Genome-wide DNA methylation profiling reveals cancer-associated changes within early colonic neoplasia
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ABSTRACT:
PROVIDER: PRJNA377844 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR5275290.fastq.gz | Fastqsanger.gz | |||
| SRR5275300.fastq.gz | Fastqsanger.gz | |||
| SRR5275310.fastq.gz | Fastqsanger.gz | |||
| SRR5275291.fastq.gz | Fastqsanger.gz | |||
| SRR5275301.fastq.gz | Fastqsanger.gz |
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Project description:Colorectal cancer (CRC) is characterized by genome-wide alterations to DNA methylation that influence gene expression and genomic stability. Less is known about the extent to which methylation is disrupted in the earliest stages of CRC development. In this study, we have combined laser-capture microdissection with reduced representation bisulfite sequencing to identify cancer-associated DNA methylation changes in human aberrant crypt foci (ACF), the earliest putative precursor to CRC. Using this approach, methylation profiles have been generated for 10 KRAS-mutant ACF and 10 CRCs harboring a KRAS mutation, as well as matched samples of normal mucosa. Of 811 differentially methylated regions (DMRs) identified in ACF, 537 (66%) were hypermethylated and 274 (34%) were hypomethylated. DMRs located within intergenic regions were heavily enriched for AP-1 transcription factor binding sites and were frequently hypomethylated. Furthermore, gene ontology analysis demonstrated that DMRs associated with promoters were enriched for genes involved in intestinal development, including homeobox genes and targets of the Polycomb repressive complex 2. Consistent with their role in the earliest stages of colonic neoplasia, 75% of the loci harboring methylation changes in ACF were also altered in CRC samples, though the magnitude of change at these sites was lesser in ACF. Although aberrant promoter methylation was associated with altered gene expression in CRC, this was not the case in ACF, suggesting the insufficiency of methylation changes to modulate gene expression in early colonic neoplasia. Altogether, these data demonstrate that DNA methylation changes, including significant hypermethylation, occur more frequently in early colonic neoplasia than previously believed, and identify epigenomic features of ACF that may provide new targets for cancer chemoprevention or lead to the development of new biomarkers for CRC risk.
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Project description:This SuperSeries is composed of the SubSeries listed below.
2018-01-23 | GSE95656 | GEO
Project description:Sequencing data from: EARLY HUMAN DISPERSALS WITHIN THE AMERICAS
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Project description:Aberrant crypt foci (ACF) are the earliest morphologically identifiable lesions in the colon that can be detected by high-definition chromoendoscopy with contrast dye spray. Although frequently associated with synchronous adenomas, their role in colorectal tumor development, particularly in the proximal colon, is still not clear. The goal of this study was to evaluate the profile of colon-adherent bacteria associated with proximal ACF and to investigate their relationship to the presence and subtype of synchronous polyps present throughout the colon. Forty-five subjects undergoing a screening or surveillance colonoscopy were included in this retrospective study. Bacterial cells adherent to the epithelia of ACF and normal mucosal biopsies were visualized by in situ hybridization within confocal tissue sections. ACF showed significantly greater heterogeneity in their bacterial microbiome profiles compared with normal mucosa. One of the bacterial community structures we characterized was strongly correlated with the presence of synchronous polyps. Finally, using DNA mass spectrometry to evaluate a panel of colorectal cancer hotspot mutations present in the ACF, we found that three APC gene mutations were positively associated with the presence of Instestinibacter sp., whereas KRAS mutations were positively correlated with Ruminococcus gnavus. This result indicates a potential relationship between specific colon-associated bacterial species and somatically acquired CRC-related mutations. Overall, our findings suggest that perturbations to the normal adherent mucosal flora may constitute a risk factor for early neoplasia, demonstrating the potential impact of mucosal dysbiosis on the tissue microenvironment and behavior of ACF that may facilitate their progression towards more advanced forms of neoplasia.
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Project description:Stromal cells play a central role in promoting the progression of colorectal cancer. Here, we analyze molecular changes within the epithelial and stromal compartments of dysplastic aberrant crypt foci (ACF) formed in the ascending colon, where rapidly developing interval cancers occur. We found strong activation of numerous neutrophil/monocyte chemokines, consistent with localized inflammation. The data also indicated a decrease in interferon signaling and cell-based immunity. The immune checkpoint and T-cell exhaustion gene PDCD1 was one of the most significantly upregulated genes, which was accompanied by a decrease in cytotoxic T-cell effector gene expression. In addition, CDKN2A expression was strongly upregulated in the stroma and downregulated in the epithelium, consistent with diverse changes in senescence-associated signaling on the two tissue compartments. IMPLICATIONS: Decreased CD8 T-cell infiltration within proximal colon ACF occurs within the context of a robust inflammatory response and potential stromal cell senescence, thus providing new insight into potential promotional drivers for tumors in the proximal colon.
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2020-09-10 | GSE137548 | GEO
Project description:Mutation of the adenomatous polyposis coli (APC gene), an early event in the adenoma-carcinoma sequence, is present in 70-80% of sporadic human colorectal adenomas and carcinomas. To test the hypothesis that mutation of the APC gene alters microbial interactions with host intestinal mucosa prior to the development of polyposis, culture-independent methods (targeted qPCR assays and Illumina sequencing of the 16S rRNA gene V1V2 hypervariable region) were used to compare the intestinal microbial composition of 30 six-week old C57BL/6 APCMin/+ and 30 congenic wild type (WT) mice. The results demonstrate that similar to 12-14 week old APCMin/+ mice with intestinal neoplasia, 6 week old APCMin/+ mice with no detectable neoplasia, exhibit an increased relative abundance of Bacteroidetes spp in the colon. Parallel mouse RNA sequence analysis, conducted on a subset of proximal colonic RNA samples (6 APCMin/+, 6 WT) revealed 130 differentially expressed genes (DEGs, fold change ? 2, FDR <0.05). Hierarchical clustering of the DEGs was carried out by using 1-r dissimilarity measurement, where r stands for the Pearson correlation, and Ward minimum variance linkage, in order to reduce the number of input variables. When the cluster centroids (medians) were included along with APC genotype as input variables, analysis of variance and covariance (ANCOVA) with stepwise variable selection, selected two of seven mouse gene clusters, in addition to APC genotype, as significantly associated (p = 0.011 and p = 0.004) with the increased relative abundance of Bacteroidetes spp. One of the two clusters includes several downregulated genes encoding immunoglobulin variable regions and non-protein coding RNAs. These results support the concept that mutation of the APC gene alters colonic-microbial interactions prior to polyposis. It remains to be determined whether interventions directed at ameliorating dysbiosis in APCMin/+mice, such as through probiotics, prebiotics or antibiotics, could reduce tumor formation. Comparing the differential gene expressions in proximal colonic mucosal samples from 6 six-week-old female Apc Min/+ and 6 six-week-old female WT mice
2015-08-24 | E-GEOD-67634 | biostudies-arrayexpress
Project description:The earliest recognizable stages of breast neoplasia are lesions that represent a heterogeneous collection of epithelial proliferations currently classified based on morphology. Their role in the development of breast cancer is not well understood but insight into the critical events at this early stage will improve efforts in breast cancer detection and prevention. These microscopic lesions are technically difficult to study so very little is known about their molecular alterations. To characterize the transcriptional changes of early breast neoplasia, we sequenced 3'- end enriched RNAseq libraries from formalin-fixed paraffin-embedded tissue of early neoplasia samples and matched normal breast and carcinoma samples from 25 patients. We find that gene expression patterns within early neoplasias are distinct from both normal and breast cancer patterns and identify a pattern of pro-oncogenic changes, including elevated transcription of ERBB2, FOXA1, and GATA3 at this early stage. We validate these findings on a second independent gene expression profile data set generated by whole transcriptome sequencing. Measurements of protein expression by immunohistochemistry on an independent set of early neoplasias confirms that ER pathway regulators FOXA1 and GATA3, as well as ER itself, are consistently upregulated at this early stage. The early neoplasia samples also demonstrate coordinated changes in long non-coding RNA expression and microenvironment stromal gene expression patterns. This study is the first examination of global gene expression in early breast neoplasia, and the genes identified here represent candidate participants in the earliest molecular events in the development of breast cancer. 3SEQ was performed on 72 FFPE human breast samples from 25 patients: 24 normal, 25 early neoplasia, 9 carcinoma in situ, and 14 invasive cancer
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Project description:Epigenetic modifications, such as aberrant DNA promoter methylation is frequently observed in cervical cancer. Identification of hypermethylated regions maybe useful for discrimination between normal cervical epithelium and high-grade cervical intraepithelial neoplasia (CIN2/3) or worse may improve current cervical cancer population-based screening programs. In this study, the DNA methylome of high-grade CIN lesions were characterised using genome-wide methylation screening to identify potential biomarkers for early diagnosis of cervical neoplasia. Methyl-DNA Immunoprecipitation (MeDIP) combined with DNA microarray was used to compare DNA methylation profiles of epithelial cells derived from high-grade CIN lesions with normal cervical epithelium resulting in the identification of hypermethylated differentially methylated regions (DMRs). Validation of 9 selected DMRs by MSP or BSP in cervical tissue revealed methylation in 63.2-94.7% high-grade CIN and in 59.3-100% cervical carcinomas. QMSP for the two most significant high-grade CIN-specific methylation markers was applied exploring test performance in a large series of cervical scrapings. Frequency and relative level of methylation were significantly different between normal and cancer samples (p<0.001). Clinical validation of both markers in cervical scrapings from patients referred with an abnormal cervical smear, confirmed that frequency and relative level of methylation were related with increasing severity of the underlying CIN lesion (p<0.001) and the ROC analysis was discriminative (p<0.005). These possible methylation markers represent COL25A1 and KATNAL2 promoters and their observed increased methylation upon progression is in agreement with their biological function (cytoskeleton regulation). In conclusion, our newly identified hypermethylated DMRs represent specific DNA methylation patterns in high-grade CIN lesions and could be potential biomarkers for early detection. Epigenetic modifications, such as aberrant DNA promoter methylation is frequently observed in cervical cancer. Identification of hypermethylated regions maybe useful for discrimination between normal cervical epithelium and high-grade cervical intraepithelial neoplasia (CIN2/3) or worse may improve current cervical cancer population-based screening programs. In this study, the DNA methylome of high-grade CIN lesions were characterised using genome-wide methylation screening to identify potential biomarkers for early diagnosis of cervical neoplasia. Methyl-DNA Immunoprecipitation (MeDIP) combined with DNA microarray was used to compare DNA methylation profiles of epithelial cells derived from high-grade CIN lesions with normal cervical epithelium resulting in the identification of hypermethylated differentially methylated regions (DMRs). Validation of 9 selected DMRs by MSP or BSP in cervical tissue revealed methylation in 63.2-94.7% high-grade CIN and in 59.3-100% cervical carcinomas. QMSP for the two most significant high-grade CIN-specific methylation markers was applied exploring test performance in a large series of cervical scrapings. Frequency and relative level of methylation were significantly different between normal and cancer samples (p<0.001). Clinical validation of both markers in cervical scrapings from patients referred with an abnormal cervical smear, confirmed that frequency and relative level of methylation were related with increasing severity of the underlying CIN lesion (p<0.001) and the ROC analysis was discriminative (p<0.005). These possible methylation markers represent COL25A1 and KATNAL2 promoters and their observed increased methylation upon progression is in agreement with their biological function (cytoskeleton regulation). In conclusion, our newly identified hypermethylated DMRs represent specific DNA methylation patterns in high-grade CIN lesions and could be potential biomarkers for early detection. MeDIP with subsequent microarray analysis was performed on DNA isolated from frozen macrodissected epithelial tissue of CIN3 lesions (n=15) and normal cervices (n=10).
2012-11-01 | E-GEOD-36319 | biostudies-arrayexpress
Project description:ObjectivesColorectal cancer initially lies dormant as dysplasia, a premalignant state that provides an opportunity for early cancer detection. Dysplasia can be flat in morphology, focal in size, and patchy in distribution, and thus it appears "invisible" on conventional wide-field endoscopy.AimsWe aim to develop and validate a peptide that is specific for epidermal growth factor receptor (EGFR), a cell surface target that is overexpressed in colonic adenomas and is readily accessible for imaging.MethodsWe expressed and purified the extracellular domain of EGFR for use with phage display to identify a peptide QRHKPRE that binds to domain 2 of this target. A near-infrared fluorescence endoscope was used to perform in vivo imaging to validate specific peptide binding to spontaneous colonic adenomas in a mouse model with topical administration. We also validated specific peptide binding to human colonic adenomas on immunohistochemistry and immunofluorescence.ResultsAfter labeling with Cy5.5, we validated specific peptide binding to EGFR on knockdown and competition studies. Peptide binding to cells occurred within 2.46 min and had an affinity of 50 nm. No downstream signaling was observed. We measured a target-to-background ratio of 4.0±1.7 and 2.7±0.7, for polyps and flat lesions, respectively. On immunofluorescence of human colonic specimens, greater intensity from peptide binding to dysplasia than normal was found with a 19.4-fold difference.ConclusionsWe have selected and validated a peptide that can be used as a specific contrast agent to identify colonic adenomas that overexpress EGFR in vivo on fluorescence endoscopy.
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