Bevin Engelward, Sc.D.
Massachusetts Institute of Technology
R44ES024698, R44ES021116, R01ES022872, P42ES027707, P30ES002109
NIEHS grantees developed a new screening method that can detect a broad range of DNA damage in cells. According to the authors, this new method fills a gap in DNA damage testing and could make chemical safety testing faster, easier, and more accurate.
The researchers previously developed the CometChip assay, an adaptation of the standard laboratory comet assay method that detects DNA strand breaks, but with higher throughput and better reproducibility. The CometChip assay is good at detecting breaks in DNA, but it cannot pick up a common type of damage known as a bulky lesion. In this study, the research team adapted the CometChip assay so that it could identify bulky lesion DNA damage. Normally, a cell will try to repair a bulky lesion by cutting it out and replacing it with a new DNA. To capture this process, the researchers treated cells with two compounds that prevented them from synthesizing the new DNA to repair bulky lesions, which halted the repair process and generated unrepaired single-stranded DNA that the CometChip assay could detect.
To test their new system, the researchers exposed liver stem cells to ultraviolet light, which is known to produce bulky lesions. After verifying that they could detect the lesions, they tested the system with nine chemicals, seven of which are known to lead to single-stranded DNA breaks or bulky lesions, and found that the test accurately detected all of them.
Citation: Ngo LP, Owiti NA, Swartz C, Winters J, Su Y, Ge J, Xiong A, Han J, Recio L, Samson LD, Engelward BP. 2019. Sensitive CometChip assay for screening potentially carcinogenic DNA adducts by trapping DNA repair intermediates. Nucleic Acids Res 48(3):e13.