title: Silencing of GATA3 defines a novel stem cell-like subgroup of ETP-ALL.
abstract: BACKGROUND
  GATA3 is pivotal for the development of T lymphocytes. While its effects in later stages of T cell differentiation are well recognized, the role of GATA3 in the generation of early T cell precursors (ETP) has only recently been explored. As aberrant GATA3 mRNA expression has been linked to cancerogenesis, we investigated the role of GATA3 in early T cell precursor acute lymphoblastic leukemia (ETP-ALL).
  
  
  METHODS
  We analyzed GATA3 mRNA expression by RT-PCR (n = 182) in adult patients with T-ALL. Of these, we identified 70 of 182 patients with ETP-ALL by immunophenotyping. DNA methylation was assessed genome wide (Illumina Infinium® HumanMethylation450 BeadChip platform) in 12 patients and GATA3-specifically by pyrosequencing in 70 patients with ETP-ALL. The mutational landscape of ETP-ALL with respect to GATA3 expression was investigated in 18 patients and validated by Sanger sequencing in 65 patients with ETP-ALL. Gene expression profiles (Affymetrix Human genome U133 Plus 2.0) of an independent cohort of adult T-ALL (n = 83) were used to identify ETP-ALL and investigate GATA3lowand GATA3highexpressing T-ALL patients. In addition, the ETP-ALL cell line PER-117 was investigated for cytotoxicity, apoptosis, GATA3 mRNA expression, DNA methylation, and global gene expression before and after treatment with decitabine.
  
  
  RESULTS
  In our cohort of 70 ETP-ALL patients, 33 % (23/70) lacked GATA3 expression and were thus defined as GATA3low. DNA methylation analysis revealed a high degree of GATA3 CpG island methylation in GATA3lowcompared with GATA3highETP-ALL patients (mean 46 vs. 21 %, p < 0.0001). Genome-wide expression profiling of GATA3lowETP-ALL exhibited enrichment of myeloid/lymphoid progenitor (MLP) and granulocyte/monocyte progenitor (GMP) genes, while T cell-specific signatures were downregulated compared to GATA3highETP-ALL. Among others, FLT3 expression was upregulated and mutational analyses demonstrated a high rate (79 %) of FLT3 mutations. Hypomethylating agents induced reversal of GATA3 silencing, and gene expression profiling revealed downregulation of hematopoietic stem cell genes and upregulation of T cell differentiation.
  
  
  CONCLUSIONS
  We propose GATA3lowETP-ALL as a novel stem cell-like leukemia with implications for the use of myeloid-derived therapies.
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany. lars.fransecky@charite.de.
authors.forename: L
authors.identifier: http://orcid.org/0000-0002-3658-0284
authors.initials: L
authors.lastname: Fransecky
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Neumann
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Heesch
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Schlee
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Ortiz-Tanchez
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Heller
authors.affiliation: Department of Hematology and Oncology, University Hospital Mannheim, Medical Faculty Mannheim of the University of Heidelberg, Mannheim, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Mossner
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schwartz
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
authors.forename: L H
authors.initials: LH
authors.lastname: Mochmann
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Isaakidis
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Bastian
authors.affiliation: Division of Children´s Leukaemia and Cancer, Telethon Kids Institute, University of Western Australia, Perth, Australia.
authors.forename: U R
authors.initials: UR
authors.lastname: Kees
authors.affiliation: Department of Internal Medicine 3, University Hospital Grosshadern, Ludwig-Maximilians-Universität (LMU), Munich, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Herold
authors.affiliation: Department of Internal Medicine 3, University Hospital Grosshadern, Ludwig-Maximilians-Universität (LMU), Munich, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Spiekermann
authors.affiliation: Department of Medicine II, Hematology/Oncology, Goethe University Hospital, Frankfurt/Main, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Gökbuget
authors.affiliation: Department of Hematology and Oncology, Charité, University Hospital Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.
authors.forename: C D
authors.initials: CD
authors.lastname: Baldus
keywords: Decitabine; ETP-ALL; GATA3; PER-117