title: MicroRNA-34b promoter hypermethylation induces CREB overexpression and contributes to myeloid transformation.
abstract: MicroRNA-34b down-regulation in acute myeloid leukemia was previously shown to induce CREB overexpression, thereby causing leukemia proliferation in vitro and in vivo. The role of microRNA-34b and CREB in patients with myeloid malignancies has never been evaluated. We examined microRNA-34b expression and the methylation status of its promoter in cells from patients diagnosed with myeloid malignancies. We used gene expression profiling to identify signatures of myeloid transformation. We established that microRNA-34b has suppressor ability and that CREB has oncogenic potential in primary bone marrow cell cultures and in vivo. MicroRNA-34b was found to be up-regulated in pediatric patients with juvenile myelomonocytic leukemia (n=17) and myelodysplastic syndromes (n=28), but was down-regulated in acute myeloid leukemia patients at diagnosis (n=112). Our results showed that hypermethylation of the microRNA-34b promoter occurred in 66% of cases of acute myeloid leukemia explaining the low microRNA-34b levels and CREB overexpression, whereas preleukemic myelodysplastic syndromes and juvenile myelomonocytic leukemia were not associated with hypermethylation or CREB overexpression. In paired samples taken from the same patients when they had myelodysplastic syndrome and again during the subsequent acute myeloid leukemia, we confirmed microRNA-34b promoter hypermethylation at leukemia onset, with 103 CREB target genes differentially expressed between the two disease stages. This subset of CREB targets was confirmed to associate with high-risk myelodysplastic syndromes in a separate cohort of patients (n=20). Seventy-eight of these 103 CREB targets were also differentially expressed between healthy samples (n=11) and de novo acute myeloid leukemia (n=72). Further, low microRNA-34b and high CREB expression levels induced aberrant myelopoiesis through CREB-dependent pathways in vitro and in vivo. In conclusion, we suggest that microRNA-34b controls CREB expression and contributes to myeloid transformation from both healthy bone marrow and myelodysplastic syndromes. We identified a subset of CREB target genes that represents a novel transcriptional network that may control myeloid transformation.
authors.affiliation: Women and Child Health Department, Hematology-Oncology Laboratory, University of Padova, Padova, Italy. martina.pigazzi@unipd.it
authors.forename: Martina
authors.initials: M
authors.lastname: Pigazzi
authors.forename: Elena
authors.initials: E
authors.lastname: Manara
authors.forename: Silvia
authors.initials: S
authors.lastname: Bresolin
authors.forename: Claudia
authors.initials: C
authors.lastname: Tregnago
authors.forename: Alessandra
authors.initials: A
authors.lastname: Beghin
authors.forename: Emma
authors.initials: E
authors.lastname: Baron
authors.forename: Emanuela
authors.initials: E
authors.lastname: Giarin
authors.forename: Er-Chieh
authors.initials: EC
authors.lastname: Cho
authors.forename: Riccardo
authors.initials: R
authors.lastname: Masetti
authors.forename: Dinesh S
authors.initials: DS
authors.lastname: Rao
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Sakamoto
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Basso
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics; D019175:DNA Methylation; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic; D018922:HL-60 Cells; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053631:Interleukin Receptor Common gamma Subunit / Q000172:deficiency / Q000235:genetics; D007951:Leukemia, Myeloid / Q000235:genetics; D051379:Mice; D016688:Mice, Inbred NOD; D018345:Mice, Knockout; D016513:Mice, SCID; D035683:MicroRNAs / Q000235:genetics*; D009190:Myelodysplastic Syndromes / Q000235:genetics; D022423:Myeloid Cells / Q000378:metabolism* / Q000473:pathology; D011401:Promoter Regions, Genetic / Q000235:genetics*
chemical_list: C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; C507942:Il2rg protein, mouse; D053631:Interleukin Receptor Common gamma Subunit; C522425:MIRN34 microRNA, human; D035683:MicroRNAs