Animal Models Of Cancer Cachexia Research Articles

The xanthine oxidase inhibitor oxypurinol reduces cancer cachexia-induced cardiomyopathy

Cachexia is a common complication of cancer and may be responsible for 22% of all cancer-related deaths. The exact cause of death in cancer cachexia patients is unknown. Recently, atrophy of the heart has been described in cancer cachexia animal models, which resulted in impaired cardiac function and is likely to contribute to mortality. In cancer patients hyperuricaemia independent of tumour lysis syndrome is often associated with a worse prognosis. Xanthine oxidase (XO) metabolizes purines to uric acid and its inhibition has been shown to improve clinical outcome in patients with chronic heart failure. The rat Yoshida AH-130 hepatoma cancer cachexia model was used in this study. Rats were treated with 4 or 40 mg/kg/d oxypurinol or placebo starting one day after tumour-inoculation for maximal 15 days. Cardiac function was analyzed by echocardiography on day 11. Here we show that inhibition of XO by oxypurinol significantly reduces wasting of the heart and preserves cardiac function. LVEF was higher in tumour-bearing rats treated with 4 mg/kg/d (61±4%) or 40 mg/kg/d (64±5%) oxypurinol vs placebo (51±3%, both p<0.05). Fractional shortening was improved by 4 mg/kg/d (43±3%) oxypurinol vs placebo (30±2, p<0.05), while 40 mg/kg/d oxypurinol (41±5%) did not reach statistical significance. Cardiac output was increased in the 4 mg/kg/d dose only (71±11 mL/min vs placebo 38±4 mL/min, p<0.01). Inhibition of XO with oxypurinol has beneficial effects on cardiac mass and function in a rat model of severe cancer cachexia, suggesting that XO might be a viable drug target in cancer cachexia.

Simvastatin reduces wasting and improves cardiac function as well as outcome in experimental cancer cachexia

Chronic inflammation is common in cancer cachexia (CC) and directly involved in the atrophy seen in this condition. Recently, several groups have described a form of cardiomyopathy in CC animal models. Hence, we investigated the effect of simvastatin with its known anti-inflammatory and cardioprotective effects in a rat model of CC. Juvenile Wister Han rats (weight approx. 200 g) were inoculated with Yoshida AH-130 hepatoma cells and treated once daily with 0.1, 1, 10 or 20 mg/kg/d simvastatin or placebo for 14 days. Body weight and body composition (NMR) were assessed at baseline and at the end of the study. Cardiac function was analysed by echocardiography at baseline and day 11. Tumour-bearing, placebo-treated rats lost 47.9±3.8 g of their initial body weight. Treatment with 0.1, 1, 10 or 20 mg/kg/d simvastatin significantly reduced wasting by 39.6%, 47.6%, 28.5% and 35.4%, respectively (all p<0.05 vs. placebo). This was mainly due to reduced atrophy of lean mass, i.e. muscle mass. Cardiac function was significantly improved, e.g. cardiac output (untreated sham: 78.9 mL/min) was severely impaired in tumour-bearing rats (42.4 mL/min) and improved by 1, 10 or 20 mg/kg/d simvastatin (62.2, 59.0 and 57.0 mL/min, respectively, all p<0.05 vs. placebo). Most importantly, 10 or 20 mg/kg/d simvastatin reduced mortality (HR:0.16, 95%CI:0.04-0.76, p=0.021 and HR:0.16, 95%CI:0.03-0.72, p=0.017 vs placebo, respectively). Simvastatin attenuated loss of body weight as well as muscle mass and improved cardiac function leading to improved survival in this CC model. Simvastatin may be beneficial in a clinical setting to treat CC.

Neural invasion induces cachexia via astrocytic activation of neural route in pancreatic cancer

Pancreatic cancer is characterized by a high frequency of cachexia, pain and neural invasion (N-inv). Neural damage is occurred by N-inv and modulates pain and muscle atrophy via the activation of astrocyte in the connected spine. The activated astrocyte by N-inv, thus, may affect cachexia in pancreatic cancer. Clinical studies in patients and autopsy cases with pancreatic cancer have revealed that N-inv is related to cachexia and astrocytic activation. We established a novel murine model of cancer cachexia using N-inv of human pancreatic cancer cells. Mice with N-inv showed a loss of body weight, skeletal muscle and fat mass without appetite loss, which are compatible with an animal model of cancer cachexia. Activation of astrocytes in the spinal cord connected with N-inv was observed in our model. Experimental cachexia was suppressed by disrupting neural routes or inhibiting the activation of astrocytes. These data provide the first evidence that N-inv induces cachexia via astrocytic activation of neural route in pancreatic cancer.

Myocardial dysfunction in an animal model of cancer cachexia

Aims Fatigue is a common syndrome in cancer patients independent of anti-tumor therapies or tumor type and is a problematic symptom in persons with incurable tumor disease. In rodents, tumor-induced fatigue is associated with a progressive loss of skeletal muscle mass and increased expression of biomarkers of muscle protein degradation. The purpose of the present study was to determine if muscle wasting and the expression of biomarkers of muscle protein degradation occur in the hearts of tumor-bearing mice, and if these effects of tumor growth are associated with cardiac dysfunction. Main Methods The colon 26 adenocarcinoma cell line was implanted into female CD2F1 mice and the amount of skeletal muscle wasting, in vivo heart function, in vitro cardiomyocyte function, and biomarkers of muscle protein degradation were determined. Key Findings The expression of biomarkers of protein degradation were increased in both the gastrocnemius and heart muscle of tumor-bearing mice and associated with systolic dysfunction in vivo. Cardiomyocyte function was significantly depressed during both cellular contraction and relaxation. Significance These results suggest that heart muscle is directly affected by tumor growth, with myocardial function more severely compromised at the cellular level than what is observed using clinical methods.

Myocardial dysfunction in an animal model of cancer cachexia

Aims Fatigue is a common occurrence in cancer patients regardless of tumor type or anti-tumor therapies and is an especially problematic symptom in persons with incurable tumor disease. In rodents, tumor-induced fatigue is associated with a progressive loss of skeletal muscle mass and increased expression of biomarkers of muscle protein degradation. The purpose of the present study was to determine if muscle wasting and expression of biomarkers of muscle protein degradation occur in the hearts of tumor-bearing mice, and if these effects of tumor growth are associated with changes in cardiac function. Main methods The colon26 adenocarcinoma cell line was implanted into female CD2F1 mice and skeletal muscle wasting, in vivo heart function, in vitro cardiomyocyte function, and biomarkers of muscle protein degradation were determined. Key findings Expression of biomarkers of protein degradation were increased in both the gastrocnemius and heart muscle of tumor-bearing mice and caused systolic dysfunction in vivo. Cardiomyocyte function was significantly depressed during both cellular contraction and relaxation. Significance These results suggest that heart muscle is directly affected by tumor growth, with myocardial function more severely compromised at the cellular level than what is observed using echocardiography.

Formoterol fumarate and roxithromycin effects on muscle mass in an animal model of cancer cachexia

Our study probed the effects of the beta-2 adrenergic agonist, formoterol and the macrolide antibiotic, roxithromycin, on muscle wasting in a well-characterized animal model of cancer cachexia. Female Wistar rats were inoculated with Yoshida AH130 ascites hepatoma (AH) cells to induce rapid and severe cachexia as demonstrated by wet weight determinations of the hearts, gastrocnemius muscles and carcasses. The control animals received saline (vehicle) inoculations. The AH-inoculated rats were treated once daily for four days by i.p. injection with a vehicle control, 1 mg/kg formoterol, 5 and 50 mg/kg roxithromycin or 1 mg/kg formoterol plus 5, 25, 40 and 50 mg/kg roxithromycin. The saline-inoculated animals were treated by i.p. injection with vehicle control, 1 mg/kg formoterol, 5 and 40 mg/kg roxithromycin. As a result, formoterol alone reduced the loss of muscle mass in the AH-inoculated rats by approximately one-half, consistent with literature reports. Roxithromycin alone at 5 mg/kg did not affect muscle mass in the AH-inoculated rats. Roxithromycin given alone at 50 mg/kg reduced the loss of muscle mass in AH-inoculated animals by approximately one-half. With respect to the antagonizing muscle loss, formoterol combined with either 5 or 25 mg/kg roxithromycin did not reach statistical significance versus formoterol alone, while formoterol plus either 40 or 50 mg/kg roxithromycin enhanced protection against muscle loss versus formoterol alone. The gastrocnemius weights in the AH-inoculated rats treated with formoterol combined with 40 mg/kg roxithromycin were not significantly different from the muscle weights in the saline-inoculated controls. To sum up, formoterol and roxithromycin apparently exert anti-cachectic effects in an additive fashion and may offer the potential for combination therapy in cachexia.

Effects of Curcumin on Tumor Growth and Muscle Mass in a Mouse Model of Cancer Cachexia

Purpose/Objectives: To determine whether a diet containing 1% curcumin, a highly colored botanical food containing compounds that suppress expression of proinflammatory mediators implicated in the pathobiology of tumor-induced muscle wasting, would preserve muscle mass in two animal models of cancer cachexia.

Comparison of Animal Models for Head and Neck Cancer Cachexia

Despite its negative impact on cancer patients, there are few animal models of cancer cachexia. Our hypothesis was that different human cell lines would variably induce cachexia. Prospective animal study. We established two xenograft models in athymic mice and compared these with a cachexigenic cell line, the murine adenocarcinoma 16 (MAC16) cell line. Eight-week-old female, athymic mice were injected with human head and neck cell lines (JHU022, JHU012) and the MAC16 cell line. Body weight, food intake, body composition, leg weights, serum cytokines, and lipid mobilizing factor (LMF) were compared. Mean food intake for all groups was equivalent. Mean percent change in body weight after 18 days was 18%, 19%, 12%, and 3% for control, JHU012, JHU022, and MAC16 experimental groups, respectively. Both JHU022- and MAC16-injected mice showed wasting even when tumor burden was low. In contrast, mice injected with JHU012 developed larger tumors yet lacked evidence of cachexia. These mice demonstrated loss of lean body mass but not fat mass. Serum cytokine levels for interleukin (IL)-1 alpha and IL-1 beta were elevated in JHU022-bearing mice, whereas IL-1 alpha, IL-6, interferon (IFN)-gamma, and tumor necrosis factor alpha (TNF)-alpha were elevated in MAC16-bearing mice. LMF was present in both the JHU022 and JHU012 cell lines. The JHU022 cell line caused more severe cachexia than the JHU012 cells, suggesting these cell lines may be used to further study cancer cachexia. IL-1 alpha and IL-1 beta in the JHU022 model may be mediators of cachexia, whereas TNF-alpha, IFN-gamma, and IL-6 may be mediators in MAC16-induced cachexia.

The Feed Factor: Estrogenic Variability in Lab Animal Diets

Animal studies have long been a cornerstone of biomedical and environmental health research, and scientists need assurance that animals used in these studies are being cared for in ways that will not unknowingly influence experimental outcomes. But a growing number of scientists have voiced concern over the possibility that certain estrogenic compounds present in lab animal feed may skew test results. These compounds are deemed potentially problematic because they can bind to estrogen receptors and induce estrogen-like effects in animals, humans, and cells grown in culture. Some experts have advocated strict standardization of rodent chows and even the removal of dietary phytoestrogens. This emergent controversy was the focus of “DIET II—The Effect of Variability in Estrogenic Activity of Commercial Animal Feeds: Interaction with Manufacturers, NIH Officials, and Scientific Societies to Develop a Solution,” a full-day meeting held 3 August 2006 in Research Triangle Park, North Carolina. The meeting, the second in a series on the topic, was cosponsored by the NIEHS and the NIH Office of Dietary Supplements (ODS). Discussions at the meeting centered on the variation in estrogenic activity between feed batches, the effects of these estrogenic components on endocrine-related end points, and the difficulties inherent in comparing, interpreting, and reproducing these end points over time within and between different laboratories when background levels of diet-related estrogenic activity are not adequately documented. Findings presented at this meeting made it clear that researchers studying estrogen-related end points can not afford to overlook the influence of the test rodent’s diet. “This workshop is an excellent example of the cumulative and self-correcting nature of the scientific process,” said ODS nutritionist Elizabeth Yetley, a conference co-organizer. “That is, through the accumulation of results from a body of experimental evidence, the importance of approaches for better-defined animal diets relative to their potential estrogenic activity have been identified, and measures to improve future research in this area are being undertaken by the scientific community.” Participants at the conference—organized by NIEHS scientists Jerrold Heindel and Julius Thigpen, along with Yetley and University of Missouri–Columbia biologist Frederick vom Saal—included investigators from the endocrine disruptor research community as well as representatives from animal feed companies. This spectrum of representatives reflected the fact that, in Heindel’s words, “researchers and animal care divisions of research institutions are beginning to pay attention to the phytoestrogen issue, and feed manufacturers want to know what the scientific community wants.” Heindel described a sincere interest on the part of both sides to reach a “win–win” solution, one that would yield animal diets of a known estrogenicity that could be used by researchers in all fields of physiology and toxicology, but that also would not unduly burden the feed manufacturers.

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 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.

Regulation of Protein Catabolism by Muscle-Specific and Cytokine-Inducible Ubiquitin Ligase E3α-II during Cancer Cachexia

The progressive depletion of skeletal muscle is a hallmark of many types of advanced cancer and frequently is associated with debility, morbidity, and mortality. Muscle wasting is primarily mediated by the activation of the ubiquitin-proteasome system, which is responsible for degrading the bulk of intracellular proteins. E3 ubiquitin ligases control polyubiquitination, a rate-limiting step in the ubiquitin-proteasome system, but their direct involvement in muscle protein catabolism in cancer remains obscure. Here, we report the full-length cloning of E3alpha-II, a novel "N-end rule" ubiquitin ligase, and its functional involvement in cancer cachexia. E3alpha-II is highly enriched in skeletal muscle, and its expression is regulated by proinflammatory cytokines. In two different animal models of cancer cachexia, E3alpha-II was significantly induced at the onset and during the progression of muscle wasting. The E3alpha-II activation in skeletal muscle was accompanied by a sharp increase in protein ubiquitination, which could be blocked by arginine methylester, an E3alpha-selective inhibitor. Treatment of myotubes with tumor necrosis factor alpha or interleukin 6 elicited marked increases in E3alpha-II but not E3alpha-I expression and ubiquitin conjugation activity in parallel. E3alpha-II transfection markedly accelerated ubiquitin conjugation to endogenous cellular proteins in muscle cultures. These findings show that E3alpha-II plays an important role in muscle protein catabolism during cancer cachexia and suggest that E3alpha-II is a potential therapeutic target for muscle wasting.

Adaptation of the ubiquitin-proteasome proteolytic pathway in cancer cachexia.

The ubiquitin-proteasome proteolytic pathway is of major importance in the breakdown of skeletal muscle proteins. The first step in this pathway is the covalent attachment of polyubiquitin chains to the targeted protein. Polyubiquitinylated proteins are then recognized and degraded by the 26S proteasome complex. In this review, we critically analyze recent findings in the regulation of ubiquitinylation of protein substrates and of their subsequent proteasome-dependent degradation in animal models of cancer cachexia. In particular, we discuss the influence of various mediators (anorexia, hormones, prostaglandins, cytokines, and proteolysis-inducing factor) in signaling the activation of ubiquitin-proteasome proteolysis in skeletal muscle. These findings have lead to new concepts that are starting to be used for preventing cachexia in cancer and other wasting diseases.

Energy expenditure and protein synthesis rates in an animal model of cancer cachexia

Food intake and energy expenditure of cachectic tumour bearing mice were measured during the course of weight loss. Four weeks after implantation of the MAC-16 tumour the body weight was reduced by 20%, there was no significant reduction in food intake, and body composition analysis revealed that both body fat and protein mass were decreased. Oxygen consumption and carbon dioxide production were measured over a 24h period both before and at weekly intervals after tumour implantation. There was a gradual increase in the rates of both oxygen consumption and carbon dioxide production per gram body weight. Similarly, energy expenditure per gram body weight was increased during the 3rd (11%) and 4th (23%) weeks. In contrast, the food intake per gram body weight was unchanged during the first three weeks and increased by only 8% during the 4th week. Despite the development of cachexia, rates of protein synthesis in the liver, heart, kidney and skeletal muscle were the same four weeks after tumour implantation as those in non-tumour bearing mice. Thus, in this murine model of cancer cachexia a negative energy balance resulted from failure of food intake to compensate for increased energy demands. These findings point to the unique pattern of metabolic alterations which occur in different models of cancer cachexia.

Amino Acid Metabolism in Human Cancer Cachexia

Cancer cachexia is a complex syndrome that occurs with variable incidence in patients with solid tumors and those with hematologic malignancies. It is associated with characteristic physical and laboratory findings, and at a more fundamental level, with significant abnormalities in carbohydrate, lipid, and protein metabolism. These alterations in intermediary metabolism are demonstrable early in the syndrome, even before the onset of weight loss, when the more characteristic features of cancer cachexia are evident. Progressive wasting of peripheral protein stores is a major feature of cancer cachexia and often one of the most graphic realities of malignancy for patients and their families. Unfortunately, significant problems with the animal models of cancer cachexia make conclusions derived from animal studies difficult to extrapolate to humans. Data from human studies indicate that human cancer cachexia is associated with minimal aberrations in circulating free amino acid concentrations; increased whole-body protein turnover, synthesis, and catabolism; reduced rates of skeletal muscle protein synthesis; and increased rates of hepatic protein synthesis. Whether or not these alterations represent pathologic responses or physiologic adaptation by the host to the presence of malignancy remains to be seen. Future investigations must focus on more careful evaluation of interorgan amino acid metabolism, investigation of skeletal muscle protein catabolic rates in cancer cachexia, and definition of the roles of altered hormonal and cytokine regulation of these processes. Such studies will more precisely define the level at which amino acid metabolism is altered significantly and, we hope, permit more specific therapeutic intervention designed to reverse the debilitating effects of cancer cachexia.