Low carbohydrate diets containing soy protein and fish oil slow the growth of established NNK-induced lung tumors.

We recently found that a diet composed of 15% of total calories as carbohydrate (CHO), primarily as amylose, 35% soy protein and 50% fat, primarily as fish oil (FO) (15%Amylose/Soy/FO) was highly effective at preventing lung nodule formation in a nicotine-derived nitrosamine ketone (NNK)-induced lung cancer model. We asked herein whether adopting such a diet once cancers are established might also be beneficial. To test this, NNK-induced lung nodules were established in mice on a Western diet and the mice were then either kept on a Western diet or switched to various low CHO diets. Since we previously found that sedentary mice develop more lung nodules than active mice, we also compared the effect of exercise in this cancer progression model. We found that switching to a 15%Amylose/Soy/FO diet reduced lung nodules and slowed tumor growth with both 'active' and 'sedentary' mice. Ki67, cleaved caspase 3 and Terminal Deoxynucleotidyl Transferase-Mediated dUTP Nick End Labeling assays suggested that the efficacy of the 15%Amylose/Soy/FO in lowering tumor nodule count and size was not due to a reduction in tumor cell proliferation, but to an increase in apoptosis. The 15%Amylose/Soy/FO diet also significantly lowered liver fatty acid synthase and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 expression, pointing to a global metabolic switch from glycolysis to fatty acid oxidation. Mice fed the 15%Amylose/Soy/FO diet also had significantly reduced plasma levels of interleukin (IL)-1ß, IL-6 and tumor necrosis factor α. These results suggest that the 15%Amylose/Soy/FO diet may slow tumor growth by suppressing proinflammatory cytokines, inducing a metabolic switch away from glycolysis and inducing apoptosis in tumors.

The effect of diet and exercise on tobacco carcinogen-induced lung cancer.

In previous studies, we found that low-carbohydrate (CHO) diets reduced the incidence of tumors in mice genetically predisposed to cancer. However, because >90% of human cancers arise via carcinogen-induced somatic mutations, we investigated, herein, the role that different types and levels of CHO, protein and lipid play in lung cancer induced by the tobacco-specific carcinogen, nicotine-derived nitrosamine ketone (NNK) in A/J mice. We found lowering CHO levels significantly reduced lung nodules and blood glucose levels. We also found that soy protein was superior to casein and that coconut oil was ineffective at reducing lung nodules. Diets containing amylose or inulin (at 15% of total calories), soy protein (at 35%) and fat (at 50%, 30% being fish oil) were the most effective at reducing lung nodules. These fish oil-containing diets increased plasma levels of the ketone body, ß-hydroxybutyrate, while reducing both insulin and 8-isoprostane in plasma and bronchoalveolar interleukin-12 and lung PGE2 levels. After only 2 weeks on this diet, the levels of γ-H2AX were significantly reduced, 24 hours after NNK treatment. Housing these mice in two-tiered rat cages with exercise wheels led to similar mouse weights on the different diets, whereas keeping mice in standard mouse cages led to both significant weight differences between the low-CHO, soy protein, fish oil diet and Western diet and substantially more lung nodules than in the two-tiered cages. Our results suggest that low-CHO, soy protein, fish oil-containing diets, together with exercise, may reduce the incidence of lung cancer.

The effect of smoking on chronic inflammation, immune function and blood cell composition.

Smoking is the number one risk factor for cancer mortality but only 15-20% of heavy smokers develop lung cancer. It would, therefore, be of great benefit to identify those at high risk early on so that preventative measures can be initiated. To investigate this, we evaluated the effects of smoking on inflammatory markers, innate and adaptive immune responses to bacterial and viral challenges and blood cell composition. We found that plasma samples from 30 heavy smokers (16 men and 14 women) had significantly higher CRP, fibrinogen, IL-6 and CEA levels than 36 non-smoking controls. Whole blood samples from smokers, incubated for 7 h at 37 °C in the absence of any exogenous stimuli, secreted significantly higher levels of IL-8 and a number of other cytokines/chemokines than non-smokers. When challenged for 7 h with E. coli, whole blood samples from smokers secreted significantly lower levels of many inflammatory cytokines/chemokines. However, when stimulated with HSV-1, significantly higher levels of both PGE2 and many cytokines/chemokines were secreted from smokers' blood samples than from controls. In terms of blood cell composition, red blood cells, hematocrits, hemoglobin levels, MCV, MCH, MCHC, Pct and RDW levels were all elevated in smokers, in keeping with their compromised lung capacity. As well, total leukocytes were significantly higher, driven by increases in granulocytes and monocytes. In addition, smokers had lower NK cells and higher Tregs than controls, suggesting that smoking may reduce the ability to kill nascent tumor cells. Importantly, there was substantial person-to person variation amongst smokers with some showing markedly different values from controls and others showing normal levels of many parameters measured, indicating the former may be at significantly higher risk of developing lung cancer.

Exploratory examination of inflammation state, immune response and blood cell composition in a human obese cohort to identify potential markers predicting cancer risk.

Obesity has reached epidemic proportions and is often accompanied by elevated levels of pro-inflammatory cytokines that promote many chronic diseases, including cancer. However, not all obese people develop these diseases and it would be very helpful to identify those at high risk early on so that preventative measures can be instituted. We performed an extensive evaluation of the effects of obesity on inflammatory markers, on innate and adaptive immune responses, and on blood cell composition to identify markers that might be useful in distinguishing those at elevated risk of cancer. Plasma samples from 42 volunteers with a BMI>35 had significantly higher CRP, PGE2, IL-1RA, IL-6 and IL-17 levels than 34 volunteers with normal BMIs. Of the cytokines and chemokines tested, only IL-17 was significantly higher in men with a BMI>35 than women with a BMI>35. As well, only IL-17 was significantly higher in those with a BMI>35 that had type 2 diabetes versus those without type 2 diabetes. Whole blood samples from participants with a BMI>35, when challenged with E. coli, produced significantly higher levels of IL-1RA while HSV-1 challenge resulted in significantly elevated IL-1RA and VEGF, and a non-significant increase in G-CSF and IL-8 levels. T cell activation of PBMCs, via anti-CD3 plus anti-CD28, resulted in significantly higher IFNγ production from volunteers with a BMI>35. In terms of blood cells, red blood cell distribution width (RDW), monocytes, granulocytes, CD4+T cells and Tregs were all significantly higher while, natural killer (NK) and CD8+ T cells were all significantly lower in the BMI>35 cohort, suggesting that obesity may reduce the ability to kill nascent tumor cells. Importantly, however, there was considerable person-to-person variation amongst participants with a BMI>35, with some volunteers showing markedly different values from controls and others showing normal levels of many parameters measured. These person-to-person variations may prove useful in identifying those at high risk of developing cancer.

Effect of age on chronic inflammation and responsiveness to bacterial and viral challenges.

To identify reliable biomarkers of age-related changes in chronic inflammation and responsiveness to bacterial and viral challenges, we evaluated endogenous and ex vivo stimulated levels of 18 inflammatory markers, using whole blood collected in EDTA and sodium heparin tubes from 41 healthy volunteers, i.e., 11 men + 10 women aged 20-35 and 10 men + 10 women aged 50-77. These studies revealed significant differences in the levels of inflammatory markers when blood was collected in EDTA versus sodium heparin and age related differences in these biomarkers were confirmed with blood collected in EDTA from 120 healthy volunteers in 3 age categories, ie, 20 men + 20 women, aged 20-35, 36-49 and 50-77. Studies with unstimulated blood samples, to measure levels of chronic inflammation, revealed a significant increase with age in IL-12p70, CRP and PGE2, consistent with the concept of "inflammaging", and a decrease in G-CSF in both men and women. Interestingly, in response to E. coli stimulation, PGE2 levels were markedly reduced in the 50-77 year old cohort while they were increased following Herpes Simplex virus-1 (HSV-1) stimulation, along with IL-8. In addition, unlike E. coli, HSV-1 potently stimulated IFNα production, but levels were dramatically reduced in the older cohort, consistent with a reduced ability to generate an anti-viral response. We also found platelets and CD8+ T cells were reduced with age while CD4+ T cells were significantly increased, resulting in a substantially higher CD4/CD8 ratio in the older cohort. Surprisingly, however, we found that the older cohort exhibited more T cell proliferation and IFNγ production in response to anti-CD3+anti-CD28 stimulation. Importantly, there was considerable person-to-person variation in these inflammatory markers in all age groups, making possible comparisons between a person's "inflammage" and chronological age. These assays should help to identify individuals at high risk of autoimmune disorders and cancer.