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: Takayuki Tsujioka, Akira Yokoi, Yoshitaro Itano, Kentaro Takahashi, Mamoru Ouchida, Shuichiro Okamoto, Toshinori Kondo, Shin-ichiro Suemori, Yumi Tohyama, Kaoru Tohyama
• Journal: Scientific reports (Sci Rep) Vol. 5 Pg. 16709 (Nov 18 2015) ISSN: 2045-2322 [Electronic] England
• PMID: 26577244 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antimetabolites, Antineoplastic
• RNA, Small Interfering
• Decitabine
• Steroid Hydroxylases
• cholesterol 25-hydroxylase
• Azacitidine

Topics

• Antimetabolites, Antineoplastic (pharmacology)
• Azacitidine (analogs & derivatives, pharmacology)
• Bone Marrow Cells (drug effects, metabolism)
• Cell Death (drug effects, genetics)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• DNA Methylation (drug effects)
• Decitabine
• Epigenesis, Genetic (drug effects)
• Gene Expression Profiling
• Gene Expression Regulation, Leukemic (drug effects)
• Gene Knockout Techniques
• HL-60 Cells
• Humans
• Leukemia (genetics, metabolism)
• Myelodysplastic Syndromes (genetics, metabolism)
• Promoter Regions, Genetic
• RNA, Small Interfering (genetics)
• Signal Transduction
• Steroid Hydroxylases (genetics, metabolism)
• Transcriptome