title: Potential advantages of DNA methyltransferase 1 (DNMT1)-targeted inhibition for cancer therapy.
abstract: The deoxyribonucleic acid (DNA) methyltransferase (DNMT) inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) has been used as a drug in a part of cancer therapy. However, because of its incorporation into DNA during DNA synthesis, 5-aza-dC can cause DNA damage, mutagenesis, and cytotoxicity. In view of the adverse effects of 5-aza-dC, DNMT-targeted inhibition may be a more effective approach than treatment with 5-aza-dC. To address the possibility of DNMT-targeted cancer therapy, we compared the effects of treatment with small interfering ribonucleic acids (siRNAs) specific for DNMT1 or DNMT3b and treatment with 5-aza-dC on transcription, cell growth, and DNA damage in gastric cancer cells. We found that DNMT1-targeted inhibition induced the re-expression and reversed DNA methylation of five (CDKN2A, RASSF1A, HTLF, RUNX3, and AKAP12B) out of seven genes examined, and 5-aza-dC reactivated and demethylated all seven genes. In contrast, DNMT3b siRNAs did not show any effect. Furthermore, the double knockdown of DNMT1 and DNMT3b did not show a synergistic effect on gene re-expression and demethylation. In addition, DNMT1 siRNAs showed an inhibitory effect of cell proliferation in the cancer cells and the induction of cell death without evidence of DNA damage, whereas treatment with 5-aza-dC caused DNA damage as demonstrated by the comet assay. These results provide a rationale for the development of a DNMT1-targeted strategy as an effective epigenetic cancer therapy.
authors.affiliation: National Research Laboratory for Cancer Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul, 110-799, South Korea.
authors.forename: Yeonjoo
authors.initials: Y
authors.lastname: Jung
authors.forename: Jinah
authors.initials: J
authors.lastname: Park
authors.forename: Tai Young
authors.initials: TY
authors.lastname: Kim
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Park
authors.forename: Hyun-Soon
authors.initials: HS
authors.lastname: Jong
authors.forename: Seock-Ah
authors.initials: SA
authors.lastname: Im
authors.forename: Keith D
authors.initials: KD
authors.lastname: Robertson
authors.forename: Yung-Jue
authors.initials: YJ
authors.lastname: Bang
authors.forename: Tae-You
authors.initials: TY
authors.lastname: Kim
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000201:enzymology; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors*; D004249:DNA Damage / Q000187:drug effects; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D044127:Epigenesis, Genetic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing; D006801:Humans; D034741:RNA, Small Interfering / Q000008:administration & dosage*; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000201:enzymology; D014162:Transfection; D000097584:DNA Methyltransferase 3B
chemical_list: D000964:Antimetabolites, Antineoplastic; D001374:Azacitidine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000077209:Decitabine; D034741:RNA, Small Interfering; D000097584:DNA Methyltransferase 3B; C000619380:DNMT1 protein, human