Indomethacin and ibuprofen preserve gastrocnemius muscle mass in mice bearing the colon-26 adenocarcinoma

Inflammation as a Therapeutic Target in Cancer Cachexia

Cachexia is a common complication of cancer and is associated with poor quality of life and a decrease in survival. Many patients with cancer cachexia suffer from inflammation associated with elevated cytokines, such as interleukin-1beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor (TNF). Single-agent trials to treat cancer cachexia have not led to substantial benefit as the type of cytokine which is elevated has rarely been specified and targeted. Cachexia may also be multifactorial, involving inflammation, anorexia, catabolism, depression, and pain, and targeting the multiple causes will likely be necessary to achieve improvement in weight and appetite. A PUBMED search revealed over 3000 articles on cancer cachexia in the past ten years. We attempted to review any studies related to inflammation and cancer cachexia identified by Google Scholar and PUBMED and further search for articles listed in their references. The National Comprehensive Cancer Network (NCCN) guidelines do not provide any suggestion for managing cancer cachexia except a dietary consult. A more targeted approach to developing therapies for cancer cachexia might lead to more personalized and effective therapy.

Muscle protein breakdown is impaired during immobilization compared to during a subsequent retraining period in older men: no effect of anti-inflammatory medication

Muscle inactivity reduces muscle protein synthesis (MPS), whereas a subsequent period of rehabilitation resistance training (retraining) increases MPS. However, less is known regarding muscle protein breakdown (MPB) during such conditions. Furthermore, nonsteroidal anti-inflammatory drugs (NSAIDs) may have a dampening effect on MPB during periods of inactivity in older individuals. Thus, we measured the average MPB, by use of the deuterated water methodology, during an immobilization period and a subsequent retraining period in older individuals with and without NSAID treatment. Eighteen men (60–80 years: range) were randomly assigned to ibuprofen (1200 mg/d, Ibu) or placebo (Plc). One lower limb was immobilized in a cast for 2 weeks and retrained for 2 weeks, and 2 × 20 g of whey protein was ingested daily during both periods. Besides MPB, the protein expression of different muscle degradation signaling molecules was investigated. MPB was lower during immobilization compared to retraining (p < 0.01). NSAID treatment did not affect the MPB rate during immobilization or retraining (p > 0.05). The protein expression of muscle degradation signaling molecules changed during the study intervention but were unaffected by NSAID treatment. The finding that MPB was lower during immobilization than during retraining indicates that an increased MPB may play an important role in the muscle protein remodeling processes taking place within the initial retraining period. Moreover, NSAID treatment did not significantly influence the MPB rate during 2 weeks of lower limb immobilization or during 2 weeks of subsequent retraining in older individuals.

A meal with mixed soy/whey proteins is as efficient as a whey meal in counteracting the age-related muscle anabolic resistance only if the protein content and leucine levels are increased

With aging, skeletal muscle becomes resistant to the anabolic effect of dietary proteins and sarcopenia develops. Animal proteins, which are rich in leucine, are recommended for the elderly, but it is not known whether their replacement by plant proteins would maintain the health and physical independence of this population. Aged rats were fed with animal proteins (casein and whey proteins) with different leucine contents and compared to rats fed with diets in which whey was substituted with soy proteins and by increasing the total protein content or not. Our results clearly showed that the meal with mixed soy/whey proteins allowed the anabolic response of skeletal muscle during aging only if the protein content was increased by 25%. Indeed, if the protein content of the soy/whey diet was decreased to a similar protein content such as a whey diet, i.e. 13%, the anabolic effect decreased. The same observation was recorded if the whey proteins were totally substituted with soy proteins.

Taltirelin alleviates fatigue-like behavior in mouse models of cancer-related fatigue

Fatigue affects most cancer patients and has numerous potential causes, including cancer itself and cancer treatment. Cancer-related fatigue (CRF) is not relieved by rest, can decrease quality of life, and has no FDA-approved therapy. Thyrotropin-releasing hormone (TRH) has been proposed as a potential novel treatment for CRF, but its efficacy against CRF remains largely untested. Thus, we tested the TRH analog, taltirelin (TAL), in mouse models of CRF. To model fatigue, we used a mouse model of chemotherapy, a mouse model of radiation therapy, and mice bearing colon 26 carcinoma tumors. We used the treadmill fatigue test to assess fatigue-like behavior after treatment with TAL. Additionally, we used wild-type and TRH receptor knockout mice to determine which TRH receptor was necessary for the actions of TAL. Tumor-bearing mice displayed muscle wasting and all models caused fatigue-like behavior, with mice running a shorter distance in the treadmill fatigue test than controls. TAL reversed fatigue-like behavior in all three models and the mouse TRH₁ receptor was necessary for the effects of TAL. These data suggest that TAL may be useful in alleviating fatigue in all cancer patients and provide further support for evaluating TAL as a potential therapy for CRF in humans.

Effects of low-dose ibuprofen supplementation and resistance training on bone and muscle in postmenopausal women: A randomized controlled trial

PURPOSE

To compare the effects of nine months of exercise training and ibuprofen supplementation (given immeditately after exercise sessions) on bone and muscle in postmenopausal women.

METHODS

In a double-blind randomized trial, participants (females: n = 90, mean age 64.8, SD 4.3 years) were assigned (computer generated, double blind) to receive supervised resistance training or stretching 3 days/week, and ibuprofen (400 mg, post-exercise) or placebo (i.e. 4 groups) for 9 months. In this proof-of-concept study the sample size was halved from required 200 identified via 90% power calculation. Baseline and post-intervention testing included: Dual energy x-ray absorptiometry (DXA) for lumbar spine, femoral neck, and total body areal bone mineral density (aBMD); geometry of proximal femur; total body lean tissue and fat mass; predicted 1-repetition maximum muscle strength testing (1RM; biceps curl, hack squat).

RESULTS

Exercise training or ibuprofen supplementation had no effects on aBMD of the lumbar spine, femoral neck, and total body. There was a significant exercise × supplement × time interaction for aBMD of Ward's region of the femoral neck (p = 0.015) with post hoc comparison showing a 6% decrease for stretching with placebo vs. a 3% increase for stretching with ibuprofen (p = 0.017). Resistance training increased biceps curl and hack squat strength vs. stretching (22% vs. 4% and 114% vs. 12%, respectively) (p < 0.01) and decreased percent body fat compared to stretching (2% vs. 0%) (p < 0.05).

CONCLUSIONS

Ibuprofen supplementation provided some benefits to bone when taken independent of exercise training in postmenopausal women. This study provides evidence towards a novel, easily accessible stimulus for enhancing bone health [i.e. ibuprofen].

Ibuprofen ameliorates fatigue- and depressive-like behavior in tumor-bearing mice

AIMS

Cancer-related fatigue (CRF) is often accompanied by depressed mood, both of which reduce functional status and quality of life. Research suggests that increased expression of pro-inflammatory cytokines is associated with skeletal muscle wasting and depressive- and fatigue-like behaviors in rodents and cancer patients. We have previously shown that treatment with ibuprofen, a nonsteroidal anti-inflammatory drug, preserved muscle mass in tumor-bearing mice. Therefore, the purpose of the present study was to determine the behavioral effects of ibuprofen in a mouse model of CRF.

MAIN METHODS

Mice were injected with colon-26 adenocarcinoma cells and treated with ibuprofen (10mg/kg) in the drinking water. Depressive-like behavior was determined using the forced swim test (FST). Fatigue-like behaviors were determined using voluntary wheel running activity (VWRA) and grip strength. The hippocampus, gastrocnemius muscle, and serum were collected for cytokine analysis.

KEY FINDINGS

Tumor-bearing mice showed depressive-like behavior in the FST, which was not observed in mice treated with ibuprofen. VWRA and grip strength declined in tumor-bearing mice, and ibuprofen attenuated this decline. Tumor-bearing mice had decreased gastrocnemius muscle mass and increased expression of IL-6, MAFBx and MuRF mRNA, biomarkers of protein degradation, in the muscle. Expression of IL-1β and IL-6 was also increased in the hippocampus. Treatment with ibuprofen improved muscle mass and reduced cytokine expression in both the muscle and hippocampus of tumor-bearing mice.

SIGNIFICANCE

Ibuprofen treatment reduced skeletal muscle wasting, inflammation in the brain, and fatigue- and depressive-like behavior in tumor-bearing mice. Therefore, ibuprofen warrants evaluation as an adjuvant treatment for CRF.

Modulating exercise-induced hormesis: Does less equal more?

Hormesis encompasses the notion that low levels of stress stimulate or upregulate existing cellular and molecular pathways that improve the capacity of cells and organisms to withstand greater stress. This notion underlies much of what we know about how exercise conditions the body and induces long-term adaptations. During exercise, the body is exposed to various forms of stress, including thermal, metabolic, hypoxic, oxidative, and mechanical stress. These stressors activate biochemical messengers, which in turn activate various signaling pathways that regulate gene expression and adaptive responses. Historically, antioxidant supplements, nonsteroidal anti-inflammatory drugs, and cryotherapy have been favored to attenuate or counteract exercise-induced oxidative stress and inflammation. However, reactive oxygen species and inflammatory mediators are key signaling molecules in muscle, and such strategies may mitigate adaptations to exercise. Conversely, withholding dietary carbohydrate and restricting muscle blood flow during exercise may augment adaptations to exercise. In this review article, we combine, integrate, and apply knowledge about the fundamental mechanisms of exercise adaptation. We also critically evaluate the rationale for using interventions that target these mechanisms under the overarching concept of hormesis. There is currently insufficient evidence to establish whether these treatments exert dose-dependent effects on muscle adaptation. However, there appears to be some dissociation between the biochemical/molecular effects and functional/performance outcomes of some of these treatments. Although several of these treatments influence common kinases, transcription factors, and proteins, it remains to be determined if these interventions complement or negate each other, and whether such effects are strong enough to influence adaptations to exercise.

Cancer cachexia update in head and neck cancer: Pathophysiology and treatment

The pathophysiology of cancer cachexia remains complex. A comprehensive literature search was performed up to April 2013 using PubMed, the Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, and the Google search engine. In this review, we focus on the different mediators of impaired anabolism and upregulated catabolism that alter the skeletal muscle homeostasis resulting in the wasting of cancer cachexia. We present recent evidence of targeted treatment modalities from clinical trials along with their potential mechanisms of action. We also report on the most current evidence from randomized clinical trials using multimodal treatments in patients with cancer cachexia, but also the evidence from head and neck cancer-specific trials. A more complete understanding of the pathophysiology of the syndrome may lead to more effective targeted therapies and improved outcomes for patients.

The skeletal muscle arachidonic acid cascade in health and inflammatory disease

Muscle atrophy and weakness are often observed in patients with chronic inflammatory diseases, and are the major clinical features of the autoimmune myopathies, polymyositis and dermatomyositis. A general understanding of the pathogenesis of muscle atrophy and the impaired muscle function associated with chronic inflammatory diseases has not been clarified. In this context, arachidonic acid metabolites, such as the prostaglandin and leukotriene subfamilies, are of interest because they contribute to immune and nonimmune processes. Accumulating evidence suggests that prostaglandins and leukotrienes are involved in causing muscular pain and inflammation, and also in myogenesis and the repair of muscles. In this Review, we summarize novel findings that implicate prostaglandins and leukotrienes in the muscle atrophy and weakness that occur in inflammatory diseases of the muscles, with a focus on inflammatory myopathies. We discuss the role of the arachidonic acid cascade in skeletal muscle growth and function, and individual metabolites as potential therapeutic targets for the treatment of inflammatory muscle diseases.

Arachidonic acid supplementation enhances in vitro skeletal muscle cell growth via a COX-2-dependent pathway

Arachidonic acid (AA) is the metabolic precursor to a diverse range of downstream bioactive lipid mediators. A positive or negative influence of individual eicosanoid species [e.g., prostaglandins (PGs), leukotrienes, and hydroxyeicosatetraenoic acids] has been implicated in skeletal muscle cell growth and development. The collective role of AA-derived metabolites in physiological states of skeletal muscle growth/atrophy remains unclear. The present study aimed to determine the direct effect of free AA supplementation and subsequent eicosanoid biosynthesis on skeletal myocyte growth in vitro . C2C12 (mouse) skeletal myocytes induced to differentiate with supplemental AA exhibited dose-dependent increases in the size, myonuclear content, and protein accretion of developing myotubes, independent of changes in cell density or the rate/extent of myogenic differentiation. Nonselective (indomethacin) or cyclooxygenase 2 (COX-2)-selective (NS-398) nonsteroidal anti-inflammatory drugs blunted basal myogenesis, an effect that was amplified in the presence of supplemental free AA substrate. The stimulatory effects of AA persisted in preexisting myotubes via a COX-2-dependent (NS-389-sensitive) pathway, specifically implying dependency on downstream PG biosynthesis. AA-stimulated growth was associated with markedly increased secretion of PGF2α and PGE2; however, incubation of myocytes with PG-rich conditioned medium failed to mimic the effects of direct AA supplementation. In vitro AA supplementation stimulates PG release and skeletal muscle cell hypertrophy via a COX-2-dependent pathway.

NF-κB inhibition protects against tumor-induced cardiac atrophy in vivo

Cancer cachexia is a severe wasting syndrome characterized by the progressive loss of lean body mass and systemic inflammation. It occurs in approximately 80% of patients with advanced malignancy and is the cause of 20% to 30% of all cancer-related deaths. The mechanism by which striated muscle loss occurs is the tumor release of pro-inflammatory cytokines, such as IL-1, IL-6, and TNF-α. These cytokines interact with their cognate receptors on muscle cells to enhance NF-κB signaling, which then mediates muscle loss and significant cardiac dysfunction. Genetic inhibition of NF-κB signaling has demonstrated its predominant role in skeletal muscle loss. Therefore, we tested two novel drugs designed to specifically inhibit NF-κB by targeting the IκB kinase (IKK) complex: Compound A and NEMO binding domain (NBD) peptide. Using an established mouse model of cancer cachexia (C26 adenocarcinoma), we determined how these drugs affected the development of tumor-induced cardiac atrophy and function. Echocardiographic and histological analysis revealed that both Compound A and NBD inhibit cardiac NF-κB activity and prevent the development of tumor-induced systolic dysfunction and atrophy. This protection was independent of any effects of the tumor itself (Compound A) or tumor-secreted cytokines (NBD). This study identifies for the first time, to our knowledge, that drugs targeting the IKK complex are cardioprotective against cancer cachexia-induced cardiac atrophy and systolic dysfunction, suggesting therapies that may help reduce cardiac-associated morbidities found in patients with advanced malignancies.

Molecular, cellular and physiological characterization of the cancer cachexia-inducing C26 colon carcinoma in mouse

BACKGROUND

The majority of cancer patients experience dramatic weight loss, due to cachexia and consisting of skeletal muscle and fat tissue wasting. Cachexia is a negative prognostic factor, interferes with therapy and worsens the patients' quality of life by affecting muscle function. Mice bearing ectopically-implanted C26 colon carcinoma are widely used as an experimental model of cancer cachexia. As part of the search for novel clinical and basic research applications for this experimental model, we characterized novel cellular and molecular features of C26-bearing mice.

METHODS

A fragment of C26 tumor was subcutaneously grafted in isogenic BALB/c mice. The mass growth and proliferation rate of the tumor were analyzed. Histological and cytofluorometric analyses were used to assess cell death, ploidy and differentiation of the tumor cells. The main features of skeletal muscle atrophy, which were highlighted by immunohistochemical and electron microscopy analyses, correlated with biochemical alterations. Muscle force and resistance to fatigue were measured and analyzed as major functional deficits of the cachectic musculature.

RESULTS

We found that the C26 tumor, ectopically implanted in mice, is an undifferentiated carcinoma, which should be referred to as such and not as adenocarcinoma, a common misconception. The C26 tumor displays aneuploidy and histological features typical of transformed cells, incorporates BrdU and induces severe weight loss in the host, which is largely caused by muscle wasting. The latter appears to be due to proteasome-mediated protein degradation, which disrupts the sarcomeric structure and muscle fiber-extracellular matrix interactions. A pivotal functional deficit of cachectic muscle consists in increased fatigability, while the reported loss of tetanic force is not statistically significant following normalization for decreased muscle fiber size.

CONCLUSIONS

We conclude, on the basis of the definition of cachexia, that ectopically-implanted C26 carcinoma represents a well standardized experimental model for research on cancer cachexia. We wish to point out that scientists using the C26 model to study cancer and those using the same model to study cachexia may be unaware of each other's works because they use different keywords; we present strategies to eliminate this gap and discuss the benefits of such an exchange of knowledge.

Reduction of low grade inflammation restores blunting of postprandial muscle anabolism and limits sarcopenia in old rats

Ageing is characterized by a decline in muscle mass that could be explained by a defect in the regulation of postprandial muscle protein metabolism. Indeed, the stimulatory effect of food intake on protein synthesis and its inhibitory effect on proteolysis is blunted in old muscles from both animals and humans. Recently, low grade inflammation has been suspected to be one of the factors responsible for the decreased sensitivity of muscle protein metabolism to food intake. This study was undertaken to examine the effect of long-term prevention of low grade inflammation on muscle protein metabolism during ageing. Old rats (20 months of age) were separated into two groups: a control group and a group (IBU) in which low grade inflammation had been reduced with a non-steroidal anti inflammatory drug (ibuprofen). After 5 months of treatment, inflammatory markers and cytokine levels were significantly improved in treated old rats when compared with the controls: -22.3% fibrinogen, -54.2% alpha2-macroglobulin, +12.6% albumin, -59.6% IL(6) and -45.9% IL(1beta) levels. As expected, food intake had no effect on muscle protein synthesis or muscle proteolysis in controls whereas it significantly increased muscle protein synthesis by 24.8% and significantly decreased proteolysis in IBU rats. The restoration of muscle protein anabolism at the postprandial state by controlling the development of low grade inflammation in old rats significantly decreased muscle mass loss between 20 and 25 months of age. In conclusion, the observations made in this study have identified low grade inflammation as an important target for pharmacological, nutritional and lifestyle interventions that aim to limit sarcopenia and muscle weakness in the rapidly growing elderly population in Europe and North America.

Effects of eicosapentaenoic and docosahexaenoic n-3 fatty acids from fish oil and preferential Cox-2 inhibition on systemic syndromes in patients with advanced lung cancer

Under the common denomination of Systemic Immune-Metabolic Syndrome (SIMS), we grouped many symptoms that share a similar pathophysiologic background. SIMS is the result of the dysfunctional interaction of tumor cells, stroma cells, and the immune system, leading to the release of cytokines and other systemic mediators such as eicosanoids. SIMS includes systemic syndromes such as paraneoplastic hemopathies, hypercalcemia, coagulopathies, fatigue, weakness, cachexia, chronic nausea, anorexia, and early satiety among others. Eicosapentaenoic and docosahexaenoic n-3 fatty acids from fish oil can help in the management of persistent chronic inflammatory states, but treatment's compliance is generally poor. Preferentially, Cox-2 inhibition can create a favorable pattern of cytokines by decreasing the production of certain eicosanoids, although their role in SIMS is unknown. The aim of this study was to test the hypothesis that by modulating systemic inflammation through an eicosanoid-targeted approach, some of the symptoms of the SIMS could be controlled. We exclusively evaluated 12 patients for compliance. Patients were assigned 1 of the 4 treatment groups (15-, 12-, 9-, or 6-g dose, fractionated every 8 h). For patients assigned to 15 and 12 doses, the overall compliance was very poor and unsatisfactory for patients receiving the 9-g dose. The maximum tolerable dose was calculated to be around 2 capsules tid (6 g of fish oil per day). A second cohort of 22 patients with advanced lung cancer and SIMS were randomly assigned to receive either fish oil, 2 g tid, plus placebo capsules bid (n = 12) or fish oil, 2 g tid, plus celecoxib 200 mg bid (n = 10). All patients in both groups received oral food supplementation. After 6 wk of treatment, patients receiving fish oil + placebo or fish oil + celecoxib showed significantly more appetite, less fatigue, and lower C-reactive protein (C-RP) values than their respective baselines values (P < 0.02 for all the comparisons). Additionally, patients in the fish oil + celecoxib group also improved their body weight and muscle strength compared to baseline values (P < 0.02 for all the comparisons). Comparing both groups, patients receiving fish oil + celecoxib showed significantly lower C-RP levels (P = 0.005, t-test), higher muscle strength (P = 0.002, t-test) and body weight (P = 0.05, t-test) than patients receiving fish oil + placebo. The addition of celecoxib improved the control of the acute phase protein response, total body weight, and muscle strength. Additionally, the consistent nutritional support used in our patients could have helped to maximize the pharmacological effects of fish oil and/or celecoxib. This study shows that by modulating the eicosanoid metabolism using a combination of n-3 fatty acids and cyclooxygenase-2 inhibitor, some of the signs and symptoms associated with a SIMS could be ameliorated.

Cancer cachexia syndrome in head and neck cancer patients: part I. Diagnosis, impact on quality of life and survival, and treatment

BACKGROUND

Cancer cachexia is a debilitating, wasting condition that affects many cancer patients, including those with head and neck cancer. The overall incidence of cancer cachexia is quite high for some types of cancer, and cachexia will be the main cause of death for more than 20% of all cancer patients. This syndrome uniquely challenges patients with head and neck cancer. This article outlines the diagnosis of cancer cachexia, reviews its impact on patient quality of life (QOL) and survival, and updates the reader on potential therapies that may suppress it.

METHODS

A comprehensive literature search was performed using PubMed of the National Library of Medicine, which includes more than 15 million citations back to the 1950s. The Cochrane Library and Google search engine were used as well.

RESULTS

This syndrome differs significantly from starvation, and thus accurate and timely diagnosis is essential. Nutritional therapy alone is insufficient. Current management strategies include corticosteroids and megesterol acetate, in conjunction with nutritional therapy. Future strategies may include nutraceuticals, omega-3 fatty acids, inflammatory antagonists, and other targeted treatments.

CONCLUSIONS

Because cancer cachexia differs significantly from starvation, nutritional supplementation must be used in conjunction with other anti-cachexia agents to reverse the chronic systemic inflammatory state and the effects of circulating tumor-derived factors seen in cachexia. Careful identification of patients at risk and those suffering from this syndrome will lead to better outcomes and treatments. Ultimately, more research is needed to better treat this devastating condition.

Cancer-Associated Cachexia and Underlying Biological Mechanisms

Cancer metastases (spread to distant organs from the primary tumor site) signify systemic, progressive, and essentially incurable malignant disease. Anorexia and wasting develop continuously throughout the course of incurable cancer. Overall, in Westernized countries nearly exactly half of current cancer diagnoses end in cure and the other half end in death; thus, cancer-associated cachexia has a high prevalence. The pathophysiology of cancer-associated cachexia has two principal components: a failure of food intake and a systemic hypermetabolism/hypercatabolism syndrome. The superimposed metabolic changes result in a rate of depletion of physiological reserves of energy and protein that is greater than would be expected based on the prevailing level of food intake. These features indicate a need for nutritional support, metabolic management, and a clear appreciation of the context of life-limiting illness.

Inhibitors of COX activity preserve muscle mass in mice bearing the Lewis lung carcinoma, but not the B16 melanoma

Tumor-induced skeletal muscle wasting (SMW) contributes to the fatigue and weakness experienced by persons with cancer cachexia. Tumor necrosis factor-alpha (TNFa) and cyclooxygenase (COX) activity have been implicated in SMW in some animal models of cancer cachexia. We report that indomethacin, a nonspecific inhibitor of COX, and NS398, a specific inhibitor of COX2, preserved muscle mass and reduced type 1 TNF receptors in muscles of mice bearing the Lewis lung carcinoma, but not in mice bearing the B16 melanoma. These data suggest that tumor-induced SMW can occur via a COX2-independent pathway. The COX2-dependent pathway may involve reducing the catabolic effects of TNFa in muscle. Further study is needed to understand the relationship between COX and SMW, and whether patients with cancer cachexia might benefit from COX inhibitors.

Conjugated linoleic acid preserves muscle mass in mice bearing the Lewis lung carcinoma, but not the B16 melanoma

Conjugated linoleic acid (CLA), which is found in dairy products, reduces synthesis of tumor necrosis factor-alpha (TNFa), a pro-inflammatory cytokine that plays a major role in tumor-induced skeletal muscle wasting (SMW). The B16 melanoma expresses TNFa mRNA, and induced SMW with no change in muscle levels of TNFa type 1 receptor (TNFR1) protein. A diet containing .5% CLA had no effect on SMW or TNFR1 in mice bearing B16 tumors. In contrast, the Lewis lung carcinoma expresses low levels of TNFa mRNA, induced SMW, and increased muscle levels of TNFR1. A diet containing .5% CLA reduced SMW, but had no effect on muscle levels of TNFR1. We conclude that that tumor-induced SMW can occur independent of muscle levels of TNFR1. Further study is needed before CLA can be tested in persons with cancer cachexia.

Myofiber degeneration/regeneration is induced in the cachecticApcMin/+mouse

Cachexia is characterized as an inflammatory state induced by the cancer environment, which is accompanied by the loss of muscle and fat mass. Well-investigated mechanisms of cachexia include the suppression of myofiber protein synthesis and the induction of the protein degradation. However, it is not well characterized whether chronic inflammation during cachexia induces myofiber degeneration, which contributes to muscle mass loss and decreased functional capacity. The purpose of this study was to determine whether Apc(Min/+) mice, which demonstrate a chronic systemic inflammatory state due to an intestinal tumor burden, undergo cachexia and whether the myofibers exhibit signs of degeneration and/or regeneration. Six-month-old female Apc(Min/+) body weight decreased 21% compared with C57BL/6 mice and was not the result of blunted growth. Apc(Min/+) gastrocnemius muscle was reduced 45%, and soleus mean fiber cross-sectional area decreased 24% vs. C57BL/6 mice. Soleus muscle morphology demonstrated pathology of myofibers undergoing degeneration and/or regeneration. These data demonstrate that the Apc(Min/+) mouse becomes cachectic by 6 mo of age and that skeletal muscle degeneration and regeneration may be related to the muscle loss.

Conjugated linoleic acid preserves gastrocnemius muscle mass in mice bearing the colon-26 adenocarcinoma

Cancer cachexia is a syndrome of weight loss, muscle wasting, fatigue, and anorexia that occurs in patients with advanced or recurrent solid tumor disease. Tumor necrosis factor-alpha (TNFalpha) and prostaglandin E2 (PGE2) have been implicated in the biology of cachexia and serve as possible targets for treatment of this condition. Conjugated linoleic acid (CLA) is a polyunsaturated fatty acid that alters the synthesis of PGE2 and reduces the negative effects of TNF on body weight of healthy mice. We hypothesized that a diet supplemented with .5% CLA might reduce muscle wasting in mice bearing the colon-26 adenocarcinoma, an animal model of cancer cachexia. CLA preserved gastrocnemius muscle mass and reduced TNF receptors in muscle of tumor-bearing mice. These data suggest that CLA may preserve muscle mass by reducing the catabolic effects of TNF on skeletal muscle.

Indomethacin preserves muscle mass and reduces levels of E3 ligases and TNF receptor type 1 in the gastrocnemius muscle of tumor-bearing mice

Tumor-induced skeletal muscle wasting involves tumor necrosis factor (TNF) and the ubiquitin-proteasome pathway of muscle protein degradation. In this study, growth of the colon-26 adenocarcinoma in mice was associated with diminished gastrocnemius muscle mass and increased muscle levels of actin, ubiquitin-conjugated proteins, free ubiquitin, E3 ubiquitin ligases, and the type 1 TNF receptor (TNFR1). Indomethacin at 1 or 5 mg/kg/day reduced tumor growth and muscle levels of TNFR1. However, only the 5 mg dose of indomethacin reduced muscle wasting and muscle levels of the E3 ligases and actin. These data suggest that the beneficial effects of indomethacin in the treatment of tumor-induced skeletal muscle wasting may involve inhibition of TNF- and ubiquitin-mediated pathways of muscle protein degradation. These data also demonstrate that E3 ligases, which are involved in disuse atrophy, also are associated with tumor-induced skeletal muscle wasting.