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Highly-sensitive DNA hydroxymethylation analysis to aid clinic evaluation of myelodysplastic syndromes (MDS)

ABSTRACT: Aberrant DNA hydroxymethylation (5hmC) has been reported in patients with myelodysplastic syndromes (MDS). The dysregulation of 5hmC is not only observed in patients with TET2 mutations, but also those bearing other genetic defects, suggesting that 5hmC might act as a valuable epigenetic mark to reflect the status of MDS. To further evaluate the function of 5hmC during MDS pathogenesis, we reported herein an improved highthroughput 5hmC analysis method based on CMS-IP using low input DNA (10 ng) purified from bone marrow aspirates of MDS patients. Our analysis revealed relatively higher heterogeneity of 5hmC signals in MDS patients compared with those of healthy donors, CMML and AML patients. Our systematic bioinformatic analysis further unveiled that 5hmC signatures could be used to separate patients with good and poor clinical outcomes. At the molecular level, we observed dynamic changes of 5hmC within several key transcription factor binding motifs that are essential for hemopoiesis and myeloid lineage specification, which might result in impaired transcriptional outputs during leukemogenesis. Interestingly, we also observed massive changes in 5hmC and transcriptomes in patient showing response to hypomethylating agents (HMA) treatment, suggesting the prognostic value of 5hmC in evaluating epigenetic therapy. Overall, our high-sensitive 5hmC analysis method provides a useful means to greatly facilitate the clinic evaluation for MDS.

ORGANISM(S): Homo sapiens

PROVIDER: GSE148357 | GEO | 2022/07/01

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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Highly-sensitive DNA hydroxymethylation analysis to aid clinic evaluation of myelodysplastic syndromes (MDS)

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