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Chromosome 12p deletions in TEL-AML1 childhood acute lymphoblastic leukemia are associated with retrotransposon elements and occur postnatally.

ABSTRACT: TEL-AML1 (ETV6-RUNX1) is the most common translocation in the childhood leukemias, and is a prenatal mutation in most children. This translocation has been detected at a high rate among newborns ( approximately 1%); therefore, the rate-limiting event for leukemia seems to be secondary mutations. One such frequent mutation in this subtype is partial deletion of chromosome 12p, trans from the translocation. Nine del(12p) breakpoints within six leukemia cases were sequenced to explore the etiology of this genetic event, and most involved cryptic sterile translocations. Twelve of 18 del(12p) parent sequences involved in these breakpoints were located in repeat regions (8 of these in long interspersed nuclear elements). This stands in contrast with TEL-AML1, in which only 21 of 110 previously assessed breakpoints (19%) occur in DNA repeats (P=0.0001). An exploratory assessment of archived neonatal blood cards revealed significantly more long interspersed nuclear element CpG methylations in individuals at birth who were later diagnosed with TEL-AML1 leukemia, compared with individuals who did not contract leukemia (P=0.01). Nontemplate nucleotides were also more frequent in del(12p) than in TEL-AML1 junctions (P=0.004), suggesting formation by terminal deoxynucleotidyl transferase. Assessment of six archived neonatal blood cards indicated that no del(12p) rearrangements backtracked to birth, although two of these patients were previously positive for TEL-AML1 using the same assay with comparable sensitivity. These data are compatible with a two-stage natural history: TEL-AML1 occurs prenatally, and del(12p) occurs postnatally in more mature cells with a structure that suggests the involvement of retrotransposon instability.

SUBMITTER: Wiemels JL

PROVIDER: S-EPMC2597307 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature

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Chromosome 12p deletions in TEL-AML1 childhood acute lymphoblastic leukemia are associated with retrotransposon elements and occur postnatally.

Wiemels Joseph L JL Hofmann Jerry J Kang Michelle M Selzer Rebecca R Green Roland R Zhou Mi M Zhong Sheng S Zhang Luoping L Smith Martyn T MT Marsit Carmen C Loh Mignon M Buffler Patricia P Yeh Ru-Fang RF

Cancer research 20081201 23

TEL-AML1 (ETV6-RUNX1) is the most common translocation in the childhood leukemias, and is a prenatal mutation in most children. This translocation has been detected at a high rate among newborns ( approximately 1%); therefore, the rate-limiting event for leukemia seems to be secondary mutations. One such frequent mutation in this subtype is partial deletion of chromosome 12p, trans from the translocation. Nine del(12p) breakpoints within six leukemia cases were sequenced to explore the etiology ...[more]

PMID: 19047175

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Project description:Purpose: To investigate metabolic adaptation of leukaemia in two different microenvironments: central nervous system and spleen Methods: The REH (TEL-AML1) cell line representing a standard-risk subtype was used. Cells were transplanted into immunodeficient mice. CNS tropism was demonstrated and ALL blasts invaded the leptomeninges in a timeframe ranging from 4 to 5 weeks. At experimental endpoint, blasts were retrieved from the CNS and periphery (spleen), and their gene expression profiles were compared using RNA-sequencing. The raw reads were pre-processed with Cutadapt v.1.5 and Sickle v.0.940 software. Transcript expression quantification was performed using Kallisto v.0.42.4 software against combined human and mouse transcriptomes, Ensembl GRCh38.79 and GRCm38.78, respectively. Read counts related to human transcripts were collected, rounded, and summarized into gene specific read counts. Gene-based differential expression analysis was done with DESeq2 R-package. Preprocessed RNA expression data from RNA sequencing was analysed further using single sample gene set enrichment analysis (ssGSEA). Results: The human REH cells’ gene expression profiles clustered according to site of colonization in the transplanted mice; CNS versus spleen. Top differentially expressed genes were associated with cellular metabolism or stress responses. ssGSEA analysis identified positive correlation of lipid and lipoprotein metabolism signatures in CNS-derived cells, with particular propensity towards fatty acid synthesis. On the other hand, oxidative phosphorylation processes, linked to fatty acid degradation, were negatively correlated with CNS involvement and enriched in REH cells from the spleen of transplanted mice. Conclusions: We demonstrate that leukaemic cells undergo widespread dynamic rewiring of metabolism when switching from bone marrow to CNS microenvironments, resulting in altered therapeutic vulnerabilities. We observed a strong fatty-acid synthesis signature in CNS leukaemia, highlighting Stearoyl-CoA desaturase (SCD1) as a key player.

Dataset Information

Chromosome 12p deletions in TEL-AML1 childhood acute lymphoblastic leukemia are associated with retrotransposon elements and occur postnatally.

Publications

Chromosome 12p deletions in TEL-AML1 childhood acute lymphoblastic leukemia are associated with retrotransposon elements and occur postnatally.

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