title: The C/EBPdelta tumor suppressor is silenced by hypermethylation in acute myeloid leukemia.
abstract: Aberrant DNA methylation is the most frequent molecular alteration in acute myeloid leukemia (AML). To identify methylation-silenced genes in AML, we performed microarray analyses in U937 cells exposed to the demethylating agent 5-aza-deoxy-cytidine. Overall, 274 transcripts were significantly induced. Interestingly, C/EBPdelta expression was significantly induced (more than 10-fold) by demethylation whereas expression of all other C/EBP family members remained unchanged. The C/EBPdelta promoter was strongly methylated in different leukemic cell lines and showed signs of a repressed chromatin state. Analyses of the promoter regions of the entire C/EBP family (alpha, beta, gamma, delta, epsilon, zeta) in bone marrow samples from AML patients (n = 80) and controls (n = 15) by mass spectrometry revealed that C/EBPdelta is the most commonly hypermethylated C/EBP gene in AML. Hypermethylation occurred in more than 35% of AML patients at primary diagnosis. A significant correlation (P = .016) was observed between hypermethylation of the C/EBPdelta promoter and low expression of C/EBPdelta in AML patients. C/EBPdelta promoter activity was strongly repressed by methylation in vitro, and transcriptional repression partially depended on MeCP2 activity. C/EBPdelta exhibited growth-inhibitory properties in primary progenitor cells as well as in Flt3-ITD-transformed cells. Taken together, C/EBPdelta is a novel tumor suppressor gene in AML that is silenced by promoter methylation.
authors.affiliation: Department of Medicine, Hematology and Oncology, University of Münster, Domagkstrasse 3, 48129 Münster, Germany.
authors.forename: Shuchi
authors.initials: S
authors.lastname: Agrawal
authors.forename: Wolf-Karsten
authors.initials: WK
authors.lastname: Hofmann
authors.forename: Nicola
authors.initials: N
authors.lastname: Tidow
authors.forename: Mathias
authors.initials: M
authors.lastname: Ehrich
authors.forename: Dirk
authors.initials: D
authors.lastname: van den Boom
authors.forename: Steffen
authors.initials: S
authors.lastname: Koschmieder
authors.forename: Wolfgang E
authors.initials: WE
authors.lastname: Berdel
authors.forename: Hubert
authors.initials: H
authors.lastname: Serve
authors.forename: Carsten
authors.initials: C
authors.lastname: Müller-Tidow
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000235:genetics / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly / Q000187:drug effects / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D005260:Female; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051783:Methyl-CpG-Binding Protein 2 / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis* / Q000235:genetics; D020298:U937 Cells
chemical_list: D000964:Antimetabolites, Antineoplastic; C497392:MECP2 protein, human; D051783:Methyl-CpG-Binding Protein 2; D025521:Tumor Suppressor Proteins; D051743:CCAAT-Enhancer-Binding Protein-delta; D000077209:Decitabine; D001374:Azacitidine