Unknown,Transcriptomics,Genomics,Proteomics

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Next generation sequencing identifies major DNA methylation changes during progression of Ph+ chronic myeloid leukemia

ABSTRACT: Little is known about the impact of DNA methylation on the evolution/progression of chronic myeloid leukemia (CML). We investigated the methylome of CML patients in chronic phase (CP-CML), accelerated phase (AP-CML) and blast crisis (BC-CML) as well as in controls by reduced representation bisulfite sequencing. While only ~600 differentially methylated CpG sites were identified in samples obtained from CP-CML patients compared to controls, ~6,500 differentially methylated CpG sites were found in cells from BC-CML patients. In the majority of affected CpG sites methylation was increased. In CP-CML patients who progressed to AP-CML/BC-CML, we identified up to 897 genes which were methylated at the time of progression but not at the time of diagnosis. Using RNA-sequencing, we observed downregulated expression of many of these genes in BC-CML compared to CP-CML-derived cells. Several of them are well-known tumor suppressor genes or regulators of cell proliferation. 5-aza-2 -deoxycytidine treatment of CML cells resulted in gene re-expression and in a dose-dependent cell growth reduction. Single nucleotide variants of certain epigenetic modifiers during CML progression were not found. Together, our results demonstrate that methylation changes occur frequently during CML progression and may provide a useful basis for revealing new targets of therapy in advanced CML.

INSTRUMENT(S): Galaxy Server, Illumina HiSeq 2000

ORGANISM(S): Homo sapiens

SUBMITTER: Gerwin Heller

PROVIDER: E-MTAB-4333 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:MiR-142 is dynamically expressed and plays a regulatory role in hematopoiesis. Based on the simple observation that miR-142 levels are significantly lower in CD34+CD38- cells from blast crisis (BC) chronic myeloid leukemia (CML). CML patients compared with chronic phase (CP) CML patients (p=0.002), we hypothesized that miR-142 deficit plays a role in BC transformation. To test this hypothesis, we generated a miR-142 KO BCR-ABL (i.e., miR-142−/−BCR-ABL) mouse by crossing a miR-142−/− mouse with a miR-142+/+BCR-ABL mouse. While the miR-142+/+BCR-ABL mice developed and died of CP CML, the miR-142−/−BCR-ABL mice developed a BC-like phenotype in the absence of any other acquired gene mutations and died significantly sooner than miR-142+/+BCR-ABL CP controls (p=0.001). Leukemic stem cell (LSC)-enriched Lineage-Sca-1+c-Kit+ cells (LSKs) from diseased miR-142−/−BCR-ABL mice transplanted into congenic recipients, recapitulated the BC features thereby suggesting stable transformation of CP-LSCs into BC-LSCs in the miR-142 KO CML mouse. Single cell (sc) RNA-seq profiling showed that miR-142 deficit changed the cellular landscape of the miR-142−/−BCR-ABL LSKs compared with miR-142+/+BCR-ABL LSKs with expansion of myeloid-primed and loss of lymphoid-primed factions. Bulk RNA-seq analyses along with unbiased metabolomic profiling and functional metabolic assays demonstrated enhanced fatty acid β-oxidation (FAO) and oxidative phosphorylation (OxPhos) in miR-142−/−BCR-ABL LSKs vs miR-142+/+BCR-ABL LSKs. MiR-142 deficit enhanced FAO in miR-142−/−BCR-ABL LSKs by increasing the expression of CPT1A and CPT1B, that controls the cytosol-to-mitochondrial acyl-carnitine transport, a critical step in FAO. MiR-142 deficit also enhanced OxPhos in miR-142−/−BCR-ABL LSKs by increasing mitochondrial fusion and activity. As the homeostasis and activity of LSCs depend on higher levels of these oxidative metabolism processes, we then postulate that miR-142 deficit is a potentially druggable target for BC-LSCs. To this end, we developed a novel CpG-miR-142 mimic oligonucleotide (ODN; i.e., CpG-M-miR-142) that corrected the miR-142 deficit and alone or in combination with a tyrosine kinase inhibitor (TKI) significantly reduced LSC burden and prolonged survival of miR-142−/−BCR-ABL mice. The results from murine models were validated in BC CD34+CD38- primary blasts and patient-derived xenografts (PDXs). In conclusion, an acquired miR-142 deficit sufficed in transforming CP-LSCs into BC-LSCs, via enhancement of bioenergetic oxidative metabolism in absence of any additional gene mutations, and likely represent a novel therapeutic target in BC CML.

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Next generation sequencing identifies major DNA methylation changes during progression of Ph+ chronic myeloid leukemia

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