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Updated: Jun 2, 2026
A Simple, Rapid, and Quantitative Assay to Measure Repair of DNA-protein Crosslinks on Plasmids Transfected into Mammalian Cells
Published on: March 5, 2018
Mechlorethamine-induced DNA-protein cross-linking in human fibrosarcoma (HT1080) cells
Erin D Michaelson-Richie1, Xun Ming, Simona G Codreanu
1Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Abstract:
Antitumor nitrogen mustards, such as bis(2-chloroethyl)methylamine (mechlorethamine), are useful chemotherapeutic agents with a long history of clinical application. The antitumor effects of nitrogen mustards are attributed to their ability to induce DNA-DNA and DNA-protein cross-links (DPCs) that block DNA replication. In the present work, a mass spectrometry-based methodology was employed to characterize in vivo DNA-protein cross-linking following treatment of human fibrosarcoma (HT1080) cells with cytotoxic concentrations of mechlorethamine. A combination of mass spectrometry-based proteomics and immunological detection was used to identify 38 nuclear proteins that were covalently cross-linked to chromosomal DNA following treatment with mechlorethamine. Isotope dilution HPLC-ESI(+)-MS/MS analysis of total proteolytic digests revealed a concentration-dependent formation of N-[2-(S-cysteinyl)ethyl]-N-[2-(guan-7-yl)ethyl]methylamine (Cys-N7G-EMA) conjugates, indicating that mechlorethamine cross-links cysteine thiols within proteins to N-7 positions of guanine in DNA.
