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:Sessile serrated adenomas are now recognized as precursor lesions of a substantial subset of colorectal cancers arising via a so-called “serrated pathway”. However, their biological markers remain to be defined. The aim of our study was to identify differentially expressed genes in sessile serrated adenomas, hyperplastic polyps and tubular adenomas. Gene expression analysis demonstrated molecular differences between polyp types. Further studies using QRT-PCR on Cathepsin E demonstrated a significantly (p< 0.05) higher expression in sessile serrated adenomas as compared to both other polyp types. Trefoil Factor 1, showed the same trend of expression for sessile serrated adenomas as compared to hyperplastic polyps, and was significantly higher in both polyps compared to tubular adenomas. Immunohistochemistry for both proteins demonstrated strong cytoplasmic staining of abnormal crypts in all sessile serrated adenomas while staining in tubular adenomas and hyperplastic polyps was weak and focal. BRAF and KRAS mutation analysis were employed to further validate polyp discrimination. The findings demonstrated the positive association of the BRAF mutation, V600E, with sessile serrated adenomas and KRAS mutations with tubular adenomas (P<0.05). This study demonstrates CTSE and TFF1 over-expression in sessile serrated adenomas compared to both hyperplastic polyps and tubular adenomas. Keywords: colonic polyp tissue comparison, linear modelling, SSA
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: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:Sessile serrated adenomas are now recognized as precursor lesions of a substantial subset of colorectal cancers arising via a so-called “serrated pathway”. However, their biological markers remain to be defined. The aim of our study was to identify differentially expressed genes in sessile serrated adenomas, hyperplastic polyps and tubular adenomas. Gene expression analysis demonstrated molecular differences between polyp types. Further studies using QRT-PCR on Cathepsin E demonstrated a significantly (p< 0.05) higher expression in sessile serrated adenomas as compared to both other polyp types. Trefoil Factor 1, showed the same trend of expression for sessile serrated adenomas as compared to hyperplastic polyps, and was significantly higher in both polyps compared to tubular adenomas. Immunohistochemistry for both proteins demonstrated strong cytoplasmic staining of abnormal crypts in all sessile serrated adenomas while staining in tubular adenomas and hyperplastic polyps was weak and focal. BRAF and KRAS mutation analysis were employed to further validate polyp discrimination. The findings demonstrated the positive association of the BRAF mutation, V600E, with sessile serrated adenomas and KRAS mutations with tubular adenomas (P<0.05). This study demonstrates CTSE and TFF1 over-expression in sessile serrated adenomas compared to both hyperplastic polyps and tubular adenomas. Keywords: colonic polyp tissue comparison, linear modelling, SSA Microarray analysis was performed on 13 SSAs and 11 TAs. SSAs were from 4 males and 9 females (mean age of 75) and TAs were from 5 males and 6 females (mean age of 72). Samples were directly hybridised to each other (SSA versus TA) or to a pooled normal control (SSA versus control). A linear model (Smyth 2004) was fitted to the data bringing together the three contrasts: SSA versus control, TA versus control and SSA versus TA. Human OligoLibrary (Compugen Human Oligo Library (v1) containing 18861 60-mer oligonucleotides, representing approximately 16,000 unique genes) by the Adelaide Microarray Centre (Australia) was used. Slides were scanned using a GenePix 3000B scanner (Axon Instruments, Sunnydale, CA), and the Spot package (CSIRO, Australia) was used to identify spots and estimate fore- and background intensities (using a morphological opening background estimator) (Yang, Buckley et al. 2001; Ritchie 2004). Data analysis was performed in R (www.r-project.org) using the Limma package of Bioconductor (Gentleman, Carey et al. 2004; Smyth 2004). Loess print tip method was used to correct for dye-bias and intensity within each group of adjacent spots printed by one pin (Yang, Dudoit et al. 2002). Linear modelling was performed with the Limma package of Bioconductor (Smyth 2004).
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:Aberrant DNA methylation is frequent in colorectal cancer (CRC), but the underlying mechanisms and pathological consequences are poorly understood. Ten-Eleven Translocation (TET) dioxygenases and Thymine DNA Glycosylase (TDG) mediate active DNA demethylation by generating and removing oxidized cytosine species. TET1 and TDG mutations, and altered levels of oxidized cytosines have been identified in human CRC. To investigate the TET-TDG demethylation axis in intestinal tumorigenesis, we generated ApcMin mice that are devoid of Tet1 and/or Tdg, and characterized the methylome and transcriptome of intestinal adenomas. There were increased numbers (>30) of adenomas in ApcMin mice expressing the dominant-negative TdgN151A allele, whereas Tet1-deficient and Tet1/Tdg-double heterozygous ApcMin adenomas were larger and displayed features of erosion and invasion. Methylome analysis revealed reduction in global DNA hypomethylation in colonic adenomas from Tet1- and Tdg-mutant ApcMin mice, and hypermethylation of CpG islands in Tet1-mutant ApcMin mice. In addition, RNA sequencing showed upregulation of inflammatory, immune and interferon response genes in Tet1- and Tdg-mutant colonic adenomas compared to control ApcMin adenomas. The corresponding 127-gene inflammatory signature separated human colonic adenocarcinomas in four groups, closely aligned with their microsatellite or chromosomal instability, and characterized by different levels of DNA methylation and DNMT1 expression that anti-correlated with TET1 expression. These findings demonstrate a novel mechanism of epigenetic regulation during intestinal tumorigenesis by which TET1-TDG-mediated DNA demethylation may decrease methylation levels and inflammatory/interferon/immune responses, and is linked to the type of genomic instability.