Fish oil supplementation in F1 generation associated with naproxen, clenbuterol, and insulin administration reduce tumor growth and cachexia in Walker 256 tumor-bearing rats

Inflammation as a Therapeutic Target in Cancer Cachexia

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

Consumption of latex from Euphorbia tirucalli L. promotes a reduction of tumor growth and cachexia, and immunomodulation in Walker 256 tumor-bearing rats

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia tirucalli L. is an African plant that grows well in Brazil. Individuals diagnosed with cancer frequently consume latex from E. tirucalli, dissolved in drinking water. In vitro studies confirm the antitumor potential of E. tirucalli latex, but in vivo evaluations are scarce.

AIM OF THE STUDY

To evaluate the effect of intake of an aqueous solution of E. tirucalli latex on tumor growth, cachexia, and immune response in Walker 256 tumor-bearing rats.

MATERIALS AND METHODS

Latex from E. tirucalli was collected and analyzed by LC-MS. Sixty male Wistar rats (age, 90 days) were randomly divided into four groups: C, control group (without tumor); W, Walker 256 tumor-bearing group; SW1, W animals but treated with 25 μL latex/mL water; and SW2, W animals but treated with 50 μL latex/mL water. Animals received 1 mL of latex solution once a day by gavage. After 15 d, animals were euthanized, tumor mass was determined, and glucose and triacylglycerol serum levels were measured by using commercial kits. Change in the body weight during tumor development was calculated, and proliferation capacity of tumor cells was assessed by the Alamar Blue assay. Phagocytosis and superoxide anion production by peritoneal macrophages and circulating neutrophils were analyzed by enzymatic and colorimetric assays. Data are analyzed by one-way ANOVA followed by Tukey's post-hoc test, with the significance level set at 5%.

RESULTS

The analysis of the latex revealed the presence of triterpenes. The ingestion of the latex aqueous solution promoted 40% and 60% reduction of the tumor mass in SW1 and SW2 groups, respectively (p < 0.05). The proliferative capacity of tumor cells from SW2 group was 76% lower than that of cells from W group (p < 0.0001). Animals treated with latex gained, on average, 20 g (SW1) and 8 g (SW2) weight. Glucose and triacylglycerol serum levels in SW1 and SW2 animals were similar to those in C group rats. Peritoneal macrophages and blood neutrophils from SW1 and SW2 animals produced 30-40% less superoxide anions than those from W group animals (p < 0.05), but neutrophils from SW2 group showed an increased phagocytic capacity (20%, vs. W group).

CONCLUSIONS

E. tirucalli latex, administered orally for 15 d, efficiently reduced tumor growth and cachexia in Walker 256 tumor-bearing rats. Decreased tumor cell proliferative capacity was one of the mechanisms involved in this effect. Further, the data suggest immunomodulatory properties of E. tirucalli latex. The results agree with folk data on the antitumor effect of latex ingestion, indicating that it may be useful as an adjunct in the treatment of cancer patients. For this, further in vivo studies in animal and human models need to be conducted.

New insights on the regulation of cancer cachexia by N-3 polyunsaturated fatty acids

Cancer cachexia is a multifactorial syndrome that develops during malignant tumor growth. Changes in plasma levels of several hormones and inflammatory factors result in an intense catabolic state, decreased activity of anabolic pathways, anorexia, and marked weight loss, leading to cachexia development and/or accentuation. Inflammatory mediators appear to be related to the control of a highly regulated process of muscle protein degradation that accelerates the process of cachexia. Several mediators have been postulated to participate in this process, including TNF-α, myostatin, and activated protein degradation pathways. Some interventional therapies have been proposed, including nutritional (dietary, omega-3 fatty acid supplementation), hormonal (insulin), pharmacological (clenbuterol), and nonpharmacological (physical exercise) therapies. Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid, are recognized for their anti-inflammatory properties and have been used in therapeutic approaches to treat or attenuate cancer cachexia. In this review, we discuss recent findings on cellular and molecular mechanisms involved in inflammation in the cancer cachexia syndrome and the effectiveness of n-3 PUFAs to attenuate or prevent cancer cachexia.

Cancer cachexia: Diagnosis, assessment, and treatment

Cancer cachexia is a multi-factorial syndrome, which negatively affects quality of life, responsiveness to chemotherapy, and survival in advanced cancer patients. Our understanding of cachexia has grown greatly in recent years and the roles of many tumor-derived and host-derived compounds have been elucidated as mediators of cancer cachexia. However, cancer cachexia remains an unmet medical need and attempts towards a standard treatment guideline have been unsuccessful. This review covers the diagnosis, assessment, and treatment of cancer cachexia; the elements impeding the formulation of a standard management guideline; and future directions of research for the improvement and standardization of current treatment procedures.

Exercício de força associado a óleo de peixe reduzem massa tumoral e caquexia em ratos

OBJETIVO: Investigar o efeito do treinamento de salto associado à suplementação com óleo de peixe (1g/kg peso corporal/dia) em ratos portadores do tumor de Walker 256, sobre parâmetros bioquímicos de caquexia e crescimento tumoral.MÉTODOS: Oitenta Ratos foram divididos em sedentário sem ou com tumor (S ou SW), exercitado (EX ou EXW), suplementado com óleo de peixe (SO ou SWO) e suplementado e exercitado (EXO ou EXWO). Sessões de treinamento de salto consistiram de 10 séries com duração de 30 segundos e intervalo de 1 minuto entre cada série. Após seis semanas de treinamento, células do tumor de Walker 256 foram inoculadas e após 15 dias os animais foram mortos.RESULTADOS: O peso médio do tumor no grupo SW foi de 25,32 g, p<0,05 vs. ao dos SWO, EXW e EXWO (~11 g). O grupo SW apresentou hipoglicemia, hiperlactatemia, hipertriacilglicerolemia e perda de peso (-7,52±3,19g), caracterizando estado caquético. Suplementação com óleo de peixe (SWO), exercício (EXW) e associação de ambos (EXWO) impediram a instalação da caquexia (p<0,05 vs. SW). No grupo SWO, EXW e suas associações (EXWO) promoveram ganho de peso (p<0,05 vs. SW), mas inferior ao da suplementação isolada (p<0,05 vs. SWO). A proliferação celular in vitro das células tumorais foi menor no grupo SWO (p<0,05 vs. SW) e o exercício reduziu ainda mais (p<0,05 vs. SW e SWO), não havendo incremento quando se associaram ambas as terapias. Lipoperoxidação (p<0,05) foi maior nos SWO, EXW, EXWO vs. S. A expressão de Bcl-2 foi menor também nestes grupos vs. SW.CONCLUSÕES: O treinamento de força e a suplementação com óleo de peixe foram eficazes em evitar a caquexia e induzir a redução do crescimento tumoral, da proliferação tumoral e expressão de Bcl-2, mas a associação de ambos não promoveu efeito aditivo.

Antitumor and anti-cachectic effects of shark liver oil and fish oil: comparison between independent or associative chronic supplementation in Walker 256 tumor-bearing rats

BACKGROUND

Shark liver oil (SLOil) and fish oil (FOil), which are respectively rich in alkylglycerols (AKGs) and n-3 polyunsaturated fatty acids (PUFAs), are able to reduce the growth of some tumors and the burden of cachexia. It is known that FOil is able to reduce proliferation rate and increase apoptotic cells and lipid peroxidation of tumor cells efficiently. However, there are few reports revealing the influence of SLOil on these parameters. In the current study, effects of FOil chronic supplementation on tumor growth and cachexia were taken as reference to compare the results obtained with SLOil supplementation. Also, we evaluated if the association of SLOil and FOil was able to promote additive effects.

METHODS

Weanling male Wistar rats were divided into 4 groups: fed regular chow (C), supplemented (1 g/kg body weight) with SLOil (CSLO), FOil (CFO) and both (CSLO + FO). After 8 weeks half of each group was inoculated with Walker 256 cells originating new groups (W, WSLO, WFO and WSLO + FO). Biochemical parameters of cachexia, tumor weight, hydroperoxide content, proliferation rate and percentage of apoptotic tumor cells were analysed. Fatty acids and AKG composition of tumor and oils were obtained by high performance liquid chromatography and gas chromatography - mass spectrometry, respectively. Statistical analysis was performed by unpaired t-test and one-way ANOVA followed by a post hoc Tukey test.

RESULTS

Fourteen days after inoculation, SLOil was able to restore cachexia parameters to control levels, similarly to FOil. WSLO rats presented significantly lower tumor weight (40%), greater tumor cell apoptosis (~3-fold), decreased tumor cell proliferation (35%), and higher tumor content of lipid hydroperoxides (40%) than observed in W rats, but FOil showed more potent effects. Supplementation with SLOil + FOil did not promote additive effects. Additionally, chromatographic results suggested a potential incorporation competition between the n-3 fatty acids and the AKGs in the tumor cells' membranes.

CONCLUSIONS

SLOil is another marine source of lipids with similar FOil anti-cachectic capacity. Furthermore, despite being less potent than FOil, SLOil presented significant in vivo antitumor effects. These results suggest that the chronic supplementation with SLOil may be adjuvant of the anti-cancer therapy.

Tumor growth reduction is regulated at the gene level in Walker 256 tumor-bearing rats supplemented with fish oil rich in EPA and DHA

We investigated the effect of fish oil (FO) supplementation on tumor growth, cyclooxygenase 2 (COX-2), peroxisome proliferator-activated receptor gamma (PPARγ), and RelA gene and protein expression in Walker 256 tumor-bearing rats. Male Wistar rats (70 days old) were fed with regular chow (group W) or chow supplemented with 1 g/kg body weight FO daily (group WFO) until they reached 100 days of age. Both groups were then inoculated with a suspension of Walker 256 ascitic tumor cells (3×10⁷ cells/mL). After 14 days the rats were killed, total RNA was isolated from the tumor tissue, and relative mRNA expression was measured using the 2^-ΔΔCT method. FO significantly decreased tumor growth (W=13.18±1.58 vs WFO=5.40±0.88 g, P<0.05). FO supplementation also resulted in a significant decrease in COX-2 (W=100.1±1.62 vs WFO=59.39±5.53, P<0.001) and PPARγ (W=100.4±1.04 vs WFO=88.22±1.46, P<0.05) protein expression. Relative mRNA expression was W=1.06±0.022 vs WFO=0.31±0.04 (P<0.001) for COX-2, W=1.08±0.02 vs WFO=0.52±0.08 (P<0.001) for PPARγ, and W=1.04±0.02 vs WFO=0.82±0.04 (P<0.05) for RelA. FO reduced tumor growth by attenuating inflammatory gene expression associated with carcinogenesis.

Clinical evaluation and optimal management of cancer cachexia

Cancer anorexia-cachexia syndrome (CACS) is a complex metabolic syndrome, different from malnutrition and sarcopenia, which is very common in cancer patients. Treatment for CACS is based on nutritional support and CACS pathophysiology-modulating drugs. The most commonly used are megestrol acetate (MA) and corticosteroids. The efficacy of MA has been confirmed by multiple clinical trials and meta-analyses. Glucocorticoids are also effective but should only be used for short periods and in selected cases. Future strategies should include intensified research into potentially effective drugs (ω-3 fatty acids, thalidomide, cannabinoids, ghrelin, bortezomib, and COX-2 inhibitors), combined treatment and new drugs (anti-IL-6 monoclonal antibodies, melanocortin, β-2 antagonists, and androgen receptor-modulating analogues). We propose a review based on the literature on the pathophysiology of CACS, the diagnostic criteria and treatment, and future strategies.

Effect of endurance training upon lipid metabolism in the liver of cachectic tumour-bearing rats

The syndrome of cancer cachexia is accompanied by several alterations in lipid metabolism, and the liver is markedly affected. Previous studies showed that moderate exercise training may prevent liver fat accumulation through diminished delivery of lipids to the liver, increased hepatic oxidation and increased incorporation of triacylglycerol (TAG) into very low density lipoprotein (VLDL). Our aim was to examine the influence of moderate intensity training (8 weeks) upon TAG content, VLDL assembly and secretion, apolipoprotein B (apoB) and microsomal transfer protein (MTP) gene expression in the liver of cachectic tumour-bearing rats. Animals were randomly assigned to a sedentary control (SC), sedentary tumour-bearing (ST) or exercise-trained control (EC) or to an exercise trained tumour-bearing (ET) group. Trained rats ran on a treadmill (60% VO(2max)) for 60 min day(-1), 5 day week(-1), for 8 weeks. TAG content and the rate of VLDL secretion (followed for 3 h), as well as mRNA expression of apoB and MTP, and total cholesterol, VLDL-TAG, VLDL-cholesterol, high density lipoprotein cholesterol (HDL-cholesterol) and tumour weight were evaluated. VLDL-cholesterol showed a decrease in ST (p < 0.05) in relation to SC. Serum TAG, VLDL-TAG and tissue TAG content were all increased in ST (p < 0.01), when compared with SC. ST showed a lower rate of VLDL secretion (p < 0.05) and reduced expression of apoB (p < 0.001) and MTP (p < 0.001), when compared with SC. These parameters were restored to control values (p < 0.05) when the animals were submitted to the exercise training protocol. Tumour weight decreased 10-fold after training (p < 0.001). It is possible to affirm, therefore, that endurance training promoted the re-establishment of lipid metabolism in cachectic tumour-bearing animals, especially in relation to VLDL secretion and assembly.

Role of beta-adrenoceptor signaling in skeletal muscle: implications for muscle wasting and disease

The importance of beta-adrenergic signaling in the heart has been well documented, but it is only more recently that we have begun to understand the importance of this signaling pathway in skeletal muscle. There is considerable evidence regarding the stimulation of the beta-adrenergic system with beta-adrenoceptor agonists (beta-agonists). Although traditionally used for treating bronchospasm, it became apparent that some beta-agonists could increase skeletal muscle mass and decrease body fat. These so-called "repartitioning effects" proved desirable for the livestock industry trying to improve feed efficiency and meat quality. Studying beta-agonist effects on skeletal muscle has identified potential therapeutic applications for muscle wasting conditions such as sarcopenia, cancer cachexia, denervation, and neuromuscular diseases, aiming to attenuate (or potentially reverse) the muscle wasting and associated muscle weakness, and to enhance muscle growth and repair after injury. Some undesirable cardiovascular side effects of beta-agonists have so far limited their therapeutic potential. This review describes the physiological significance of beta-adrenergic signaling in skeletal muscle and examines the effects of beta-agonists on skeletal muscle structure and function. In addition, we examine the proposed beneficial effects of beta-agonist administration on skeletal muscle along with some of the less desirable cardiovascular effects. Understanding beta-adrenergic signaling in skeletal muscle is important for identifying new therapeutic targets and identifying novel approaches to attenuate the muscle wasting concomitant with many diseases.

Metabolic fluxes in the liver of rats bearing the Walker-256 tumour: influence of the circulating levels of substrates and fatty acids

Studies on fatty acid and amino acid metabolism in the liver of Walker-256 tumour-bearing rats have revealed several changes. Comparisons, however, have been based on experiments performed with non-physiological, frequently unrealistic, substrate concentrations. The aim of the present work was to examine the influence of physiological substrate concentrations on gluconeogenesis, ketogenesis and related parameters. Isolated livers were perfused and substrates were infused at concentrations that were reported to occur in healthy and tumour-bearing rats. Ketogenesis and the mitochondrial NADH/NAD+ ratio were smaller in the tumour-bearing condition at low (0.2 mM) and high (0.8 mM) oleate concentrations. In the absence of oleate, gluconeogenesis from alanine (0.7 mM) and gluconeogenesis plus the associated changes in oxygen uptake due to lactate/pyruvate (2/0.2 and 6/0.3 mM) were smaller in livers of tumour-bearing rats. However, the response of gluconeogenesis from lactate/pyruvate in livers of tumour-bearing rats to 0.8 mM oleate was more pronounced so that a trend towards normalization was apparent at high substrate and oleate concentrations. Gluconeogenesis from 0.7 mM alanine was not significantly changed by oleate in the tumour-bearing state; in the control condition, stimulation occurred at 0.2 mM oleate and inhibition at 0.8 mM oleate. This diminution almost equalized the hepatic alanine-dependent gluconeogenesis of both control and tumour-bearing rats. Ureogenesis was smaller in the tumour-bearing state and was not affected by oleate. It was concluded that the high concentrations of fatty acids and lactate/pyruvate, which predominate in rats bearing the Walker-256 tumour, could be effective in normalizing the gluconeogenic response of livers from tumour-bearing rats.

Omega-3 fatty acids for the treatment of cancer cachexia: issues in designing clinical trials of dietary supplements

Complementary and alternative medicine (CAM) is increasingly popular, despite the limited evidence of the efficacy and safety of some forms of CAM. Cancer patients often turn to CAM therapies for the relief of treatment- induced side-effects and comorbidities. Cancer-associated weight loss commonly results in decreased functional status, life expectancy, and quality of life. Despite the high morbidity and mortality associated with cancer cachexia, mainstream treatments do not sustain weight. Although nutritional supplements are commonly used, many of these have not been tested in clinical trials. The issues faced in dietary supplement research differ from those in pharmaceutical drug trials. These include problems with standardization, contamination, and compliance documentation. A double-blind, randomized, placebo-controlled trial is proposed to evaluate the efficacy and safety of fish oil supplementation for the treatment of cachexia in pancreatic cancer patients. The primary outcome measure will be lean body mass; secondary outcomes include functional status and quality of life. The methodology of the clinical trial is reviewed here and the unique problems faced by investigators in designing studies of dietary supplements are discussed.

Ratio of n6 to n-3 Fatty Acids in the Diet Affects Tumor Growth and Cachexia in Walker 256 Tumor-Bearing Rats

In this study we investigate the impact of the dietary ratio of n-6 to n-3 fatty acids (FAs) from postweaning until adult age upon tumor growth, lipid peroxidation in tumor tissue, and metabolic indicators of cancer cachexia in Walker 256 tumor-bearing rats. Weanling male Wistar rats received a normal low-fat (40 g/kg diet) chow diet or high-fat diets (300 g/kg) that included fish oil (FO) or sunflower oil or blends of FO and sunflower oil to yield n-6 to n-3 FA ratios of approximately 6:1, 30:1, and 60:1 ad libitum. After 8 wk, half of each group was inoculated with 1 ml of 2 x 10(7) Walker 256 cells. At the 14th day after tumor inoculation, the animals were killed, and tumors and blood were removed. The different diets did not modify the blood parameters in the absence of tumor bearing, except the high-FO diet, which decreased serum cholesterol and triacylglycerol concentrations. Tumor weight in chow-fed rats was 19 g, and these rats displayed cancer cachexia, characterized by hypoglycemia, hyperlacticidemia, hypertriacylglycerolemia, loss of body weight, and food intake reduction. Tumor weight in FO-fed rats was 7.7 g, and these animals gained body weight (14.6 g) and maintained blood metabolic parameters similar to non-tumor-bearing animals. Tumor weight in rats fed the diet with an n-6 to n-3 FA ratio of 6:1 was similar to tumor-bearing, chow-fed rats, but they gained 2 g in the body weight and blood metabolic parameters were similar to those in non-tumor-bearing rats. However, a further increase in the n-6 FA content of the diet did not change the cachectic state associated with tumor bearing. In this experimental model, a dietary n-6 to n-3 FA ratio of 6:1 was able to increase food intake and body weight, restore the biochemical blood parameters of cachexia, and prevent the development of cancer cachexia.

Effect of chronic fish oil supplementation on renal function of normal and cachectic rats

In the present study we determined the effect of chronic diet supplementation with n-3 PUFA on renal function of healthy and cachectic subjects by providing fish oil (1 g/kg body weight) to female rats throughout pregnancy and lactation and then to their offspring post-weaning and examined its effect on renal function parameters during their adulthood. The animals were divided into four groups of 5-10 rats in each group: control, control supplemented with fish oil (P), cachectic Walker 256 tumor-bearing (W), and W supplemented with fish oil (WP). Food intake was significantly lower in the W group compared to control (12.66 +/- 4.24 vs 25.30 +/- 1.07 g/day). Treatment with fish oil significantly reversed this reduction (22.70 +/- 2.94 g/day). Tumor growth rate was markedly reduced in the P group (16.41 +/- 2.09 for WP vs 24.06 +/- 2.64 g for W). WP group showed a significant increase in mean glomerular filtration rate compared to P and control (1.520 +/- 0.214 ml min-1 kg body weight-1; P < 0.05). Tumor-bearing groups had low urine osmolality compared to control rats. The fractional sodium excretion decreased in the W group compared to control (0.43 +/- 0.16 vs 2.99 +/- 0.87%; P < 0.05), and partially recovered in the WP group (0.90 +/- 0.20%). In summary, the chronic supplementation with fish oil used in this study increased the amount of fat in the diet by only 0.1%, but caused remarkable changes in tumor growth rate and cachexia, also showing a renoprotective function.