ABSTRACT
TEN-ELEVEN-TRANSLOCATION-2 (TET2) and DNA-METHYLTRANSFERASE-3A (DNMT3A), both encoding proteins involved in regulating DNA methylation, are mutated in hematological malignancies affecting both myeloid and lymphoid lineages. We previously reported an association of TET2 and DNMT3A mutations in progenitors of patients with angioimmunoblastic T-cell lymphomas (AITL). Here, we report on the cooperative effect of Tet2 inactivation and DNMT3A mutation affecting arginine 882 (DNMT3A(R882H)) using a murine bone marrow transplantation assay. Five out of eighteen primary recipients developed hematological malignancies with one mouse developing an AITL-like disease, two mice presenting acute myeloid leukemia (AML)-like and two others T-cell acute lymphoblastic leukemia (T-ALL)-like diseases within 6 months following transplantation. Serial transplantations of DNMT3A(R882H) Tet2(-/-) progenitors led to a differentiation bias toward the T-cell compartment, eventually leading to AITL-like disease in 9/12 serially transplanted recipients. Expression profiling suggested that DNMT3A(R882H) Tet2(-/-) T-ALLs resemble those of NOTCH1 mutant. Methylation analysis of DNMT3A(R882H) Tet2(-/-) T-ALLs showed a global increase in DNA methylation affecting tumor suppressor genes and local hypomethylation affecting genes involved in the Notch pathway. Our data confirm the transformation potential of DNMT3A(R882H) Tet2(-/-) progenitors and represent the first cooperative model in mice involving Tet2 inactivation driving lymphoid malignancies.
Subject(s)
DNA (Cytosine-5-)-Methyltransferases/genetics , DNA Methylation/genetics , DNA-Binding Proteins/genetics , Lymphoproliferative Disorders/genetics , Mutation , Proto-Oncogene Proteins/genetics , Animals , Cell Differentiation , DNA Methyltransferase 3A , Dioxygenases , Genes, Tumor Suppressor , Lymphoproliferative Disorders/etiology , Mice , Receptors, Notch/geneticsABSTRACT
FISH identified a cryptic t(5;14)(q35;q32) in T acute lymphoblastic leukemia (ALL), whereas it was not observed in B ALL samples. This translocation is present in five out of 23 (22%) children and adolescents with T ALL tested. RanBP17, a gene coding for a member of the importin beta protein family, and Hox11Like2, an orphan homeobox gene were mapped close to the chromosome 5 breakpoints and CTIP2, which is highly expressed during normal T cell differentiation, was localized in the vicinity of the chromosome 14 breakpoints. The Hox11L2 gene was found to be transcriptionally activated as a result of the translocation, probably under the influence of CTIP2 transcriptional regulation elements. These data establish the t(5;14)(q35;q32) as a major abnormality, and Hox11 family member activation as an important pathway in T ALL leukemogenesis.
Subject(s)
Chromosomes, Human, Pair 14 , Chromosomes, Human, Pair 5 , Homeodomain Proteins/genetics , Leukemia-Lymphoma, Adult T-Cell/genetics , Oncogene Proteins/genetics , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Translocation, Genetic/genetics , Adolescent , Adult , Amino Acid Sequence , Case-Control Studies , Cell Transformation, Neoplastic , Child , Child, Preschool , Chromosome Breakage , Cytogenetic Analysis , Female , Humans , Leukemia-Lymphoma, Adult T-Cell/etiology , Male , Molecular Sequence Data , Precursor Cell Lymphoblastic Leukemia-Lymphoma/etiology , Proto-Oncogene Proteins , Sequence Alignment , ran GTP-Binding Protein/geneticsABSTRACT
Extranodal, nasal-type natural killer (NK)/T-cell lymphoma (NKCL) is an aggressive malignancy with poor prognosis in which, usually, signal transducer and activator of transcription 3 (STAT3) is constitutively activated and oncogenic. Here, we demonstrate that STAT3 activation mostly results from constitutive Janus kinase (JAK)3 phosphorylation on tyrosine 980, as observed in three of the four tested NKCL cell lines and in 20 of the 23 NKCL tumor samples under study. In one of the cell lines and in 4 of 19 (21%) NKCL primary tumor samples, constitutive JAK3 activation was related to an acquired mutation (A573V or V722I) in the JAK3 pseudokinase domain. We then show that constitutive activation of the JAK3/STAT3 pathway has a major role in NKCL cell growth and survival and in the invasive phenotype. Indeed, NKCL cell growth was slowed down in vitro by targeting JAK3 with chemical inhibitors or small-interfering RNAs. In a human NKCL xenograft mouse model, tumor growth was significantly delayed by the JAK3 inhibitor CP-690550. Altogether, the constitutive activation of JAK3, which can result from JAK3-activating mutations, is a frequent feature of NKCL that deserves to be tested as a therapeutic target.
Subject(s)
Janus Kinase 3/genetics , Lymphoma, Extranodal NK-T-Cell/genetics , Lymphoma, Extranodal NK-T-Cell/pathology , Mutation , Adult , Aged , Aged, 80 and over , Animals , Case-Control Studies , Cell Line, Tumor , Cell Proliferation , Cell Survival/genetics , Disease Models, Animal , Female , Gene Expression Regulation, Neoplastic , Humans , Janus Kinase 3/antagonists & inhibitors , Janus Kinase 3/metabolism , Lymphoma, Extranodal NK-T-Cell/drug therapy , Lymphoma, Extranodal NK-T-Cell/metabolism , Male , Mice , Middle Aged , Neoplasm Invasiveness , Neoplasm Metastasis , Neoplasm Staging , Phosphorylation , Piperidines/administration & dosage , Piperidines/pharmacology , Protein Kinase Inhibitors/administration & dosage , Protein Kinase Inhibitors/pharmacology , Pyrimidines/administration & dosage , Pyrimidines/pharmacology , Pyrroles/administration & dosage , Pyrroles/pharmacology , Tumor Burden/drug effects , Tumor Burden/genetics , Xenograft Model Antitumor AssaysABSTRACT
BACKGROUND: The molecular bases of the cellular changes that occur during human megakaryocyte (MK) ontogeny remain unknown, and may be important for understanding the significance of MK differentiation from human embryonic stem cells (hESCs) METHODS: We optimized the differentiation of MKs from hESCs, and compared these with MKs obtained from primary human hematopoietic tissues at different stages of development. RESULTS: Transcriptome analyses revealed a close relationship between hESC-derived and fetal liver-derived MKs, and between neonate-derived and adult-derived MKs. Major changes in the expression profiles of cell cycle and transcription factors (TFs), including MYC and LIN28b, and MK-specific regulators indicated that MK maturation progresses during ontogeny towards an increase in MK ploidy and a platelet-forming function. Important genes, including CXCR4, were regulated by an on-off mechanism during development. DISCUSSION: Our analysis of the pattern of TF network and signaling pathways was consistent with a growing specialization of MKs towards hemostasis during ontogeny, and support the idea that MKs derived from hESCs reflect primitive hematopoiesis.
Subject(s)
Hematopoiesis , Megakaryocytes/cytology , Flow Cytometry , Gene Expression Profiling , Humans , Megakaryocytes/metabolism , Real-Time Polymerase Chain ReactionSubject(s)
Chromosomes, Human, Pair 1/genetics , Chromosomes, Human, Pair 22/genetics , DNA-Binding Proteins/genetics , Leukemia, Myeloid/diagnosis , Oncogene Proteins, Fusion/genetics , Proteins/genetics , RNA-Binding Proteins , Translocation, Genetic , Acute Disease , Antigens, CD/analysis , Child, Preschool , Humans , Leukemia, Myeloid/genetics , Neoplasm, Residual , Reverse Transcriptase Polymerase Chain Reaction/methods , Sensitivity and Specificity , Trans-ActivatorsABSTRACT
The t(1;22)(p13;q13) translocation is specifically associated with infant acute megakaryoblastic leukemia (M7). We have recently characterized the two genes involved in this translocation: OTT (One Two Two) and MAL (Megakaryoblastic Acute Leukemia) respectively located on chromosome 1 and 22. The t(1;22) translocation results in the fusion of these genes in all the cases studied to date. We summarize here present knowledge regarding this translocation.
Subject(s)
Chromosomes, Human, Pair 1 , Chromosomes, Human, Pair 22 , Leukemia, Megakaryoblastic, Acute/genetics , Translocation, Genetic , HumansABSTRACT
The recurrent t(1;22)(p13;q13) translocation is exclusively associated with infant acute megakaryoblastic leukemia. We have identified the two genes involved in this translocation. Both genes possess related sequences in the Drosophila genome. The chromosome 22 gene (megakaryocytic acute leukemia, MAL) product is predicted to be involved in chromatin organization, and the chromosome 1 gene (one twenty-two, OTT) product is related to the Drosophila split-end (spen) family of proteins. Drosophila genetic experiments identified spen as involved in connecting the Raf and Hox pathways. Because almost all of the sequences and all of the identified domains of both OTT and MAL proteins are included in the predicted fusion protein, the OTT-MAL fusion could aberrantly modulate chromatin organization, Hox differentiation pathways, or extracellular signaling.