Project description:Epidemiological studies highlight a strong association between obesity and colorectal cancer (CRC). This association appears stronger in men and a role for sex hormones is indicated by epidemiological studies. Especially estrogen is protective against CRC and correlated to several aspects of the metabolic syndrome. Anti-inflammatory and anti-tumorigenic effects of estrogen in colon have been demonstrated to act via estrogen receptor beta (ERβ). This led us to hypothesize that estrogenic signaling, through both systemic and local effects might modulate the colon microenvironment during HFD-induced obesity. In order to test our hypothesis mice were fed a control diet or a high fat diet (HFD) for 3 weeks and treated with different estrogenic ligands. In the present study, we demonstrate that there are sex-differences in the response to HFD-induced obesity and in the colon transcriptome. Both sexes develop obesity with an impaired circadian rhythm but the male metabolic profile is more sensitive to HFD and increased the colon epithelial cell proliferation. Females were resistant to impaired glucose metabolism, but HFD-feeding increased the infiltration of macrophages. Estrogen signaling in males, via ERα, presented anti-obesogenic effects. However, systemic and/or local activation of both ERα and ERβ restored the circadian rhythm in the males. In females, systemic activation of ERα restored the circadian rhythm, however, systemic and/or local activation of ERβ down-regulated the expression of macrophage markers. These results suggest that estrogen signaling through systemic and/or local activation of ERβ can regulate the colon microenvironment during HFD-induced obesity.
Project description:High-fat diet and obesity are high risk factors for colorectal cancer. The underlying mechanism is still unclear. Environmental factors alter the epigenome to affect gene expression thus the phenotype. In response to external stimuli, the cis-regulatory regions, especially enhancer loci, are key elements for regulating selective gene expression. We thus explored the effects of high-fat diet and the accompanying obesity on gene expression and the enhancer landscape in colon epithelium. High-fat diet exposed binding sites of transcription factors downstream of signaling pathways important in the initiation and progression of colon cancer. Meantime, colon-specific enhancers were lost rendering the cells potential for dedifferentiation. The alteration at enhancer regions drives a specific transcription program promoting colon cancer progression. The comprehensive interrogation of enhancer changes by high-fat diet in colon epithelium provides a number of insights into the underlying biology of high-fat diet and obesity in increasing colon cancer risk, and provides potential therapeutic targets to treat obese colon cancer patients.
Project description:Methylation of p16 promoter resulting in epigenetic gene silencing- known as p16 epimutation- is common in human colorectal cancer (CRC). Using mouse models, we demonstrated that p16 epimutation cooperates with mutant Apc to promote colon cancer development. To comprehensively characterize immune function within the tumor microenvironment (TME), we performed single-cell RNA sequencing (scRNA-seq) of colon tumors in these animals.
Project description:High-fat diet and obesity are high risk factors for colorectal cancer. The underlying mechanism is still unclear. Environmental factors alter the epigenome to affect gene expression thus the phenotype. In response to external stimuli, the cis-regulatory regions, especially enhancer loci, are key elements for regulating selective gene expression. We thus explored the effects of high-fat diet and the accompanying obesity on gene expression and the enhancer landscape in colon epithelium. High-fat diet exposed binding sites of transcription factors downstream of signaling pathways important in the initiation and progression of colon cancer. Meantime, colon-specific enhancers were lost rendering the cells potential for dedifferentiation. The alteration at enhancer regions drives a specific transcription program promoting colon cancer progression. The comprehensive interrogation of enhancer changes by high-fat diet in colon epithelium provides a number of insights into the underlying biology of high-fat diet and obesity in increasing colon cancer risk, and provides potential therapeutic targets to treat obese colon cancer patients. We measured gene expression in colon epithelium from wild type mice and NAG-1 (non-steroidal anti-inflammatory drug (NSAID)-activated gene-1) transgenic mice fed either a 10% fat diet (LF) or a 60% fat diet (HF) for 20 weeks, using Agilent Whole Mouse Genome 4x44 multiplex format oligo arrays (014868) (Agilent Technologies) following the Agilent 1-color microarray-based gene expression analysis protocol. The ChIP-seq component of the study is included in GSE46748.
Project description:Estrogen signals play an important role in the phenotype of estrogen receptor positive breast cancer. However, comprehensive analyses of the effect of estrogen signals on the tumor microenvironment and sur-vival in large cohorts of primary breast cancer patients have been lacking. We aimed to test the hypothesis that estrogen reactivity affects gene expression and immune cell infiltration profiles in the tumor microenvi-ronment and survival.
Project description:Obesity is a worldwide epidemic associated with increased risk and progression of colon cancer. Here, we aimed to determine the role of adipose triglyceride lipase (ATGL), responsible for intracellular lipid droplet (LDs) utilization, in obesity driven colonic tumorigenesis. In local colon cancer patients, significantly increased ATGL levels in tumor tissue, compared to controls, were augmented in obese individuals. Elevated ATGL levels in human colon cancer cells (CCC) relative to non-transformed were augmented by an obesity mediator, oleic acid (OA). In CCC and colonospheres, enriched in colon cancer stem cells (CCSC), inhibition of ATGL prevented LDs utilization and inhibited OA-stimulated growth through retinoblastoma-mediated cell-cycle arrest. Further, transcriptomic analysis of CCC, with inhibited ATGL, revealed targeted pathways driving tumorigenesis and high-fat-diet obesity facilitated tumorigenic pathways. Inhibition of ATGL in colonospheres revealed targeted pathways in human colonic tumor crypt base cells (enriched in CCSC) derived from colon cancer patients. In CCC and colonospheres, we validated selected transcripts targeted by ATGL inhibition, some with emerging roles in colonic tumorigeneses (ATG2B, PCK2, PGAM1, SPTLC2, IGFBP1, ABCC3) and others with established roles (MYC, MUC2). These findings demonstrate obesity-promoted, ATGL-mediated colonic tumorigenesis and establishes therapeutic significance of ATGL in obesity reinforced colon cancer progression.