Abstract 893: Metabolomic profiling of APCΔ14/+ mice maintained on a methyl donor deficient diet reveals alterations to methionine and fatty acid metabolism associated with cancer protection

Abstract

Abstract Our laboratory has previously demonstrated that administration of a diet deficient in methyl donor nutrients (folic acid, methionine, choline and vitamin B12) reduces tumor multiplicity by greater than 95% in ApcMin/+ mice. However, the mechanism by which this dramatic cancer protection is afforded is unknown. To begin to identify the metabolic consequences of methyl donor deficiency, we have conducted an LC/MS-based metabolic profiling analysis of colonic mucosa collected from ApcΔ14/+ mice fed a methyl donor deficient (MDD) diet for 17 weeks. Methyl donor deficiency causes significant alterations to a number of key metabolic pathways, including those involved in the methionine cycle, fatty acid oxidation, and tryptophan catabolism. We observed significant reductions in methionine (65% reduction, p<0.001) and betaine (70% reduction, p<0.001), accompanied by large increases in homocysteine (88.6-fold increase, p<0.001) and S-adenosylmethionine (17.2-fold increase, p<0.001), confirming that dietary methyl donor deficiency alters one-carbon metabolites in the colon. MDD mice were found to have reduced levels of acyl-carnitines and free carnitine (58% reduction, p<0.001). Additionally, we detected a reduction in the critical metabolic component, acetyl CoA, suggesting decreased transport of fatty acids into the mitochondria for use in fatty acid oxidation (FAO). Finally, we observed changes in the mucosal levels of tryptophan (32% reduction, p = 0.02), kynurenine (2.8-fold increase, p = 0.008) and indolepropionate (5.1-fold increase, p = 0.005), that were retained for seven weeks beyond active methyl donor deficiency. Taken together, these findings suggest that dietary methyl donor deficiency significantly disrupts the methionine cycle, inhibits fatty acid transport and oxidation, and may induce long-term changes to tryptophan metabolism. This study has improved our understanding of the molecular mechanisms underlying the cancer protection conveyed by dietary methyl donor deficiency and has identified metabolic pathways that are candidate targets for chemopreventive intervention. Citation Format: Matthew P. Hanley, Daniel W. Rosenberg. Metabolomic profiling of APCΔ14/+ mice maintained on a methyl donor deficient diet reveals alterations to methionine and fatty acid metabolism associated with cancer protection. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 893. doi:10.1158/1538-7445.AM2015-893