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Combined mismatch and nucleotide excision repair defects in a human cell line: mismatch repair processes methylation but not UV- or ionizing radiation-induced DNA damage

journal contribution
posted on 2023-06-08, 16:17 authored by Mark O'DriscollMark O'Driscoll, S Martinelli, C Ciotta, P Karran
Interaction between long patch mismatch repair (MMR) and persistent DNA O6-methylguanine or 6-thioguanine (6-TG) is implicated in the cytotoxicity of methylating agents and 6-TG, respectively. Human cells with defective MMR tolerate DNA methylation damage and are cross-resistant to 6-TG. To determine whether MMR contributes to the lethal effects of persistent UV-induced DNA lesions, MMR deficiency was introduced into nucleotide excision repair (NER)-defective XP12RO cells. The doubly repair-defective cells, designated XP12ROB4, did not express detectable hMSH2 protein. They had the mutator phenotype, N-methyl-N-nitrosourea and 6-TG resistance typical of MMR-defective cells. Active MMR was not required for the cytotoxicity of UV light, and the hMSH2 defect did not detectably alter the survival of XP12ROB4. The level of spontaneous or UV-induced SCE was also similar in XP12RO and XP12ROB4, indicating that hMSH2 is not required for this recombination process. The combined deficiency in MMR and NER did not confer a significant degree of tolerance to ionizing radiation, and the survival of XP12RO and XP12ROB4 after gamma-radiation was similar. Although it recognizes and processes some persistent damaged or modified DNA base pairs, MMR is unlikely to serve as a general sensor of DNA damage.

History

Publication status

  • Published

Journal

Carcinogenesis

ISSN

0143-3334

Publisher

Oxford University Press

Issue

5

Volume

20

Page range

799-804

Department affiliated with

  • Sussex Centre for Genome Damage Stability Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2013-11-22

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