Epigenetic effects of high-fat diet on intestinal tumorigenesis in C57BL/6J- mice.

Aim: Obesity and obesogenic diets might partly accelerate cancer development through epigenetic mechanisms. To determine these early effects, we investigated the impact of three days of a high-fat diet on epigenomic and transcriptomic changes in murine intestinal epithelia.

Method: ChIP-Seq and RNA-Seq were performed on small intestinal epithelia of WT and male mice fed high-fat diet (HFD) or low-fat diet (LFD) for three days to identify genomic regions associated with differential H3K27ac levels as a marker of variant enhancer loci (VELs) as well as differentially expressed genes (DEGs).

Results: Regarding epigenetic and transcriptomic changes, diet type (LFD . HFD) showed a significant impact, and genotype (WT . ) showed a small impact. Compared to LFD, HFD resulted in 1306 gained VELs, 230 lost VELs, 133 upregulated genes, and 127 downregulated genes in WT mice, with 1056 gained VELs, 371 lost VELs, 222 upregulated genes, and 182 downregulated genes in mice. Compared to the WT genotype, the genotype resulted in zero changed VELs for either diet type group, 21 DEGs for LFD, and 48 DEGs for HFD. Most gained VELs, and upregulated genes were associated with lipid metabolic processes. Gained VELs were also associated with Wnt signaling. Downregulated genes were associated with antigen presentation and processing.

Conclusion: Three days of HFD-induced epigenomic and transcriptomic changes involving metabolic and immunologic pathways that may promote tumor growth in the genetically predisposed murine intestine without affecting key cancer signaling pathways.