MicroRNAs distinguish cytogenetic subgroups in pediatric AML and contribute to complex regulatory networks in AML-relevant pathways

ABSTRACT: microRNAs, important regulators of cell proliferation and apoptosis, have been shown to be involved in the pathogenesis of acute myeloid leukemia in adulthood AML. However, comprehensive studies in AML of children and adolescents are missing so far. We investigated the miRNA expression profiles of different AML subtypes from 102 pediatric patients in comparison to CD34+ cells from healthy donors and adult AML patients, in order to identify differentially expressed miRNAs. Pediatric samples with core factor binding acute myeloid leukemia and promyelocytic leukemia could be distinguished from each other and MLL rearranged AML subtypes by 9 and 18 miRNAs, respectively. miR-126, -146a, -181a/b, -100, and miR-125b were identified as highest differentially expressed with marked difference of expression between pediatric and adulthood samples of the same cytogenetic subgroup. We next isolated the miRNA targeting complex from t(8;21) and t(15;17) cell line models and comprehensively identified bound miRNAs and targeted mRNAs by a newly devised immunoprecipitation assay followed by rapid microarray detection. Our findings indicate separate binding preferences for the four human Argonaute proteins. Subsequent bioinformatic analysis revealed a concerted action of different Ago proteins in the regulation of AML-relevant pathways, providing an experimental based database of miRNA-mRNA target interaction in Argonaute proteins. Ago-associated microRNAs: Co-immunoprecipitation in the acute myeloid leukemia cell line models, KASUMI-1 and NB4, of the four human Argonaute complexes using monoclonal antibodies and stringent washing conditions. We performed photo-activated UV cross-linking using 4M-bM-^@M-^Y-thioruidine before cell lysis. Unspecific binding to the bead matrix and to the Fc part of the monoclonal rat antibody were recorded and corrected by empty bead controls and an antibody isotype control. Argonaute-associated miRNAs/mRNAs and unspecific bound miRNAs/mRNAs of the isotype control were identified by microarray hybridization. These experiments were performed in triplicates. Ago-associated mRNAs: Co-immunoprecipitation in the acute myeloid leukemia cell line models, KASUMI-1 and NB4, of the four human Argonaute complexes using monoclonal antibodies and stringent washing conditions. We performed photo-activated UV cross-linking using 4M-bM-^@M-^Y-thioruidine before cell lysis. Unspecific binding to the bead matrix and to the Fc part of the monoclonal rat antibody were recorded and corrected by empty bead controls and an antibody isotype control. Argonaute-associated miRNAs/mRNAs and unspecific bound miRNAs/mRNAs of the isotype control were identified by microarray hybridization. These experiments were performed in triplicates. AML-patient microRNAs: RNA extraction using the TRIzol protocol (Invitrogen), labeling of RNA with Cy3- (universal reference) and Cy5-Dyes (samples) using a truncated and mutated RNA ligase, hybridization of miRNAs over night at 42M-BM-0C using miRXplore microarrays and the a-Hyb Hybridization Station (MACS molecular Miltenyi Biotec)

ORGANISM(S): Homo sapiens

SUBMITTER: Pablo Landgraf 

PROVIDER: E-GEOD-35320 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress