title: Radiation-induced genomic instability is associated with DNA methylation changes in cultured human keratinocytes.
abstract: The mechanism by which radiation-induced genomic instability is initiated, propagated and effected is currently under intense scrutiny. We have investigated the potential role of altered genomic methylation patterns in the cellular response to irradiation and have found evidence for widespread dysregulation of CpG methylation persisting up to 20 population doublings post-irradiation. Similar effects are seen with cells treated with medium from irradiated cells (the 'bystander effect') rather than subjected to direct irradiation. Using an arbitrarily primed methylation sensitive PCR screening method we have demonstrated that irradiation causes reproducible alterations in the methylation profile of a human keratinocyte cell line, HPV-G, and have further characterised one of these sequences as being a member of a retrotransposon element derived sequence family on chromosome 7; MLT1A. Multiple changes were also detected in the screen, which indicate that although the response of cells is predominantly hypermethylation, specific hypomethylation occurs as well. Sequence specific changes are also reported in the methylation of the pericentromeric SAT2 satellite sequence. This is the first demonstration that irradiation results in the induction of heritable methylation changes in mammalian cells, and provides a link between the various non-radiological instigators of genomic instability, the perpetuation of the unstable state and several of its manifestations.
authors.affiliation: Laboratory of Stem Cell biology, Department of Anatomy, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK.
authors.forename: Sahana
authors.initials: S
authors.lastname: Kaup
authors.forename: Valerie
authors.initials: V
authors.lastname: Grandjean
authors.forename: Rajarshi
authors.initials: R
authors.lastname: Mukherjee
authors.forename: Aparna
authors.initials: A
authors.lastname: Kapoor
authors.forename: Edward
authors.initials: E
authors.lastname: Keyes
authors.forename: Colin B
authors.initials: CB
authors.lastname: Seymour
authors.forename: Carmel E
authors.initials: CE
authors.lastname: Mothersill
authors.forename: Paul N
authors.initials: PN
authors.lastname: Schofield
mesh_terms: D001483:Base Sequence; D002450:Cell Communication; D002460:Cell Line; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics; D019175:DNA Methylation / Q000528:radiation effects*; D004276:DNA, Satellite / Q000235:genetics / Q000528:radiation effects; D042822:Genomic Instability / Q000528:radiation effects*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000528:radiation effects; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D018626:Retroelements / Q000235:genetics / Q000528:radiation effects
chemical_list: D004276:DNA, Satellite; D018626:Retroelements