Expression data from ALL samples for patients included in the Dutch Childhood Oncology Group
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ABSTRACT: Childhood acute lymphoblastic leukemia (ALL) comprises a large group of genetic subtypes with a favorable prognosis characterized by a TEL-AML1-fusion, hyperdiploidy (>50 chromosomes) or E2A-PBX1 fusion and a smaller group with unfavorable outcome characterized by either a BCR-ABL-fusion, MLL-rearrangement or T-ALL. About 25% of precursor B-ALL are currently genetically unclassified and have an intermediate prognosis. The present study used genome-wide strategies to reveal new biological insights and advance the prognostic classification of childhood ALL. A double-loop cross validation was used to construct a classifier based on gene expression in ALL cells from 190 newly diagnosed cases (COALL cohort, GEO GSE13425) with a prediction accuracy of 90%. T-ALL, TEL-AML1-positive, hyperdiploid and E2A-rearranged cases were identified with 100% sensitivity and ≥94% specificity. The classifier accuracy was confirmed in an independent cohort of 107 cases (87.9%, DCOG cohort, GEO GSE13351). Keywords: gene expression study for classification of ALL subtypes
Project description:Childhood acute lymphoblastic leukemia (ALL) comprises a large group of genetic subtypes with a favorable prognosis characterized by a TEL-AML1-fusion, hyperdiploidy (>50 chromosomes) or E2A-PBX1 fusion and a smaller group with unfavorable outcome characterized by either a BCR-ABL-fusion, MLL-rearrangement or T-ALL. About 25% of precursor B-ALL are currently genetically unclassified and have an intermediate prognosis. The present study used genome-wide strategies to reveal new biological insights and advance the prognostic classification of childhood ALL. A double-loop cross validation was used to construct a classifier based on gene expression in ALL cells from 190 newly diagnosed cases (COALL cohort, GEO GSE13425) with a prediction accuracy of 90%. T-ALL, TEL-AML1-positive, hyperdiploid and E2A-rearranged cases were identified with 100% sensitivity and ≥94% specificity. The classifier accuracy was confirmed in an independent cohort of 107 cases (87.9%, DCOG cohort, GEO GSE13351). Keywords: gene expression study for classification of ALL subtypes
Project description:Childhood acute lymphoblastic leukemia (ALL) comprises a large group of genetic subtypes with a favorable prognosis characterized by a TEL-AML1-fusion, hyperdiploidy (>50 chromosomes) or E2A-PBX1 fusion and a smaller group with unfavorable outcome characterized by either a BCR-ABL-fusion, MLL-rearrangement or T-ALL. About 25% of precursor B-ALL are currently genetically unclassified and have an intermediate prognosis. The present study used genome-wide strategies to reveal new biological insights and advance the prognostic classification of childhood ALL. A double-loop cross validation was used to construct a classifier based on gene expression in ALL cells from 190 newly diagnosed cases (COALL cohort, GEO GSE13425) with a prediction accuracy of 90%. T-ALL, TEL-AML1-positive, hyperdiploid and E2A-rearranged cases were identified with 100% sensitivity and â?¥94% specificity. The classifier accuracy was confirmed in an independent cohort of 107 cases (87.9%, DCOG cohort, GEO GSE13351). Experiment Overall Design: Bone marrow and peripheral blood samples were collected at diagnosis and frozen. After thawing, RNA was extracted, labelled and hybridized to Affymetrix U133 Plus 2.0 arrays.
Project description:Childhood acute lymphoblastic leukemia (ALL) comprises a large group of genetic subtypes with a favorable prognosis characterized by a TEL-AML1-fusion, hyperdiploidy (>50 chromosomes) or E2A-PBX1 fusion and a smaller group with unfavorable outcome characterized by either a BCR-ABL-fusion, MLL-rearrangement or T-ALL. About 25% of precursor B-ALL are currently genetically unclassified and have an intermediate prognosis. The present study used genome-wide strategies to reveal new biological insights and advance the prognostic classification of childhood ALL. A double-loop cross validation was used to construct a classifier based on gene expression in ALL cells from 190 newly diagnosed cases (COALL cohort, GEO GSE13425) with a prediction accuracy of 90%. T-ALL, TEL-AML1-positive, hyperdiploid and E2A-rearranged cases were identified with 100% sensitivity and â¥94% specificity. The classifier accuracy was confirmed in an independent cohort of 107 cases (87.9%, DCOG cohort, GEO GSE13351). Experiment Overall Design: 190 bone marrow and peripheral blood samples were collected at diagnosis and frozen. They were later thawed and hybridized to Affymetrix U133A arrays.
Project description:Background; The t(12;21)(p13;q22) translocation is found in 20 to 25% of cases of childhood B-lineage acute lymphoblastic leukemia (B-ALL). This rearrangement results in the fusion of ETV6 (TEL) and RUNX1 (AML1) genes and defines a relatively uniform category, although only some patients suffer very late relapse. TEL/AML1-positive patients are thus an interesting subgroup to study, and such studies should elucidate the biological processes underlying TEL/AML1 pathogenesis. We report an analysis of gene expression in 60 children with B-lineage ALL using Agilent whole genome oligo-chips (44K-G4112A) and/or real time RT-PCR. Results; We compared the leukemia cell gene expression profiles of 16 TEL/AML1-positive ALL patients to those of 44 TEL/AML1-negative patients, whose blast cells did not contain any additional recurrent translocation. Microarray analyses of 26 samples allowed the identification of genes differentially expressed between the TEL/AML1-positive and negative ALL groups. Gene enrichment analysis defined five enriched GO categories: cell differentiation, cell proliferation, apoptosis, cell motility and response to wounding, associated with 14 genes â??RUNX1, TCFL5, TNFRSF7, CBFA2T3, CD9, SCARB1, TP53INP1, ACVR1C, PIK3C3, EGFL7, SEMA6A, CTGF, LSP1, TFPIâ?? highlighting the biology of the TEL/AML1 sub-group. These results were first confirmed by the analysis of an additional microarray data-set (7 patient samples) and second by real-time RT-PCR quantification and clustering using an independent set (27 patient samples). Over-expression of RUNX1 (AML1) was further investigated and in one third of the patients correlated with cytogenetic findings. Conclusions; Gene expression analyses of leukemia cells from 60 children with TEL/AML1-positive and -negative B-lineage ALL led to the identification of five biological processes, associated with 14 validated genes characterizing and highlighting the biology of the TEL/AML1-positive ALL sub-group. Experiment Overall Design: We carried out a prospective multicentric study on childhood B-ALL leukemia to elucidate the molecular processes involved in TEL/AML1-positive leukemia. All the patients included in this study received treatment according to the French FRALLE 2000 trial. We used Agilent whole-genome oligo-chips (44K-G4112A) to compare the gene expression signatures of TEL/AML1-positive patients to those of TEL/AML1-negative patients with no recurrent chimeric products irrespective of their clinical risk category. Previous microarray gene expression studies had revealed the effect of chromosomal alteration on transcription profiles, so we excluded from our cohort those patients with other recurrent chromosomal translocations or fusion transcripts (BCR/ABL, E2A/PBX1, MLL rearrangements). We then searched for the biological pathways associated with genes differentially expressed in TEL/AML1-positive leukemia (ETV6/RUNX1).
Project description:The t(12;21) translocation is the most common genetic rearrangement in childhood acute lymphoblastic leukemia (ALL) and gives rise to the TEL-AML1 fusion gene, which functions as a transcription factor. TEL-AML1 expression in EML1 cells results in an impairment of differentiation along the B-lymphoid lineage.
Project description:The t(12;21) translocation is the most common genetic rearrangement in childhood acute lymphoblastic leukemia (ALL) and gives rise to the TEL-AML1 fusion gene, which functions as a transcription factor. TEL-AML1 expression in EML1 cells results in an impairment of differentiation along the B-lymphoid lineage. We analyzed gene expression profiles of EML1 cells after expression of TEL-AML1
Project description:Around 20-25% of childhood acute lymphoblastic leukemias carry the TEL-AML1 (TA) fusion gene. It is a fusion of two central hematopoietic transcription factors, TEL (ETV6) and AML1 (RUNX1). Despite its prevalence, the exact genomic targets of TA have remained elusive. We evaluated gene loci and enhancers targeted by TA genome-wide in precursor B acute leukemia cells using global nuclear run-on sequencing (GRO-seq).
Project description:Around 20-25% of childhood acute lymphoblastic leukemias carry the TEL-AML1 (TA) fusion gene. It is a fusion of two central hematopoietic transcription factors, TEL (ETV6) and AML1 (RUNX1). Despite its prevalence, the exact genomic targets of TA have remained elusive. We evaluated gene loci and enhancers targeted by TA genome-wide in precursor B acute leukemia cells using global nuclear run-on sequencing (GRO-seq). Nascent RNA expression profiles were generated with GRO-seq after TEL-AML1 expression in the Nalm6 pre-B-ALL cell line in four different time points (0, 4, 12 and 24 h). TEL-AML1-mut and luciferase induction cell lines were used as controls. Two replicates were included for all six samples.
Project description:Background The t(12;21)(p13;q22) translocation is found in 20 to 25% of cases of childhood B-lineage acute lymphoblastic leukemia (B-ALL). This rearrangement results in the fusion of ETV6 (TEL) and RUNX1 (AML1) genes and defines a relatively uniform category, although only some patients suffer very late relapse. TEL/AML1-positive patients are thus an interesting subgroup to study, and such studies should elucidate the biological processes underlying TEL/AML1 pathogenesis. We report an analysis of gene expression in 60 children with B-lineage ALL using Agilent whole genome oligo-chips (44K-G4112A) and/or real time RT-PCR. Results We compared the leukemia cell gene expression profiles of 16 TEL/AML1-positive ALL patients to those of 44 TEL/AML1-negative patients, whose blast cells did not contain any additional recurrent translocation. Microarray analyses of 26 samples allowed the identification of genes differentially expressed between the TEL/AML1-positive and negative ALL groups. Gene enrichment analysis defined five enriched GO categories: cell differentiation, cell proliferation, apoptosis, cell motility and response to wounding, associated with 14 genes –RUNX1, TCFL5, TNFRSF7, CBFA2T3, CD9, SCARB1, TP53INP1, ACVR1C, PIK3C3, EGFL7, SEMA6A, CTGF, LSP1, TFPI— highlighting the biology of the TEL/AML1 sub-group. These results were first confirmed by the analysis of an additional microarray data-set (7 patient samples) and second by real-time RT-PCR quantification and clustering using an independent set (27 patient samples). Over-expression of RUNX1 (AML1) was further investigated and in one third of the patients correlated with cytogenetic findings. Conclusions Gene expression analyses of leukemia cells from 60 children with TEL/AML1-positive and -negative B-lineage ALL led to the identification of five biological processes, associated with 14 validated genes characterizing and highlighting the biology of the TEL/AML1-positive ALL sub-group. Keywords: Acute lymphoblastic leukemia, gene expression profiles, TEL/AML1 fusion transcript, functional annotation
Project description:There is increasing evidence that microRNA and transcription factors interact in an instructive fashion in normal and malignant hematopoiesis. We explored the impact of TEL-AML1 (ETV6-RUNX1), the most common fusion protein in childhood leukemia, on miRNA expression and the leukemic phenotype. Using RNA interference, miRNA expression arrays, and quantitative PCR, we identified miRNA-494 and miRNA-320a to be upregulated upon TEL-AML1 silencing independently of TEL expression. Chromatin immunoprecipitation analysis identified miRNA-494 as a direct miRNA target of the fusion protein TEL-AML1. Using bioinformatic analysis as well as functional luciferase experiments we demonstrate that survivin is a target of the two miRNAs. MiRNA-494 and -320a were introduced to the cells by transfection and survivin expression determined by western blot analysis. These miRNAs blocked survivin expression and resulted in apoptosis in a similar manner as TEL-AML1 silencing by itself; this silencing was also shown to be DICER-dependent. MiRNAs-494 and -320a are expressed at lower levels in TEL-AML1+ leukemias compared to immunophenotype-matched non-TEL-AML1 ALL subtypes, and within TEL-AML1+ leukemias their expression is correlated to survivin levels. In summary our data suggest that TEL-AML1 might exert its anti-apoptotic action at least in part by suppressing miRNA-494 and miRNA-320a, lowering their expression causing enhanced survivin expression.