title: Five-aza-2'-deoxycytidine-induced hypomethylation of cholesterol 25-hydroxylase gene is responsible for cell death of myelodysplasia/leukemia cells.
abstract: DNA methyltransferase inhibitors (DNMT inhibitors) are administered for high-risk MDS, but their action mechanisms are not fully understood. Hence, we performed a genome-wide DNA methylation assay and focused on cholesterol 25-hydroxylase (CH25H) among the genes whose expression was up-regulated and whose promoter region was hypomethylated after decitabine (DAC) treatment in vitro. CH25H catalyzes hydroxylation of cholesterol and produces 25-hydroxycholesterol (25-OHC). Although CH25H mRNA expression level was originally low in MDS/leukemia cell lines, exposure to DNMT inhibitors enhanced CH25H mRNA expression. The promoter region of CH25H was originally hypermethylated in HL-60 and MDS-L cells, but DAC treatment induced their hypomethylation together with increased CH25H mRNA expression, activation of CH25H-oxysterol pathway, 25-OHC production and apoptotic cell death. We further confirmed that normal CD34-positive cells revealed hypomethylated status of the promoter region of CH25H gene. CH25H-knockdown by transfection of shRNA lentiviral vector into the cell lines partially protected the cells from DAC-induced cell death. Exogenous addition of 25-OHC suppressed leukemic cell growth. The present study raises a possibility that DNMT inhibitors activate CH25H-oxysterol pathway by their hypomethylating mechanism and induce leukemic cell death. Further investigations of the promoter analysis of CH25H gene and therapeutic effects of DNMT inhibitors on MDS/leukemia will be warranted.
authors.affiliation: Department of Laboratory Medicine, Kawasaki Medical School, Okayama 701-0192, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tsujioka
authors.affiliation: Eisai Co., Ltd., Tsukuba, Ibaraki, 300-2635, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Yokoi
authors.affiliation: Department of Anesthesiology, Kawasaki Medical School, Okayama 701-0192, Japan.
authors.forename: Yoshitaro
authors.initials: Y
authors.lastname: Itano
authors.affiliation: Eisai Co., Ltd., Tsukuba, Ibaraki, 300-2635, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Molecular Genetics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Ouchida
authors.affiliation: Department of Laboratory Medicine, Kawasaki Medical School, Okayama 701-0192, Japan.
authors.forename: Shuichiro
authors.initials: S
authors.lastname: Okamoto
authors.affiliation: Division of Hematology, Department of Internal Medicine, Kawasaki Medical School, Okayama 701-0192, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Kondo
authors.affiliation: Department of Laboratory Medicine, Kawasaki Medical School, Okayama 701-0192, Japan.
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Suemori
authors.affiliation: Division of Biochemistry, Faculty of Pharmaceutical Sciences, Himeji Dokkyo University, Hyogo 670-8524, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Tohyama
authors.affiliation: Department of Laboratory Medicine, Kawasaki Medical School, Okayama 701-0192, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tohyama
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001854:Bone Marrow Cells / Q000187:drug effects / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019175:DNA Methylation / Q000187:drug effects*; D000077209:Decitabine; D044127:Epigenesis, Genetic / Q000187:drug effects; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D055786:Gene Knockout Techniques; D018922:HL-60 Cells; D006801:Humans; D007938:Leukemia / Q000235:genetics* / Q000378:metabolism; D009190:Myelodysplastic Syndromes / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D013250:Steroid Hydroxylases / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome
chemical_list: D000964:Antimetabolites, Antineoplastic; D034741:RNA, Small Interfering; D000077209:Decitabine; D013250:Steroid Hydroxylases; C507384:cholesterol 25-hydroxylase; D001374:Azacitidine