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Genome-scale DNA methylation profiling of TEL/AML positive childhood acute lymphoblastic leukaemia

ABSTRACT: DNA methylation profiling of 48 samples to determine a DNA methylation signature specific to leukaemic bone marrow samples. Matching Leukaemia bone marrow and day 28 remission bone marrow or post induction follow up (follow up up to 2 years post induction) genomic DNA were extracted from archived microscope smear slides from 11 children diagnosed with TEL/AML positive Acute Lymphoblastic Leukaemia (ALL). Unmatched bone marrow samples from an additional 8 children were also analysed. Primary tissue control samples from CD34+ and CD19+ bone marrow from adult and childhood samples as well as model cell lines (cancer and non cancerous) were compared to primary diseased samples. Disease specific DNA methylation changes were identified from these results and then verified using SEQUENOM EpiTYPER.

ORGANISM(S): Homo sapiens

PROVIDER: GSE29189 | GEO | 2012/12/31

SECONDARY ACCESSION(S): PRJNA139999

REPOSITORIES: GEO

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Project description:TET2 is a close relative of TET1, an enzyme that converts 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) in DNA. The gene encoding TET2 resides at chromosome 4q24, in a region showing recurrent microdeletions and copy-neutral loss of heterozygosity (CN-LOH) in patients with diverse myeloid malignancies. Somatic TET2 mutations are frequently observed in myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), MDS/MPN overlap syndromes including chronic myelomonocytic leukaemia (CMML), acute myeloid leukaemias (AML) and secondary AML (sAML). We show here that TET2 mutations associated with myeloid malignancies compromise catalytic activity. Bone marrow samples from patients with TET2 mutations displayed uniformly low levels of 5hmC in genomic DNA compared to bone marrow samples from healthy controls. Moreover, small hairpin RNA (shRNA)-mediated depletion of Tet2 in mouse haematopoietic precursors skewed their differentiation towards monocyte/macrophage lineages in culture. There was no significant difference in DNA methylation between bone marrow samples from patients with high 5hmC versus healthy controls, but samples from patients with low 5hmC showed hypomethylation relative to controls at the majority of differentially methylated CpG sites. Our results demonstrate that Tet2 is important for normal myelopoiesis, and suggest that disruption of TET2 enzymatic activity favours myeloid tumorigenesis. Measurement of 5hmC levels in myeloid malignancies may prove valuable as a diagnostic and prognostic tool, to tailor therapies and assess responses to anticancer drugs. Genome wide DNA methylation profiling of patients samples with various myeloid malignancies and diffrential levels of 5hmC.The Illumina Infinium 27k Human DNA methylation Beadchip v1.2 was used to obtain DNA methylation profiles across approximately 27,000 CpGs in bone marrow samples and occasionally peripheral blood samples. Samples included 28 control healthy bone marrows, 29 patients samples with low 5hmC levels (7 patients with wild-type TET2 and 22 mutant TET2) and 24 with high levels of 5hmC (22 with wild-type TET2 and 2 mutant TET2). Bisulphite converted DNA from 81 samples was hybridised to the Illumina Infinium 27k Human Methylation Beadchip v1.2

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Genome-scale DNA methylation profiling of TEL/AML positive childhood acute lymphoblastic leukaemia

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