Polar, functionalized guanine-O6 derivatives resistant to repair by O6-alkylguanine-DNA alkyltransferase: implications for the design of DNA-modifying drugs

Eur J Med Chem. 2006 Mar;41(3):330-9. doi: 10.1016/j.ejmech.2005.11.007. Epub 2006 Feb 3.


The protein O6-alkylguanine-DNA alkyltransferase (Atase) is responsible for the repair of DNA lesions generated by several clinically important anti-cancer drugs; this is manifest as active resistance in those cancer cell lines proficient in Atase expression. Novel O6-substituted guanine analogues have been synthesized, bearing acidic, basic and hydrogen bonding functional groups. In contrast to existing O6-modified purine analogues, such as methyl or benzyl, the new compounds were found to resist repair by Atase even when tested at concentrations much higher than O6-benzylguanine, a well-established Atase substrate active both in vitro and in vivo. The inactivity of the new purines as covalent substrates for Atase indicates that agents to deliver these groups to DNA would represent a new class of DNA-modifying drug that circumvents Atase-mediated resistance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallography, X-Ray
  • DNA / chemistry
  • DNA / drug effects
  • DNA Repair Enzymes / chemistry*
  • Drug Design*
  • Guanine / analogs & derivatives*
  • Guanine / chemistry*
  • Guanine / pharmacology
  • Humans
  • Models, Biological
  • Molecular Structure
  • Mutation
  • O(6)-Methylguanine-DNA Methyltransferase / genetics
  • O(6)-Methylguanine-DNA Methyltransferase / metabolism*
  • Purines / chemistry*
  • Purines / pharmacology
  • Substrate Specificity


  • Purines
  • Guanine
  • DNA
  • O(6)-Methylguanine-DNA Methyltransferase
  • DNA Repair Enzymes