Project description:Mutations in the nucleophosmin 1 (NPM1) gene are considered as a founder event in the pathogenesis of acute myeloid leukemia (AML). To address the role of clonal evolution in relapsed NPM1 mutated (NPM1mut) AML, we applied high-resolution genome-wide single-nucleotide polymorphism (SNP) array profiling to detect copy number alterations (CNA) and uniparental disomies (UPD) and performed comprehensive gene mutation screening in 53 paired bone marrow/peripheral blood samples obtained at diagnosis and relapse. At diagnosis, 15 aberrations (CNAs, n=10; UPDs, n=5) were identified in 13 patients (25%), whereas at relapse 56 genomic alterations (CNAs, n=46; UPDs, n=10) were detected in 29 patients (55%) indicating an increase in genomic complexity. Recurrent aberrations acquired at relapse included deletions affecting tumor suppressor genes [ETV6 (n=3), TP53 (n=2), NF1 (n=2), WT1 (n=3), FHIT (n=2)] and homozygous FLT3 mutations acquired via UPD13q (n=7). DNMT3A mutations (DNMT3Amut) showed the highest stability (97%). Persistence of DNMT3Amut in 5 patients who lost NPM1mut at relapse suggests that DNMT3Amut may precede NPM1mut in AML pathogenesis. Of note, all relapse samples shared at least one genetic aberration with the matched primary AML sample implying common ancestral clones. In conclusion, our study reveals novel insights into clonal evolution in NPM1mut AML. Bone marrow or peripheral blood samples from diagnosis, remission and relapse of 53 NPM1 mutated AML patient were analyzed on the Affymetrix Genome-Wide Human SNP 6.0 Array. Raw data (CEL-Files) were transformed to genotyping files (CHP) with Genotyping Console Version 4.2 from Affymetrix. Bioinformatic evaluation of CNAs was performed using dChipSNP and circular binary segmentation .
Project description:Gene expression in NPM1 wildtype and mutated AML patients with high or low hsa_circ_0075001 expression In acute myeloid leukemia there is growing evidence for splicing pattern deregulation, including differential expression of linear splice isoforms of the commonly mutated gene nucleophosmin (NPM1). In this study, we detect circular RNAs of NPM1 and quantify circRNA hsa_circ_0075001 in a cohort of NPM1 wildtype and mutated acute myeloid leukemia (n=46). Hsa_circ_0075001 expression correlates positively with total NPM1 expression, but is independent of the NPM1 mutational status. High versus low hsa_circ_0075001 expression defines patient subgroups characterized by distinct gene expression patterns, such as lower expression of components of the Toll-like receptor signaling pathway in high hsa_circ_0075001 expression cases. Global evaluation of circRNA expression in sorted healthy hematopoietic controls (n=10) and acute myeloid leukemia (n=10) reveals circRNA transcripts for 47.9% of all highly expressed genes. While circRNA expression correlates globally with parental gene expression, we identify hematopoietic differentiation-associated as well as acute myeloid leukemia subgroup-specific circRNA signatures.
Project description:Background: MicroRNAs are regulators of gene expression, mainly functioning by decreasing mRNA levels of their multiple targets. Deregulated microRNA expression has been shown for acute myeloid leukemia, a disease also characterized by altered gene expression associated with distinct genomic aberrations such as nucleophosmin (NPM1) mutations. To further illuminate the role of deregulated microRNA and gene expression in cytogenetically normal acute myeloid leukemia with NPM1 mutation, we performed an integrative analysis of microRNA and mRNA expression data sets. Design and Methods: Both microRNA and gene expression profiles were measured in a cohort of 43 adult acute myeloid leukemia patient samples (n=42 cytogenetically normal, n=1 del7q; median age 46 years [range 23-60]) of known NPM1 mutation status (n=23 mutated, n=20 wild-type) and data integratively analyzed. Putative microRNA-mRNA interactions were validated by quantitative RT-PCR, Western Blot and luciferase reporter assays. For selected microRNAs, sensitivity of microRNA-overexpressing cells to cytarabine treatment was tested by FACS viability and cell proliferation assays. Results: Our integrative approach of analyzing both microRNA and gene expression profiles in parallel resulted in a refined list of putative target genes affected by NPM1 mutation-associated microRNA deregulation. Of 177 putative microRNA - target mRNA interactions, we could identify and validate 77 novel candidates with known or potential implication in leukemogenesis, such as IRF2-miR-20a, KIT-miR-20a and MN1-miR-15a. Furthermore, our data showed that deregulated expression of tumor suppressor microRNAs such as miR-29a and miR-30c might contribute to the sensitivity to cytarabine, which is observed in NPM1-mutated acute myeloid leukemia. Conclusions: Overall, our observations highlight that integrative data analysis approaches can improve insights into leukemia biology, and lead to the identification of novel microRNA - target gene interactions of potential relevance for acute myeloid leukemia treatment. MicroRNA and gene expression profiles were measured in a cohort of 43 adult (42 cytogenetically normal and 1 del7q) acute myeloid leukemia patient samples of known NPM1 mutation status (n=23 mutated, n=20 wild-type). This submission represents the mRNA expression component of the study. The miRNA expression data will be deposited as supplementary information along with the accompanying manuscript.
Project description:Mutations in the nucleophosmin 1 (NPM1) gene are considered as a founder event in the pathogenesis of acute myeloid leukemia (AML). To address the role of clonal evolution in relapsed NPM1 mutated (NPM1mut) AML, we applied high-resolution genome-wide single-nucleotide polymorphism (SNP) array profiling to detect copy number alterations (CNA) and uniparental disomies (UPD) and performed comprehensive gene mutation screening in 53 paired bone marrow/peripheral blood samples obtained at diagnosis and relapse. At diagnosis, 15 aberrations (CNAs, n=10; UPDs, n=5) were identified in 13 patients (25%), whereas at relapse 56 genomic alterations (CNAs, n=46; UPDs, n=10) were detected in 29 patients (55%) indicating an increase in genomic complexity. Recurrent aberrations acquired at relapse included deletions affecting tumor suppressor genes [ETV6 (n=3), TP53 (n=2), NF1 (n=2), WT1 (n=3), FHIT (n=2)] and homozygous FLT3 mutations acquired via UPD13q (n=7). DNMT3A mutations (DNMT3Amut) showed the highest stability (97%). Persistence of DNMT3Amut in 5 patients who lost NPM1mut at relapse suggests that DNMT3Amut may precede NPM1mut in AML pathogenesis. Of note, all relapse samples shared at least one genetic aberration with the matched primary AML sample implying common ancestral clones. In conclusion, our study reveals novel insights into clonal evolution in NPM1mut AML.
Project description:NPM1-mutated acute myeloid leukemia (AML) accounts for one third of AML in adults. NPM1-mutated AML maintenance depends on the interaction between mutated NPM1 (NPM1c) and the nuclear exporter Exportin 1 (XPO1). In this work, we show that continous XPO1 inhibition is necessary to achieve stable disruption of the NPM1c-XPO1 interaction and to induce HOX downregulation and differentiation of AML cells with mutated NPM1. In contrast, intermittent XPO1 inhibition only results in minimal transcriptional perturbation and limited antileukemic activity.
Project description:Background: MicroRNAs are regulators of gene expression, mainly functioning by decreasing mRNA levels of their multiple targets. Deregulated microRNA expression has been shown for acute myeloid leukemia, a disease also characterized by altered gene expression associated with distinct genomic aberrations such as nucleophosmin (NPM1) mutations. To further illuminate the role of deregulated microRNA and gene expression in cytogenetically normal acute myeloid leukemia with NPM1 mutation, we performed an integrative analysis of microRNA and mRNA expression data sets. Design and Methods: Both microRNA and gene expression profiles were measured in a cohort of 43 adult acute myeloid leukemia patient samples (n=42 cytogenetically normal, n=1 del7q; median age 46 years [range 23-60]) of known NPM1 mutation status (n=23 mutated, n=20 wild-type) and data integratively analyzed. Putative microRNA-mRNA interactions were validated by quantitative RT-PCR, Western Blot and luciferase reporter assays. For selected microRNAs, sensitivity of microRNA-overexpressing cells to cytarabine treatment was tested by FACS viability and cell proliferation assays. Results: Our integrative approach of analyzing both microRNA and gene expression profiles in parallel resulted in a refined list of putative target genes affected by NPM1 mutation-associated microRNA deregulation. Of 177 putative microRNA - target mRNA interactions, we could identify and validate 77 novel candidates with known or potential implication in leukemogenesis, such as IRF2-miR-20a, KIT-miR-20a and MN1-miR-15a. Furthermore, our data showed that deregulated expression of tumor suppressor microRNAs such as miR-29a and miR-30c might contribute to the sensitivity to cytarabine, which is observed in NPM1-mutated acute myeloid leukemia. Conclusions: Overall, our observations highlight that integrative data analysis approaches can improve insights into leukemia biology, and lead to the identification of novel microRNA - target gene interactions of potential relevance for acute myeloid leukemia treatment.
Project description:The epigenetic machinery is frequently altered in acute myeloid leukemia (AML). Focusing on cytogenetically normal (CN) AML, we previously described an abnormal H3K27me3 enrichment covering 70 kb on the HIST1 cluster (6.p22). Here, we further investigate the molecular, functional, and prognosis significance of this epigenetic alteration in NPM1-mutated (NPM1mut) CN-AML. H3K27me3 HIST1high group of patients