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The effect of Msh2 knockdown on methylating agent induced toxicity in DNA glycosylase deficient cells

N Cooley1, R H Elder, A C Povey

  • 1Centre for Occupational and Environmental Health, School of Community Based Medicine, Faculty of Medical and Human Sciences, University of Manchester, Manchester M139PL, United Kingdom.

Toxicology
|December 23, 2009
PubMed

Insights

MSH2 knockdown increases resistance to 6-thioguanine (6-TG) and temozolomide (TMZ) in DNA repair deficient cells. The protein MSH2

Area of Science:

  • Molecular Biology
  • Genetics
  • Cancer Research

Background:

  • DNA mismatch repair (MMR) protein MSH2 is crucial for DNA repair.
  • Interactions between MMR and base excision repair (BER) pathways are not fully understood.

Purpose of the Study:

  • To investigate the impact of MSH2 knockdown on cellular sensitivity to DNA damaging agents.
  • To explore the interplay between MSH2 and BER pathway components (MPG, NTH1).

Main Methods:

  • Utilized shRNA to achieve MSH2 gene knockdown in mouse embryonic fibroblasts.
  • Employed MTT and clonogenic assays to assess drug-induced toxicity.
  • Generated cell lines deficient in either alkylpurine DNA N-glycosylase (Mpg) or endonuclease III homologue (Nth1).

Main Results:

  • MSH2 knockdown conferred resistance to 6-thioguanine (6-TG) across proficient and deficient BER cell lines.
  • Resistance to temozolomide (TMZ) upon MSH2 knockdown was observed in specific BER-proficient and deficient contexts.
  • MSH2 knockdown did not alter sensitivity to methyl methanesulfonate (MMS).

Conclusions:

  • MSH2 plays a significant role in modulating toxicity induced by 6-TG and O(6)-methylguanine.
  • The influence of MSH2 on drug sensitivity is dependent on the presence of other DNA repair proteins.
  • Findings highlight the complex crosstalk between DNA repair pathways.

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