Project description:Cancer-associated IDH mutations are characterized by neomorphic enzyme activity and resultant 2 hydroxyglutarate (2HG) production. Mutational and epigenetic profiling of a large AML patient cohort revealed that IDH1/2-mutant AMLs display global DNA hypermethylation and a specific hypermethylation signature. Furthermore, expression of 2HG-producing IDH alleles in cells rapidly induced global DNA hypermethylation. In the AML cohort, IDH1/2 mutations were mutually exclusive with mutations in the α-ketoglutarate-dependent enzyme TET2, and TET2 loss-of function mutations associated with similar epigenetic defects as IDH1/2 mutants. Consistent with these genetic and epigenetic data, expression of IDH mutants impaired TET2 catalytic function in cells. Finally, either expression of mutant IDH1/2 or Tet2 depletion impaired hematopoietic differentiation and increased stem cell marker expression, suggesting a shared pro-leukemogenic effect. DNA methylation and gene expression profiling in IDH1/2 mutant vs. IDH1/2 wild-type AML
Project description:Cancer-associated IDH mutations are characterized by neomorphic enzyme activity and resultant 2 hydroxyglutarate (2HG) production. Mutational and epigenetic profiling of a large AML patient cohort revealed that IDH1/2-mutant AMLs display global DNA hypermethylation and a specific hypermethylation signature. Furthermore, expression of 2HG-producing IDH alleles in cells rapidly induced global DNA hypermethylation. In the AML cohort, IDH1/2 mutations were mutually exclusive with mutations in the α-ketoglutarate-dependent enzyme TET2, and TET2 loss-of function mutations associated with similar epigenetic defects as IDH1/2 mutants. Consistent with these genetic and epigenetic data, expression of IDH mutants impaired TET2 catalytic function in cells. Finally, either expression of mutant IDH1/2 or Tet2 depletion impaired hematopoietic differentiation and increased stem cell marker expression, suggesting a shared pro-leukemogenic effect.
Project description:Loss-of-function TET2 mutations (TET2MT) are common in myeloid neoplasia. TET2, a DNA dioxygenase, requires 2-oxoglutarate and Fe(II) to oxidize 5-methylcytosine. TET2MT thus result in hypermethylation and transcriptional repression. Ascorbic acid (AA) increases dioxygenase activity by facilitating Fe(III)/Fe(II) redox reaction and may alleviate some biological consequences of TET2MT by restoring dioxygenase activity. Here, we report the utility of AA in the prevention of TET2MT MN, clarify the mechanistic underpinning of the TET2-AA interactions, and demonstrate that the ability of AA to restore TET2 activity in cells depends on N- and C-terminal lysine acetylation and nature of TET2MT. Consequently, pharmacologic modulation of acetyltransferases and histone deacetylases may regulate TET dioxygenase-dependent AA effects. Thus, our study highlights the contribution of factors that may enhance or attenuate AA effects on TET2 and provides a rationale for novel therapeutic approaches including combinations of AA with class I/II HDAC inhibitor or sirtuin activators in TET2MT leukemia.
Project description:Concomitant multiple hematological malignancies are rare and challenging to diagnose. They represent a unique model to explore the multistep process of oncogenesis. Here, we report the unique case of 62 years-old man with cardiac tamponade as first manifestation of ALK negative anaplastic large T-cell lymphoma (ALK- ALCL). Following chemotherapy, he showed one year later ALK- ALCL concurrent with diffuse large B-cell lymphoma (DLBCL-NOS) and acute monoblastic leukemia (AML-M5) in a single excisional lymph node. Clinical, pathological and multiomics data (whole exome and targeted deep sequencing, spatial transcriptomics) were analyzed. Two somatic TET2 gene mutations at high allele burden were shared by all three neoplasms, uninvolved bone marrow and CD34+ hematopoietic stem and progenitor cells (HSPCs). Secondary hits characterized each malignancy. ALK- ALCL (pericardial and nodal) showed TP53 and LYN deleterious mutations, DLBCL-NOS disclosed KRAS, STAT6, CREBBP and ATM alterations and AML-M5 had JAK3, PPM1D, NF1 and KMT2D mutations and a complex karyotype. Furthermore we demonstrated that spatial transcriptomics can identify the specific signatures of the three neoplasms. Two TET2 mutations at high allele burden in CD34+HSPCs conferred the favorable soil and the genotoxic stress from chemotherapy likely contributed to multiple hematological malignancies oncogenesis. Our case confirms the pathogenetic link between clonal hematopoiesis and cytotoxic T-cell lymphoma, so far only suspected. Most importantly, this is the first study to document the oncogenic phylogeny of concurrent T-, B-, and myeloid neoplasms from CD34+ HSPCs clone(s) in a single specimen.
Project description:The distinction between the Burkitt lymphoma and diffuse large B-cell lymphoma is imprecise using current diagnostic criteria. We applied transcriptional and genomic profiling to molecularly define Burkitt lymphoma. Gene expression profiling employing Affymetrix GeneChips (U133A) was performed in 220 mature aggressive B-cell lymphomas, including a core group of eight Burkitt lymphomas, which fulfilled all diagnostic criteria of the WHO classification. A molecular signature of Burkitt lymphoma was generated. Chromosomal abnormalities were detected by interphase fluorescence in-situ hybridization and array comparative genomic hybridization. The molecular Burkitt lymphoma signature identified 44 cases. Fifteen of these cases lacked a morphology typical for Burkitt/Burkitt-like lymphoma. The vast majority (88%) of the 176 lymphomas without the molecular Burkitt lymphoma signature represented diffuse large B-cell lymphomas. In 20% of these cases a MYC break was detectable which was associated with complex chromosomal changes. Our molecular definition of Burkitt lymphoma sharpens and extends the spectrum of Burkitt lymphoma. In mature aggressive B-cell lymphomas without a Burkitt lymphoma signature, a chromosomal break in the MYC locus proved to be associated with adverse clinical outcome. Experiment Overall Design: 220 diffuse large B-cell lymphoma and Burkitt lymphoma samples hybridized to 221 HGU133A Affymetrix GeneChips
Project description:DDX3X is a ubiquitously expressed RNA helicase involved in multiple stages of RNA biogenesis. DDX3X is frequently mutated in Burkitt lymphoma but the functional basis for this is unknown. Here, we show that loss-of-function DDX3X mutations are also commonly found in MYC-translocated diffuse large B cell lymphoma and reveal functional co-operation between mutant DDX3X and MYC. We show that DDX3X promotes translation of mRNAs encoding components of the core translational machinery, thereby driving global protein synthesis. Loss-of-function DDX3X mutations moderate MYC-driven global protein synthesis, thereby buffering MYC-induced proteotoxic stress during early lymphomagenesis. Established lymphoma cells subsequently restore full protein synthetic capacity by ectopic expression of DDX3Y, a Y-chromosome homologue that is normally expressed exclusively in testis. These findings highlight the vulnerability of MYC-driven lymphoma to proteotoxic stress and identify an unexpected male-specific mechanism of carcinogenesis, namely the commandeering of a testis-specific Y-chromosome gene to drive full malignant transformation.
Project description:DDX3X is a ubiquitously expressed RNA helicase involved in multiple stages of RNA biogenesis. DDX3X is frequently mutated in Burkitt lymphoma but the functional basis for this is unknown. Here, we show that loss-of-function DDX3X mutations are also commonly found in MYC-translocated diffuse large B cell lymphoma and reveal functional co-operation between mutant DDX3X and MYC. We show that DDX3X promotes translation of mRNAs encoding components of the core translational machinery, thereby driving global protein synthesis. Loss-of-function DDX3X mutations moderate MYC-driven global protein synthesis, thereby buffering MYC-induced proteotoxic stress during early lymphomagenesis. Established lymphoma cells subsequently restore full protein synthetic capacity by ectopic expression of DDX3Y, a Y-chromosome homologue that is normally expressed exclusively in testis. These findings highlight the vulnerability of MYC-driven lymphoma to proteotoxic stress and identify an unexpected male-specific mechanism of carcinogenesis, namely the commandeering of a testis-specific Y-chromosome gene to drive full malignant transformation.
Project description:Hematopoietic stem cells sustain life-long blood production. While they are the known cellular origin of aging-associated myeloid malignancies, such as acute myeloid leukemia (AML), mechanisms driving their malignant transformation have remained elusive. Epigenetic dysregulation following acquired loss-of-function mutations of DNA methyl-cytosine dioxygenase Ten-Eleven Translocation-2 (TET2) occurs frequently in the elderly leading to cytosine hypermethylation in and around DNA binding sites of master transcription factors, including PU.1. Here we show that Tet2 deficient hematopoietic stem and progenitor cells (HSPC) undergo malignant transformation upon compromised PU.1 gene regulation. Leukemic stem and progenitor cells show hypermethylation at PU.1 binding sites and fail to activate PU.1-depenent myeloid enhancers, and are hallmarked by a defined signature of impaired genes shared with human AML. Our study demonstrates that Tet2 and PU.1 cooperate in suppressing leukemogenesis in HSPC and establishes a methylation sensitive PU.1-dependent gene network as a unifying feature in acute myeloid leukemia.