A Nitrogen Mustard Induces Formation of DNA-Histone Cross-Links in Nucleosome Core Particles.
CHEMICAL RESEARCH IN TOXICOLOGY(2019)
摘要
Nitrogen mustards have long been used in cancer chemotherapy, and their cytotoxicity has traditionally been attributed to the formation of DNA interstrand cross-links and DNA monoalkylation. Recent studies have shown that exposure to nitrogen mustards also induces the formation of DNA-protein cross-links (DPCs) via bridging between N7 of a deoxyguanosine residue in the DNA and the side chain of a Cys residue in the protein. However, the formation of nitrogen mustard-induced DNA histone cross-links has never been observed. Herein, we demonstrate that treating reconstituted nucleosome core particles (NCPs) with the nitrogen mustard mechlorethamine results in the formation of DNA-histone cross links in addition to DNA monoalkylation and interstrand cross-link formation. The yields of these three types of DNA lesions in the NCPs decreased in the following order: DNA monoalkylation >> DNA interstrand cross-links > DNA-histone cross-links. Mechanistic studies involving tailless histones and competitive inhibition by a polyamine demonstrated that Lys residues in the N- and C-terminal tails of the histones were the predominant sites involved in DNA histone cross-link formation. Given that NCPs are the fundamental repeating units of chromatin in eukaryotes, our findings suggest that nitrogen mustard-induced formation of DNA-histone cross-links may occur in living cells and that DPC formation may contribute to the cytotoxicity of nitrogen mustards.
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关键词
nitrogen mustard,dna–histone,cross-links
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