DNA interstrand crosslinks are induced in cells prelabelled with 5-bromo-2′-deoxyuridine and exposed to UVC radiation

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• 作者：Andrzej Wojcik ; Agnieszka Bochenek ; Anna Lankoff ; Halina Lisowska ; Anna Padjas ; Irena Szumiel ; Clemens von Sonntag and Gü ; nter Obe
• 关键词：UV radiation ; BrdU ; DNA interstrand crosslinks ; Comet assay ; Rad51C ; Chromosomal aberrations ; cDDP
• 刊名：Journal of Photochemistry and Photobiology B: Biology
• 出版年：2006
• 出版时间：3 July 2006
• 年：2006
• 卷：84
• 期：1
• 页码：15-20
• 全文大小：201 K

文摘

It has been observed previously that 5-bromo-2′-deoxyuridine (BrdU) potentiates the effect of UVC radiation on the level of sister chromatid exchanges. It is not known which type of DNA damage is responsible for this enhancing effect and we have proposed this to be the DNA interstrand crosslink (ICL) which, theoretically, may arise in cells that are labelled with BrdU for one round of replication and exposed to UVC radiation. The aim of the present investigation was to verify if ICLs are indeed formed during this irradiation scenario. CHO-K1 cells were prelabelled with BrdU and exposed to UVC. ICLs were detected by a modified version of the comet assay that relies on the reduction of induced DNA migration in the agarose gel. Carboplatin was used as a positive control. We found that BrdU + UVC treatment indeed results in a reduction of the damage induced by gamma-radiation. Furthermore, we observed that CL-V4B cells exposed to BrdU + UVC, but not to UVC alone, showed a very high level of chromosomal damage. These cells have a deficient Rad51C paralog that renders them extremely sensitive towards ICLs. Interestingly, the cytogenetic results did not correlate with cell survival, where it was found that the CL-V4B cells tolerate BrdU + UVC better than the wild type cells. The possible reasons are discussed. Taken together our results indicate that ICLs are formed in DNA that was prelabelled with BrdU and exposed to UVC radiation.