Skip to Main content Skip to Navigation
Journal articles

Crosstalk between repair pathways elicits double-strand breaks in alkylated DNA and implications for the action of temozolomide

Abstract : Temozolomide (TMZ), a DNA methylating agent, is the primary chemotherapeutic drug used in glioblastoma treatment. TMZ induces mostly N-alkylation adducts (N7-methylguanine and N3-methyladenine) and some O 6 -methylguanine (O 6 mG) adducts. Current models propose that during DNA replication, thymine is incorporated across from O 6 mG, promoting a futile cycle of mismatch repair (MMR) that leads to DNA double-strand breaks (DSBs). To revisit the mechanism of O 6 mG processing, we reacted plasmid DNA with N-methyl-N-nitrosourea (MNU), a temozolomide mimic, and incubated it in Xenopus egg-derived extracts. We have shown that in this system, MMR proteins are enriched on MNU-treated DNA and we observed robust, MMR-dependent, repair synthesis. Our evidence also suggests that MMR, initiated at O 6 mG:C sites, is strongly stimulated in cis by repair processing of other lesions, such as N-alkylation adducts. Importantly, MNU-treated plasmids display DSBs in extracts, the frequency of which increases linearly with the square of alkylation dose. We suggest that DSBs result from two independent repair processes, one involving MMR at O 6 mG:C sites and the other involving base excision repair acting at a nearby N-alkylation adduct. We propose a new, replication-independent mechanism of action of TMZ, which operates in addition to the well-studied cell cycle-dependent mode of action.
Document type :
Journal articles
Complete list of metadata

https://hal.archives-ouvertes.fr/hal-03373140
Contributor : Shingo Fujii Connect in order to contact the contributor
Submitted on : Monday, October 11, 2021 - 1:01:45 PM
Last modification on : Tuesday, October 19, 2021 - 10:59:17 PM

File

21 eLife author version.pdf
Files produced by the author(s)

Identifiers

Collections

Citation

Robert Fuchs, Asako Isogawa, Joao Paulo, Kazumitsu Onizuka, Tatsuro Takahashi, et al.. Crosstalk between repair pathways elicits double-strand breaks in alkylated DNA and implications for the action of temozolomide. eLife, eLife Sciences Publication, 2021, 10, ⟨10.7554/eLife.69544⟩. ⟨hal-03373140⟩

Share

Metrics

Record views

35

Files downloads

17