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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
PubMed

Insights

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.

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