[Design of oligonucleotide inhibitors of the human DNA-methyltransferase 1].

Mammalian DNA methyltransferase 1 (Dnmt1) is responsible for copying DNA methylation patterns during cell division. A number of studies demonstrate that Dnmt1 plays an important role in carcinogenesis, that causes, in particular, significant interest in searching for specific inhibitors of this enzyme. In the present study, with the purpose of design of oligonucleotide inhibitors of human Dnmt1, a number of single-, double-stranded and hairpin DNA-structures, containing canonical or modified enzyme recognition site 5'-CG were constructed on the basis of uniform 22 b sequence. It was shown, that such structural features as C:A-mismatch, phosphorothioates and hairpin are capable to incrementally increase oligonucleotide affinity to Dnmt1. The improvement of inhibitor properties were also achieved by substitution of target cytosine with 5,6-dihydro-5-azacytosine, 5-methyl-2-pyrimidinone and 6-methyl-pyrrolo-[2,3-d]-2-pyrimidinone. The concentrations of the most efficient oligonucleotides caused 50% inhibition of methylation of 1 microM conventional DNA substrate, polymer poly(dI-dC) * poly(dI-dC), were about 10(-7) M. In the equal in vitro conditions the constructed oligonucleotide inhibitors demonstrated much stronger effect compared to known inhibitors of Dnmt1, which were used as controls.