Related Experiment Video
Updated: Aug 7, 2026
09:42
Immunostaining for DNA Modifications: Computational Analysis of Confocal Images
Published on: September 7, 2017
DNA methylation as a marker for the past and future
Toshikazu Ushijima1, Takeshi Nakajima, Takao Maekita
1Carcinogenesis Division, National Cancer Center Research Institute, Chuo-ku, Tokyo, Japan.
Journal of Gastroenterology
|June 27, 2006
Summary
Helicobacter pylori (HP) infection induces aberrant DNA methylation in the stomach, potentially leading to cancer. DNA methylation levels decrease after HP eradication but remain higher in gastric cancer patients, suggesting it may mark cancer risk.
Area of Science:
- Oncology
- Molecular Biology
- Epigenetics
Background:
- Aberrant DNA methylation of CpG islands in gene promoter regions can inactivate tumor-suppressor genes, similar to mutations.
- In gastric cancers, genes like CDKN2A, CDH1, and MLH1 are frequently inactivated by methylation rather than mutations.
- Novel tumor-suppressor genes inactivated by promoter methylation are continually being identified.
Purpose of the Study:
- To investigate the role of Helicobacter pylori (HP) infection in inducing aberrant DNA methylation in gastric mucosa.
- To examine the dynamics of DNA methylation levels in relation to active HP infection and its eradication.
- To assess the correlation between DNA methylation levels and the presence of gastric cancer.
Main Methods:
- Examined a panel of CpG islands in gastric mucosae from individuals with and without HP infection.
- Quantified DNA methylation levels in gastric mucosae.
- Compared methylation levels between individuals with active HP infection, post-eradication, and those without active infection, including gastric cancer patients.
Main Results:
- HP infection was found to induce aberrant methylation in gastric mucosae.
- Some CpG islands were consistently methylated during HP infection, while others were resistant.
- Methylation levels fluctuated with active HP infection and decreased after eradication.
- Individuals without active HP infection but with gastric cancer had higher methylation levels than those without cancer.
Conclusions:
- Helicobacter pylori infection is a driver of aberrant DNA methylation in the gastric mucosa.
- DNA methylation levels in gastric mucosa are dynamic and influenced by HP infection status.
- Elevated DNA methylation may serve as a biomarker for past carcinogen exposure and future gastric cancer risk.
Related Concept Videos
01:37Epigenetic Regulation
Epigenetic changes alter the physical structure of the DNA without changing the genetic sequence and often regulate whether genes are turned on or off. This regulation ensures that each cell produces only proteins necessary for its function. For example, proteins that promote bone growth are not produced in muscle cells. Epigenetic mechanisms play an essential role in healthy development. Conversely, precisely regulated epigenetic mechanisms are disrupted in diseases like cancer.
X-chromosome...
X-chromosome...
01:46Epigenetic Regulation
Epigenetic mechanisms play an essential role in healthy development. Conversely, precisely regulated epigenetic mechanisms are disrupted in diseases like cancer.
03:17Inheritance of Chromatin Structures
Epigenetics is the study of inherited changes in a cell's phenotype without changing the DNA sequences. It provides a form of memory for the differential gene expression pattern to maintain cell lineage, position-effect variegation, dosage compensation, and maintenance of chromatin structures such as telomeres and centromeres. For example, the structure and location of the centromere on chromosomes are epigenetically inherited. Its functionality is not dictated or ensured by the underlying DNA...
03:00Next-generation Sequencing
The first human genome sequencing project cost $2.7 billion and was declared complete in 2003, after 15 years of international cooperation and collaboration between several research teams and funding agencies. Today, with the advent of next-generation sequencing technologies, the cost and time of sequencing a human genome have dropped over 100 fold.
Next-Generation Sequencing Methods
Although all next-generation methods use different technologies, they all share a set of standard features.
Next-Generation Sequencing Methods
Although all next-generation methods use different technologies, they all share a set of standard features.
02:32Histone Modification
The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
02:30Genomic Imprinting and Inheritance
Diploid organisms inherit genetic material through chromosomes from both parents. Copies of the same gene are known as alleles. In most cases, both alleles are simultaneously expressed and allow various cellular processes to function optimally. If one of the alleles is missing or mutated, the expression of the other allele can compensate; however, this is not true for all genes.
The expression of some genes depends on which parent passed the gene to the offspring, through a phenomenon known as...
The expression of some genes depends on which parent passed the gene to the offspring, through a phenomenon known as...