state III mitochondrial respiration was 20% lower (10 mM glutamate, 5 mM malate, 5 mM adenosine diphosphate; p < 0.05) and acceptor control ratio (state III/state II) was 15% lower in the TB vs. N-TB (p < 0.05), with the latter suggesting uncoupling. Lower VDAC protein content suggested reduced mitochondrial content in TB versus N-TB (p < 0.05). Skeletal muscle in C26-induced cancer cachexia exhibits reductions in: maximal mitochondrial respiration capacity, mitochondrial coupling and mitochondrial content.

Moderate Exercise Improves Experimental Cancer Cachexia by Modulating the Redox Homeostasis

Cachexia is a debilitating syndrome that complicates the management of cancer patients. Muscle wasting, one of the main features of cachexia, is associated with hyper-activation of protein degradative pathways and altered mitochondrial function that could both result from impaired redox homeostasis. This study aimed to investigate the contribution of oxidative stress to cancer-induced cachexia in the presence or in the absence of moderate exercise training. Mice bearing the colon C26 carcinoma, either sedentary or exercised, were used. The former showed muscle wasting and redox imbalance, with the activation of an antioxidant response and with upregulation of markers of proteasome-dependent protein degradation and autophagy. Moderate exercise was able to relieve muscle wasting and prevented the loss of muscle strength; such a pattern was associated with reduced levels of Reactive Oxygen Species (ROS), carbonylated proteins and markers of autophagy and with improved antioxidant capacity. The muscle of sedentary tumor hosts also showed increased levels of molecular markers of mitophagy and reduced mitochondrial mass. Conversely, exercise in the C26 hosts led to increased mitochondrial mass. In conclusion, moderate exercise could be an effective non-pharmacological approach to prevent muscle wasting in cancer patients, decreasing muscle protein catabolism and oxidative stress and preserving mitochondria.