title: DNA methylation and sensitivity to antimetabolites in cancer cell lines.
abstract: The prediction of the cellular direction of metabolic pathways toward either DNA synthesis or DNA methylation is crucial for determining the susceptibility of cancers to anti-metabolites such as fluorouracil (5-FU). We genotyped the methylenetetrahydrofolate reductase (MTHFR) gene in NCI-60 cancer cell lines, and identified the methylation status of 24 tumor suppressor genes using methylation-specific multiplex ligation-dependent probe amplification. The susceptibility of the cancer cell lines to seven antimetabolites was then determined. Cells homozygous for CC at MTHFR-A1298C were significantly more sensitive to cyclocytidine, cytarabine (AraC) and floxuridine than those with AA or AC (p=0.0215, p=0.0166, and p=0.0323, respectively), and carried more methylated tumor suppressor genes (p=0.0313). Among the 12 tumor suppressor genes which were methylated in >25% of cancer cell lines, the methylation status of TIMP3, APC and IGSF4 significantly correlated with sensitivity to pyrimidine synthesis inhibitors. In particular, cells with methylated TIMP3 had reduced mRNA levels and were significantly more sensitive to aphidicolin-glycinate, AraC and 5-FU than cells with unmethylated TIMP3. We speculate that MTHFR-A1298C homozygous CC might direct the methylation rather than the synthesis of DNA, and result in the methylation of several tumor suppressor genes such as TIMP3. These genes could be useful biological markers for predicting the efficacy of antimetabolites.
authors.affiliation: Department of Surgical Oncology, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan. sasakishin@kantoh.rofuku.go.jp
authors.forename: Shin
authors.initials: S
authors.lastname: Sasaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Kobunai
authors.forename: Joji
authors.initials: J
authors.lastname: Kitayama
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Nagawa
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology* / Q000627:therapeutic use; D045744:Cell Line, Tumor; D019175:DNA Methylation; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor; D006801:Humans; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics* / Q000502:physiology; D009369:Neoplasms / Q000188:drug therapy / Q000235:genetics*; D011110:Polymorphism, Genetic; D011743:Pyrimidines / Q000096:biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000235:genetics
chemical_list: D000964:Antimetabolites, Antineoplastic; D011743:Pyrimidines; D012333:RNA, Messenger; D019717:Tissue Inhibitor of Metalloproteinase-3; D042965:Methylenetetrahydrofolate Reductase (NADPH2); C030986:pyrimidine