Implanted tumor growth is suppressed and survival is prolonged in sixty percent of food-restricted mice

Dietary energy restriction reduces high-fat diet-enhanced metastasis of Lewis lung carcinoma in mice

The objective of this study was to determine whether a reduction in energy intake ameliorated the high-fat diet-enhanced spontaneous metastasis of Lewis lung carcinoma in mice. Male C57BL/6 mice were fed the AIN93G diet, a high-fat diet or a high-fat diet with a 5% restriction of the intake. Energy restriction reduced body adiposity and body weight, but maintained growth similar to mice fed the AIN93G diet. The high-fat diet significantly increased the number and size (cross-sectional area and volume) of metastases formed in lungs. Restricted feeding reduced the number of metastases by 23%, metastatic cross-sectional area by 32% and volume by 45% compared to the high-fat diet. The high-fat diet elevated plasma concentrations of proinflammatory cytokines (monocyte chemotactic protein-1, plasminogen activator inhibitor-1, leptin), angiogenic factors (vascular endothelial growth factor, tissue inhibitor of metalloproteinase-1) and insulin. Restricted feeding significantly reduced the high-fat diet-induced elevations in plasma concentrations of proinflammatory cytokines, angiogenic factors and insulin. These results demonstrated that a reduction in diet intake by 5% reduced high-fat diet-enhanced metastasis, which may be associated with the mitigation of adiposity and down-regulation of cancer-promoting proinflammatory cytokines and angiogenic factors.

Effects of a High-Fat or High-Sucrose Diet on Ultraviolet B Irradiation-Induced Carcinogenesis and Tumor Growth in Melanin-Possessing Hairless Mice

We herein compared the effects of the chronic feeding of high-fat (HF), high-sucrose (HS), and low-fat/low-sucrose (control) diets on carcinogenesis following chronic ultraviolet B (UVB) irradiation in hairless mice. UVB irradiation-induced carcinogenesis was more prominent in HF diet-fed group than in control diet- and HS diet-fed groups. The HS diet group, as well as the HF diet one, showed tumor development and growth, increased skin matrix metalloproteinase (MMP) and blood plasminogen activator inhibitor-1 (PAI-1) levels, and decreased blood leptin and adiponectin levels after long-term UVB irradiation. These changes were smaller in the HS diet group than in the HF diet group. In addition, no difference was noted in the above changes between the control and HS diet groups. The increase induced in adipose tissue weight by the HF diet was markedly reduced by UVB irradiation. This result suggests that the abundant availability of lipids in hypertrophic adipose tissue may be related to tumor incidence and growth through increases in blood PAI-1 and skin MMP-9 expression levels and decreases in blood adiponectin levels by UVB irradiation. In conclusion, HF diet-induced hypertrophic adipose tissue is an important cancer risk factor that promotes UV irradiation-induced carcinogenesis and tumor growth.

Calorie restriction dose-dependently abates lipopolysaccharide-induced fever, sickness behavior, and circulating interleukin-6 while increasing corticosterone

In mice a 50% calorie restriction (CR) for 28days attenuates sickness behavior after lipopolysaccharide (LPS) and these mice demonstrate a central anti-inflammatory bias. This study examined the dose-dependent effect of CR on sickness behavior (fever, anorexia, cachexia) and peripheral immune markers post-LPS. Male Sprague-Dawley rats fed ad libitum or CR by 50% for 14, 21, or 28days were injected on day 15, 22, or 29 with 50μg/kg of LPS or saline (1mL/500g). Changes in body temperature (Tb), locomotor activity, body weight, and food intake were determined. A separate cohort of rats was fed ad libitum or CR by 50% for 28days and serum levels of corticosterone (CORT), interleukin 6 (IL-6), and IL-10 were determined at 0, 2, and 4h post-LPS. The rats CR for 28days demonstrated the largest attenuation of sickness behavior: no fever, limited reduction in locomotor activity, no anorexia, and reduced cachexia following LPS. Rats CR for 14 and 21days demonstrated a partial attenuation of sickness behavior. Rats CR for 14days demonstrated a larger increase in Tb, larger reduction in locomotor activity, and larger weight loss compared to rats CR for 21days. Serum CORT was increased at 2h post-LPS in ad libitum and CR groups; however it was two times larger in the CR animals. Levels of IL-6 were significantly attenuated at 2h post-LPS in the CR animals. IL-10 levels were similar post-LPS. CR results in an enhanced anti-inflammatory response in the form of increased CORT and diminished pro-inflammatory signals.

Calorie restriction attenuates LPS-induced sickness behavior and shifts hypothalamic signaling pathways to an anti-inflammatory bias

Calorie restriction (CR) has been demonstrated to alter cytokine levels; however, its potential to modify sickness behavior (fever, anorexia, cachexia) has not. The effect of CR on sickness behavior was examined in male C57BL/6J mice fed ad libitum or restricted 25% (CR25%) or restricted 50% (CR50%) in food intake for 28 days and injected with 50 μg/kg of LPS on day 29. Changes in body temperature, locomotor activity, body weight, and food intake were determined. A separate cohort of mice were fed ad libitum or CR50% for 28 days, and hypothalamic mRNA expression of inhibitory factor κB-α (IκB-α), cyclooxygenase-2 (COX-2), prostaglandin E(2) (PGE(2)), suppressor of cytokine signaling 3 (SOCS3), IL-10, neuropeptide Y (NPY), leptin, proopiomelanocortin (POMC), and corticotrophin-releasing hormone (CRH) were determined at 0, 2, and 4 h post-LPS. CR50% mice did not develop fevers, whereas the CR25% mice displayed a fever shorter in duration but with the same peak as the controls. Both CR25% and CR50% mice showed no sign of anorexia and reduced cachexia after LPS administration. Hypothalamic mRNA expression of NPY and CRH were both increased by severalfold in CR50% animals preinjection compared with controls. The CR50% mice did not demonstrate the expected rise in hypothalamic mRNA expression of COX-2, microsomal prostaglandin E synthase-1, POMC, or CRH 2 h post-LPS, and leptin expression was decreased at this time point. Increases in SOCS3, IL-10, and IκB-α expression in CR50% animals were enhanced compared with ad libitum-fed controls at 4 h post-LPS. CR results in a suppression of sickness behavior in a dose-dependent manner, which may be due to CR attenuating proinflammatory pathways and enhancing anti-inflammatory pathways.

Comparison of the effects of food versus protein restriction on selected nutritional and inflammatory markers in rats

We previously demonstrated that feeding a 2% protein AIN-76 diet ad libitum for 14 days resulted in substantial clinical and biochemical changes including weight loss, hypoglycemia, hypoalbuminemia, higher levels of plasma cytokines, oxidative stress in the liver, and activation of inflammatory signaling to interleukin (IL)-6, as compared with a 20% protein diet. In the present study, 54 rats were randomly given a standard rat chow diet ad libitum, or a 25% or 50% reduction of this intake for 14 days. The results showed that weight gain was less in the 25% food-restricted group and halted in the 50% group as compared with the control group. Unlike protein restriction, neither level of food restriction altered plasma levels of albumin and glucose, the hepatic protein abundance of signal transducers and activators of transcriptions and of mitogen-activated protein kinases, or the hepatic contents of total glutathione and malondialdehyde. The intracellular signaling in response to IL-6 stimulation was also well maintained. However, both levels of food restriction elevated IL-1 and corticosterone in plasma, did not alter ghrelin, and decreased plasma levels of free fatty acids. Because these latter 3 markers were not examined previously, 20 rats were fed an AIN-76 diet, either with 20% or 2% protein, ad libitum for 14 days. The 2% protein diet significantly decreased plasma levels of free fatty acids and increased ghrelin and corticosterone as compared with the 20% protein diet. Thus, food restriction, where all essential nutrients are reduced in proportion, is a physiologic stress that, while limiting growth, does not activate or impair the systemic inflammatory response, whereas a very low protein diet with little change in energy intake has a substantial impact on systemic inflammation, body composition, and growth.

High-fat, high-sucrose, and high-cholesterol diets accelerate tumor growth and metastasis in tumor-bearing mice

Epidemiological studies indicate that the risk factors for the development of various cancers are closely associated with metabolic symptoms such as obesity, hyperlipidemia, and insulin resistance caused by the excess consumption of high-calorie diets. However, the mechanisms of tumor growth and metastasis caused by feeding a high-calorie diet have not been clarified yet in tumor-bearing mice. In this study, we examined the effects of a high-fat (HF), a high-sucrose (HS), a high-cholesterol (HC) or a low-fat/low-sucrose (LF/LS) diet on tumor growth and metastasis in tumor-bearing mice. Angiogenic factors such as plasma leptin and monocyte chemoattractant protein-1 (MCP-1) were increased after the implantation of tumors, whereas conversely, an antiangiogenic factor, adiponectin, was reduced after the implantation of tumors in mice fed the HF, the HS, or the HC diet compared to LF/LS diet. Furthermore, we found that vascular endothelial growth factor, hypoxia inducible factor-1alpha and MCP-1 expression levels in tumors of mice fed the HF, the HS, or the HC diet were increased compared to those of mice fed the LF/LS diet. These findings suggest that the acceleration of tumor growth and metastasis by feeding the 3 diets may be due to the increase of angiogenic factors and the reduction of antiangiogenic factors.

Honey ameliorates influence of hemorrhage and food restriction on renal and hepatic functions, and hematological and biochemical variables

The objectives were to assess the effects of various diets, including total food restriction with 50% honey feeding, total food restriction with 50% dextrose feeding or adlibitum (control group) commercial regular diet, on the hematology and biochemical variables, and to assess the effects of the various diets on the influence of acute blood loss on the same parameters. Thirty Sprague-Dawley albino rats were divided into three groups, 10 rats each: group A, fed a commercial regular diet; group B, total food restriction with 50% dextrose feeding; and group C, total food restriction with 50% honey feeding. After 8 days of feeding, rats were subjected to acute blood loss (6 ml/kg) and blood investigations were performed. After acute blood loss, the same feedings were continued for a further 8 days and the blood tests were repeated at day 8 post-bleeding. Total food restriction with 50% dextrose feeding compared with commercial regular diet reduces hematological and biochemical variables. Total food restriction with 50% honey feeding compared with total food restriction with 50% dextrose feeding causes a greater reduction in fasting blood glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and triacylglycerol. Acute blood loss causes elevation of white blood cells, lymphocyte percentage, fasting blood sugar, blood urea nitrogen, alkaline phosphatase and triacylglycerol, and a reduction in serum albumen, protein, cholesterol, AST, serum creatinine and hemoglobin; the results are significant (P<0.05) concerning fasting blood glucose, AST, alkaline phosphatase, serum albumin and protein. A significant reduction in fasting blood glucose, white blood cells, BUN, AST, ALT, alkaline phosphatase and triacylglycerol, and a significant elevation of hemoglobin and serum albumin are obtained after acute blood loss in rats on total food restriction with 50% honey feeding as compared with the other two groups. Total food restriction with 50% honey feeding increases serum albumin, serum protein, fasting blood glucose, and causes lower reduction in hemoglobin as compared with the other groups. Conclusively, honey feeding during total food restriction significantly modifies and ameliorates biochemical and hematological changes observed after acute blood loss. This will pave the way to use honey as part of bleeding management and during a food restriction regimen.

The administration of naked plasmid DNA into the liver induces antitumor innate immunity in a murine liver metastasis model

BACKGROUND

Gene therapy is a promising strategy against advanced cancer; however, the safety of viral vectors and the effectiveness of non-viral vectors have not yet been established. Recently, a hydrodynamics-based procedure was reported to be an effective and safe method to deliver and transduce DNA into the liver. Herein, we propose a strategy for liver metastasis by a hydrodynamics-based procedure to deliver naked non-coding plasmid DNA (pDNA) into the liver as an immunocompetent organ.

METHODS AND RESULTS

Mice received a rapid intravenous (i.v.) injection of naked pDNA in a large volume of saline (0.1 ml/g body weight). The single administration of a naked non-coding pDNA by the hydrodynamics-based procedure before tumor cell inoculation strongly suppressed liver metastasis formation. However, the usual i.v. injection (200 microl/body) of the same dose of naked pDNA could not suppress liver metastasis formation. Following the methylation of CpG sequences within the pDNA using CpG methylase, injection of the methylated pDNA by the hydrodynamics-based procedure could not suppress liver metastasis formation. Gadolinium chloride pretreatment did not interfere with this antitumor effect, but anti-asialo GM1 antiserum treatment did. These findings indicated that natural killer (NK) cells, not Kupffer cells, were involved in this antitumor effect. The NK cytotoxic activities of liver mononuclear cells were strongly enhanced after receiving a naked pDNA by the hydrodynamics-based procedure.

CONCLUSIONS

These observations suggest that unmethylated CpG motifs in pDNA stimulated immune cells, resulting in the activation of NK cells in the liver to suppress liver metastases in a murine model.

Binding of Manumycin A Inhibits IκB Kinase β Activity

IkappaB kinase (IKK) catalytic subunits play a key role in cytokinemediated nuclear factor (NF)-kappaB signaling, and a loss of NF-kappaB function appears to inhibit inflammation and oncogenesis. Manumycin A is a potent and selective farnesyltransferase inhibitor with antitumor activity. We found that manumycin A caused a rapid and potent inhibition of IKK activity induced by tumor necrosis factor alpha in a number of cell types. Most unexpectedly, other classes of farnesyltransferase inhibitors had no inhibitory effect. To identify the molecular mechanisms of manumycin A action, cultured human HepG2 hepatoma cells were transiently transfected with various IKKalpha and IKKbeta constructs, and a striking difference in manumycin A sensitivity was observed. Furthermore, cells expressing wild-type IKKbeta and IKKbeta mutated in the activation loop at Cys-179 exhibited covalent homotypic dimerization of IKKbeta in response to manumycin A, whereas substitution of Cys-662 and -716 conferred protection against dimer formation. Direct inhibition of IKK activity and formation of stable IKKbeta dimers were observed in the presence of manumycin A that could be blocked by dithiothreitol. IKK interaction with the adaptor protein IKKgamma/NEMO was disrupted in manumycin A-treated cells. Most importantly, administration of manumycin A to mice xenografted with murine B16F10 tumors caused potent IKK-suppressive effects. Thus, manumycin A with its epoxyquinoid moieties plays an important regulatory function in IKK signaling through pathways distinct from its role as a protein farnesylation inhibitor.

Severe feed restriction enhances innate immunity but suppresses cellular immunity in chicken lines divergently selected for antibody responses

The main aim of this study was to investigate the effects of different levels of feed restriction (FR) on immune responses of chicken lines divergently selected for high (H) and low (L) antibody responses to SRBC. We hypothesized that severe feed restriction suppresses immune responses and the level of immune suppression differs between birds with different genetic background. Therefore, we tested antibody responses, blood lymphocyte proliferative responses, and production of reactive oxygen intermediates (ROI) by Zymosan A-stimulated blood cells in chicken lines maintained on 3 levels of FR. The H line birds had significantly higher antibody responses, higher ROI production, and lower corticosterone (CORT) levels when compared with the L line birds. Feed restriction induced no significant effect on specific antibody responses to either a T helper 1- (Mycobacterium butyricum) or a T helper 2- (keyhole limpet hemocyanin) type antigen. Feed-restricted birds showed a marked reduction in natural antibodies binding lipoteichoic acid, in vitro lymphocyte proliferation in response to stimulation with concanavalin A, BW gain, and relative lymphoid organ weights compared with the birds fed ad libitum. However, FR birds showed a markedly enhanced ROI production, and plasma CORT levels compared with the birds fed ad libitum. The enhanced ROI production and suppressed lymphocyte proliferation coinciding with enhanced plasma CORT levels suggest stress-mediated immunomodulating effects of FR. A significant treatment by line interaction was found for ROI production; the increase of ROI production was larger in the H line than in the L line under severe FR. The increase in CORT levels was larger in the L line than in the H line under severe FR. Furthermore, the L line gained more BW than the H line under ad libitum conditions. Finally, under severe FR, relative spleen weight was lower in the L line than in the H line. The present findings suggest genetic differences affecting physiological and immunological responses under FR conditions.

Short-term dietary restriction modulates liver lipid peroxidation in carbon tetrachloride-intoxicated rats

We investigated whether dietary restriction (DR) can protect the liver against the acute toxicity of carbon tetrachloride (CCl4). Adult female Wistar rats received a quantum of diet representing 75 and 50 percent of the food intake of control rats fed ad libitum (25% and 50% daily regimen, respectively) for 30 days. A single dose of CCl4 (3 mL kg(-1) b.w.) was administered subcutaneously at the end of the feeding period. Lipid peroxidation, as thiobarbituric acid reactive substance, conjugated dienes, lipid hydroperoxides and the hepatic markers alanine transaminase, aspartic transaminase, and alkaline phosphatase were significantly decreased in food-restricted rats. The enzymic antioxidants superoxide dismutase, catalase, glutathione peroxidase and the non-enzymic antioxidant glutathione were significantly increased in both groups. The magnitude of liver damage after CCl4 treatment was lower in food-restricted animals than in ad libitum-fed animals. The results suggest that dietary restriction increases the resistance of the liver and protects against oxidative insult produced by an acute dose of CCl4.

Nutrition and cancer: a review of the evidence for an anti-cancer diet

It has been estimated that 30–40 percent of all cancers can be prevented by lifestyle and dietary measures alone. Obesity, nutrient sparse foods such as concentrated sugars and refined flour products that contribute to impaired glucose metabolism (which leads to diabetes), low fiber intake, consumption of red meat, and imbalance of omega 3 and omega 6 fats all contribute to excess cancer risk. Intake of flax seed, especially its lignan fraction, and abundant portions of fruits and vegetables will lower cancer risk. Allium and cruciferous vegetables are especially beneficial, with broccoli sprouts being the densest source of sulforophane. Protective elements in a cancer prevention diet include selenium, folic acid, vitamin B-12, vitamin D, chlorophyll, and antioxidants such as the carotenoids (α-carotene, β-carotene, lycopene, lutein, cryptoxanthin). Ascorbic acid has limited benefits orally, but could be very beneficial intravenously. Supplementary use of oral digestive enzymes and probiotics also has merit as anticancer dietary measures. When a diet is compiled according to the guidelines here it is likely that there would be at least a 60–70 percent decrease in breast, colorectal, and prostate cancers, and even a 40–50 percent decrease in lung cancer, along with similar reductions in cancers at other sites. Such a diet would be conducive to preventing cancer and would favor recovery from cancer as well.

Food restriction attenuates blood lipid peroxidation in carbon tetrachloride-intoxicated rats

OBJECTIVE

We investigated whether food restriction offers protection against the toxicity of carbon tetrachloride (CCl(4)) and, if so, at what percentage of restriction.

METHODS

The effects of food restriction (75% and 50% of food intake) and food restriction followed by CCl(4) treatment on lipid peroxidation and antioxidant enzymes were studied in female Wistar rats. A single dose of CCl(4) (3 mL/kg of body weight, subcutaneous) was administered at the end of the 30-d feeding period.

RESULTS

The magnitude of increase in lipid peroxidation was less after CCl(4) treatment in food-restricted animals than in animals fed ad libitum (control), whereas alanine transaminase, aspartate transaminase, and alkaline phosphatase activities in plasma were enhanced due to CCl(4) treatment. The magnitude of increase in the marker enzymes was less in food-restricted animals than in control animals. Erythrocytes from food-restricted rats were more resistant to hydrogen peroxide-induced peroxidation than were those from control rats. The activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione-S-transferase were higher in food-restricted animals.

CONCLUSIONS

The present results suggested that food restriction can minimize drug-related increases in peroxidation and protect the system against drug toxicity, presumably by induction of antioxidant potential.

Cytokine responses in young and old rhesus monkeys: effect of caloric restriction

Caloric restriction (CR) is the only known intervention demonstrated to retard a great variety of aging processes, extend median and maximum life-span, and decrease the incidence of age-associated diseases in mammals. Paralleling findings from rodent studies, studies in rhesus monkeys (Macaca mulatta) suggest that CR may retard many age-sensitive parameters in primates. A recent study in rhesus monkeys showed age-related dysregulation of cytokine levels. Specifically, age-related increases in interleukin-10 (IL-10) and IL-6 proteins were observed in supernatants from lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs), and interferon-gamma (IFN-gamma) protein exhibited an age-related decrease in phytohemagglutinin (PHA)-stimulated PBMCs. To investigate effects of CR on age-related changes in cytokine production, we obtained PBMCs from control and CR rhesus monkeys aged 6-7 and 22-25 years. We evaluated IL-10 and IL-6 protein and gene expression after exposure to LPS and IFN-gamma protein and gene expression after PHA stimulation. The results revealed significantly higher levels of IFN-gamma protein and gene expression in aged monkeys on CR for 2 years compared with controls. No significant CR effects were observed on IL-10 and IL-6 protein levels. IFN-gamma plays an important role in the initial defense mechanism against viral and microbial disease and cancer. Altered regulation of IFN-gamma in old CR rhesus monkeys may be a key factor in reducing cancer incidence and other age-associated diseases.

Effects of dietary restriction on spontaneous dermatitis in NC/Nga mice

In laboratory animals, dietary restriction prolongs life span, improves physiologic function, and prevents or lessens severity of several diseases including some experimental inflammatory states. We investigated the effect of dietary restriction on a spontaneously occurring mouse model of atopic dermatitis, an inflammatory skin disease. NC/Nga mice were assigned to a group fed ad libitum or to a restricted diet group receiving 60% of the amount of food consumed by the other group. Dermatitis was characterized according to extent, intensity, and scratching time. We then used computer-assisted image analysis to quantify immunologic findings in skin sections. Extent, intensity score, and scratching time in mice with restriction increased more gradually than in mice fed ad libitum. Infiltrating inflammatory cells (CD4-positive T cells, CD8-positive T cells, eosinophils, and mast cells) as well as interleukin-4 and -5 secreted into tissue were reduced in mice with restriction. In conclusion, dietary restriction delayed onset and progression of spontaneous dermatitis in NC/Nga mice, an effect possibly involving inhibition of inflammatory infiltration cell and cytokine secretion.

Inflammatory responses to lipopolysaccharide are suppressed in 40% energy-restricted mice

To elucidate the suppressive effects of energy restriction on the inflammatory responses to lipopolysaccharide (LPS), mice were divided into a control group (fed 5.0 g diet/d; 71 kJ/d) and a 40% energy-restricted group (fed 3.0 g diet/d; 43 kJ/d) at 8-wk of age. Four weeks later, 25 microg of LPS was intraperitoneally injected. After the LPS injection, interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha were elevated in serums in the 40% energy-restricted mice and in the controls, but the extent of the elevation was significantly lower in the restricted group. The LPS-induced expression of inducible nitric oxide synthase in the liver was significantly suppressed by the energy restriction. In addition, the LPS-induced elevations of serum aspartate and alanine aminotransferase activities, which are indexes of hepatic injury, were also significantly attenuated in the restricted group. Moreover, the extent of LPS-induced alterations in hepatic structure was less in the restricted mice than in controls. Serum corticosterone level in the restricted mice was higher than that in the controls before LPS treatment (P < 0.05). Furthermore, after LPS injection, the significantly higher level of corticosterone was maintained in the restricted mice, although the LPS treatment significantly enhanced the level even in the control group. These results suggest that the extreme inflammatory responses to endotoxin are prevented in the 40% energy-restricted mice, and corticosterone participates in the preventive effects.