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Open AccessJournal Article

Aberrant Methylation in Gastric Cancer Associated with the CpG Island Methylator Phenotype

TLDR
The methylation status of five newly cloned CpG islands was examined in 56 gastric cancers and it is suggested that CIMP may be one of the major pathways that contribute to tumorigenesis in Gastric cancers.
Abstract
Aberrant methylation of 5' CpG islands is thought to play an important role in the inactivation of tumor suppressor genes in cancer. In colorectal cancer, a group of tumors is characterized by a hypermethylator phenotype termed CpG island methylator phenotype (CIMP), which includes methylation of such genes as p16 and hMLH1. To study whether CIMP is present in gastric cancer, the methylation status of five newly cloned CpG islands was examined in 56 gastric cancers using bisulfite-PCR. Simultaneous methylation of three loci or more was observed in 23 (41%) of 56 cancers, which suggests that these tumors have the hypermethylator phenotype CIMP. There was a significant concordance between CIMP and the methylation of known genes including p16, and hMLH1; methylation of p16 was detected in 16 (70%) of 23 CIMP+ tumors, 1 (8%) of 12 CIMP intermediate tumors, and 1 (5%) of 21 CIMP- tumors (P<0.0001). Methylation of the hMLH1 gene was detected in three of five tumors that showed microsatellite instability, and all three of the cases were CIMP+. The CIMP phenotype is an early event in gastric cancer, being present in the normal tissue adjacent to cancer in 5 of 56 cases. These results suggest that CIMP may be one of the major pathways that contribute to tumorigenesis in gastric cancers.

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Journal ArticleDOI

Comprehensive molecular characterization of gastric adenocarcinoma

Adam J. Bass, +257 more
- 11 Sep 2014 - 
TL;DR: A comprehensive molecular evaluation of 295 primary gastric adenocarcinomas as part of The Cancer Genome Atlas (TCGA) project is described and a molecular classification dividing gastric cancer into four subtypes is proposed.
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A Gene Hypermethylation Profile of Human Cancer

TL;DR: An unusual view of the pervasiveness of DNA alterations, in this case an epigenetic change, in human cancer is provided and a powerful set of markers are provided to outline the disruption of critical pathways in tumorigenesis and for derivation of sensitive molecular detection strategies for virtually every human tumor type.
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CpG island methylator phenotype in cancer

TL;DR: DNA hypermethylation in CpG-rich promoters is now recognized as a common feature of human neoplasia, and CIMP-associated cancers seem to have a distinct epidemiology, a distinct histology, distinct precursor lesions and distinct molecular features.
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Epigenetic patterns in the progression of esophageal adenocarcinoma.

TL;DR: The fact that the samples from these two groups of patients were histologically indistinguishable, yet molecularly distinct, suggests that the occurrence of such hypermethylation may provide a clinical tool to identify patients with premalignant Barrett's who are at risk for further progression.
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Epigenetics and cancer.

TL;DR: Epigenetic mechanisms act to change the accessibility of chromatin to transcriptional regulation locally and globally via modifications of the DNA and by modification or rearrange of nucleosomes.
References
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Journal ArticleDOI

Methylation-specific PCR: a novel PCR assay for methylation status of CpG islands

TL;DR: The use of MSP is demonstrated to identify promoter region hypermethylation changes associated with transcriptional inactivation in four important tumor suppressor genes (p16, p15, E-cadherin and von Hippel-Lindau) in human cancer.
Journal ArticleDOI

CpG islands in vertebrate genomes.

TL;DR: It is shown that CpG islands in methylated genomes are maintained, despite a tendency for 5mCpG to mutate by deamination to TpG+CpA, by the structural stability of a high G+C content alone, and that C pG islands associated with exons result from some selective importance of the arginine codon CGX.
Journal ArticleDOI

Microsatellite instability in cancer of the proximal colon

TL;DR: Colorectal tumor DNA was examined for somatic instability at (CA)n repeats on human chromosomes 5q, 15q, 17p, and 18q, and this instability was significantly correlated with the tumor's location in the proximal colon and with increased patient survival and loss of heterozygosity.
Journal ArticleDOI

CpG island methylator phenotype in colorectal cancer.

TL;DR: A pathway in colorectal cancer appears to be responsible for the majority of sporadic tumors with mismatch repair deficiency, and is defined as CpG island methylator phenotype (CIMP); CIMP+ tumors also have a high incidence of p16 and THBS1 methylation, and they include the majority with microsatellite instability related to hMLH 1 methylation.
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