C5 cytosine methylation at CpG sites enhances sequence selectivity of mitomycin C-DNA bonding.
We have established that UvrABC nuclease is equally efficient in cutting mitomycin C (MC)-DNA monoadducts formed at different sequences and that the degree of UvrABC cutting represents the extent of drug-DNA bonding. Using this method we determined the effect of C5 cytosine methylation on the DNA monoalkylation by MC and the related analogues N-methyl-7-methoxyaziridinomitosene (MS-NMA) and 10-decarbamoylmitomycin C (DC-MC). We have found that C5 cytosine methylation at CpG sites greatly enhances MC and MS-NMA DNA adduct formation at those sites while reducing adduct formation at non-CpG sequences. In contrast, although DC-MC DNA bonding at CpG sites is greatly enhanced by CpG methylation, its bonding at non-CpG sequences is not appreciably affected. These cumulative results suggest that C5 cytosine methylation at CpG sites enhances sequence selectivity of drug-DNA bonding. We propose that the methylation pattern and status (hypo- or hypermethylation) of genomic DNA may determine the cells' susceptibility to MC and its analogues, and these effects may, in turn, play a crucial role in the antitumor activities of the drugs.
Li
V S
VS
Department of Chemistry, University of Houston, Houston, Texas 77204-5641, USA.
Reed
M
M
Zheng
Y
Y
Kohn
H
H
Tang
M
M
D000477:Alkylating Agents / Q000737:chemistry*; D000818:Animals; D001388:Aziridines / Q000737:chemistry / Q000378:metabolism; D016466:CHO Cells; D018899:CpG Islands; D006224:Cricetinae; D003596:Cytosine / Q000737:chemistry* / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D018736:DNA Adducts / Q000737:chemistry / Q000378:metabolism; D004249:DNA Damage; D019175:DNA Methylation; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000378:metabolism; D029968:Escherichia coli Proteins; D006147:Guanine / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D016685:Mitomycin / Q000737:chemistry*; D008937:Mitomycins / Q000737:chemistry / Q000378:metabolism
C014658:7-methoxy-(1,2-(N-methyl)aziridino)mitosene; D000477:Alkylating Agents; D001388:Aziridines; D018736:DNA Adducts; D029968:Escherichia coli Proteins; D008937:Mitomycins; D016685:Mitomycin; D006147:Guanine; D003596:Cytosine; D004247:DNA; D004706:Endodeoxyribonucleases; C036385:endodeoxyribonuclease uvrABC