title: Aberrant DNA methylation and epigenetic inactivation of Eph receptor tyrosine kinases and ephrin ligands in acute lymphoblastic leukemia.
abstract: Eph receptors and their ephrin ligands are involved in normal hematopoietic development and tumorigenesis. Using methylated CpG island amplification/DNA promoter microarray, we identified several EPH receptor and EPHRIN genes as potential hypermethylation targets in acute lymphoblastic leukemia (ALL). We subsequently studied the DNA methylation status of the Eph/ephrin family by bisulfite pyrosequencing. Hypermethylation of EPHA2, -A4, -A5, -A6, -A7, -A10, EPHB1, -B2, -B3, -B4, EFNA1, -A3, -A5, and EFNB1 and -B2 genes was detected in leukemia cell lines and primary ALL bone marrow samples. Expression analysis of EPHB4, EFNB2, and EFNA5 genes demonstrated that DNA methylation was associated with gene silencing. We cloned the promoter region of EPHB4 and demonstrated that promoter hypermethylation can result in EPHB4 transcriptional silencing. Restoration of EPHB4 expression by lentiviral transduction resulted in reduced proliferation and apoptotic cell death in Raji cells in which EPHB4 is methylated and silenced. Finally, we demonstrated that phosphorylated Akt is down-regulated in Raji cells transduced with EPHB4. These results suggest that epigenetic silencing by hypermethylation of EPH/EPHRIN family genes contributes to ALL pathogenesis and that EPHB4 can function as a tumor suppressor in ALL.
authors.affiliation: Department of Leukemia, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Shao-Qing
authors.initials: SQ
authors.lastname: Kuang
authors.forename: Hao
authors.initials: H
authors.lastname: Bai
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Fang
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Lopez
authors.forename: Hui
authors.initials: H
authors.lastname: Yang
authors.forename: Weigang
authors.initials: W
authors.lastname: Tong
authors.forename: Zack Z
authors.initials: ZZ
authors.lastname: Wang
authors.forename: Guillermo
authors.initials: G
authors.lastname: Garcia-Manero
mesh_terms: D017209:Apoptosis / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D019175:DNA Methylation; D036388:Ephrin-B2 / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D036342:Ephrins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D044127:Epigenesis, Genetic; D015973:Gene Expression Regulation, Leukemic; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor; D006801:Humans; D019169:Jurkat Cells; D005810:Multigene Family / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D015995:Prevalence; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D036224:Receptor, EphB4 / Q000235:genetics* / Q000378:metabolism; D036081:Receptors, Eph Family / Q000235:genetics / Q000378:metabolism; D016019:Survival Analysis; D014161:Transduction, Genetic
chemical_list: D036388:Ephrin-B2; D036342:Ephrins; D036224:Receptor, EphB4; D036081:Receptors, Eph Family; D051057:Proto-Oncogene Proteins c-akt