Weight Loss and/or Sulindac Mitigate Obesity-associated Transcriptome, Microbiome, and Protumor Effects in a Murine Model of Colon Cancer.

Obesity is associated with an increased risk of colon cancer. Our current study examines whether weight loss and/or treatment with the NSAID sulindac suppresses the protumor effects of obesity in a mouse model of colon cancer. Azoxymethane-treated male FVB/N mice were fed a low-fat diet (LFD) or high-fat diet (HFD) for 15 weeks, then HFD mice were randomized to remain on HFD (obese) or switch to LFD [formerly obese (FOb-LFD)]. Within the control (LFD), obese, and FOb-LFD groups, half the mice started sulindac treatment (140 ppm in the diet). All mice were euthanized 7 weeks later. FOb-LFD mice had intermediate body weight levels, lower than obese but higher than control (P < 0.05). Sulindac did not affect body weight. Obese mice had greater tumor multiplicity and burden than all other groups (P < 0.05). Transcriptomic profiling indicated that weight loss and sulindac each modulate the expression of tumor genes related to invasion and may promote a more antitumor immune landscape. Furthermore, the fecal microbes Coprobacillus, Prevotella, and Akkermansia muciniphila were positively correlated with tumor multiplicity and reduced by sulindac in obese mice. Coprobacillus abundance was also decreased in FOb-LFD mice. In sum, weight loss and sulindac treatment, alone and in combination, reversed the effects of chronic obesity on colon tumor multiplicity and burden. Our findings suggest that an investigation regarding the effects of NSAID treatment on colon cancer risk and/or progression in obese individuals is warranted, particularly for those unable to achieve moderate weight loss. PREVENTION RELEVANCE: Obesity is a colon cancer risk and/or progression factor, but the underlying mechanisms are incompletely understood. Herein we demonstrate that obesity enhances murine colon carcinogenesis and expression of numerous tumoral procancer and immunosuppressive pathways. Moreover, we establish that weight loss via LFD and/or the NSAID sulindac mitigate procancer effects of obesity.

Dietary patterns influence epicardial adipose tissue fatty acid composition and inflammatory gene expression in the Ossabaw pig.

Epicardial adipose tissue (EAT) inflammation is implicated in the development and progression of coronary atherosclerosis. Dietary saturated and polyunsaturated fatty acids (SFAs and PUFA) can influence adipose tissue inflammation. We investigated the influence of dietary patterns, with emphasis on dietary fat type, and statin therapy, on EAT fatty acid (FA) composition and inflammatory gene expression. Thirty-two Ossabaw pigs were fed isocaloric amounts of a Heart Healthy (high in unsaturated fat) or Western (high in saturated fat) diets +/- atorvastatin for 6 months. EAT FA composition reflected dietary fat composition. There was no significant effect of atorvastatin on EAT FA composition. Total and long-chain SFAs were positively associated with inflammatory signaling (TLR2) and a gene involved in lipid mediator biosynthesis (PTGS2) (P<.0003). Medium-chain SFAs capric and lauric acids were negatively associated with IL-6 (all P<.0003). N-6 and n-3 PUFAs were positively associated with anti-inflammatory signaling genes (PPARG, FFAR4 and ADIPOQ) and long-chain n-3 PUFAs were positively associated with a gene involved in lipid mediator biosynthesis (ALOX5) (all P<.0003). These data indicate that dietary patterns, differing in fat type, influence EAT FA composition. Associations between EAT SFAs, PUFAs, and expression of genes related to inflammation provide a link between dietary quality and EAT inflammation.

The Ossabaw Pig Is a Suitable Translational Model to Evaluate Dietary Patterns and Coronary Artery Disease Risk.

Background: Animal models that mimic diet-induced human pathogenesis of chronic diseases are of increasing importance in preclinical studies. The Ossabaw pig is an established model for obesity-related metabolic disorders when fed extreme diets in caloric excess. Objective: To increase the translational nature of this model, we evaluated the effect of diets resembling 2 human dietary patterns, the Western diet (WD) and the Heart Healthy Diet (HHD), without or with atorvastatin (-S or +S) therapy, on cardiometabolic risk factors and atherosclerosis development. Methods: Ossabaw pigs (n = 32; 16 boars and 16 gilts, aged 5-8 wk) were randomized according to a 2 × 2 factorial design into 4 groups (WD-S, WD+S, HHD-S, and HHD+S) and were fed the respective diets for 6 mo. The WD (high in saturated fat, cholesterol, and refined grain) and the HHD (high in unsaturated fat, whole grain, and fruit and vegetables) were isocaloric [38% of energy (%E) from fat, 47%E from carbohydrate, and 15%E from protein]. Body composition was determined by using dual-energy X-ray absorptiometry, serum fatty acid (FA) profiles by gas chromatography, cardiometabolic risk profile by standard procedures, and degree of atherosclerosis by histopathology. Results: Serum FA profiles reflected the predominant dietary FA. Pigs fed the WD had 1- to 4-fold higher concentrations of LDL cholesterol, non-HDL cholesterol, HDL cholesterol, high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor α (TNF-α), alkaline phosphatase (ALP), and alanine aminotransferase (ALT) compared with HHD-fed pigs (all P-diet < 0.05). Statin therapy significantly lowered concentrations of LDL cholesterol (-39%), non-HDL cholesterol (-38%), and triglycerides (-6%) (P-statin < 0.02). A greater degree of atheromatous changes (macrophage infiltration, foam cells, fatty streaks) and lesion incidence was documented in the coronary arteries (P-diet < 0.05), as well as 2- to 3-fold higher lipid deposition in the aortic arch or thoracic aorta of WD- compared with HHD-fed pigs (P-diet < 0.001). Conclusions: Ossabaw pigs manifested a dyslipidemic and inflammatory profile accompanied by early-stage atherosclerosis when fed a WD compared with an HHD, which was moderately reduced by atorvastatin therapy. This phenotype presents a translational model to examine mechanistic pathways of whole food-based dietary patterns on atherosclerosis development.

Improving power to detect changes in blood miRNA expression by accounting for sources of variability in experimental designs.

BACKGROUND: Blood miRNAs are a new promising area of disease research, but variability in miRNA measurements may limit detection of true-positive findings. Here, we measured sources of miRNA variability and determine whether repeated measures can improve power to detect fold-change differences between comparison groups. METHODS: Blood from healthy volunteers (N = 12) was collected at three time points. The miRNAs were extracted by a method predetermined to give the highest miRNA yield. Nine different miRNAs were quantified using different qPCR assays and analyzed using mixed models to identify sources of variability. A larger number of miRNAs from a publicly available blood miRNA microarray dataset with repeated measures were used for a bootstrapping procedure to investigate effects of repeated measures on power to detect fold changes in miRNA expression for a theoretical case-control study. RESULTS: Technical variability in qPCR replicates was identified as a significant source of variability (P < 0.05) for all nine miRNAs tested. Variability was larger in the TaqMan qPCR assays (SD = 0.15-0.61) versus the qScript qPCR assays (SD = 0.08-0.14). Inter- and intraindividual and extraction variability also contributed significantly for two miRNAs. The bootstrapping procedure demonstrated that repeated measures (20%-50% of N) increased detection of a 2-fold change for approximately 10% to 45% more miRNAs. CONCLUSION: Statistical power to detect small fold changes in blood miRNAs can be improved by accounting for sources of variability using repeated measures and choosing appropriate methods to minimize variability in miRNA quantification. IMPACT: This study demonstrates the importance of including repeated measures in experimental designs for blood miRNA research. See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."