Project description:AML with mutated NPM1 usually carries normal karyotype (NK) but it may harbor chromosomal aberrations whose significance remains unclear. We addressed this question in 631 AML patients with mutated/cytoplasmic NPM1. An abnormal karyotype (AK) was present in 93/631 cases (14.7%), the most frequent abnormalities being +8, +4, -Y, del(9q), +21. Chromosome aberrations in NPM1-mutated AML were similar to, but occurred less frequently than additional chromosome changes found in other AML with recurrent cytogenetic abnormalities according to WHO classification. Four of the 31 NPM1-mutated AML patients karyotyped at different time points had NK at diagnosis but AK at relapse: del(9q) (n=2), t(2;11) (n=1), inv(12) (n=1). NPM1-mutated AML with NK or AK showed overlapping morphological, immunophenotypic (CD34-negativity) and gene expression profile (downregulation of CD34 and upregulation of HOX genes). No difference in survival was observed among NPM1-mutated AML patients independently of whether they carried a normal or abnormal karyotype, the NPM1-mutated/FLT3-ITD negative cases showing the better prognosis. Findings in our patients point to chromosomal aberrations as secondary events, reinforce the concept that NPM1 mutation is a founder genetic lesion and indicate that NPM1-mutated AML should be clinically handled as one entity, irrespective of the karyotype. All bone marrow samples were obtained from untreated patients at the time of diagnosis. Cells used for microarray analysis were collected from the purified fraction of mononuclear cells after Ficoll density centrifugation.
Project description:AML with mutated NPM1 usually carries normal karyotype (NK) but it may harbor chromosomal aberrations whose significance remains unclear. We addressed this question in 631 AML patients with mutated/cytoplasmic NPM1. An abnormal karyotype (AK) was present in 93/631 cases (14.7%), the most frequent abnormalities being +8, +4, -Y, del(9q), +21. Chromosome aberrations in NPM1-mutated AML were similar to, but occurred less frequently than additional chromosome changes found in other AML with recurrent cytogenetic abnormalities according to WHO classification. Four of the 31 NPM1-mutated AML patients karyotyped at different time points had NK at diagnosis but AK at relapse: del(9q) (n=2), t(2;11) (n=1), inv(12) (n=1). NPM1-mutated AML with NK or AK showed overlapping morphological, immunophenotypic (CD34-negativity) and gene expression profile (downregulation of CD34 and upregulation of HOX genes). No difference in survival was observed among NPM1-mutated AML patients independently of whether they carried a normal or abnormal karyotype, the NPM1-mutated/FLT3-ITD negative cases showing the better prognosis. Findings in our patients point to chromosomal aberrations as secondary events, reinforce the concept that NPM1 mutation is a founder genetic lesion and indicate that NPM1-mutated AML should be clinically handled as one entity, irrespective of the karyotype.
Project description:Multilineage dysplasia (MLD) has no impact on biological, clinico-pathological and prognostic features of AML with mutated nucleophosmin (NPM1) NPM1-mutated AML is a provisional entity in the WHO-2008 classification of myeloid neoplasms. The significance of concomitant multilineage dysplasia (MLD) in NPM1-mutated AML is unclear. Thus, in the WHO-2008 classification, NPM1-mutated AML with MLD is classified as AML with myelodysplasia(MD)-related changes. We evaluated the MLD impact in 378 NPM1-mutated AML patients. MLD was found in about 25% cases. Except for a lower WBC and FLT3-ITD incidence in MLD+ group, no significant differences were observed in age, sex, cytogenetics and FLT3-TKD between NPM1-mutated AML with and without MLD. Notably, NPM1-mutated AML with/without MLD showed overlapping immunophenotype (CD34-negativity) and GEP (CD34 downregulation and HOX genes upregulation). Moreover, OS and EFS did not differ among NPM1-mutated AML patients, independently of whether they carried or not MLD, the NPM1-mutated/FLT3-ITD negative cases showing the better prognosis. Lack of MLD impact on survival was confirmed by multivariate analysis that highlighted FLT3-ITD as the most significant prognostic parameter in NPM1-mutated AML. Our findings indicate that NPM1 mutations rather than MLD dictate the distinctive features of NPM1-mutated AML. Thus, irrespective of MLD, NPM1-mutated AML should be considered as one disease entity clearly distinct from AML with MD-related changes. These findings have important diagnostic and prognostic implications in AML. All bone marrow samples were obtained from untreated patients at the time of diagnosis. Cells used for microarray analysis were collected from the purified fraction of mononuclear cells after Ficoll density centrifugation. 48 samples
Project description:Multilineage dysplasia (MLD) has no impact on biological, clinico-pathological and prognostic features of AML with mutated nucleophosmin (NPM1) NPM1-mutated AML is a provisional entity in the WHO-2008 classification of myeloid neoplasms. The significance of concomitant multilineage dysplasia (MLD) in NPM1-mutated AML is unclear. Thus, in the WHO-2008 classification, NPM1-mutated AML with MLD is classified as AML with myelodysplasia(MD)-related changes. We evaluated the MLD impact in 378 NPM1-mutated AML patients. MLD was found in about 25% cases. Except for a lower WBC and FLT3-ITD incidence in MLD+ group, no significant differences were observed in age, sex, cytogenetics and FLT3-TKD between NPM1-mutated AML with and without MLD. Notably, NPM1-mutated AML with/without MLD showed overlapping immunophenotype (CD34-negativity) and GEP (CD34 downregulation and HOX genes upregulation). Moreover, OS and EFS did not differ among NPM1-mutated AML patients, independently of whether they carried or not MLD, the NPM1-mutated/FLT3-ITD negative cases showing the better prognosis. Lack of MLD impact on survival was confirmed by multivariate analysis that highlighted FLT3-ITD as the most significant prognostic parameter in NPM1-mutated AML. Our findings indicate that NPM1 mutations rather than MLD dictate the distinctive features of NPM1-mutated AML. Thus, irrespective of MLD, NPM1-mutated AML should be considered as one disease entity clearly distinct from AML with MD-related changes. These findings have important diagnostic and prognostic implications in AML.
Project description:The clinical impact of aberrant CEBPA promoter methylation (PM) in AML is controversial discussed. The aim of this study was to clarify the significance of aberrant CEBPA PM with regard to clinical features in a cohort of 572 de novo AML with wildtype CEBPA and normal karyotype. The distal promoter was methylated in 54/572 cases (9.41%) whereas proximal PM was never detected. Methylation of the core promoter was detected in only 8 of 326 cases (2.45%) and thus seems to be a rare event in AML. There was no correlation between CEBPA distal PM, age, sex, white blood cell (WBC) count or Hb levels at diagnosis. We also were not able to detect a significant correlation between the presence of CEBPA distal PM and molecular mutations such as FLT3-ITD, NPM1, AML1, MLL-PTD and IDH1. Solely the frequency of IDH2R140 mutations was significantly reduced in CEBPA distal PM positive compared to CEBPA distal PM negative cases (p=0.01). Furthermore, analysis of CEBPA mRNA expression level revealed no difference between CEBPA distal PM positive and CEBPA distal PM negative cases, suggesting that CEBPA distal PM has no influence on CEBPA expression. CEBPA distal PM did not show impact on overall survival (OS), event free survival (EFS) or incidence of relapse. Also when other mutations were taken into regard no prognostic impact of CEBPA distal PM could be shown. In contrast, a distinct expression profile of CEBPA distal PM positive cases compared to CEBPA mutated and CEBPA distal PM negative cases was observed. In addition, a significantly higher frequency of CEBPA distal PM was detected in RUNX1-RUNX1T1 positive AML compared to the CEBPA witdtype cases. We conclude that the presence of aberrant CEBPA PM has no clinical relevance and is therefore a negligible prognostic marker in de novo AML with normal karyotype. To detect underlying common differences in their gene expression profiles, we investigated 9 CEBPA methylated (unmutated), 8 CEBPA single-mutated, 10 CEBPA double-mutated, and 10 non-methylated/non-mutated cases (Affymetrix HG-U133 Plus 2.0 microarrays; Santa Clara, CA). The microarray sample preparation assay was performed as previously reported. Gene expression raw data were processed according to the manufacturer’s recommendations.
Project description:Among acute myeloid leukemias (AML) with normal karyotype (CN-AML), NPM1 and CEBPA mutations define WHO provisional entities accounting for ~60% of cases, but the remaining ~40% remains poorly characterized. By whole exome-sequencing (WES) of one CN-AML patient lacking mutations in NPM1, CEBPA, FLT3, MLL-PTD and IDH1, we newly identified a clonal somatic mutation in BCOR (BCL6 co-repressor), a gene located in chromosome X. Further analyses showed that BCOR mutations occurred in 11/262 (4.2%) CN-AML cases and represented a substantial fraction (14/82, 17.1%) of CN-AML patients showing the same genetic background as the index patient subjected to WES. BCOR somatic mutations were: i) disruptive events similar to germline BCOR mutations causing the oculo-cranio-facial-dental (OCFD) genetic syndrome; ii) associated with markedly decreased BCOR mRNA levels, absence of full-length BCOR and absent or low expression of a truncated BCOR protein; iii) almost mutually exclusive with NPM1 mutations and frequently associated with DNMT3A and RUNX1 mutations, pointing to a cooperation between these events. Finally, BCOR mutations correlated with poor outcome among a cohort of 160 CN-AML patients (28% versus 66% overall survival at 2 yrs, P=0.024). Our results implicate for the first time BCOR in the pathogenesis of CN-AML without NPM1 mutations. AML samples with normal karyotype were studied. Molecular analyses were performed for BCOR mutations. 12 BCOR wild-type cases and 12 BCOR mutated cases were hybridized to gene expression micro-arrays.
Project description:Cytogenetically normal acute myeloid leukemia (CN-AML) comprise between forty and fifty percent of all adult acute myeloid leukemia (AML) cases. In this clinically diverse group molecular aberrations such as FLT3ITD, NPM1 and CEBPA mutations recently have added to the prognostic accuracy. Aberrant DNA methylation is a hallmark of cancer including AML. We investigated in total 89 CN-AML samples in a test and a validation cohort for genome-wide promoter DNA methylation with Illumina Methylation Bead arrays and compared them to normal myeloid precursors and global gene expression. IDH and NPM1 mutations were associated with different methylation patterns (p=0.0004 and 0.04, respectively). Genome-wide methylation levels were elevated in IDH mutated samples (p=0.006). We observed a negative impact of DNA methylation on transcription. Genes targeted by Polycomb group (PcG) proteins and genes associated with bivalent histone marks in stem cells showed increased aberrant methylation in AML (p<0.0001). Furthermore, high methylation levels of PcG target genes were independently associated with better progression free (OR 0.47, p=0.01) and overall survival (OR 0.36, p=0.001). In summary, genome wide methylation patterns show preferential methylation of PcG targets with prognostic impact in CN-AML. Genome wide methylation pattern study of cytogenetically normal 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:The clinical impact of aberrant CEBPA promoter methylation (PM) in AML is controversial discussed. The aim of this study was to clarify the significance of aberrant CEBPA PM with regard to clinical features in a cohort of 572 de novo AML with wildtype CEBPA and normal karyotype. The distal promoter was methylated in 54/572 cases (9.41%) whereas proximal PM was never detected. Methylation of the core promoter was detected in only 8 of 326 cases (2.45%) and thus seems to be a rare event in AML. There was no correlation between CEBPA distal PM, age, sex, white blood cell (WBC) count or Hb levels at diagnosis. We also were not able to detect a significant correlation between the presence of CEBPA distal PM and molecular mutations such as FLT3-ITD, NPM1, AML1, MLL-PTD and IDH1. Solely the frequency of IDH2R140 mutations was significantly reduced in CEBPA distal PM positive compared to CEBPA distal PM negative cases (p=0.01). Furthermore, analysis of CEBPA mRNA expression level revealed no difference between CEBPA distal PM positive and CEBPA distal PM negative cases, suggesting that CEBPA distal PM has no influence on CEBPA expression. CEBPA distal PM did not show impact on overall survival (OS), event free survival (EFS) or incidence of relapse. Also when other mutations were taken into regard no prognostic impact of CEBPA distal PM could be shown. In contrast, a distinct expression profile of CEBPA distal PM positive cases compared to CEBPA mutated and CEBPA distal PM negative cases was observed. In addition, a significantly higher frequency of CEBPA distal PM was detected in RUNX1-RUNX1T1 positive AML compared to the CEBPA witdtype cases. We conclude that the presence of aberrant CEBPA PM has no clinical relevance and is therefore a negligible prognostic marker in de novo AML with normal karyotype.
Project description:NPM1 is the most frequently mutated gene in cytogenetically normal acute myeloid leukemia (AML). In AML cells, NPM1 mutations result in abnormal cytoplasmic localization of the mutant protein (NPM1c). NPM1 mutations are founding genetic lesions, however it is unknown whether NPM1c is required to maintain the leukemic state. Here, we show that loss of NPM1c from the cytoplasm, either through nuclear relocalization or targeted degradation, results in downregulation of homeobox (HOX) genes, and differentiation and cell growth arrest of AML cells. Additionally, we show that HOX downregulation is the earliest transcriptional event following the loss of NPM1c from the cytoplasm, preceding and promoting differentiation. Finally, we show that XPO1 inhibition efficiently relocalizes NPM1c to the nucleus, enables differentiation and prolongs survival of Npm1c+ leukemic mice. We describe an exquisite dependency of NPM1-mutant AML cells on NPM1c, providing the rationale for the use of nuclear export inhibitors in AML with mutated NPM1.