Methylation-silenced genes in colorectal cancer cell lines
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE7687 | GEO | 2007/05/14
SECONDARY ACCESSION(S): PRJNA99441
REPOSITORIES: GEO
Similar Datasets
Project description:Using an oligonucleotide array, we undertook a genome-wide search for genes upregulated following treatment with a demethylating agent in two CRC cell lines. Promoter methylation status was determined in 12 CRC cell lines and 11 CRC tissues. After the treatment, 350 genes were upregulated 1.5 fold or more. Six genes (PAGE-5, VCX, MAEL, GAGED2, UCHL1, and GAGE7), which contained putative 5'CpG islands in their promoter regions, were confirmed to be silenced in CRC cell lines. The median level of UCHL1 gene expression in cell lines with methylation was significantly lower than that in cell lines without methylation (P = 0.032). The level of methylation of UCHL1 was significantly higher in tumors than in corresponding normal mucosae (P = 0.005). Chemical genomic screening led to the identification of a specific promoter subject to hypermethylation in CRC. These results suggest that aberrant promoter methylation is the primary mechanism of transcriptional silencing of the UCHL1 gene and that methylation of the UCHL1 gene promoter increases during the development and progression of CRC Keywords: Methylation Analysis This study explored methylation-silenced genes in colorectal cancer (CRC) cell lines. Using an oligonucleotide array, a genome-wide search for genes upregulated following treatment with a demethylating agent, 5-aza-2â??-deoxycitidine, in two CRC cell lines, DLD-1 and HT-29, was performed. Promoter methylation status of candidate genes silenced and upregulated following the treatment was determined in 12 CRC cell linesby methylation-specific PCR.
2010-06-11 | E-GEOD-7687 | biostudies-arrayexpress
Project description:Determination of the profile of genes commonly aberrantly methylated in colorectal cancer (CRC) has substantial potential value for diagnostic and therapeutic application. However, our knowledge of the DNA methylation pattern in CRC is currently limited. Therefore, we analyzed the methylation profile of 27,578 CpG sites spanning more than 14,000 genes in CRC and in adjacent normal mucosa using beadchip array-based technology. We identified 621 CpG sites located in promoter region and CpG islands that were significantly hypermethylated in CRC compared to normal mucosa. Genes on chromosome 18 showed promoter hypermethylation most frequently. According to gene ontology analysis, the most common biologically relevant class of genes affected by methylation was the class associated with the cadherin signaling pathway. In comparison with genome-wide expression array, mRNA expression was more like to be down-regulated in the genes demonstrating promoter hypermethylation, although this was not statistically significant. We validated 10 CpG sites that were shown to be hypermethylated in the array studies (ADHFE1, BOLL, SLC6A15, ADAMTS5, TFPI2, EYA4, NPY, TWIST1, LAMA1, GAS7) and 2 CpG sites showing hypomethylaion (MAEL, SFT2D3) in CRC compared to normal mucosa using pyrosequencing. The methylation status measured by pyrosequencing was consistent with the methylation array data. In conclusion, we have shown that methylation profiling based on beadchip arrays is an effective method for screening for aberrantly methylated genes in CRC. In addition, we identified novel methylated genes that are candidate diagnostic or prognostic markers for CRC. We measured the methylation status of the 27,578 CpG sites (Human Methylation27 DNA Analysis BeadChip) in 22 pairs of CRC tissue and adjacent normal mucosa to identify genes that are commonly aberrantly methylated in CRC.
2010-06-24 | E-GEOD-17648 | biostudies-arrayexpress
Project description:Determination of the profile of genes commonly aberrantly methylated in colorectal cancer (CRC) has substantial potential value for diagnostic and therapeutic application. However, our knowledge of the DNA methylation pattern in CRC is currently limited. Therefore, we analyzed the methylation profile of 27,578 CpG sites spanning more than 14,000 genes in CRC and in adjacent normal mucosa using beadchip array-based technology. We identified 621 CpG sites located in promoter region and CpG islands that were significantly hypermethylated in CRC compared to normal mucosa. Genes on chromosome 18 showed promoter hypermethylation most frequently. According to gene ontology analysis, the most common biologically relevant class of genes affected by methylation was the class associated with the cadherin signaling pathway. In comparison with genome-wide expression array, mRNA expression was more like to be down-regulated in the genes demonstrating promoter hypermethylation, although this was not statistically significant. We validated 10 CpG sites that were shown to be hypermethylated in the array studies (ADHFE1, BOLL, SLC6A15, ADAMTS5, TFPI2, EYA4, NPY, TWIST1, LAMA1, GAS7) and 2 CpG sites showing hypomethylaion (MAEL, SFT2D3) in CRC compared to normal mucosa using pyrosequencing. The methylation status measured by pyrosequencing was consistent with the methylation array data. In conclusion, we have shown that methylation profiling based on beadchip arrays is an effective method for screening for aberrantly methylated genes in CRC. In addition, we identified novel methylated genes that are candidate diagnostic or prognostic markers for CRC.
2009-08-18 | GSE17648 | GEO
Project description:Colorectal cancer (CRC) is a genetically heterogeneous disease with several distinct morphological growth patterns. This study was aimed to investigate genes differentially expressed between ulcerative and polypoid colorectal CRC. cDNA microarray was first employed to compare the gene expression profiling of ulcerative and polypoid CRC with paired normal mucosa. Potential candidates identified by data filtering were further validated using quantitative real-time polymerase chain reaction, western blot and immunohistochemistry. Epigenetic regulation of gene expression was investigated using methylation-specific PCR (MSP). cDNA microarray identified 11 up-regulated and 14 down-regulated genes differentially expressed in both types of tumor compared to matched normal mucosa. Among them, S100P was the only upregulated gene preferentially associated with polypoid CRC (p = 0.032), whereas no genes demonstrated significantly differential association with ulcerative CRC. S100P protein and mRNA expression level of polypoid CRC was significantly higher than that of ulcerative CRC (p < 0.05, respectively). Immunoreactivity of S100P protein was localized predominantly in the nuclei and to a less extent in the cytoplasm. Overexpression of S100P occurred early in the adenoma stage. 80% (24/30) and 20% (6/30) polypoid CRC showed diffusely strong and moderate overexpression, respectively. In contrast, S100P was diffusely and strongly expressed in 15% (6/40) ulcerative CRC, with 52.5% (21/40) and 32.5% (13/40) tumors having moderate and weak overexpression, respectively. S100P overexpression was preferentially associated with polypoid CRC (p < 0.001). The relative methylation level determined by MSP was not statistically different between polypoid and ulcerative CRC (43.36% vs. 49.10%, p = 0.168), indicating that promoter hypomethylation was directly related to upregulation of S100P mRNA. The gene expression profiling of ulcerative and polypoid CRC with paired normal mucosa were compared. Dye swapping experiments with ulcerative CRC vs normal mucosa or polypoid CRC vs normal mucosa were performed and we averaged the log ratios of the duplicated spots on each slide.
2013-05-16 | E-GEOD-46905 | biostudies-arrayexpress
Project description:Unearthing of silenced genes in colorectal cancer (CRC) is of great importance. We employed oligonucleotide microarray to find changes in global gene expression of five CRC cell lines. These were analyzed before and after treatment with the 5-aza-2'-Deoxycitidine. Expression of the responding genes was integrated with gene expression profiling generated by microarray analysis of matched colorectal tissue samples. Selected candidates were subjected to methylation-specific PCR (MSP) and real-time quantitative reverse transcription-PCR using CRC cell lines and paired tumor and normal samples from CRC patients. Sixty eight genes were re-expressed after 5-aza-2'-Deoxycitidine treatment and over-expressed in normal colorectal mucosa, including genes that were known to be methylated in CRC. After applying study selection criteria, we identified 16 potential genes. Two candidates were selected (ASPP1 and SCARA5). Among 15 CRC cell lines, methylation was identified in SCARA5 (20%). The methylation status of SCARA5 was subsequently investigated in 23 paired colorectal tissue samples; methylation was detected in 17%, respectively. Observed promoter methylation showed a tendency towards methylation in tumor-derived samples, in SCARA5 gene. Significant down expression of SCARA5 mRNA was observed in CRC cell lines and tumor tissues compared to adjacent normal tissues (P < 0.001 and P = 0.001, respectively). The use of genome-wide screening led to the identification of a group of candidate genes. Among them, SCARA5 was methylated and markedly down-regulated in CRC. SCARA5 gene may have a role in CRC tumorigenesis.
2012-03-20 | GSE32323 | GEO
Project description:Purpose and Experimental Design: The purpose of this study is to find a methylation-related gene that could become a biomarker or therapeutic target in colorectal carcinoma (CRC). We screened candidate genes suspected to be silenced by DNA methylation using oligonucleotide microarray analysis. To investigate the clinical significance of one candidate gene (UNC5B), we analyzed the correlation between mRNA expression and clinicopathological features using clinical tissue samples. Finally, methylation specific PCR analysis was performed to reveal whether the promoter region was methylated in CRC cell lines. Results: We found 75 candidate genes that were potentially suppressed by DNA methylation in CRC. We focused on UNC5B, a possible tumor suppressor gene and regulator of apoptosis known to be inactivated in CRC. The mRNA expression analysis using tissue samples revealed that UNC5B mRNA was down-expressed in about 20% of CRC patients, and the patients with low-UNC5B-expression tumors showed a significantly higher recurrence rate after curative surgery. According to the univariate and multivariate analysis, low UNC5B expression was an independent risk factor for postoperative recurrence in stage I, II, and III CRC patients. Furthermore, patients with low expression of UNC5B in tumors had significantly poorer prognosis than those with high expression of UNC5B. Although UNC5B mRNA expression was restored by the demethylation treatment in CRC cell lines, the promoter region of UNC5B was not methylated. Conclusion: UNC5B is a potential biomarker for the selection of patients with high risk of postoperative recurrence and worse prognosis in CRC.
2011-12-04 | GSE22598 | GEO
Project description:Epigenetic regulation of tumor suppressor genes (TSGs) has been shown to play a central role in melanomagenesis. Integrating gene expression and methylation array analysis we identified novel candidate TSGs frequently methylated in melanoma. We validated the methylation status of the most promising TSGs using the highly sensitive, specific and comprehensive Sequenom Epityper assay in a large panel of melanoma cell lines and resected melanomas, and compared the findings with that from cultured melanocytes. We found transcript levels of UCHL1, COL1A2, THBS1 and TNFRSF10D were inversely correlated with promoter methylation. The effect of this methylation on expression was confirmed at the protein level. Identification of these candidate TSGs and how their silencing is related to melanoma development will increase our understanding of the etiology of this cancer and may provide tools for its early diagnosis. Analysed samples consisted of 11 melanoma cell lines and 1 neonatal foreskin melanocyte pool as a reference. Melanoma cell lines overlap with members of the DNA copy number analysis series GSE9003 and expression profiling series GSE7127 . The matching copy number data GEO samples IDs are noted in characteristics: Matching CN Sample ID and characteristics: Matching expn Sample ID columns respectively.
2011-10-24 | E-GEOD-28356 | biostudies-arrayexpress
Project description:Colorectal cancer (CRC) is a genetically heterogeneous disease with several distinct morphological growth patterns. This study was aimed to investigate genes differentially expressed between ulcerative and polypoid colorectal CRC. cDNA microarray was first employed to compare the gene expression profiling of ulcerative and polypoid CRC with paired normal mucosa. Potential candidates identified by data filtering were further validated using quantitative real-time polymerase chain reaction, western blot and immunohistochemistry. Epigenetic regulation of gene expression was investigated using methylation-specific PCR (MSP). cDNA microarray identified 11 up-regulated and 14 down-regulated genes differentially expressed in both types of tumor compared to matched normal mucosa. Among them, S100P was the only upregulated gene preferentially associated with polypoid CRC (p = 0.032), whereas no genes demonstrated significantly differential association with ulcerative CRC. S100P protein and mRNA expression level of polypoid CRC was significantly higher than that of ulcerative CRC (p < 0.05, respectively). Immunoreactivity of S100P protein was localized predominantly in the nuclei and to a less extent in the cytoplasm. Overexpression of S100P occurred early in the adenoma stage. 80% (24/30) and 20% (6/30) polypoid CRC showed diffusely strong and moderate overexpression, respectively. In contrast, S100P was diffusely and strongly expressed in 15% (6/40) ulcerative CRC, with 52.5% (21/40) and 32.5% (13/40) tumors having moderate and weak overexpression, respectively. S100P overexpression was preferentially associated with polypoid CRC (p < 0.001). The relative methylation level determined by MSP was not statistically different between polypoid and ulcerative CRC (43.36% vs. 49.10%, p = 0.168), indicating that promoter hypomethylation was directly related to upregulation of S100P mRNA.
2013-05-16 | GSE46905 | GEO
Project description:Background: In vitro models are an essential tool towards understanding the molecular characteristics of colorectal cancer (CRC) and the testing of therapies for CRC. To this end we established 21 novel CRC cell lines of which six were derived from liver metastases. Extensive genetic, genomic, transcriptomic and methylomic profiling was performed in order to characterize these new cell lines and all data is made publically available. Additionally, sensitivity of oxaliplatin was tested as a measure for chemotherapy resistance. Results: DNA copy-number alterations (CNA) were compared between primary and metastasis derived cell lines. In concordance with previous studies copy-number gain of chr20, and loss of chr8p were found highly specific for liver metastases. Previously reported BRAF-mutation associated DNA methylation profiles could be validated on the genome-wide DNA methylation profiles of these cell lines. 47.6% of the loci previously reported to associate with BRAF mutation status were reproduced in this dataset. When examining the gene expression profiles in conjunction with these DNA methylation results, we identified 20 genes of which the gene expression correlated with the DNA methylation status, including MEIS1, LRAT and STC2. These genes have previously been reported to be subject to transcriptional regulation through DNA hypermethylation, validating our approach. Conclusions: By combining mutation profiles with CNA and gene expression profiles we constructed an overview of the alterations in the major CRC-related signalling pathways. The mutation profiles, along with the genome, transcriptome and methylome data of these cell lines will be made publically available . This combined dataset puts these cell lines among the best characterized CRC cell lines, allowing researchers to select appropriate cell line models for their particular experiment, making optimal use of these novel cell lines as in vitro model for CRC. 21 CRC cell lines were analyzed
2016-02-29 | E-GEOD-67772 | biostudies-arrayexpress