Project description:Emerging data suggest that some high-risk subjects benefit more than others from preventive intervention. The goal of this study was to determine the efficacy of sulindac (Sul) and/or atorvastatin (Atorva) against spontaneous colorectal adenomas in Apc+/Min-FCCC mice in which the tumor-bearing status was known at the time of treatment initiation. Administration of Sul/Atorva to tumor-bearing mice led to a 43% reduction in the multiplicity of colorectal adenomas as compared to that of untreated tumor-bearing mice. Atorvastatin completely inhibited the formation of microadenomas in mice that were tumor-free at baseline, with associated decreases in the expression of inflammatory mediators observed. Expression of Hoxb13 and Rprm was enhanced significantly following Sul/Atorva treatment, suggesting the importance of cell cycle regulation in colon tumor inhibition. The tumor status of animals at treatment initiation dictates response to atorvastatin, sulindac and Sul/Atorva. The tumor inhibition observed with Sul/Atorva in tumor-bearing mice was greater than that achieved with either agent alone.
Project description:Chemoprevention is a pragmatic approach to reduce the risk of colorectal cancer, one of the leading causes of cancer-related death in western countries. In this regard, maslinic acid (MA), a pentacyclic triterpene extracted from wax-like coatings of olives, is known to inhibit proliferation and induce apoptosis in colon cancer cell lines without affecting normal intestinal cells. The present study evaluated the chemopreventive efficacy and associated mechanisms of maslinic acid treatment on spontaneous intestinal tumorigenesis in Apc(Min/+) mice. Twenty-two mice were randomized into 2 groups: control group and MA group, fed with a maslinic acid-supplemented diet for six weeks. MA treatment reduced total intestinal polyp formation by 45% (P<0.01). Putative molecular mechanisms associated with suppressing intestinal polyposis in Apc(Min/+) mice were investigated by comparing microarray expression profiles of MA-treated and control mice and by analyzing the serum metabolic profile using NMR techniques. The different expression phenotype induced by MA suggested that it exerts its chemopreventive action mainly by inhibiting cell-survival signaling and inflammation. These changes eventually induce G1-phase cell cycle arrest and apoptosis. Moreover, the metabolic changes induced by MA treatment were associated with a protective profile against intestinal tumorigenesis. These results show the efficacy and underlying mechanisms of MA against intestinal tumor development in the Apc(Min/+) mice model, suggesting its chemopreventive potential against colorectal cancer.
Project description:To investigate the role of RAD21 in the transcriptional regulation of global gene expression at early stage of colorectal cancer developments, we peformed the genome-wide analysis to map genomic regions bound by Rad21 in normal small testinal crypts and tumors (adenomas) harvested from Apc Min/+ mice using ChIP-seq. ChIP-seq naalysis identified high confidence RAD21 binding sites unique to normal crypts or adenomas, as well as those common to both tissues. We further performed RNA-seq to profile the changes in gene expression from normal WT crypts to adenomas at the very early stage of adenomagenesis in the context of Rad21 heterozygous loss. mRNA profiles of normal small intestinal crypts (WT) and adenomas from Apc Min/+ and Apc Min/+:Rad21+/- double mutant mouse; Mapping of Rad21 genomic binding sites in normal intestinal crypts (WT) and Apc Min/+ adenomas
Project description:We assessed differential gene expression using RNAseq in intestinal adenomas between Apc loss-of-function (Apcmin) mice, or by Apc1322T mice encoding a partially-functional Apc truncation commonly found in colorectal carcinomas.
Project description:To investigate the role of RAD21 in the transcriptional regulation of global gene expression at early stage of colorectal cancer developments, we peformed the genome-wide analysis to map genomic regions bound by Rad21 in normal small testinal crypts and tumors (adenomas) harvested from Apc Min/+ mice using ChIP-seq. ChIP-seq naalysis identified high confidence RAD21 binding sites unique to normal crypts or adenomas, as well as those common to both tissues. We further performed RNA-seq to profile the changes in gene expression from normal WT crypts to adenomas at the very early stage of adenomagenesis in the context of Rad21 heterozygous loss.
Project description:Loss of APC or activation of Braf V600E mutation in combination with Alk5 loss in the intestinal epithelium under the control of VilCreER, with or without antibiotic/sulindac treatment
Project description:We sought to identify gene transcripts altered in level between the normal epithelium and adenomas in colon of the Apc-Min/+ mouse. These differences in level can be compared to those observed for the colons of the Apc-Pirc/+ rat and the human.
Project description:Oncogenic mutations that drive colorectal cancer can be present in healthy intestines for long periods without overt consequence. Mutation of Adenomatous polyposis coli (Apc), the most common initiating event in conventional adenomas, activates Wnt signaling, hence conferring fitness on mutant intestinal stem cells (ISCs). Apc mutations may occur in ISCs that arose by routine self-renewal or by dedifferentiation of their progeny. Although ISCs of these different origins are fundamentally similar, it is unclear if both generate tumours equally well in uninjured intestines. Also unknown is whether cis-regulatory elements are substantively modulated upon Wnt hyperactivation or as a feature of subsequent tumours. Here, we show in two mouse models that adenomas are not an obligatory outcome of Apc deletion in either ISC source but require proximity of mutant intestinal crypts. Reduced crypt density abrogates, and aggregation of mutant colonic crypts augments, adenoma formation. Moreover, adenoma-resident ISCs open chromatin at thousands of enhancers that are inaccessible in Apc-null ISCs not associated with adenomas. These cis-elements explain adenoma-selective gene activity and persist, with little further expansion of the repertoire, as other oncogenic mutations accumulate. Thus, cooperativity between neighbouring mutant crypts and new accessibility at specific enhancers are key steps early in intestinal tumourigenesis.
Project description:Oncogenic mutations that drive colorectal cancer can be present in healthy intestines for long periods without overt consequence. Mutation of Adenomatous polyposis coli (Apc), the most common initiating event in conventional adenomas, activates Wnt signaling, hence conferring fitness on mutant intestinal stem cells (ISCs). Apc mutations may occur in ISCs that arose by routine self-renewal or by dedifferentiation of their progeny. Although ISCs of these different origins are fundamentally similar, it is unclear if both generate tumours equally well in uninjured intestines. Also unknown is whether cis-regulatory elements are substantively modulated upon Wnt hyperactivation or as a feature of subsequent tumours. Here, we show in two mouse models that adenomas are not an obligatory outcome of Apc deletion in either ISC source but require proximity of mutant intestinal crypts. Reduced crypt density abrogates, and aggregation of mutant colonic crypts augments, adenoma formation. Moreover, adenoma-resident ISCs open chromatin at thousands of enhancers that are inaccessible in Apc-null ISCs not associated with adenomas. These cis-elements explain adenoma-selective gene activity and persist, with little further expansion of the repertoire, as other oncogenic mutations accumulate. Thus, cooperativity between neighbouring mutant crypts and new accessibility at specific enhancers are key steps early in intestinal tumourigenesis.
Project description:Oncogenic mutations that drive colorectal cancer can be present in healthy intestines for long periods without overt consequence. Mutation of Adenomatous polyposis coli (Apc), the most common initiating event in conventional adenomas, activates Wnt signaling, hence conferring fitness on mutant intestinal stem cells (ISCs). Apc mutations may occur in ISCs that arose by routine self-renewal or by dedifferentiation of their progeny. Although ISCs of these different origins are fundamentally similar, it is unclear if both generate tumours equally well in uninjured intestines. Also unknown is whether cis-regulatory elements are substantively modulated upon Wnt hyperactivation or as a feature of subsequent tumours. Here, we show in two mouse models that adenomas are not an obligatory outcome of Apc deletion in either ISC source but require proximity of mutant intestinal crypts. Reduced crypt density abrogates, and aggregation of mutant colonic crypts augments, adenoma formation. Moreover, adenoma-resident ISCs open chromatin at thousands of enhancers that are inaccessible in Apc-null ISCs not associated with adenomas. These cis-elements explain adenoma-selective gene activity and persist, with little further expansion of the repertoire, as other oncogenic mutations accumulate. Thus, cooperativity between neighbouring mutant crypts and new accessibility at specific enhancers are key steps early in intestinal tumourigenesis.