title: Epigenetic inactivation of CHFR in human tumors.
abstract: Cell-cycle checkpoints controlling the orderly progression through mitosis are frequently disrupted in human cancers. One such checkpoint, entry into metaphase, is regulated by the CHFR gene encoding a protein possessing forkhead-associated and RING finger domains as well as ubiquitin-ligase activity. Although defects in this checkpoint have been described, the molecular basis and prevalence of CHFR inactivation in human tumors are still not fully understood. To address this question, we analyzed the pattern of CHFR expression in a number of human cancer cell lines and primary tumors. We found CpG methylation-dependent silencing of CHFR expression in 45% of cancer cell lines, 40% of primary colorectal cancers, 53% of colorectal adenomas, and 30% of primary head and neck cancers. Expression of CHFR was precisely correlated with both CpG methylation and deacetylation of histones H3 and H4 in the CpG-rich regulatory region. Moreover, CpG methylation and thus silencing of CHFR depended on the activities of two DNA methyltransferases, DNMT1 and DNMT3b, as their genetic inactivation restored CHFR expression. Finally, cells with CHFR methylation had an intrinsically high mitotic index when treated with microtubule inhibitor. This means that cells in which CHFR was epigenetically inactivated constitute loss-of-function alleles for mitotic checkpoint control. Taken together, these findings shed light on a pathway by which mitotic checkpoint is bypassed in cancer cells and suggest that inactivation of checkpoint genes is much more widespread than previously suspected.
authors.affiliation: Department of Molecular Biology, Cancer Research Institute, Sapporo Medical University, Sapporo 060-8556, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Toyota
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Ayumi
authors.initials: A
authors.lastname: Satoh
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ogi
authors.forename: Takefumi
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Hiromu
authors.initials: H
authors.lastname: Suzuki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Mita
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Tanaka
authors.forename: Fumio
authors.initials: F
authors.lastname: Itoh
authors.forename: Jean-Pierre J
authors.initials: JP
authors.lastname: Issa
authors.forename: Kam-Wing
authors.initials: KW
authors.lastname: Jair
authors.forename: Kornel E
authors.initials: KE
authors.lastname: Schuebel
authors.forename: Kohzoh
authors.initials: K
authors.lastname: Imai
authors.forename: Takashi
authors.initials: T
authors.lastname: Tokino
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics*; D002843:Chromatin / Q000378:metabolism; D015169:Colony Count, Microbial; D018899:CpG Islands; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D008938:Mitosis; D008957:Models, Genetic; D009363:Neoplasm Proteins; D009369:Neoplasms / Q000235:genetics*; D000075223:Poly-ADP-Ribose Binding Proteins; D011233:Precipitin Tests; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D044767:Ubiquitin-Protein Ligases; D000097584:DNA Methyltransferase 3B
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D006655:Histone Deacetylases; D006657:Histones; D009363:Neoplasm Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D044767:Ubiquitin-Protein Ligases; D000097584:DNA Methyltransferase 3B; C000619380:DNMT1 protein, human; C412002:CHFR protein, human