title: Free radical adducts induce alterations in DNA cytosine methylation.
abstract: Methylation of cytosines in DNA is important for the regulation of expression of many genes. During carcinogenesis, normal patterns of gene methylation can be altered. Oxygen radical injury, shown to damage DNA in a variety of ways associated with cancer development and other conditions, has been suggested to affect DNA methylation, but a mechanism has not been demonstrated. Using oligonucleotides containing the common oxygen radical adduct 8-hydroxyguanine to replace guanine, we found that the enzymatic methylation of adjacent cytosines is profoundly altered. Furthermore, there is a high degree of positional specificity with respect to this effect. Thus, free radical injury may explain some of the altered methylation observed during carcinogenesis.
authors.affiliation: Department of Medicine, Northwestern University Medical School, Chicago, IL 60611.
authors.forename: S A
authors.initials: SA
authors.lastname: Weitzman
authors.forename: P W
authors.initials: PW
authors.lastname: Turk
authors.forename: D H
authors.initials: DH
authors.lastname: Milkowski
authors.forename: K
authors.initials: K
authors.lastname: Kozlowski
mesh_terms: D001483:Base Sequence; D003596:Cytosine / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage; D015257:DNA-Cytosine Methylases / Q000187:drug effects / Q000378:metabolism*; D005609:Free Radicals; D006147:Guanine / Q000031:analogs & derivatives / Q000494:pharmacology; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000378:metabolism* / Q000494:pharmacology; D010100:Oxygen; D012436:S-Adenosylmethionine / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D005609:Free Radicals; D009838:Oligodeoxyribonucleotides; C024829:8-hydroxyguanine; D006147:Guanine; D012436:S-Adenosylmethionine; D003596:Cytosine; D004247:DNA; C029641:DNA modification methylase HpaII; D015257:DNA-Cytosine Methylases; D010100:Oxygen