量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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DNA methylation is one of the epigenetic modifications that occurs in genome of mammals to ensure the proper regulation of gene expression in response to environmental stimuli and stable gene silencing. However, the regulation of gene expression by DNA methylation after genotoxic stress including irradiation remains poorly understood. We hypothesized that irradiation may elicit alterations in the methylation status of DNA and subsequently alter gene expression.
In this study, using next generation sequencing technology we assessed the DNA methylation status in MIAPaCa-2 and PANC-1 cell lines (both derived from human pancreatic cancer), at 48 h after irradiation with X-ray at 4 Gy, or a carbon ion beam at 2 Gy. Methylated DNA fragments were concentrated using methyl binding protein after fragmentation of DNA to an average fragment size of 200 bp. Genome regions showing a different methylation status after irradiation were detected using MACS algorithm.
Complete methylation or de-methylation of 1.6 Mb or 6.7 Mb regions in both MIAPaCa-2 and PANC-1 cell lines occurred after X-ray irradiation, and the methylation status of 1.0 Mb or 1.7 Mb regions also changed in the both cell lines after carbon ion beam irradiation. Both X-ray and carbon ion beam irradiation altered the methylation status in approximately 5 % of these regions. As expected, in approximately 300 regions, altered DNA methylation following irradiation occurred within 500 bp upstream of a possible transcriptional start site. Studies are in progress to examine the relationship between alteration of DNA methylation status and gene expression in cells following irradiation.
Alteration in the DNA methylation profile of irradiated cancer cell lines
