Quantifying DNA damage induced by ionizing radiation and hyperthermia using single DNA molecule imaging

Vandana Singh, Pegah Johansson, Dmitry Torchinsky, Yii Lih Lin, Robin Öz, Yuval Ebenstein, Ola Hammarsten, Fredrik Westerlund

Research output: Contribution to journalArticlepeer-review


Ionizing radiation (IR) is a common mode of cancer therapy, where DNA damage is the major reason of cell death. Here, we use an assay based on fluorescence imaging of single damaged DNA molecules isolated from radiated lymphocytes, to quantify IR induced DNA damage. The assay uses a cocktail of DNA-repair enzymes that recognizes and excises DNA lesions and then a polymerase and a ligase incorporate fluorescent nucleotides at the damage sites, resulting in a fluorescent “spot” at each site. The individual fluorescent spots can then be counted along single stretched DNA molecules and the global level of DNA damage can be quantified. Our results demonstrate that inclusion of the human apurinic/apyrimidinic endonuclease 1 (APE1) in the enzyme cocktail increases the sensitivity of the assay for detection of IR induced damage significantly. This optimized assay also allowed detection of a cooperative increase in DNA damage when IR was combined with mild hyperthermia, which is sometimes used as an adjuvant in IR therapy. Finally, we discuss how the method may be used to identify patients that are sensitive to IR and other types of DNA damaging agents.

Original languageEnglish
Article number100822
JournalTranslational Oncology
Issue number10
StatePublished - Oct 2020


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