Gamma irradiation does not induce detectable changes in DNA methylation directly following exposure of human cells

• Published in: PloS one Vol. 7; no. 9; p. e44858
• Main Authors: Lahtz, Christoph, Bates, Steven E, Jiang, Yong, Li, Arthur X, Wu, Xiwei, Hahn, Maria A, Pfeifer, Gerd P
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14-09-2012; Public Library of Science (PLoS)
• Subjects: Analysis; Bioinformatics; Biology; Bisulfite; Cancer; Cancer therapies; Cells (Biology); Cesium; Cesium 137; Cesium isotopes; Cesium radioisotopes; Change detection; Chemistry; Chromosome rearrangements; CpG Islands; Cytosine; Deoxyribonucleic acid; DNA; DNA damage; DNA Damage - radiation effects; DNA methylation; DNA Methylation - radiation effects; DNA microarrays; Dose-Response Relationship, Radiation; Epithelial cells; Epithelial Cells - metabolism; Epithelial Cells - radiation effects; Explosions; Exposure; Fibroblasts; Fibroblasts - metabolism; Fibroblasts - radiation effects; Gamma irradiation; Gamma Rays; Genes; Genomics; Health aspects; Health risks; Hostages; Human populations; Humans; Ionizing radiation; Irradiation; Methylation; Mutation; Nuclear accidents; Nuclear accidents & safety; Nuclear energy; Nuclear power plants; Nuclear weapons; Radiation; Radiation damage; Radiation sources; Radiotherapy; Recovery; Sequence Analysis, DNA; Sulfites; γ Radiation; United States > US; California
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0044858

Environmental chemicals and radiation have often been implicated in producing alterations of the epigenome thus potentially contributing to cancer and other diseases. Ionizing radiation, released during accidents at nuclear power plants or after atomic bomb explosions, is a potentially serious health threat for the exposed human population. This type of high-energy radiation causes DNA damage including single- and double-strand breaks and induces chromosomal rearrangements and mutations, but it is not known if ionizing radiation directly induces changes in the epigenome of irradiated cells. We treated normal human fibroblasts and normal human bronchial epithelial cells with different doses of γ-radiation emitted from a cesium 137 ((137)Cs) radiation source. After a seven-day recovery period, we analyzed global DNA methylation patterns in the irradiated and control cells using the methylated-CpG island recovery assay (MIRA) in combination with high-resolution microarrays. Bioinformatics analysis revealed only a small number of potential methylation changes with low fold-difference ratios in the irradiated cells. These minor methylation differences seen on the microarrays could not be verified by COBRA (combined bisulfite restriction analysis) or bisulfite sequencing of selected target loci. Our study shows that acute γ-radiation treatment of two types of human cells had no appreciable direct effect on DNA cytosine methylation patterns in exposed cells.