Mechanisms and treatment of cancer cachexia.

According to a recent consensus, cachexia is a complex metabolic syndrome associated with underlying illness and characterised by loss of muscle with or without loss of fat mass. The prominent clinical feature of cachexia is weight loss. Cachexia occurs in the majority of terminal cancer patients and it is responsible for the deaths of 22% of cancer patients. Although body weight is, indeed, an important factor to be taken into consideration in any cachexia treatment, body composition, physical performance and quality of life should be monitored. From the results presented here, one can speculate that a single therapy may not be completely successful in the treatment of cachexia. From this point of view, treatments involving different combinations are more likely to be successful. The objectives of any therapeutical combination are two: an anticatabolic aim directed towards both fat and muscle catabolism and an anabolic objective leading to the synthesis of macromolecules such as contractile proteins.

Dietary supplementation with a specific combination of high protein, leucine, and fish oil improves muscle function and daily activity in tumour-bearing cachectic mice.

Cancer cachexia is characterised by metabolic alterations leading to loss of adipose tissue and lean body mass and directly compromises physical performance and the quality of life of cancer patients. In a murine cancer cachectic model, the effects of dietary supplementation with a specific combination of high protein, leucine and fish oil on weight loss, muscle function and physical activity were investigated. Male CD2F1 mice, 6-7 weeks old, were divided into body weight-matched groups: (1) control, (2) tumour-bearing, and (3) tumour-bearing receiving experimental diets. Tumours were induced by s.c. inoculation with murine colon adenocarcinoma (C26) cells. Food intake, body mass, tumour size and 24 h-activity were monitored. Then, 20 days after tumour/vehicle inoculation, the animals were killed and muscle function was tested ex vivo. Tumour-bearing mice showed reduced carcass, muscle and fat mass compared with controls. EDL muscle performance and total daily activity were impaired in the tumour-bearing mice. Addition of single nutrients resulted in no or modest effects. However, supplementation of the diet with the all-in combination of high protein, leucine and fish oil significantly reduced loss of carcass, muscle and fat mass (loss in mass 45, 52 and 65% of TB-con, respectively (P<0.02)) and improved muscle performance (loss of max force reduced to 55-64% of TB-con (P<0.05)). Moreover, total daily activity normalised after intervention with the specific nutritional combination (50% of the reduction in activity of TB-con (P<0.05)). In conclusion, a nutritional combination of high protein, leucine and fish oil reduced cachectic symptoms and improved functional performance in cancer cachectic mice. Comparison of the nutritional combination with its individual modules revealed additive effects of the single components provided.

Direct effects of doxorubicin on skeletal muscle contribute to fatigue.

Chemotherapy-induced fatigue is a multidimensional symptom. Oxidative stress has been proposed as a working mechanism for anthracycline-induced cardiotoxicity. In this study, doxorubicin (DOX) was tested on skeletal muscle function. Doxorubicin induced impaired ex vivo skeletal muscle relaxation followed in time by contraction impediment, which could be explained by DOX-induced changes in Ca(2+) responses of myotubes in vitro. The Ca(2+) responses in skeletal muscle, however, could not be explained by oxidative stress.

Interleukin-1 and beta-cell function: more than one second messenger?

Cytokines, in particular IL-1, released mainly by infiltrating macrophages, can be one of the key mediators of immune-induced beta-cell destruction in IDDM. IL-1 is able to induce suppression of insulin release and biosynthesis in cultured rat pancreatic islets. In addition, the cytokine shows clear cytotoxic effects leading to beta-cell death. The proposed mechanisms of action of IL-1 after binding to the beta-cell receptors are varied. Concerning the cytotoxic effects of the cytokine, the role of oxygen free radicals, mainly derived from arachidonate metabolism (see Fig. 1) is clear, and possibly potentiated by a cytosolic Na(+)-mediated alkalinization of the beta-cell exposed to the cytokine. In fact, an increased influx of Na+ may explain some of the cytotoxicity since it results in concomitant water uptake leading to swelling of the endoplasmic reticulum. NO formation also seems to be related to the cytokine-induced cytotoxicity since inhibition of the NO synthase abolishes the effects of the cytokine (see Fig. 1). In relation to the inhibitory effects of the cytokine on the beta-cell, different studies point toward almost all known second messenger systems already described for several hormones, such as cAMP formation, increased phospholipase C activity, changes in cytosolic Ca++, and altered gene transcription (see Fig. 1). Of particular interest is the protease activation associated with IL-1 (a serine protease) that seems to be clearly connected with the effects of the cytokine upon the beta-cell. In conclusion, the different studies devoted to the problem of IL-1 signal transduction on the beta-cell seem to indicate that the action of the cytokine on the pancreatic insulin-secreting cells is not associated with an individual second messenger system but rather seems to be related to a plurifactorial transduction system.

Beneficial immune modulatory effects of a specific nutritional combination in a murine model for cancer cachexia.

The majority of patients with advanced cancer are recognised by impaired immune competence influenced by several factors, including the type and stage of the tumour and the presence of cachexia. Recently, a specific nutritional combination containing fish oil, specific oligosaccharide mixture, high protein content and leucine has been developed aimed to support the immune system of cancer patients in order to reduce the frequency and severity of (infectious) complications. In a recently modified animal model cachexia is induced by inoculation of C26 tumour cells in mice. In a pre-cachectic state, no effect was observed on contact hypersensitivity, a validated in vivo method to measure Th1-mediated immune function, after adding the individual nutritional ingredients to the diet of tumour-bearing mice. However, the complete mixture resulted in significantly improved Th1 immunity. Moreover, in a cachectic state, the complete mixture reduced plasma levels of pro-inflammatory cytokines and beneficially affected ex vivo immune function. Accordingly, the combination of the nutritional ingredients is required to obtain a synergistic effect, leading to a reduced inflammatory state and improved immune competence. From this, it can be concluded that the specific nutritional combination has potential as immune-supporting nutritional intervention to reduce the risk of (infectious) complications in cancer patients.

Tumor necrosis factor-alpha mediates changes in tissue protein turnover in a rat cancer cachexia model.

Rats bearing the Yoshida AH-130 ascites hepatoma showed enhanced fractional rates of protein degradation in gastrocnemius muscle, heart, and liver, while fractional synthesis rates were similar to those in non-tumor bearing rats. This hypercatabolic pattern was associated with marked perturbations of the hormonal homeostasis and presence of tumor necrosis factor in the circulation. The daily administration of a goat anti-murine TNF IgG to tumor-bearing rats decreased protein degradation rates in skeletal muscle, heart, and liver as compared with tumor-bearing rats receiving a nonimmune goat IgG. The anti-TNF treatment was also effective in attenuating early perturbations in insulin and corticosterone homeostasis. Although these results suggest that tumor necrosis factor plays a significant role in mediating the changes in protein turnover and hormone levels elicited by tumor growth, the inability of such treatment to prevent a reduction in body weight implies that other mediators or tumor-related events were also involved.

Muscle protein waste in tumor-bearing rats is effectively antagonized by a beta 2-adrenergic agonist (clenbuterol). Role of the ATP-ubiquitin-dependent proteolytic pathway.

Tissue protein hypercatabolism (TPH) is a most important feature in cancer cachexia, particularly with regard to the skeletal muscle. The rat ascites hepatoma Yoshida AH-130 is a very suitable model system for studying the mechanisms involved in the processes that lead to tissue depletion, since it induces in the host a rapid and progressive muscle waste mainly due to TPH (Tessitore, L., G. Bonelli, and F. M. Baccino. 1987. Biochem. J. 241:153-159). Detectable plasma levels of tumor necrosis factor-alpha associated with marked perturbations in the hormonal homeostasis have been shown to concur in forcing metabolism into a catabolic setting (Tessitore, L., P. Costelli, and F. M. Baccino. 1993. Br. J. Cancer. 67:15-23). The present study was directed to investigate if beta 2-adrenergic agonists, which are known to favor skeletal muscle hypertrophy, could effectively antagonize the enhanced muscle protein breakdown in this cancer cachexia model. One such agent, i.e., clenbuterol, indeed largely prevented skeletal muscle waste in AH-130-bearing rats by restoring protein degradative rates close to control values. This normalization of protein breakdown rates was achieved through a decrease of the hyperactivation of the ATP-ubiquitin-dependent proteolytic pathway, as previously demonstrated in our laboratory (Llovera, M., C. García-Martínez, N. Agell, M. Marzábal, F. J. López-Soriano, and J. M. Argilés. 1994. FEBS (Fed. Eur. Biochem. Soc.) Lett. 338:311-318). By contrast, the drug did not exert any measurable effect on various parenchymal organs, nor did it modify the plasma level of corticosterone and insulin, which were increased and decreased, respectively, in the tumor hosts. The present data give new insights into the mechanisms by which clenbuterol exerts its preventive effect on muscle protein waste and seem to warrant the implementation of experimental protocols involving the use of clenbuterol or alike drugs in the treatment of pathological states involving TPH, particularly in skeletal muscle and heart, such as in the present model of cancer cachexia.

TNF and pregnancy: the paradigm of a complex interaction.

Although tumour necrosis factor-alpha (TNF) was originally described as a cytotoxic molecule produced by macrophages when activated by certain stimuli (such as bacterial endotoxin or tumour cells), a large body of evidence suggests that TNF plays a role in pregnancy. Both in humans and experimental animals, TNF is expressed and synthesized in the endometrium, placenta and fetus. Here we review evidence in support of positive roles for the cytokine in gestation (such as early pregnancy maintenance, and the contribution of TNF to the maintenance of a complex cytokine-hormone network or to parturition). We also present evidence supporting the idea that TNF acts as a negative regulator of pregnancy, or does not play any significant role in gestation at all.

Effects of tumor necrosis factor-alpha on muscle-protein turnover in female Wistar rats.

BACKGROUND: Many cancer patients experience a wasting syndrome (cachexia) characterized by weight loss and abnormalities in carbohydrate, protein, and lipid metabolism. Recent experimental studies suggest that the development of cancer cachexia involves the host's production of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha). PURPOSE: Our goal was to evaluate in rats the effects of an 8-day TNF-alpha treatment on overall protein metabolism in the liver, diaphragm, heart, and hind-leg muscles. METHODS: Four experimental groups corresponding to specific tissues (liver, diaphragm, heart, and hind-leg muscles) in female Wistar rats (100-150 g) were studied. Each group consisted of 25 TNF-alpha-treated and 25 control female Wistar rats. The TNF-alpha-treated rats were given intraperitoneal injections of recombinant-derived human TNF-alpha (0.5 mL) that was administered in two daily injections of 50 micrograms/kg (total dose of 100 micrograms/kg per day) for 8 days. Control animals followed the same injection schedule as the treatment group and received 0.5 mL of physiological saline instead of TNF-alpha. All rats were radioactively labeled with NaH14CO3 24 hours prior to TNF-alpha treatment. At 0, 1, 2, 4, and 8 days during TNF-alpha treatment, five rats per group were killed to measure the radioactive decay of labeled protein in specific tissues in order to estimate fractional protein turnover. During necropsy, the liver, hind-leg muscles (soleus muscle analyzed separately on 8th day only), heart, and diaphragm were rapidly weighed, and each was homogenized. Total protein content and total DNA were also determined. Total protein radioactivity and specific protein radioactivity (per milligram of protein) were evaluated for liver, diaphragm, heart, and hind-leg muscles. Radioactivity was counted in a liquid scintillation counter. Fractional rates of protein synthesis, protein degradation, total protein, and protein accumulation or loss were calculated. RESULTS: The TNF-alpha treatment administered to female Wistar rats for 8 days resulted in a transient decrease in food intake and body weight 24 hours after the beginning of the TNF-alpha treatment. In all types of tissues studied, TNF-alpha treatment resulted in increases in both the protein synthesis and protein degradation, with a greater increase in the protein degradation that resulted in a reduced protein accumulation following TNF-alpha treatment. This reduction in protein accumulation was directly associated with a decreased soleus muscle mass on day 8 of the treatment. CONCLUSIONS: Data suggest that TNF-alpha enhances muscle degradation in experimental situations where body weight loss is not apparent.

[Pathophysiology of neoplasic cachexia]. / Fisiopatología de la caquexia neoplásica.

The regulation of food intake is mediated by different psicological, gastrointestinal metabolic, nutritional and endocrine mechanisms. The cancer patient suffers from anorexia which results in early saciety and a reduction of appetite. Sometimes, the causes of the anorectic response are derived from the antitumoral treatment (chemotherapy, radiotherapy or immunotherapy), in some cases vomiting resulting in altered food intake. Alterations in the food taste and smell perception in addition to psychological dearrangements might also lead to the anorexia. Sometimes the tumour may play a direct effect when it is localised in either the hypothalamus or the digestive apparatus. However, in the majority of cases the origin of the anorexia associated with cancer cachexia seems to be due to the metabolic alterations induced by tumour burden. Different factors of both humoral and tumoral origin play a role in cancer anorexia. For instance, tumour necrosis factor (TNF-), a cytokine responsible for a great part of the metabolic alterations characteristic of cancer cachexia seems to be involved. In conclusion, the cancer anorexia seems to be more an effect than the cause of the weight loss and in fact the decrease in food intake might take place after weight loss is evident. In any case, the malnutrition associated with a decrease of food intake worsens the cachectic state, favouring a kind of a positive feed-back mechanism that finally leads to the patient's death.

Muscle wasting in cancer and ageing: cachexia versus sarcopenia.

Muscle wasting during cancer and ageing share many common metabolic pathways and mediators. Due to the size of the population involved, both cancer cachexia and ageing sarcopenia may represent targets for future promising clinical investigations. Cancer cachexia is a syndrome characterized by a marked weight loss, anorexia, asthenia and anemia. In fact, many patients who die with advanced cancer suffer from cachexia. The degree of cachexia is inversely correlated with the survival time of the patient and it always implies a poor prognosis. In recent years, age-related diseases and disabilities have become of major health interest and importance. This holds particularly for muscle wasting, also known as sarcopenia that decreases the quality of life of the geriatric population, increasing morbidity and decreasing life expectancy. The cachectic factors (associated with both depletion of fat stores and muscular tissue) can be divided into two categories: of tumour origin and humoural factors. In conclusion, more research should be devoted to the understanding of muscle wasting mediators, both in cancer and ageing, in particular the identification of common mediators may prove as a good therapeutic strategy for both prevention and treatment of wasting both in disease and during healthy ageing.

Blood amino acid compartmentation in mice bearing Lewis lung carcinoma.

Blood amino acid compartmentation between plasma and red blood cells was studied in mice bearing the Lewis lung carcinoma. The animals showed a change in compartmentation with an increase in the concentration of most amino acids in the plasmatic fraction with the exception of glycine, glutamine, aspartate, asparagine, and taurine. This work focuses on the importance of studying the distribution of amino acids in both fractions when performing studies concerning amino acid metabolism in tumor-bearing animals.

Calpain-3 gene expression is decreased during experimental cancer cachexia.

The Yoshida AH-130 rat ascites hepatoma is a model system for studying the mechanisms involved in the protein hypercatabolism associated with cancer cachexia. The present study was aimed at investigating if the calpain-3 gene expression in skeletal muscle was affected by tumor growth. The results presented clearly show that calpain-3 gene expression is considerably reduced in experimental cancer cachexia, while there is a reciprocal change in the expression of the ubiquitin-dependent proteolytic system and in the ubiquitous m-calpain. The results, observed during cancer cachexia, suggest a potential counterregulatory role of calpain-3 in muscle proteolysis.

Increased uncoupling protein-2 gene expression in brain of lipopolysaccharide-injected mice: role of tumour necrosis factor-alpha?

In order to understand the role of brain localized uncoupling proteins, we have examined the UCP2 and BMCP-1 gene expression in mice brain in two different catabolic states: administration of lipopolysaccharide (LPS) (2.5 mg/kg, i.p.) and tumour burden. Administration of LPS resulted in an increased UCP2 gene expression both in brain (208%) and cerebellum (77%). An increase in UCP2 gene expression was also observed after LPS treatment in double knockout mice for tumour necrosis factor-alpha (TNF) receptors 1 and 2 (75% in brain and 33% in cerebellum). Tumour growth also resulted in increased brain UCP2 gene expression (80%) in mice bearing the Lewis lung carcinoma as compared with the non-tumour-bearing controls. No changes were observed in BMCP-1 mRNA levels of either LPS-injected or tumour-bearing mice. From the results presented it may be suggested that: (a) the brain may contribute significantly to the increase in energy expenditure associated with hypermetabolic states such as fever and tumour burden, and (b) the regulation of UCP2 gene expression in brain does not seem to be influenced by TNF; therefore the action of other cytokines cannot be discarded.

Interleukin-15 mediates reciprocal regulation of adipose and muscle mass: a potential role in body weight control.

Interleukin (IL)-15 is a cytokine which is highly expressed in skeletal muscle. Cell culture studies have indicated that IL-15 may have an important role in muscle fiber growth and anabolism. However, data concerning the metabolic effects of this cytokine in vivo are lacking. In the present study, IL-15 was administered to adult rats for 7 days. While IL-15 did not cause changes in either muscle mass or muscle protein content, it induced significant changes in the fractional rates of both muscle protein synthesis and degradation, with no net changes in protein accumulation. Additionally, IL-15 administration resulted in a 33% decrease in white adipose tissue mass and a 20% decrease in circulating triacylglycerols; this was associated with a 47% lower hepatic lipogenic rate and a 36% lower plasma VLDL triacylglycerol content. The decrease in white fat induced by IL-15 was in adipose tissue. No changes were observed in the rate of lipolysis as a result of cytokine administration. These findings indicate that IL-15 has significant effects on both protein and lipid metabolism, and suggest that this cytokine may participate in reciprocal regulation of muscle and adipose tissue mass.

Mice lacking TNFalpha receptors 1 and 2 are resistant to death and fulminant liver injury induced by agonistic anti-Fas antibody.

The liver is particularly susceptible to Fas-mediated cytotoxicity. Mice given an adequate parenteral dose of agonistic anti-Fas antibody (aFas) or of FasL are known to develop a devastating liver injury and to die in a few hours. The present work shows that mice lacking TNFR1 and TNFR2 (R(-)) both survive a single dose of aFas, otherwise rapidly lethal, and develop a mild form of hepatic damage, compared to the much more severe liver injury that in a few hours strikes wild-type mice (R(+)), eventually involving increased activity of proteases of different families (caspase 3-, 8-, and 9-like, calpains, cathepsin B). Neither the overall tissue levels of Fas and FasL nor Fas expression at the hepatocyte surface are altered in the liver of R(-) animals. The DNA-binding activity of the NF-kappaB transcription factor is enhanced after aFas treatment, but much more markedly in R(-) than in R(+) mice. Bcl2, while unchanged in untreated animals, is markedly upregulated in R(-) but not in R(+) mice challenged with aFas. The requirement of a normal TNFR1/TNFR2 phenotype for full deployment of the general and liver-specific aFas toxicity in mice most likely implies that treatment with aFas in some way results in activation of the TNFalpha-TNFRs system and that this activation synergizes with Fas-mediated signals in causing the fulminant liver injury and the animal death. The precise cellular and molecular details underlying this interplay between Fas- and TNFRs-mediated signaling systems in the general and liver-specific aFas toxicity largely remain to be clarified.

The ubiquitin-dependent proteolytic pathway in skeletal muscle: its role in pathological states.

It is generally accepted that muscle wasting is caused by an increase in protein breakdown which seems to be associated with an ATP-dependent, non-lysosomal proteolytic system based on conjugation of proteins to the small polypeptide ubiquitin. Increases in ubiquitin conjugates and in ubiquitin mRNAs are found in the skeletal muscle of experimental animals with various pathological conditions such as infection, acidosis or cancer cachexia. In this review, Josep Argilés and Francisco López-Soriano discuss the role of the ubiquitin-dependent proteolytic pathway in muscle weight loss in pathological situations.

Skeletal muscle wasting in tumor-bearing rats is associated with MyoD down-regulation.

Cachexia is a syndrome characterized by profound skeletal muscle wasting that frequently complicates malignancies. A number of studies indicate that protein hypercatabolism, largely mediated by classical hormones and cytokines, is the major component of muscle depletion. Impaired regeneration has been suggested to contribute to the reduction of muscle size. In particular, it has been shown that the expression of MyoD, a muscle-specific transcription factor, is down-regulated by cytokines such as TNFalpha and IFNgamma in a NF-kappaB-dependent posttranscriptional manner. The present study investigated whether modulations of the transcription factor MyoD are associated with the onset of muscle wasting in a well established model of cancer cachexia. Rats bearing the Yoshida AH-130 hepatoma develop a condition of muscle protein hypercatabolism, largely dependent on TNFalpha bioactivity. In the gastrocnemius of these animals the expression of MyoD was markedly reduced, paralleling the decrease of muscle weight. This pattern is associated with increased nuclear translocation of AP-1, while DNA-binding assays did not detect any change in NF-kappaB activity. This is the first observation demonstrating that muscle depletion in tumor-bearing rats is associated with a down-regulation of MyoD levels. Although the underlying mechanisms remain to be clarified, this change is compatible with the hypothesis that a reduced expression of molecules involved in the regulation of the regenerative response may concur to muscle wasting in cancer cachexia.

Cancer-associated malnutrition.

Malnutrition is a common problem among patients with cancer, affecting up to 85% of patients with certain cancers (e.g. pancreas). In severe cases, malnutrition can progress to cachexia, a specific form of malnutrition characterised by loss of lean body mass, muscle wasting, and impaired immune, physical and mental function. Cancer cachexia is also associated with poor response to therapy, increased susceptibility to treatment-related adverse events, as well as poor outcome and quality of life. Cancer cachexia is a complex, multifactorial syndrome, which is thought to result from the actions of both host- and tumour-derived factors, including cytokines involved in a systemic inflammatory response to the tumour. Early intervention with nutritional supplementation has been shown to halt malnutrition, and may improve outcome in some patients. However, increasing nutritional intake is insufficient to prevent the development of cachexia, reflecting the complex pathogenesis of this condition. Nutritional supplements containing anti-inflammatory agents, for example the polyunsaturated fatty acid (PUFA) eicosapentanoic acid (EPA), have been shown to be more beneficial to malnourished patients than nutritional supplementation alone. EPA has been shown to interfere with multiple mechanisms implicated in the pathogenesis of cancer cachexia, and in clinical studies, has been associated with reversal of cachexia and improved survival.

Administration of tumor necrosis factor-alpha results in a decreased placental transfer of amino acids in the rat.

The administration of an acute tumor necrosis factor-alpha (TNF) dose (100 micrograms/kg BW) to 20-day pregnant rats resulted in a substantial decrease in the fetal availability of maternally administered amino acids, as measured by the accumulation of alpha-amino-[1-14C]isobutyrate ([14C]AIB) and [1-14C]cycloleucine ([14C]CLEU), nonmetabolizable analogs of the amino acids alanine and leucine, respectively. Thus, TNF treatment resulted in a decreased accumulation of the tracers in the whole fetus as well as in fetal liver. The cytokine also caused important changes on the maternal liver, where it increased both [14C]AIB and [14C]CLEU accumulation. In skeletal muscle and heart, TNF treatment resulted in decreased [14C]AIB accumulation, but increased [14C]CLEU. These changes in tissue amino acid uptake were accompanied by changes in circulating amino acids. TNF treatment promoted an increase in the concentrations of both alanine and leucine in the maternal circulation, whereas no changes in the circulating concentrations of these amino acids were observed in the fetuses. The decreased fetal accumulation of maternally derived amino acid analogs is partially explained by a decrease in fetal blood flow [as measured by the accumulation of [14C]1,1,1-trichloro-2,2- bis-(p-chlorophenyl)ethane] induced by the cytokine). It is suggested that the cytokine may be involved in fetal growth impairment during pathological states (such as tumor growth or chronic infection) by promoting a decreased transplacental passage of amino acids, essential compounds for both protein accretion and oxidation in fetal metabolism.