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Agglomerates of aberrant DNA methylation are associated with toxicant-induced malignant transformation

Paul L Severson1, Erik J Tokar, Lukas Vrba

  • 1Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, USA.

Epigenetics
|September 15, 2012
PubMed

Insights

Environmental toxins like arsenicals can cause cancer by altering DNA methylation patterns. This study reveals agglomerative DNA methylation, a widespread epigenetic change, is linked to toxicant-induced malignant transformation.

Area of Science:

  • Environmental epigenetics
  • Carcinogenesis research
  • Toxicology

Background:

  • Epigenetic dysfunction, including aberrant DNA methylation, is a key factor in cancer development.
  • Environmental carcinogens like arsenicals and cadmium can induce malignant transformation through epigenetic mechanisms.
  • Agglomerative DNA methylation, leading to long-range epigenetic silencing, is observed in clinical cancers.

Purpose of the Study:

  • To investigate the role of agglomerative DNA methylation in toxicant-induced malignant transformation using in vitro models.
  • To identify specific gene clusters targeted by arsenical-induced agglomerative DNA methylation.
  • To explore the relationship between toxicant-induced epigenetic changes and histone modifications.

Main Methods:

  • Utilized in vitro model systems of toxicant-induced malignant transformation.
  • Analyzed DNA methylation patterns, focusing on agglomerative events, in arsenite-transformed cells.
  • Examined gene expression and histone modifications (H3K27me3, H3K9me3) in relation to DNA methylation.
  • Validated findings in other cancer cell lines and clinical cancer specimens.

Main Results:

  • Hundreds of aberrant DNA methylation events were identified during malignant transformation, including agglomerative patterns.
  • The protocadherin (PCDH), HOXC, and HOXD gene clusters were targeted by arsenite-induced agglomerative DNA methylation.
  • These arsenical-induced epigenetic changes were found to be common and clinically relevant across various models and human cancers.
  • A significant association was observed between histone H3 lysine-9 trimethylation domains and toxicant-induced agglomerative DNA methylation.

Conclusions:

  • Toxicant-induced malignant transformation is associated with agglomerative DNA methylation.
  • Epigenetic dysfunction, particularly agglomerative DNA methylation, plays a crucial role in environmental carcinogen-induced cancer.
  • Aberrant linkage between histone H3 lysine-9 trimethylation and toxicant-induced agglomerative DNA methylation may occur during malignant transformation.

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