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13q12.2 deletions in acute lymphoblastic leukemia lead to upregulation of FLT3 through enhancer hijacking.

ABSTRACT: Mutations in the FMS-like tyrosine kinase 3 (FLT3) gene in 13q12.2 are among the most common driver events in acute leukemia, leading to increased cell proliferation and survival through activation of the phosphatidylinositol 3-kinase/AKT-, RAS/MAPK-, and STAT5-signaling pathways. In this study, we examine the pathogenetic impact of somatic hemizygous 13q12.2 microdeletions in B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) using 5 different patient cohorts (in total including 1418 cases). The 13q12.2 deletions occur immediately 5' of FLT3 and involve the PAN3 locus. By detailed analysis of the 13q12.2 segment, we show that the deletions lead to loss of a topologically associating domain border and an enhancer of FLT3. This results in increased cis interactions between the FLT3 promoter and another enhancer located distally to the deletion breakpoints, with subsequent allele-specific upregulation of FLT3 expression, expected to lead to ligand-independent activation of the receptor and downstream signaling. The 13q12.2 deletions are highly enriched in the high-hyperdiploid BCP ALL subtype (frequency 3.9% vs 0.5% in other BCP ALL) and in cases that subsequently relapsed. Taken together, our study describes a novel mechanism of FLT3 involvement in leukemogenesis by upregulation via chromatin remodeling and enhancer hijacking. These data further emphasize the role of FLT3 as a driver gene in BCP ALL.

SUBMITTER: Yang M

PROVIDER: S-EPMC7498303 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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13q12.2 deletions in acute lymphoblastic leukemia lead to upregulation of FLT3 through enhancer hijacking.

Yang Minjun M Safavi Setareh S Woodward Eleanor L EL Duployez Nicolas N Olsson-Arvidsson Linda L Ungerbäck Jonas J Sigvardsson Mikael M Zaliova Marketa M Zuna Jan J Fioretos Thoas T Johansson Bertil B Nord Karolin H KH Paulsson Kajsa K

Blood 20200801 8

Mutations in the FMS-like tyrosine kinase 3 (FLT3) gene in 13q12.2 are among the most common driver events in acute leukemia, leading to increased cell proliferation and survival through activation of the phosphatidylinositol 3-kinase/AKT-, RAS/MAPK-, and STAT5-signaling pathways. In this study, we examine the pathogenetic impact of somatic hemizygous 13q12.2 microdeletions in B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) using 5 different patient cohorts (in total including 1418 cas ...[more]

PMID: 32384149

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Project description:Childhood acute lymphoblastic leukemia (ALL) is characterized by recurrent genetic aberrations. The identification of those abnormalities is clinically important because they are considered significant risk-stratifying markers.There are insufficient data of cytogenetic profiles in Saudi Arabian patients with childhood ALL leukemia. We have examined a cohort of 110 cases of ALL to determine the cytogenetic profiles and prevalence of FLT3 mutations and analysis of the more frequently observed abnormalities and its correlations to other biologic factors and patient outcomes and to compare our results with previously published results.Patients-We reviewed all cases from 2007 to 2016 with an established diagnosis of childhood ALL. Of the 110 patients, 98 were B-lineage ALL and 12 T-cell ALL. All the patients were treated by UKALL 2003 protocol and risk stratified according previously published criteria. Cytogenetic analysis-Chromosome banding analysis and fluorescence in situ hybridization were used to detect genetic aberrations. Analysis of FLT3 mutations-Bone marrow or blood samples were screened for FLT3 mutations (internal tandem duplications, and point mutations, D835) using polymerase chain reaction methods.Cytogenetic analysis showed chromosomal anomalies in 68 out of 102 cases with an overall incidence 66.7%. The most frequent chromosomal anomalies in ALL were hyperdiploidy, t(9;22), t(12;21), and MLL gene rearrangements. Our data are in accordance with those published previously and showed that FLT3 mutations are not common in patients with ALL (4.7%) and have no prognostic relevance in pediatric patients with ALL. On the contrary, t(9;22), MLL gene rearrangements and hypodiploidy were signs of a bad prognosis in childhood ALL with high rate of relapse and shorter overall survival compared with the standard-risk group (P = .031).The event-free survival was also found to be worse (P = .040).Our data are in accordance with those published previously, confirming the overall frequency of cytogenetic abnormalities and their prognostic relevance.

Dataset Information

13q12.2 deletions in acute lymphoblastic leukemia lead to upregulation of FLT3 through enhancer hijacking.

Publications

13q12.2 deletions in acute lymphoblastic leukemia lead to upregulation of FLT3 through enhancer hijacking.

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