A combination of a nutritional supplement and eicosapentaenoic acid was given to patients with advanced pancreatic cancer to assess its effect on the ongoing cachectic process. The administration of a fish oil-enriched nutritional supplement providing 2g eicosapentaenoic acid and around 600kcal per day resulted in a significant change in the metabolic disposition of patients with advanced pancreatic cancer. Consumption of the supplement resulted in a reversal of weight loss and a gain in lean body mass in association with a reversal of negative nitrogen balance. Performance status and appetite improved. Production of interleukin-6 was reduced and the acute phase protein response stabilised, insulin concentration increased and proteolysis inducing factor excretion fell. These changes were associated with a rise in energy intake, a fall in relative resting energy expenditure and a normalisation of the metabolic response to feeding and substrate utilisation. The increase in acute phase protein synthesis with feeding was abolished after the administration of the fish oil-enriched nutritional supplement. The progressive nutritional and functional deterioration of advanced pancreatic cancer patients thus seems to be associated with broadly pro-inflammatory metabolic mediators and a progressive acute phase protein response. This deterioration may in part be resistant to conventional nutritional supplementation because of further stimulation of acute phase protein production by feeding. The provision of a fish oil-enriched nutritional supplement normalises the metabolic milieu, stabilises the acute phase protein response and abolishes the stimulation of acute phase protein production by feeding. One explanation to account for the effects observed after intervention would be that it to allows dietary amino acids to be used for lean tissue anabolism with the consequent potential for quality of life and survival benefit.

Indiana University-Purdue University Indianapolis (IUPUI) / Growth differentiation factor 11 (GDF11) is important in regulating early fetal development of the axial skeleton and various visceral organs. Its actions on the adult body are less clear, and recent studies have led to conflicting accounts of GDF11’s ability to affect cardiac hypertrophy and skeletal muscle regeneration. If boosting GDF11 levels in adults had the ability to rejuvenate tissues and reverse the effects of aging, then the therapeutic possibilities are potentially vast. We attempted to provide clarification of this controversial topic by studying the effects of supraphysiologic levels of GDF11 in a mouse model using injected Chinese hamster ovary cells producing GDF11. We found that increasing endogenous levels of GDF11 in this in vivo mouse model resulted in overall bodily wasting, specifically with evidence of cardiac and skeletal muscle atrophy. In light of these results, caution must be exercised if GDF11 is ever considered as a potential therapeutic agent.

No description available.

No description available.

Cancer cachexia is a chronic wasting syndrome characterised by loss of weight, composed principally of muscle and fat. Patients with advanced cachexia demonstrate loss of appetite, early satiety, severe weight loss, weakness, anaemia and fluid retention. Affected individuals are also likely to report/experience decreased quality of life, decreased levels of physical performance, increased levels of fatigue, increased risks of treatment failure (be it chemotherapy, radiotherapy or surgery), increased risks of treatment side effects, and an increased mortality rate. Cachexia is therefore an extremely important, yet often underappreciated cause of cancer patient morbidity and mortality which requires urgent attention. Weight loss is significantly associated with cancer morbidity and mortality. It has been observed that half of all cancer patients experience weight loss and one-third lose more than 5% of their original body weight. Skeletal muscle loss appears to be the most significant event in cachexia and is associated with a poor outcome. However it is not known why some patients with the same tumour lose weight and muscle mass whilst others do not. The main aim of this thesis was to determine if the genetic makeup of individual patients might contribute to their propensity to lose weight or skeletal muscle. Previous studies had suggested an association between weight loss and SNPs on genes concerned with innate immunity and particularly the cell adhesion molecule Pselectin, however the strength of any gene association study depends on the precision with which it is possible to characterise the phenotype in question. A second aim of this thesis was to explore refining the clinical phenotyping of patients to discriminate those with evidence of muscle fibre atrophy versus those without. Phenotype The conventional phenotype for cachexia is weight loss (WL) but it is unknown the extent to which loss of body mass reflects loss of muscle or fat mass. Recent progress in cross sectional imaging analysis means that it is now possible to gain a direct measure of muscle mass from routine diagnostic CT scanning. However, in the absence of a longitudinal series of scans it is not possible to estimate whether low muscularity (LM) is longstanding or not. By combining a measure of active weight loss with low muscularity it was hoped that such a composite measure would reflect actual muscle loss/fibre atrophy. Compared with non-cachectic cancer patients, patients with LM or LM+ > 2%WL, mean muscle fibre diameter was reduced by about 25% (p = 0.02 and p = 0.001 respectively). No significant difference in muscle fibre diameter was observed if patients had WL alone. Regardless of classification, there was no difference in fibre number or proportion of fibre type across all myosin heavy chain isoforms. Mean muscle protein content was reduced and the ratio of RNA/DNA decreased in patients with either > 5%WL or LM+ > 2%WL. These findings support the use of composite measures (WL and LM) to try and identify those patients with evidence of active muscle fibre atrophy. This novel clinical phenotyping provides an accurate method to enable the conduct of candidate gene studies in the investigation of the genetics of cancer cachexia where the primary focus is on muscle wasting rather than overall weight loss. Genotype In an ideal world it would be possible to explore the entire genome and look for associations with the different phenotypes of cachexia. However, to do so would require considerable resource in terms of the cost of genome wide analysis and the cost of phenotyping large enough cohorts of patients (3000-10000). To address these issues I therefore adopted a candidate gene approach. A total of 154 genes associated with cancer cachexia were identified and explored for associated polymorphisms. Of these 154 genes, 119 had a combined total of 281 polymorphisms with functional and/or clinical significance in terms of cachexia associated with them. Of these, 80 polymorphisms (in 51 genes) were replicated in more than one study with 24 polymorphisms found to influence two or more hallmarks of cachexia (i.e. inflammation, loss of fat mass and/or lean mass and reduced survival). Such election of candidate genes and polymorphisms is a key element of multigene study design. The systematic review provides a contemporary basis to select genes and/or polymorphisms for further association studies in cancer cachexia, and to develop their potential as susceptibility biomarkers of cachexia. Phenotype – genotype associations A total of 1276 patients were recruited, phenotyped and genotyped. There were 545 new patients and 731 patients from a previous study. In our new cohort and in keeping with the previous literature, patients who carried the C allele of the rs6136 SNP in the SELP gene, were at a reduced risk of developing cachexia defined by WL. This association applied to all degrees of weight loss ( > 5%, > 10% or > 15%), and not just at the > 10% level as described previously in the literature. When examining newly identified SNPs in a stage 1 analysis for the weight loss phenotype that included 1276 cancer patients, twelve new candidate SNPs were significant. Six of these SNPs are associated with muscle metabolism in five genes (IGF1, CPN1, FOXO1, FOXO3, and ACVR2B), three are associated with adipose tissue metabolism in two genes (LEPR and TOMM40 (APOE on the reverse strand)), two with corticosteroid signalling in one gene (IFT172 (GCKR on the reverse strand)) and one with the immune response in one gene (TLR4). Two polymorphisms (rs1935949 and rs4946935) in the gene encoding for FOXO3 were consistently associated with WL of increasing severity ( > 5% and > 10%). On the basis that WL is a continuum in the cachectic process, the observation that both SELP and FOXO3 associate with the higher degrees of WL suggests that these genetic signatures may be of particular significance. The role of P-selectin in the genesis of cachexia remains to be determined. When examining all SNPs in a stage 1 analysis for the LM phenotype, 5 SNPs were associated significantly with the cachexia phenotype: (i) rs4291 in the angiotensin converting enzyme (ACE) gene in chromosome 17; this gene has been associated with muscle function and metabolism; (ii) rs10636 in chromosome 16 in the metallothionein 2a gene; this gene has been shown to be involved in zinc dyshomeostasis which may contribute to cancer cachexia; (iii) rs1190584 in chromosome 14 in the WDR20 gene; this gene encodes a WD repeat-containing protein that functions to preserve and regulate the activity of the USP12-UAF1 deubiquitinating enzyme complex; (iv) rs3856806 in the peroxisome proliferator-activated receptor gamma (PPARG) gene in chromosome 3 which has been demonstrated to be involved in fatty acid and glucose metabolism; and (v) rs3745012 in chromosome 18 in the lipin 2 (LPIN2) gene; this gene represents a candidate gene for human lipodystrophy, characterised by loss of body fat, fatty liver, hypertriglyceridemia, and insulin resistance. When examining all SNPs in a stage 1 analysis for the LM + > 2%WL phenotype 4 SNPs were associated significantly with the cachexia phenotype. rs12409877 in the leptin receptor (LEPR) located on chromosome 3, LEPR binds leptin and is involved in adipose tissue regulation. rs2268757 located in the activin receptor type-2B (ACVR2B) gene on chromosome 3, ACVR2B is a high affinity activin type 2 receptor which mediates signalling by a subset of TGF-β family ligands including myostatin, activin, GDF11 and others. SNPs in the tumour necrosis factor (TNF) (rs1799964) and ACE (rs4291) genes were also significantly associated with the phenotype. Whether genes demonstrating significant associations with the cachexia phenotypes had altered transcript expression in muscle from cancer patients with or without those phenotypes was also investigated.

Thesis (PhD) -- University of South Australia, 1992

Thesis (PhD) -- University of South Australia, 1992

Background: Diet and exercise have been recommended to reduce the risk of colorectal cancer (CRC) in individuals with obesity. However, the effects of these interventions on muscle remodeling during CRC initiation in individuals who were previously obese is unknown. Since CRC is associated with a high-risk of cachexia, it is important to understand how diet and exercise interventions can impact muscle remodeling in populations at risk of developing CRC-induced cachexia. Our aim was to investigate the effects of weight loss, with or without exercise, on markers of muscle remodeling in a mouse model of CRC. We hypothesized that exercise plus weight loss would increase muscle mass, reduce muscle fibro/fatty tissue, and increase muscle stem/progenitor cell content compared to weight loss alone. Methods: Mice consumed a high-fat diet (HFD) to induce obesity or a control (CON) diet. Subsequently, mice received injections of azoxymethane (AOM) to induce CRC. Then, weight loss was induced in HFD mice by placing them on the CON diet and those mice either remained sedentary (HFD-SED) or completed a treadmill exercise intervention (HFD-EX). Results: After 40 weeks, mice were sacrificed and analyzed for markers of muscle remodeling. HFD-SED and HFD-EX showed weight loss and a loss in percent fat mass when looking at changes between sacrifice and before AOM injections (p<0.05 vs. CON). HFD-SED and HFD-EX had increased lean mass (p<0.05 vs. CON), and HFD-EX had increased tibialis anterior (TA) weight (p<0.05 vs. CON). The proportion of medium-sized fibers increased (p<0.05 vs. HFD-SED and CON) in HFD-EX, but there were no differences in overall cross-sectional area, myonuclei per fiber, or myonuclear domain. HFD-SED had increased fibrosis (p<0.05 vs. HFD-EX and CON) and adiposity (p<0.05 vs. CON). The number of committed (Pax7+MyoD+) satellite cells (SCs) and FAPs was greater in HFD-EX (p<0.05 vs. CON). There were no differences in uncommitted (Pax7+MyoD-) or differentiated (Pax7-MyoD+) SCs. Additionally, nuclear p-NF-κB was reduced following exercise (p<0.05), specifically in the interstitium with a significant decrease in the number of interstitial p-NF-κB cells in the HFD-EX group (p<0.05 vs. CON and HFD-SED). Conclusions: Findings suggest that a HFD, followed by weight loss with exercise, can reduce fibrotic and fatty degeneration of the muscle and improve markers of muscle remodeling. These findings provide the rationale to further examine exercise interventions for maintaining muscle quality during weight loss interventions to reduce CRC-induced cachexia.

Cachexia or muscle atrophy is a condition that is associated with a variety of diseases such as chronic heart failure and cancer. In North America, Europe and Japan, more than 8 million patients suffer from cachexia, and it is estimated that cachexia is the cause of death in 30% of cancer patients. Unfortunately, there is no available treatment for cachexia. Bexarotene, a retinoid X receptor (RXR) agonist, is a FDA approved drug used to treat cancer and is able to induce myogenic differentiation in embryonic stem cells. In this study, we investigated the mechanism by which bexarotene enhances myogenic differentiation. The Akt signaling pathway is required for myogenesis and thus we examined its involvement in bexarotene-enhanced myogenic differentiation. We showed that bexarotene, through the activation of RXR signaling, regulates Akt2 expression to enhance myoblast differentiation and fusion. Additionally, we showed that Akt2, but neither Akt1 nor Akt3, is required for bexarotene-enhanced differentiation. Furthermore, we showed that the activation of RXR signaling by bexarotene correlates with a specific histone acetylation mark at the Akt2 locus. More importantly, we demonstrated that bexarotene is able to rescue myoblast differentiation in an in vitro cachexia system. Taken together, our data revealed the significance of Akt2 in bexarotene-enhanced myogenic differentiation and the potential of using bexarotene as a treatment for cachexia.

This work examines skeletal muscle catabolism in cancer and its attenuation by Eicosapentaenoic Acid (EPA). In vivo studies in mice bearing a cachexia inducing murine colon adenocarcinoma - MAC16, demonstrated an elevation in the gastrocnemius muscle in the activity and expression of regulatory components of the ubiquitin-proteasome proteolytic pathway. This was accompanied by an accelerated loss of muscle tissue correlating with an increase in overall weight loss, all of which were attenuated by prior daily dosing with EPA. Recently a proteolysis inducing factor (PIF) has been isolated from the MAC16 tumour, and from the serum and urine of cachectic cancer patients. Previous studies have shown that PIF induces protein degradation in vitro, and that this is possibly mediated through 15-hydroxyeicosatetraenoic acid (15-HETE), a metabolite of the n-6 polyunsaturated fatty acid- arachidonate. Employing the murine myoblast cell line C2C12, it was shown that both PIF and 15-HETE increased protein degradation and expression of proteasome subunits, processes which were again attenuated by prior incubation in EPA. Similarly, in NMRI mice which had been fasted for 24hours, EPA and the lipoxygenase inhibitor CV-6504 (but not structurally related fatty acids) inhibited skeletal muscle proteolysis and expression of various proteasome subunits, showing that firstly, EPA may be anti-cachexic partly through its ability to influence 15-HETE production; and secondly that the effect is specific for EPA as other fatty acids had no effect. Previous studies have suggested the involvement of the signal transduction family NFKB in response to PIF in the liver. It has been demonstrated here that both PIF and 15-HETE increased nuclear translocation of NFKB in the skeletal muscle of tumour bearing mice and that EPA inhibited this process by its ability to prevent the degradation of the NFKB inhibitor protein IKB. When an NFKB inhibitor was added to C2C12 myotubes, prior to the addition of PIF, proteasome activity and protein degradation was inhibited, showing that NFKB is responsible for the increased proteasome activity and muscle catabolism induced by PIF. Taken together this work suggests that 15-hydroxyeicosatetraenoic acid is the intracellular mediator for PIF induced protein degradation in skeletal muscle and that elevated muscle catabolism is accomplished through an increased functioning of the ubiquitin-proteasome pathway, a process possibly mediated through an NFKB dependent mechanism. The anticachectic (and possibly the anti-tumourigenic) effects of EPA appear to be achieved in part by its ability to inhibit the degradation of IKB and possibly by its ability to interfere with 15-HETE production.