Five-aza-2′-deoxycytidine-induced hypomethylation of cholesterol 25-hydroxylase gene is responsible for cell death of myelodysplasia/leukemia cells

• Published in: Scientific reports Vol. 5; no. 1; p. 16709
• Main Authors: Tsujioka, Takayuki, Yokoi, Akira, Itano, Yoshitaro, Takahashi, Kentaro, Ouchida, Mamoru, Okamoto, Shuichiro, Kondo, Toshinori, Suemori, Shin-ichiro, Tohyama, Yumi, Tohyama, Kaoru
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18-11-2015; Nature Publishing Group
• Subjects: 38; 38/109; 38/39; 38/43; 38/77; 631/80/82/23; 692/308/575; Antimetabolites, Antineoplastic - pharmacology; Azacitidine - analogs & derivatives; Azacitidine - pharmacology; Bone Marrow Cells - drug effects; Bone Marrow Cells - metabolism; Cell Death - drug effects; Cell Death - genetics; Cell Line, Tumor; Cell Proliferation - drug effects; Decitabine; DNA Methylation - drug effects; Epigenesis, Genetic - drug effects; Gene Expression Profiling; Gene Expression Regulation, Leukemic - drug effects; Gene Knockout Techniques; HL-60 Cells; Humanities and Social Sciences; Humans; Leukemia - genetics; Leukemia - metabolism; multidisciplinary; Myelodysplastic Syndromes - genetics; Myelodysplastic Syndromes - metabolism; Promoter Regions, Genetic; RNA, Small Interfering - genetics; Science; Signal Transduction; Steroid Hydroxylases - genetics; Steroid Hydroxylases - metabolism; Transcriptome
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep16709

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.