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Abstract
The global burden of cancer cachexia is increasing along with drastic increase in cancer patients. Cancer itself leads to cachexia, and cachexia development is associated with events like altered hemodynamics, and reduced functional capacity of the heart among others which lead to failure of the heart and are called cardiovascular complications associated with cancer cachexia. In some patients, the anti-cancer therapy also leads to this cardiovascular complications. So, in this review, an attempt is made to understand the mechanisms, pathophysiology of cardiovascular events in cachectic patients. Important processes which cause cardiovascular complications include alterations in the structure of the heart, loss of cardiac mass and functioning, cardiac fibrosis and cardiac remodeling, apoptosis, cardiac muscle atrophy, and mitochondrial alterations. Previously, the available treatment options were limited to nutraceuticals and physical exercise. Recently, studies with some prospective agents that can improve cardiac health have been reported, but whether their action is effective in cardiovascular complications associated with cancer cachexia is not known or are under trial.
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Martin A, Freyssenet D. Phenotypic features of cancer cachexia-related loss of skeletal muscle mass and function: lessons from human and animal studies. J Cachexia Sarcopenia Muscle 2021; 12:252-273. [PMID: 33783983 PMCID: PMC8061402 DOI: 10.1002/jcsm.12678] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/22/2020] [Accepted: 12/30/2020] [Indexed: 12/18/2022] Open
Abstract
Cancer cachexia is a complex multi-organ catabolic syndrome that reduces mobility, increases fatigue, decreases the efficiency of therapeutic strategies, diminishes the quality of life, and increases the mortality of cancer patients. This review provides an exhaustive and comprehensive analysis of cancer cachexia-related phenotypic changes in skeletal muscle at both the cellular and subcellular levels in human cancer patients, as well as in animal models of cancer cachexia. Cancer cachexia is characterized by a major decrease in skeletal muscle mass in human and animals that depends on the severity of the disease/model and the localization of the tumour. It affects both type 1 and type 2 muscle fibres, even if some animal studies suggest that type 2 muscle fibres would be more prone to atrophy. Animal studies indicate an impairment in mitochondrial oxidative metabolism resulting from a decrease in mitochondrial content, an alteration in mitochondria morphology, and a reduction in mitochondrial metabolic fluxes. Immuno-histological analyses in human and animal models also suggest that a faulty mechanism of skeletal muscle repair would contribute to muscle mass loss. An increase in collagen deposit, an accumulation of fat depot outside and inside the muscle fibre, and a disrupted contractile machinery structure are also phenotypic features that have been consistently reported in cachectic skeletal muscle. Muscle function is also profoundly altered during cancer cachexia with a strong reduction in skeletal muscle force. Even though the loss of skeletal muscle mass largely contributes to the loss of muscle function, other factors such as muscle-nerve interaction and calcium handling are probably involved in the decrease in muscle force. Longitudinal analyses of skeletal muscle mass by imaging technics and skeletal muscle force in cancer patients, but also in animal models of cancer cachexia, are necessary to determine the respective kinetics and functional involvements of these factors. Our analysis also emphasizes that measuring skeletal muscle force through standardized tests could provide a simple and robust mean to early diagnose cachexia in cancer patients. That would be of great benefit to cancer patient's quality of life and health care systems.
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Affiliation(s)
- Agnès Martin
- Inter‐university Laboratory of Human Movement BiologyUniversité de Lyon, University Jean Monnet Saint‐EtienneSaint‐ÉtienneFrance
| | - Damien Freyssenet
- Inter‐university Laboratory of Human Movement BiologyUniversité de Lyon, University Jean Monnet Saint‐EtienneSaint‐ÉtienneFrance
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Dolly A, Dumas JF, Servais S. Cancer cachexia and skeletal muscle atrophy in clinical studies: what do we really know? J Cachexia Sarcopenia Muscle 2020; 11:1413-1428. [PMID: 33053604 PMCID: PMC7749617 DOI: 10.1002/jcsm.12633] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/24/2020] [Accepted: 09/16/2020] [Indexed: 12/16/2022] Open
Abstract
Research investigators have shown a growing interest in investigating alterations underlying skeletal muscle wasting in patients with cancer. However, skeletal muscle dysfunctions associated with cancer cachexia have mainly been studied in preclinical models. In the present review, we summarize the results of clinical studies in which skeletal muscle biopsies were collected from cachectic vs. non-cachectic cancer patients. Most of these studies suggest the presence of significant physiological alterations in skeletal muscle from cachectic cancer patients. We suggest a hypothesis, which connects structural and metabolic parameters that may, at least in part, be responsible for the skeletal muscle atrophy characteristic of cancer cachexia. Finally, we discuss the importance of a better standardization of the diagnostic criteria for cancer cachexia, as well as the requirement for additional clinical studies to improve the robustness of these conclusions.
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Affiliation(s)
- Adeline Dolly
- INSERM UMR 1069, Nutrition Croissance et Cancer, Université de Tours, Tours, France
| | - Jean-François Dumas
- INSERM UMR 1069, Nutrition Croissance et Cancer, Université de Tours, Tours, France
| | - Stéphane Servais
- INSERM UMR 1069, Nutrition Croissance et Cancer, Université de Tours, Tours, France
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Anoveros‐Barrera A, Bhullar AS, Stretch C, Esfandiari N, Dunichand‐Hoedl AR, Martins KJ, Bigam D, Khadaroo RG, McMullen T, Bathe OF, Damaraju S, Skipworth RJ, Putman CT, Baracos VE, Mazurak VC. Clinical and biological characterization of skeletal muscle tissue biopsies of surgical cancer patients. J Cachexia Sarcopenia Muscle 2019; 10:1356-1377. [PMID: 31307124 PMCID: PMC9536086 DOI: 10.1002/jcsm.12466] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 05/10/2019] [Accepted: 05/28/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Researchers increasingly use intraoperative muscle biopsy to investigate mechanisms of skeletal muscle atrophy in patients with cancer. Muscles have been assessed for morphological, cellular, and biochemical features. The aim of this study was to conduct a state-of-the-science review of this literature and, secondly, to evaluate clinical and biological variation in biopsies of rectus abdominis (RA) muscle from a cohort of patients with malignancies. METHODS Literature was searched for reports on muscle biopsies from patients with a cancer diagnosis. Quality of reports and risk of bias were assessed. Data abstracted included patient characteristics and diagnoses, sample size, tissue collection and biobanking procedures, and results. A cohort of cancer patients (n = 190, 88% gastrointestinal malignancies), who underwent open abdominal surgery as part of their clinical care, consented to RA biopsy from the site of incision. Computed tomography (CT) scans were used to quantify total abdominal muscle and RA cross-sectional areas and radiodensity. Biopsies were assessed for muscle fibre area (μm2 ), fibre types, myosin heavy chain isoforms, and expression of genes selected for their involvement in catabolic pathways of muscle. RESULTS Muscle biopsy occurred in 59 studies (total N = 1585 participants). RA was biopsied intraoperatively in 40 studies (67%), followed by quadriceps (26%; percutaneous biopsy) and other muscles (7%). Cancer site and stage, % of male participants, and age were highly variable between studies. Details regarding patient medical history and biopsy procedures were frequently absent. Lack of description of the population(s) sampled and low sample size contributed to low quality and risk of bias. Weight-losing cases were compared with weight stable cancer or healthy controls without considering a measure of muscle mass in 21 out of 44 studies. In the cohort of patients providing biopsy for this study, 78% of patients had preoperative CT scans and a high proportion (64%) met published criteria for sarcopenia. Fibre type distribution in RA was type I (46% ± 13), hybrid type I/IIA (1% ± 1), type IIA (36% ± 10), hybrid type IIA/D (15% ± 14), and type IID (2% ± 5). Sexual dimorphism was prominent in RA CT cross-sectional area, mean fibre cross-sectional area, and in expression of genes associated with muscle growth, apoptosis, and inflammation (P < 0.05). Medical history revealed multiple co-morbid conditions and medications. CONCLUSIONS Continued collaboration between researchers and cancer surgeons enables a more complete understanding of mechanisms of cancer-associated muscle atrophy. Standardization of biobanking practices, tissue manipulation, patient characterization, and classification will enhance the consistency, reliability, and comparability of future studies.
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Affiliation(s)
- Ana Anoveros‐Barrera
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental SciencesUniversity of AlbertaEdmontonABCanada
| | - Amritpal S. Bhullar
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental SciencesUniversity of AlbertaEdmontonABCanada
| | | | - Nina Esfandiari
- Department of Oncology, Faculty of Medicine and DentistryUniversity of AlbertaEdmontonABCanada
| | - Abha R. Dunichand‐Hoedl
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental SciencesUniversity of AlbertaEdmontonABCanada
| | - Karen J.B. Martins
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental SciencesUniversity of AlbertaEdmontonABCanada
| | - David Bigam
- Department of Surgery, Faculty of Medicine and DentistryUniversity of AlbertaEdmontonABCanada
| | - Rachel G. Khadaroo
- Department of Surgery, Faculty of Medicine and DentistryUniversity of AlbertaEdmontonABCanada
| | - Todd McMullen
- Department of Surgery, Faculty of Medicine and DentistryUniversity of AlbertaEdmontonABCanada
| | - Oliver F. Bathe
- Department of OncologyUniversity of CalgaryCalgaryABCanada
- Department of SurgeryUniversity of CalgaryCalgaryABCanada
| | - Sambasivarao Damaraju
- Department of Laboratory Medicine and PathologyUniversity of AlbertaEdmontonABCanada
- Department of Oncology, Faculty of Medicine and DentistryUniversity of AlbertaEdmontonABCanada
| | | | - Charles T. Putman
- Faculty of Kinesiology, Sport, and Recreation, Faculty of Medicine and DentistryUniversity of AlbertaEdmontonABCanada
| | - Vickie E. Baracos
- Department of Oncology, Faculty of Medicine and DentistryUniversity of AlbertaEdmontonABCanada
| | - Vera C. Mazurak
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental SciencesUniversity of AlbertaEdmontonABCanada
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Bossola M, Marzetti E, Rosa F, Pacelli F. Skeletal muscle regeneration in cancer cachexia. Clin Exp Pharmacol Physiol 2016; 43:522-7. [DOI: 10.1111/1440-1681.12559] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Maurizio Bossola
- Department of Surgery; Catholic University of the Sacred Heart School of Medicine; Rome Italy
| | - Emanuele Marzetti
- Department of Geriatrics, Neurosciences and Orthopedics; Catholic University of the Sacred Heart School of Medicine; Rome Italy
| | - Fausto Rosa
- Department of Surgery; Catholic University of the Sacred Heart School of Medicine; Rome Italy
| | - Fabio Pacelli
- Department of Surgery; Catholic University of the Sacred Heart School of Medicine; Rome Italy
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Tardif N, Klaude M, Lundell L, Thorell A, Rooyackers O. Autophagic-lysosomal pathway is the main proteolytic system modified in the skeletal muscle of esophageal cancer patients. Am J Clin Nutr 2013; 98:1485-92. [PMID: 24108784 DOI: 10.3945/ajcn.113.063859] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND In cancer cachexia, muscle depletion is related to morbidity and mortality. Muscle-wasting mechanisms in cancer patients are not fully understood. OBJECTIVE We investigated the involvement of the proteolytic systems (proteasome, autophagic-lysosomal, calpain, and caspase) in muscle wasting during cancer cachexia. DESIGN Esophageal cancer patients [n = 14; mean ± SD age: 64.1 ± 6.6 y] and weight-stable control patients undergoing reflux surgery (n = 8; age: 57.5 ± 5.8 y) were included. Enzymatic activities were measured in the vastus lateralis and diaphragm. Protein expressions were also measured in the vastus lateralis of control (n = 7) and cancer (n = 8) patients. RESULTS Proteasome, calpain, and caspase 3 activities in the vastus lateralis and diaphragm muscles did not differ between the 2 groups. Cathepsin B and L activities were 90% (± SD) [2.4 ± 0.2 compared with 1.3 ± 0.2 pmol 7-amido-4-methylcoumarin (AMC) · μg protein⁻¹ · min⁻¹; P < 0.001] and 115% (5.3 ± 0.4 compared with 2.5 ± 0.3 pmol AMC · μg protein⁻¹ · min⁻¹; P < 0.001) greater, respectively, in the vastus lateralis of cancer patients than in that of control subjects. We observed (in conjunction with increased lysosomal protease activities) higher microtubule-associated protein 1 light chain 3B-II/I ratios (0.14 ± 0.08 compared with 0.04 ± 0.04) and cathepsin B and L expressions in the vastus lateralis of cancer patients than in that of control subjects (P < 0.05). Protein expression of p62 in the vastus lateralis did not differ between the 2 groups. CONCLUSIONS The autophagic-lysosomal pathway in the skeletal muscle of cancer patients was modified, whereas other proteolytic systems were unchanged. These findings suggest involvement of the autophagic-lysosomal proteolytic system during cancer cachexia development in humans.
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Affiliation(s)
- Nicolas Tardif
- Departments of Anesthesiology and Intensive Care (NT, MK, and OR) and Surgery (LL), Gastrocentrum, Karolinska University Hospital Huddinge and Karolinska Institutet, Stockholm, Sweden, and the Department of Clinical Science, Danderyds Hospital & Department of Surgery, Ersta Hospital, Stockholm, Sweden (AT)
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Muscaritoli M, Molfino A, Gioia G, Laviano A, Rossi Fanelli F. The "parallel pathway": a novel nutritional and metabolic approach to cancer patients. Intern Emerg Med 2011; 6:105-12. [PMID: 20596799 DOI: 10.1007/s11739-010-0426-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 06/16/2010] [Indexed: 12/14/2022]
Abstract
Cancer-associated malnutrition results from a deadly combination of anorexia, which leads to reduced food intake, and derangements of host metabolism inducing body weight loss, and hindering its reversal with nutrient supplementation. Cancer patients often experience both anorexia and weight loss, contributing to the onset of the clinical feature named as anorexia-cachexia syndrome. This condition has a negative impact upon patients' nutritional status. The pathogenesis of the anorexia-cachexia syndrome is multifactorial, and is related to: tumour-derived factors, host-derived factors inducing metabolic derangements, and side effects of anticancer therapies. In addition, the lack of awareness of cancer patients' nutritional issues and status by many oncologists, frequently results in progressive weight loss going undiagnosed until it becomes severe. The critical involvement of host inflammatory response in the development of weight loss, and, in particular, lean body mass depletion, limits the response to the provision of standard nutrition support. A novel nutritional and metabolic approach, named "parallel pathway", has been devised that may help maintain or improve nutritional status, and prevent or delay the onset of cancer cachexia. Such an approach may improve tolerance to aggressive anticancer therapies, and ameliorate the functional capacity and quality of life even in advanced disease stages. The "parallel pathway" implies a multiprofessional and multimodal approach aimed at ensuring early, appropriate and continuous nutritional and metabolic support to cancer patients in any phase of their cancer journey.
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Affiliation(s)
- Maurizio Muscaritoli
- Department of Clinical Medicine, Sapienza University of Rome, viale dell'Università, 37, 00185, Rome, Italy.
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Smith IJ, Aversa Z, Hasselgren PO, Pacelli F, Rosa F, Doglietto GB, Bossola M. Calpain activity is increased in skeletal muscle from gastric cancer patients with no or minimal weight loss. Muscle Nerve 2011; 43:410-4. [PMID: 21305563 DOI: 10.1002/mus.21893] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2010] [Indexed: 11/06/2022]
Abstract
The influence of cancer on skeletal muscle calpain expression and activity in humans is poorly understood. We tested the hypothesis that calpain activity is increased in skeletal muscle from gastric cancer patients with no or <5% weight loss. Muscle biopsies were obtained from rectus abdominis muscle in 15 patients who underwent surgery for gastric cancer and had <5% weight loss and also in 15 control patients. Calpain activity was determined using a calpain-specific substrate in the absence or presence of calcium. The expression of μ- and m-calpain, calpastatin, atrogin-1, and MuRF1 was determined by real-time polymerase chain reaction. Calpain activity was increased by 70% in cancer patients compared with controls. There were no differences in mRNA levels for μ- and m-calpain, calpastatin, atrogin-1, or MuRF1 between control and cancer patients. Calpain activity may be increased in muscle from gastric cancer patients even before changes in molecular markers of muscle wasting and significant weight loss occur.
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Affiliation(s)
- Ira J Smith
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
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Eley HL, Russell ST, Tisdale MJ. Mechanism of activation of dsRNA-dependent protein kinase (PKR) in muscle atrophy. Cell Signal 2010; 22:783-90. [PMID: 20074639 DOI: 10.1016/j.cellsig.2010.01.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 12/22/2009] [Accepted: 01/05/2010] [Indexed: 12/30/2022]
Abstract
The role of Ca(2+) in the activation of PKR (double-stranded-RNA-dependent protein kinase), which leads to skeletal muscle atrophy, has been investigated in murine myotubes using the cell-permeable Ca(2+) chelator BAPTA/AM (1,2-bis (o-aminphenoxy) ethane-N,N,N',N'-tetraacetic acid tetra (acetoxymethyl) ester). BAPTA/AM effectively attenuated both the increase in total protein degradation, through the ubiquitin-proteasome pathway, and the depression of protein synthesis, induced by both proteolysis-inducing factor (PIF) and angiotensin II (Ang II). Since both protein synthesis and degradation were attenuated this suggests the involvement of PKR. Indeed BAPTA/AM attenuated both the activation (autophosphorylation) of PKR and the subsequent phosphorylation of eIF2alpha (eukaryotic initiation factor 2alpha) in the presence of PIF, suggesting the involvement of Ca(2+) in this process. PIF also induced an increase in the activity of both caspases-3 and -8, which was attenuated by BAPTA/AM. The increase in caspase-3 and -8 activity was shown to be responsible for the activation of PKR, since the latter was completely attenuated by the specific caspase-3 and -8 inhibitors. These results suggest that Ca(2+) is involved in the increase in protein degradation and decrease in protein synthesis by PIF and Ang II through activation of PKR by caspases-3 and -8.
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Affiliation(s)
- H L Eley
- Aston University, Birmingham, United Kingdom
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Abstract
Up to 50% of cancer patients suffer from a progressive atrophy of adipose tissue and skeletal muscle, called cachexia, resulting in weight loss, a reduced quality of life, and a shortened survival time. Anorexia often accompanies cachexia, but appears not to be responsible for the tissue loss, particularly lean body mass. An increased resting energy expenditure is seen, possibly arising from an increased thermogenesis in skeletal muscle due to an increased expression of uncoupling protein, and increased operation of the Cori cycle. Loss of adipose tissue is due to an increased lipolysis by tumor or host products. Loss of skeletal muscle in cachexia results from a depression in protein synthesis combined with an increase in protein degradation. The increase in protein degradation may include both increased activity of the ubiquitin-proteasome pathway and lysosomes. The decrease in protein synthesis is due to a reduced level of the initiation factor 4F, decreased elongation, and decreased binding of methionyl-tRNA to the 40S ribosomal subunit through increased phosphorylation of eIF2 on the alpha-subunit by activation of the dsRNA-dependent protein kinase, which also increases expression of the ubiquitin-proteasome pathway through activation of NFkappaB. Tumor factors such as proteolysis-inducing factor and host factors such as tumor necrosis factor-alpha, angiotensin II, and glucocorticoids can all induce muscle atrophy. Knowledge of the mechanisms of tissue destruction in cachexia should improve methods of treatment.
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Affiliation(s)
- Michael J Tisdale
- Nutritional Biomedicine, School of Life and Health Sciences, Aston University, Birmingham, UK.
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Busquets S, Deans C, Figueras M, Moore-Carrasco R, López-Soriano FJ, Fearon KCH, Argilés JM. Apoptosis is present in skeletal muscle of cachectic gastro-intestinal cancer patients. Clin Nutr 2007; 26:614-8. [PMID: 17688974 DOI: 10.1016/j.clnu.2007.06.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 03/27/2007] [Accepted: 06/18/2007] [Indexed: 11/20/2022]
Abstract
BACKGROUND & AIMS Previous studies of our research group have shown that apoptosis is present in skeletal muscle of tumour-bearing animals subject to cachexia. For this reason we decided to investigate the apoptosis in skeletal muscle of cancer patients. METHODS AND RESULTS In the present study, muscle biopsies from weight-losing patients with upper gastro-intestinal cancer showed a significant increase in muscle DNA fragmentation (three-fold), as compared with control subjects. The increase in DNA laddering was associated with an increase in poly(ADP-ribose) polymerase (PARP) cleavage (four-fold) as measured by western blotting. These two events indicate the presence of muscle apoptosis. These changes were associated with a decrease in MyoD protein content, suggesting important alterations in skeletal muscle physiology. CONCLUSIONS The results presented therefore confirm that apoptosis is also present in human subjects undergoing cancer cachexia.
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Affiliation(s)
- Sílvia Busquets
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain
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Abstract
PURPOSE OF REVIEW Cancer anorexia-cachexia syndrome is becoming a critical component in the comprehensive approach to cancer patients because it influences morbidity, mortality and quality of life. Consequently, pathogenic mechanisms have been elucidated to facilitate development of better therapies. Reported findings indicate that increased production of reactive oxygen species and reduced activity of antioxidant enzymes contribute to development of anorexia and cachexia in cancer. RECENT FINDINGS Systemic inflammation impairs tryptophan handling, promoting oxidative stress, which appears to mimic hypothalamic negative feedback signalling. Thus, tryptophan contributes to cancer anorexia by stimulating hypothalamic serotonergic activity and promoting oxidative stress, because neuroinflammation facilitates tryptophan degradation into free radical generators via the kynurenine pathway. Upregulation of protein degradation by increased oxidative stress has been documented in cancer. Also, hypothalamic, cytokine-mediated suppression of fatty acid oxidation reduces food intake, and triggers mitochondrial biogenesis and oxidative gene expression in skeletal muscle, thus potentially increasing oxidative stress. SUMMARY Increased oxidative stress contributes to cancer anorexia and cachexia. Preliminary clinical data on the efficacy of antioxidant therapy in cancer patients are encouraging, but uncertainty persists regarding the optimal dose and timing of administration. Also, better biological/genetic characterization of those cancer patients who are more likely to obtain significant clinical benefits appears necessary.
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