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Gene expression profiles of MLL-AF4 acute lymphoblastic leukaemia blasts retrieved from central nervous system and spleen

ABSTRACT: Gene expression profiles of MLL-AF4 acute lymphoblastic leukaemia blasts retrieved from central nervous system and spleen

PROVIDER: PRJNA557461 | ENA |

REPOSITORIES: ENA

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			Action	DRS
	SRR9861664_1.fastq.gz	Fastqsanger.gz
	SRR9861664_2.fastq.gz	Fastqsanger.gz
	SRR9861665_1.fastq.gz	Fastqsanger.gz
	SRR9861665_2.fastq.gz	Fastqsanger.gz
	SRR9861666_1.fastq.gz	Fastqsanger.gz

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Project description:Purpose: To investigate metabolic adaptation of leukaemia in two different microenvironments: central nervous system and spleen Methods: The SEM (MLL-AF4) cell-line representing a high-risk subtype was used. Cells were transplanted into immunodeficient mice. CNS tropism was demonstrated and 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 SEM cells’ gene expression profiles clustered according to site of colonization in the transplanted mice; CNS versus spleen. The 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 SEM 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.

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.

Project description:Malignant transformation in a multipotential precursor has recently been shown to underlie mixed phenotype acute leukaemias. In contrast, and despite the conclusive demonstration that MLL-AF4 infant ALL arises in utero. In order to address this we purified haematopoietic stem/progenitor cell (HSPC) populations from four non-lineage switching presentation infant ALL cases and one ALL presentation which went on to lineage switch at relapse. The specific MLL-AF4 fusion event was determined in unsorted samples by LDI-PCR and identified in purified populations by nested PCR. In three cases where non-lineage restricted populations were able to be purified, MLL-AF4 was identified in the CD34+CD38-CD45RA+ population (LK228, LK230, LS01), the CD34+CD38-CD45RA-CD90- multipotential progenitor population (MPP, LS01) and even a candidate CD34+CD38-CD45RA-CD90+ haematopoietic stem cell (HSC) population (LK228) Interestingly, in a single non-switched MLL-AF9 case analysed for external comparison, the fusion was only identified in CD19+ blast/B cell populations, not in any HSPC population. Unexpectedly, we were also able to identify the presence of the MLL-AF4 fusion in apparently normally differentiated CD34-CD19/3-HLA-DR+CD14/11c+ monocytes/dendritic cells from the peripheral blood/bone marrow of 4/5 cases examined. This finding was further supported by single cell analysis of LS01PALL which identified the fusion in 2/22 CD34-CD19/3-HLA-DR+CD14/11c+ monocytes/dendritic cells analysed. Furthermore, the matched AML sample (LS01RAML) also contained MLL-AF4 positive mature T lymphoid cells. These data imply that MLL-AF4 does not impose a complete block on normal haematopoietic differentiation, and raise the question of what additional factors contribute to leukaemic lineage determination in the setting of the MLL-AF4 translocation. To examine the functional capacity of MLL-AF4 transformed precursor cells we generated a patient-derived xenograft model using NOD-scid/IL2Rγ-/- (NSG) mice. Serial xenotransplantation identified an MLL-AF4 positive clone persisting within the human CD34+CD38-CD45RA-CD90+ compartment across four generations of mice, confirming self-renewal of this population. Together these data identify an early multipotent progenitor or HSC as the putative cell of origin for MLL-AF4 ALL. Furthermore, they demonstrate that MLL-AF4, uniquely amongst MLL fusion genes, imposes a profound lymphoid bias on the developing leukemia but without completely abolishing broader, non-malignant, haematopoietic differentiation.

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Gene expression profiles of MLL-AF4 acute lymphoblastic leukaemia blasts retrieved from central nervous system and spleen

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