Epigenetic Status Of CEBPA Promoter and Expression Of CEBPα Correlates With Molecular Genetic Subtype and CD2 Aberrant Expression In B Cell Precursor ALL

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2573-2573
Author(s):  
Lucie Slamova ◽  
Julia Starkova ◽  
Karel Fiser ◽  
Eva Fronkova ◽  
Leona Rezkova Reznickova ◽  
...  
Keyword(s):  
B Cell ◽  
Early Phase ◽  
Conflicts Of Interest ◽  
Fusion Gene ◽  
Lymphoblastic Leukemia ◽  
Methylation Status ◽  
Fisher Exact Test ◽  
Cell Precursor ◽  
Aberrant Expression ◽  
Mll Gene

Abstract CCAAT/enhancer binding protein alpha (CEBPα) is one of the crucial transcription factors involved in hematopoietic differentiation and leukemogenesis. CEBPα promotes myeloid differentiation by up-regulation of lineage specific genes and by cell proliferation arrest. Epigenetic regulation of CEBPα expression through DNA methylation has been demonstrated in acute myeloid leukemia (AML) (Figueroa et al, Cancer Cell, 2010). However, only limited data are available regarding CEBPA promoter methylation and its expression in B cell precursor acute lymphoblastic leukemia (BCP-ALL). Methylation status of CEBPA promoter (-295 to -593bp upstream of the transcription start site (TSS), 24 CpG dinucleotides) was analyzed by bisulfite sequencing. Five subgroups of BCP-ALLs were analyzed: MLL gene rearranged (n=5), hyperdiploid (n=6), mBCR-ABLpos(n=5), ETV6-RUNX1pos(n=6) and other BCP-ALLs (no hyperdiploidy, MLL gene rearrangement, BCR-ABL or ETV6-RUNX1 fusion gene (“BCP-others”, n=29)). CEBPA promoter was hypermethylated in MLL-rearranged, hyperdiploid and ETV6-RUNX1pos BCP-ALL (5/5, 6/6 and 4/6 respectively). Surprisingly CEBPA promoter was hypomethylated in all mBCR-ABLpos cases (5/5). In subgroup of other BCP-ALLs both hypermethylation (10/29) and hypomethylation of CEBPA promoter (19/29) were detected (Figure 1A). In previous study we found association of CD2 (LFA-2) aberrant expression and switch to the monocytic lineage during the early phase of treatment in BCP-ALLs (Slamova et al, ASH 2012). We were interested if a possible link between hypomethylation of CEBPA promoter correlates with aberrant expression of CD2. There was a significant association between aberrant expression of CD2 antigen and hypomethylation in CEBPA promoter in BCP-others (Fisher exact test, p<0.0001). Interestingly, in the only hypomethylated ETV6-RUNX1pos case we found aberrant CD2 expression on blasts, which is exceptional in ETV6-RUNX1pos ALL. We next asked whether methylation of CEBPA promoter correlates with CEBPα expression. It is generally accepted that promoter hypomethylation is often associated with increased expression of the relevant gene. Our data prove that in general, this holds true also for BCP-ALL. However, in two genetically defined subsets we observed either high expression despite hypermethylation (MLL-rearranged ALL) or low expression despite hypomethylation (mBCR-ABLpos ALL) (Figure 1B). In BCP-others hypomethylation of CEBPA promoter was significantly associated with upregulation of myeloid antigens (CD14 and/or CD33) and downregulation of B cell marker CD19 on blasts during the first weeks of the treatment (Fisher test, p=0.0009). In summary Methylation status of CEBPA promoter correlates with genetic subtypes of BCP-ALL. The notion that hypomethylation leads to overexpression was confirmed in majority of BCP-ALLs, while in mBCR-ABLpos and MLL gene rearranged BCP-ALL it did not follow this pattern. Hypomethylation of CEBPA promoter in BCP- others correlates with CD2 expression on blasts and increased CEBPα gene expression. During the early phase of the treatment in other BCP-ALLs with hypomethylated CEBPA promoter increase of myeloid and decrease of B lymphoid markers on blasts was observed. Supported by: GACR P301/10/1877, GACR P304/12/2214, GAUK 914613, UNCE 204012, NT13462, NT12397- 4, project for conceptual development of research organization (Ministry of Health, CZ) 00064203, the FACS Aria instrument was supported by EU-Prague project CZ.2.16/3.1.00/24022 Disclosures: No relevant conflicts of interest to declare.

Epigenetic Changes in CEBPα Gene and Xenotransplantation Model of B Cell Precursor Acute Lymphoblastic Leukemia Switching to Monocytoid Lineage During the Early Phase of the Treatment

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 876-876
Author(s):  
Lucie Slamova ◽  
Julia Starkova ◽  
Beat C Bornhauser ◽  
Eva Fronkova ◽  
Marketa Kubricanova Zaliova ◽  
...  
Keyword(s):  
B Cell ◽  
Early Phase ◽  
Promoter Region ◽  
Molecular Mechanisms ◽  
Bisulfite Sequencing ◽  
Lymphoblastic Leukemia ◽  
Methylation Status ◽  
Cell Precursor ◽  
Aberrant Expression ◽  
Fisher Test

Abstract Abstract 876 Immunophenotypic instability during early phase of ALL treatment is a frequent observation during flow cytometric minimal residual disease (FC MRD) monitoring. Antigens typically involved include CD10, CD20, CD34 and CD45 and these changes do not usually revoke initial disease classification and do not hamper FC MRD detection. We previously described a subtype of B-cell precursor (BCP) ALL with striking immunophenotypic instability towards monocytoid lineage within the first month of therapy (switching ALL-swALL). Blasts expressing both B and monocytoid markers emerged at early time points on days 8 and 15 of treatment while later only those blasts with pure monocytoid phenotype were present. Incidence of swALL in childhood was unexpectedly high (3-4% of all pediatric BCP ALL) as confirmed in two national reference labs. This phenomenon was associated with aberrant expression of CD2 (LFA-2) on diagnostic blasts (Mejstrikova et al, ASH 2010). The leukemic origin of monocytoid blasts was proven by the detection of clone-specific immunoreceptor gene rearrangements (Ig-TCR). No common genetics aberration was found in a cohort of swALL (n=17), MLL gene was always in germline configuration. We found an increased rate of alteration in IKZF1 gene compared to control BCP ALL cases (p=0.012). An expression analysis of the key hematopoietic regulators showed a difference in CEBPα expression, which is an important transcription factor in transdifferentiation of B cells into macrophages (Xie et al., Cell 2004). Expression of CEBPα is increased in swALL compared to other BCP ALL cases (p=0.01) already at diagnosis prior switching, however, the expression is lower compared to AML (p=0.002). We analyzed CEBPα the methylation status of the promoter region of this gene. Demethylation of CEBPα promoter region analyzed by bisulfite sequencing (295bp-594bp of promoter region) was found in 10/12 swALL cases, while it was seen in only 6/28 control BCP ALLs (Fisher test, p=0.0004). The only cases having demetylation in CEBPα were 5/5 BCR-ABLpos and 1/4 ETV6-RUNX1pos. Whole genome ERRBS method (Enhanced Reduced Representation Bisulfite Sequencing) confirmed this methylation pattern of CEBPα in 7 patients (4 swALL,3 BCP ALL). In order to establish an in vivo model to study the underlying molecular mechanisms, we transplanted ALL cells from 7 swALL patients intrafemorally into NOD-SCIDIL2Rgammanull (NSG) mice. Successfulstable engraftment was achieved only in 2 out of 7 swALL cases (28%) (Fisher test, p=0.049).Interestingly in these two cases, the 200 bp promoter region of CEBPα was methylated to some extent at diagnosis and completely methylated after engraftment into mice, suggesting the possibility of a selective advantage in this context. We treated engrafted animals with prednisolone and in both cases we observed demethylation of CEBPα promoter. Because the rate of engraftment of ALL in NSG is usually very high, these observations may indicate that the biology of this particular subset of patient is distinct. Conclusion: We described a novel subtype of BCP-ALL with the demethylation of CEBPα promoter region, increased CEBPα expression and immunophenotypic shift towards monocytic lineage during first weeks of the therapy. We identified CEBPα as the potential regulator of this lineage plasticity. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Novel MEIS1-FOXO1 Fusion Gene in a Case of Pediatric B-Cell Precursor Acute Lymphoblastic Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5283-5283
Author(s):  
Chuang Jiang ◽  
Jiabi Qian ◽  
Wenge Hao ◽  
Wei LIU ◽  
Shuhong Shen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Conflicts Of Interest ◽  
Residual Disease ◽  
Fusion Gene ◽  
Lymphoblastic Leukemia ◽  
Functional Study ◽  
Cell Precursor ◽  
Foxo1 Gene

Abstract Background: Thanks to the total therapy and systemic basic-translation research, the overall survival rate in children with acute lymphoblastic leukemia (ALL) has dramatically improved to almost 90% over these past few decades. FOXO1 gene belongs to the forkhead family of transcription factors, which play roles in myogenic growth and differentiation. Translocation of FOXO1 with PAX3 has been reported in pediatric alveolar rhabdomyosarcoma. In B-cell precursor ALL, two cases with FOXO1 fusions have been identified already, while its function on ALL remains unknown. Here, we report a novel MEIS1-FOXO1 fusion gene in a case with B-ALL. Methods: Flowcytometery, karyotype, RT-PCR and fluorescence in were employed, MEIS1-FOXO1 was identified as novel fusion gene in a case of pediatric BCP-ALL. Using IL-3 dependent BaF3 cells as study model to test the leukemia transformation potential of MEIS1-FOXO1. Results: A novel MEIS1-FOXO1 fusion was identified in one cease of pediatric B-ALL. Panel next generation sequencing (NGS) showed that the leukemia clone had concurrent NRASG12D, TP53R273H, WHSC1E1099K, ABCC1R1166X, PHGR1H37P, HOXA3P219L and DSTP4606L somatic mutation. This patient was enrolled in CCCG-ALL2015 clinical trial (ChiCTR-IPR-14005706) and achieved completed remission and low minimal residual disease (MRD) level (MRD<0.01%) at day 19 from induction therapy. Functional study showed that MEIS1-FOXO1 fusion gene can potentiate BaF3 cells growth independent of IL3 supplement, as compared to those without MEIS1-FOXO1 fusion transduction. In the meanwhile, we have found that MEIS1-FOXO1 fusion gene can drive cells into S-phase with concurrent decreased G0/G1 phase, which might be its oncogenic role in leukemogenesis. Using qPCR methods, we have found that MEIS1-FOXO1 fusion gene altered the cell cycle related genes expression. Conclusions: Integrating the FOXO1-fusion reports, our data have added more evidence to underline the role of FOXO1 deregulation in the pathogenesis of acute lymphoblastic leukemia. Novel fusion of MEIS1-FOXO1 can potentiate B-ALL via cell cycle entry. Detailed mechanisms involved into the MEIS1-FOXO1 should be further investigated. Figure. Figure. Disclosures No relevant conflicts of interest to declare.

Single-Cell Phospho-Profiling in Pediatric B-Cell Precursor Acute Lymphoblastic Leukemia Reveals Signaling Differences in Cytogenetic and Prognostic Subgroups.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2653-2653
Author(s):  
Manon Queudeville ◽  
Sarah M. Eckhoff ◽  
Klaus-Michael Debatin ◽  
Lueder H. Meyer
Keyword(s):  
Flow Cytometry ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Single Cell ◽  
Poor Prognosis ◽  
Conflicts Of Interest ◽  
Fusion Gene ◽  
Lymphoblastic Leukemia ◽  
Cell Precursor ◽  
Cytogenetic Aberrations

Abstract Abstract 2653 Poster Board II-629 Oncogenesis and tumor progression are supported by alterations in cellular signaling. We used phospho-specific antibodies in combination with surface staining in flow cytometry to analyze specific signaling profiles of leukemia cells at a single cell level. We anayzed 22 xenograft samples derived from NOD/SCID-mice transplanted with primary pediatric B- cell precursor acute lymphoblastic leukemia (BCP- ALL) cells. The cells were isolated from the spleens of leukemia bearing mice and stimulated ex vivo in vitro with different stimulants and cytokines. Activation of various phosphoepitopes was analyzed by flow cytometry and compared to the basal state of unstimulated samples. TEL/AML1 fusion and MLL-rearrangements are the most common cytogenetic aberrations in childhood BCP- ALL and are associated with a good or very poor prognosis, respectively. Although there were no differences detectable in basal phosphorylation between the different cytogenetic subgroups, TEL/AML1- positive samples (n= 5) displayed a significantly lower phosphorylation of extracellular regulated kinase (ERK1/2) after stimulation with PMA (Phorbol-12-myristat-13-acetate, activator of protein kinase C) or interleukin 7 (IL-7), while they showed a significantly higher activation of p38 after stimulation with PMA, compared to samples without translocation (n= 13). Additionally, the fusion gene negative samples showed a downregulation of STAT1-phosphorylation after stimulation with interleukin 10 (IL-10) whereas the TEL/AML1-positive samples showed no change. Interestingly, the MLL- positive samples (n= 3) also did not show a difference in STAT1-phosphorylation after IL-10, but showed significantly stronger STAT1 activation in response to interferon alpha (IFN-a) compared to samples without fusion genes. Moreover, the MLL- positive samples also displayed a weaker reaction in ERK-phosphorylation after IL-7 compared to the leukemia samples without cytogenetic aberrations. Differences in other prognostic subgroups analysed include a weaker phosphorylation of p38 and JNK after anisomycin in samples where the patient initially presented with hyperleucocytosis (> 100.000 WBC/μl) (n= 3), an indicator of poor prognosis. A decrease in STAT3- activation after IL-10 was observed in samples where the patients displayed bone marrow remission on day 15 of therapy (n= 8), compared to no change in the samples of patients with > 5% residual blasts (n= 8), indicative of therapy resistance, at this timepoint. Similar to the results for the cytogenetic subgroups, there were no differences detectable at basal phosphorylation levels between the prognostic subgroups. Taken together, these data show that basal phosphorylation states of specific signaling molecules do not discriminate between the different prognostic subgroups of BCP- ALL analyzed. Cytogenetic and other prognostic subgroups however display specific profiles of signaling networks after stimulation. This strategy will prove helpful to identify mechanisms by which different subgroups with distinct clinical outcomes interpret environmental signals and hereby define pathways important for continued survival, proliferation and resistance eventually leading to novel biomarkers and targeted therapies. Disclosures: No relevant conflicts of interest to declare.

scholarly journals NUTM1 is a recurrent fusion gene partner in B-cell precursor acute lymphoblastic leukemia associated with increased expression of genes on chromosome band 10p12.31-12.2

Haematologica ◽  
2019 ◽  
Vol 104 (10) ◽  
pp. e455-e459 ◽  
Author(s):  
Femke M. Hormann ◽  
Alex Q. Hoogkamer ◽  
H. Berna Beverloo ◽  
Aurélie Boeree ◽  
Ilse Dingjan ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Fusion Gene ◽  
Lymphoblastic Leukemia ◽  
Chromosome Band ◽  
Cell Precursor ◽  
Expression Of Genes

scholarly journals PAX5-AUTS2: A recurrent fusion gene in childhood B-cell precursor acute lymphoblastic leukemia

2012 ◽  
Vol 36 (8) ◽  
pp. e178-e181 ◽  
Author(s):  
Dagmar Denk ◽  
Karin Nebral ◽  
Jutta Bradtke ◽  
Gertrud Pass ◽  
Anja Möricke ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Fusion Gene ◽  
Lymphoblastic Leukemia ◽  
Cell Precursor

Two Distinct Subsets of dic(9;12)(p12;p11.2) among Children with B-Cell Precursor Acute Lymphoblastic Leukemia (ALL): PAX5-ETV6 and ETV6-RUNX1 Rearrangements: A Report from the Children’s Oncology Group.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1439-1439 ◽  
Author(s):  
Julie M. Gastier-Foster ◽  
Andrew J. Carroll ◽  
Denise Ell ◽  
Richard Harvey ◽  
I-Ming Chen ◽  
...  
Keyword(s):  
B Cell ◽  
Gene Rearrangement ◽  
Fusion Gene ◽  
Lymphoblastic Leukemia ◽  
Cytogenetic Abnormality ◽  
Fish Analysis ◽  
Oncology Group ◽  
Rt Pcr ◽  
Cell Precursor ◽  
Pediatric All

Abstract The dic(9;12)(p12;p11.2) has been described as a rare cytogenetic abnormality in pediatric precursor B-cell ALL. Initial studies suggested that the rearrangement is associated with a favorable outcome, and recent studies demonstrated the presence of a PAX5-ETV6 fusion gene was associated with this cytogenetic abnormality. Twenty cases with a cytogenetic dic(9;12) were identified in the Children’s Oncology Group (COG) cytogenetics databases. FISH analysis with the ETV6-RUNX1 (TEL-AML1) probes was done on 12 of these samples. Five cases were positive for fusion, indicating a cryptic t(12;21)(p13;q22), and also had loss of the ETV6 probe from the chromosome 12 not involved in the t(12;21). Seven cases were negative for fusion and had loss of an ETV6 signal, although one of the latter had a diminished ETV6 signal identified. To determine whether both PAX5-ETV6 and ETV6-RUNX1 rearrangements occurred in some patients, a diagnostic sample from each patient was analyzed by RT-PCR for the PAX5-ETV6 and ETV6-RUNX1 fusion genes. Primers from exon 3 of PAX5 and exon 3 of ETV6 were used for the PAX5-ETV6 analysis and from exon 5 of ETV6 and exon 4 of RUNX1 for the ETV6-RUNX1 analysis. Of the 20 cases, only 8 were RT-PCR positive for the PAX5-ETV6 fusion with the above primers; however, an additional 2 were RT-PCR positive with alternate primers, and all 10 of these were negative for the ETV6-RUNX1 fusion by RT-PCR. Of the remaining 10 patients, 9 were RT-PCR positive for the ETV6-RUNX1 fusion, including all of the ETV6-RUNX1 cases positive by FISH. The gene rearrangement associated with the dic(9;12) in these cases is not known. One patient was negative for both fusions by RT-PCR, negative by FISH for ETV6-RUNX1 rearrangement, yet had loss of an ETV6 signal. No cytogenetic differences could be seen between the 2 groups, either in the appearance of the dic(9;12) or in the other abnormalities identified. These results demonstrate the presence of two mutually exclusive dic(9;12) rearrangements in pediatric ALL; one associated with ETV6-RUNX1 rearrangement and one resulting in PAX5-ETV6 fusion. Both PAX5-ETV6 and ETV6-RUNX1 rearrangements are associated with a favorable prognosis. However, molecular analysis of the dic(9;12) patients must be performed to determine whether the dicentric chromosome results in PAX5-ETV6 fusion or whether the case has ETV6-RUNX1 fusion.

ERG Intragenic Deletion Characterizes a Distinct Oncogenic Subtype of B-Cell Precursor Acute Lymphoblastic Leukemia with a Favourable Outcome Despite Frequent IKZF1 Deletions

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 121-121
Author(s):  
Emmanuelle Clappier ◽  
André Baruchel ◽  
Jérôme Rapion ◽  
Aurélie Caye ◽  
Ahlème Khemiri ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Favourable Outcome ◽  
Fish Analysis ◽  
Cell Precursor ◽  
Pcr Assay ◽  
Genetic Lesion ◽  
Intragenic Deletion

Abstract Abstract 121 The genetic landscape of B-cell precursor acute lymphoblastic leukemia (BCP-ALL) in children above 10 years and adolescents remains poorly defined. Specifically, more than half of these patients have none of the cytogenetic abnormalities that define oncogenic subtypes and underlie risk stratification. To uncover new genetic abnormalities in these unassigned cases, we studied 85 BCP-ALL from patients aged 10 to 17 diagnosed at St-Louis hospital (Paris, France), for which the main classifying genetic lesions were assessed (i.e. high hyperdiploidy, t(12;21)/ETV6-RUNX1, t(1;19)/TCF3-PBX1, t(9;22)/BCR-ABL1, iAMP21, MLL translocations, low hypodiploidy, and near haploidy). Fifty of these BCP-ALL presented no classifying genetic lesions. Paired leukemic and remission samples could be analysed by high density array-CGH (Agilent 1M arrays) in 17 of these unassigned cases. We focused on acquired, focal, and recurrent copy-number abnormalities. A mono-allelic intragenic deletion of the ETS-related Gene (ERG) was found in 3 cases. ERG belongs to the ETS family of transcription factors and is implicated in chromosomal translocations associated with several cancer types including acute myeloid leukemia. The possibility of a cryptic unbalanced translocation was ruled out in the 3 cases by FISH analysis. The deletions encompassed exons 3 to 7, or 3 to 9, and the breakpoints were tightly clustered. Based on the breakpoint sequences we designed a PCR assay that allowed us to screen ERG intragenic deletions in the whole cohort. ERG deletion was identified in 9 additional cases, none of them having any of the known classifying genetic lesions, bringing up to 25% (12 out of 50) the frequency of ERG deletion in unassigned BCP-ALL of children older than 10. These results suggested that ERG deletion characterized a novel oncogenic subtype of BCP-ALL. Of note, these results were consistent with independent data of Harvey et al. (2010) that reported ERG deletions in a distinct gene-expression cluster. To confirm and extend these findings in the whole population of paediatric BCP-ALL, we used our breakpoint-specific PCR assay to screen ERG deletions in an independent cohort of 822 unselected patients aged 1 to 17, enrolled in the EORTC 58951 trial. ERG deletion was identified in 31/822 (3.7%) patients. Again, none of them had another known classifying genetic lesion, confirming that ERG deletion characterizes a distinct oncogenic subtype. Patients with ERG deletion were significantly older compared to other patients (median 7.0 vs 4.0, p=0.002), but they had similar white blood counts at diagnosis. They had a favourable outcome, with a 8-year event free survival (EFS) of 82.4% and overall survival (OS) of 96.0%, which is similar to EFS of 83.4% and OS of 91.6% obtained for patients having no very high risk initial features (i.e. no t(9;22)/BCR-ABL1, MLL rearrangement or haploidy/low hypodiploidy). IKZF1 deletion is a cooperative genetic lesion that has been recently shown to be associated with a poor outcome in BCP-ALL. Remarkably, the incidence of IKZF1 deletions in patients with ERG deletion was significantly higher than in other BCR-ABL1-negative patients, especially when considering the IKZF1 intragenic deletion Δ4-7 (10/31, 32.3% vs 34/744, 4.6%, P<0.001), and this regardless of age. Surprisingly, IKZF1 deletion had no impact on the prognosis of ERG deleted patients. Indeed, patients combining ERG and IKZF1 Δ4-7 deletions had a better outcome than other BCR-ABL1-negative patients with IKZF1 deletions (8-year EFS 83.3% vs 53.0%, hazard ratio (HR) 0.19, 95% CI 0.02–1.41; p=0.069). Altogether, we have identified a novel oncogenic subtype of BCP-ALL characterized by ERG deletion. This subtype is frequently associated with IKZF1 deletions, suggesting a preferred oncogenic cooperation. Importantly, despite having older age and frequent IKZF1 deletions, which are factors usually predictive of a poor prognosis, patients with ERG deletion have a favourable outcome. Therefore, this genetic abnormality may be systematically assessed as part of the diagnostic work-up of BCP-ALL and taken into account when considering treatment stratification. Disclosures: No relevant conflicts of interest to declare.

Spontaneous Mutations of Bcor and Jak1/2 genes Lead to an Aggressive Leukemia of B-1 Progenitor B Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3573-3573
Author(s):  
Sheryl M Gough ◽  
Liat Goldberg ◽  
Marbin Pineda ◽  
Robert L Walker ◽  
Yuelin J Zhu ◽  
...  
Keyword(s):  
High Risk ◽  
B Cell ◽  
Progenitor Cell ◽  
Conflicts Of Interest ◽  
Fusion Gene ◽  
Hot Spot ◽  
Lymphoblastic Leukemia ◽  
Hematologic Malignancies ◽  
Janus Kinase ◽  
Hematopoietic Stem

Abstract NUP98 gene fusions, generated by non-random chromosomal translocations, are associated with a wide spectrum of high risk hematologic malignancies and have been shown to alter normal hematopoietic stem and progenitor cell (HSPC) gene expression programs. A recurrent t(11;17)(p15;p13) translocation in patients with AML leads to the production of a NUP98–PHF23 (NP23) fusion gene. The consequent NP23 fusion protein retains the PHD domain, known to bind H3K4me3, and is thought to have aberrant chromatin regulation properties. We have generated a transgenic mouse model of the NUP98-PHF23 gene fusion which develops a range of hematologic malignancies, most commonly pre-T LBL and AML. However, approximately 10% of NP23 mice develop an aggressive B-1 progenitor acute lymphoblastic leukemia (pro B-1 ALL). B-1 and B-2 lymphocytes have distinct developmental pathways and are thought to represent arms of the innate and adaptive immune systems, respectively. Mature B-2 lymphocytes predominate in the peripheral circulation, and are characterized by expression of B220; whereas B-1 lymphocytes are more prevalent in the pleural and peritoneal cavities, and do not express B220. Murine B cell malignancies typically stain positive for B220, and represent transformed B-2 cells. In the present study, NP23 progenitor ALLs displayed an immunophenotype (Lin-B220- CD19+ AA4.1+) that was identical to that of the recently described B-1 progenitor cell. All B-1 progenitor ALLs exhibited clonal rearrangements of the IgH gene locus. Specifically, these rearrangements involve favored usage of 3’ VH regions, similar to observations with fetal B-1 progenitor cells, further supporting the notion that these are leukemias of B-1 progenitors. Using whole exome sequencing, we found acquired mutations in the BCL6 interacting corepressor (Bcor) gene in 5 out of 7 B-1 progenitor leukemias. The mutations were all frame shift or nonsense mutations, and were located within a 9 bp “hot spot” in Bcor exon 8. In addition, 4 of 7 cases had somatic mutations of Janus kinase 1 (Jak1) or 2 (Jak2), and 7/7 cases showed hyperphosphorylation of Stat3 or Stat5, consistent with the contention that the Jak1/2 mutations are activating mutations, and leading to a hypothesis that the NP23 pro B-1 ALLs which do not harbor Jak1/2 mutations may have acquired an unidentified mutation in the Jak-Stat pathway. Of note, Jak1/2 mutations have previously been identified in a subset of high-risk pediatric B-cell precursor ALL patients. The striking correlation between Bcor and Jak1/2 mutations, occurring specifically in a subset of NP23 leukemias, implies that these three mutations (NP23, Bcor, and Jak1/2) collaborate and provide the oncogenic setting for B-1 progenitor transformation. Disclosures No relevant conflicts of interest to declare.

Amplification of RUNX1 gene in two new cases of childhood B-cell precursor acute lymphoblastic leukemia: A case report

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. e21000-e21000
Author(s):  
A. Fauzdar ◽  
A. Mahajan ◽  
D. Jain ◽  
M. Mishra ◽  
V. Raina
Keyword(s):  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Chromosome 21 ◽  
Fish Analysis ◽  
Cell Precursor ◽  
Childhood All ◽  
Mll Gene ◽  
Runx1 Gene

e21000 Background: Chromosome abnormalities of leukemia cells have important prognostic significance in childhood acute lymphoblastic leukemia (ALL). B-cell precursor acute lymphoblastic leukemia (BCP-ALL) ETV6/RUNX1 (alias TEL/AML1) is most frequent i.e. 15 - 35% in the children with 2 - 18 age group. We report two new cases with Pre B- cell ALL without ETV6/RUNX1 rearrangement, showing amplification of AML1 gene detected by FISH analysis. Methods: Bone marrow samples were analyzed for chromosomal abnormalities with conventional G-banding techniques and interphase fluorescence in situ hybridization (FISH) using probes to detect BCR/ABL t(9;22)(q34-q11) fusion, cryptic TEL/AML1 t(12:21)(p13-q22) and MLL rearrangement for del 11q23. Results: In first case a 3-year girl with four copies of AML (RUNX1) gene were observed in 95% of the cell with normal two copies of TEL (ETV6) gene in both interphase and metaphase FISH. We observed BCR-ABL negative translocation and no MLL gene rearrangement in all the interphase cells after doing FISH. We got a normal 46XX karyotype from bone marrow with conventional cytogenetics (CC) in the same patient. In second case, a 4-year male we observed four copies of AML and two copies of TEL gene in more than 80% of cells. In this patient, we got BCR-ABL negative translocation and three copies of MLL gene without any rearrangement through FISH. We got normal 46XY karyotype in the same patient through CC. Conclusions: In both the patients, we observed hyperdiploidy detected with four copies of RUNX1 gene showing tetrasomy of chromosome 21 detected with metaphase FISH analysis whereas G-banding shows normal diploidy. Bone marrow karyotype in combination with molecular cytogenetic techniques like FISH should be done for improvement in sensitivity and accurate cytogenetic analysis in childhood ALL patients for proper identification of prognostic group for optimum treatment. This is one of the few reported studies worldwide for amplification of RUNX1 gene from Indian subcontinent in childhood BCP-ALL. No significant financial relationships to disclose.

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