Project description:Oral intake of high fat diet and acidic bile salts may promote the oxidative stress-induced Warburg effect in the tumor The promotion of the carcinogenesis may be associated with high fat diet-related dysbiosis
Project description:Obesity is an independent risk factor for colorectal cancer (CRC) although the underlying mechanisms have not been elucidated. Dietary nutrients play a key role in both the prevention and promotion of CRC. While iron is an essential nutrient, excess iron is associated with carcinogenesis. Unlike the systemic compartment, the intestinal lumen lacks an efficient system to regulate iron. In conditions when dietary iron malabsorption and intestinal inflammation co-exist, greater luminal iron is associated with increased intestinal inflammation and a shift in the gut microbiota to more pro-inflammatory strains. However, treatments designed to reduce luminal, including diet restriction and chelation, are associated with lower intestinal inflammation and the colonization of protective gut microbes. Obesity is associated with inflammation-induced, hepcidin-mediated, iron metabolism dysfunction characterized by iron deficiency and dietary iron malabsorption. Obesity is also linked to intestinal inflammation. Currently, there is a fundamental gap in understanding how altered iron metabolism impacts CRC risk in obesity.
The investigator’s objective is to conduct a crossover controlled feeding trial of: 1) a "Typical American" diet with "high" heme/non-heme iron", 2) a "Typical American" diet with "low" iron, and 3) a Mediterranean diet with "high" non heme iron and examine effects on colonic and systemic inflammation and the gut microbiome.
Project description:Several aspects common to a Western lifestyle, including obesity and decreased physical activity, are known risks for gastrointestinal cancers. There is an increasing amount of evidence suggesting that diet profoundly affects the composition of the intestinal microbiota. Moreover, there is now unequivocal evidence linking a dysbiotic gut to cancer development. Yet, the mechanisms through which high-fat diet (HFD)-mediated changes in the microbial community impact the severity of tumorigenesis in the gut, remain to be determined. Here we demonstrate that HFD promotes tumor progression in the small intestine of genetically susceptible K-rasG12Dint mice independent of obesity. HFD consumption in conjunction with K-Ras mutation mediates a shift in the composition of gut microbiota, which is associated with a decrease in Paneth cell antimicrobial host defense that compromises dendritic cell (DC) recruitment and MHC-II presentation in the gut-associated lymphoid tissues (GALTs). DC recruitment in GALTs can be normalized, and tumor progression attenuated completely, when K-rasG12Dint mice are supplemented with the short-chain fatty acid butyrate, a bacterial fermentation endproduct. Importantly, Myd88-deficiency completely blocks tumor progression in K-rasG12Dint mice. Transfer of fecal samples from diseased donors into healthy adult K-rasG12Dint mice is sufficient to transmit disease in the absence of HFD. Furthermore, treatment with antibiotics completely blocks HFD-induced tumor progression, suggesting a pivotal role for distinct microbial shifts in aggravating disease in the small intestine. Collectively, these data underscore the importance of the reciprocal interaction between host and environmental factors in selecting intestinal microbiota that favor carcinogenesis, and suggest tumorigenesis may be transmissible among genetically predisposed individuals. 3 mice each for each treatment.
Project description:Background: Post-menopausal obesity is an established risk factor for breast cancer. Consumption of diets high in fat is known to be highly correlated with obesity. In this, we sought to evaluate the interaction(s) between high fat diet, weight gain and mammary carcinogenesis using an obese-resistant and obese-prone rat model with direct correlates to human disease. Methods: Female obese-prone (OP) and obese-resistant (OR) weanling rats were placed on either a low fat (10% kcal) or a high fat (39% kcal) n-6 polyunsaturated (PUFA) safflower diet for 30 days. At post natal day (PND) 50, global gene expression profiling was performed on microdissected mammary epithlelium from one cohort of rats and another cohort of rats were given a single oral gavage of either 7,12-dimethylbenz[a]anthracene (DMBA at 14 mg/kg) or vehicle. Rats were then maintained on the diets and body weights, food consumption and development of mammary lesions were monitored weekly. Results: The DMBA-treated OR rats on the 39% safflower diet had significantly greater incidence of ductal carcinoma-in-situ (DCIS) lesions and significantly greater DCIS multiplicity than DMBA-treated OR rats on the 10% safflower diet. These differences were not seen in the OP strain. Gene expression analysis of mammary ductal epithelium from OR rats on the high fat diet showed significant upregulation of proliferation-related genes compared to those consuming the low fat safflower diet. Again, these differences were not seen in the OP strain. Conclusion: Our findings indicate that consumption of high fat safflower diet enhances mammary carcinogenesis in an OR rat strain through increased proliferation of mammary epithelium at the time of exposure, but not in the OP rat strain. Thus, the diet-induced increase in sensitivity was strain-specific and independent of weight gain or obesity level.
Project description:Background: Post-menopausal obesity is an established risk factor for breast cancer. Consumption of diets high in fat is known to be highly correlated with obesity. In this, we sought to evaluate the interaction(s) between high fat diet, weight gain and mammary carcinogenesis using an obese-resistant and obese-prone rat model with direct correlates to human disease. Methods: Female obese-prone (OP) and obese-resistant (OR) weanling rats were placed on either a low fat (10% kcal) or a high fat (39% kcal) n-6 polyunsaturated (PUFA) safflower diet for 30 days. At post natal day (PND) 50, global gene expression profiling was performed on microdissected mammary epithlelium from one cohort of rats and another cohort of rats were given a single oral gavage of either 7,12-dimethylbenz[a]anthracene (DMBA at 14 mg/kg) or vehicle. Rats were then maintained on the diets and body weights, food consumption and development of mammary lesions were monitored weekly. Results: The DMBA-treated OR rats on the 39% safflower diet had significantly greater incidence of ductal carcinoma-in-situ (DCIS) lesions and significantly greater DCIS multiplicity than DMBA-treated OR rats on the 10% safflower diet. These differences were not seen in the OP strain. Gene expression analysis of mammary ductal epithelium from OR rats on the high fat diet showed significant upregulation of proliferation-related genes compared to those consuming the low fat safflower diet. Again, these differences were not seen in the OP strain. Conclusion: Our findings indicate that consumption of high fat safflower diet enhances mammary carcinogenesis in an OR rat strain through increased proliferation of mammary epithelium at the time of exposure, but not in the OP rat strain. Thus, the diet-induced increase in sensitivity was strain-specific and independent of weight gain or obesity level. Female obese-prone (OP) and obese-resistant (OR) weanling rats were placed on either a low fat (10% kcal) or a high fat (39% kcal) n-6 polyunsaturated (PUFA) safflower diet for 30 days. At post natal day (PND) 50, global gene expression profiling was performed on microdissected mammary epithlelium from one cohort of rats and another cohort of rats were given a single oral gavage of either 7,12-dimethylbenz[a]anthracene (DMBA at 14 mg/kg) or vehicle. Rats were then maintained on the diets and body weights, food consumption and development of mammary lesions were monitored weekly.