title: Azacytidine and decitabine induce gene-specific and non-random DNA demethylation in human cancer cell lines.
abstract: The DNA methyltransferase inhibitors azacytidine and decitabine represent archetypal drugs for epigenetic cancer therapy. To characterize the demethylating activity of azacytidine and decitabine we treated colon cancer and leukemic cells with both drugs and used array-based DNA methylation analysis of more than 14,000 gene promoters. Additionally, drug-induced demethylation was compared to methylation patterns of isogenic colon cancer cells lacking both DNA methyltransferase 1 (DNMT1) and DNMT3B. We show that drug-induced demethylation patterns are highly specific, non-random and reproducible, indicating targeted remethylation of specific loci after replication. Correspondingly, we found that CG dinucleotides within CG islands became preferentially remethylated, indicating a role for DNA sequence context. We also identified a subset of genes that were never demethylated by drug treatment, either in colon cancer or in leukemic cell lines. These demethylation-resistant genes were enriched for Polycomb Repressive Complex 2 components in embryonic stem cells and for transcription factor binding motifs not present in demethylated genes. Our results provide detailed insights into the DNA methylation patterns induced by azacytidine and decitabine and suggest the involvement of complex regulatory mechanisms in drug-induced DNA demethylation.
authors.affiliation: Division of Epigenetics, Deutsches Krebsforschungszentrum, Heidelberg, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Hagemann
authors.forename: Oliver
authors.initials: O
authors.lastname: Heil
authors.forename: Frank
authors.initials: F
authors.lastname: Lyko
authors.forename: Bodo
authors.initials: B
authors.lastname: Brueckner
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002843:Chromatin / Q000378:metabolism; D018899:CpG Islands / Q000235:genetics; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects* / Q000235:genetics; D000077209:Decitabine; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D055786:Gene Knockout Techniques; D052138:Genes, Neoplasm / Q000235:genetics*; D015894:Genome, Human / Q000235:genetics; D045325:HCT116 Cells; D018922:HL-60 Cells; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D011485:Protein Binding / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D000097584:DNA Methyltransferase 3B
chemical_list: D001374:Azacitidine; D002843:Chromatin; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000077209:Decitabine; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D000097584:DNA Methyltransferase 3B; C000619380:DNMT1 protein, human