Marcus S. Cooke, Ph.D.
Florida International University
NIEHS grantees developed a high-resolution accurate mass spectrometry (HRMS) method for determining the totality of DNA crosslinks, a type of DNA damage. They tested the approach on cells exposed to agents known to cause DNA crosslinking and found that the method can detect both expected and unexpected crosslinks in biological samples.
DNA crosslinks, especially interstrand crosslinks (ICLs), can be toxic to cells because they link DNA strands together, blocking replication and transcription. Environmental sources of ICLs, such as formaldehyde, can lead to adverse health effects because they can block essential cellular processes. Because they can interfere with rapidly dividing cells associated with tumors, ICL-forming agents are also used in therapeutic cancer drugs, such as chlorambucil.
The researchers used a combination of three enzymes to break up the DNA sample and to detect the total DNA crosslinks present in the sample using HRMS. They tested their method by screening for crosslinks in DNA treated with formaldehyde and chlorambucil, which are both known to induce DNA crosslinks. The results showed that all expected crosslinks were detected successfully, along with various unexpected crosslinks. Using HRMS, they were able to determine the molecular formulas and chemical structures of these unexpected crosslinks.
According to the authors, this method offered structural insights into ICLs caused by chemical exposures and provided a platform for development of predictive diagnostic tests that might improve the use of clinical crosslinking agents.
Citation: Hu CW, Chang YJ, Cooke MS, Chao MR. 2019. DNA crosslinkomics: a tool for the comprehensive assessment of interstrand crosslinks using high resolution mass spectrometry. Anal Chem 91(23):15193–15203.