title: Homeobox gene expression in acute myeloid leukemia is linked to typical underlying molecular aberrations.
abstract: BACKGROUND
  Although distinct patterns of homeobox (HOX) gene expression have been described in defined cytogenetic and molecular subsets of patients with acute myeloid leukemia (AML), it is unknown whether these patterns are the direct result of transcriptional alterations or rather represent the differentiation stage of the leukemic cell.
  
  
  METHODS
  To address this question, we used qPCR to analyze mRNA expression of HOXA and HOXB genes in bone marrow (BM) samples of 46 patients with AML and sorted subpopulations of healthy BM cells. These various stages of myeloid differentiation represent matched counterparts of morphological subgroups of AML. To further study the transcriptional alterations of HOX genes in hematopoiesis, we also analyzed gene expression of epigenetic modifiers in the subpopluations of healthy BM and leukemic cells.
  
  
  RESULTS
  Unsupervised hierarchical clustering divided the AMLs into five clusters characterized by the presence of prevalent molecular genetic aberrations. Notably, the impact of genotype on HOX gene expression was significantly more pronounced than that of the differentiation stage of the blasts. This driving role of molecular aberrations was best exemplified by the repressive effect of the PML-RARa fusion gene on HOX gene expression, regardless of the presence of the FLT3/ITD mutation. Furthermore, HOX gene expression was positively correlated with mRNA levels of histone demethylases (JMJD3 and UTX) and negatively correlated with gene expression of DNA methyltranferases. No such relationships were observed in subpopulations of healthy BM cells.
  
  
  CONCLUSIONS
  Our results demonstrate that specific molecular genetic aberrations, rather than differentiation per se, underlie the observed differences in HOX gene expression in AML. Moreover, the observed correlations between epigenetic modifiers and HOX expression that are specific to malignant hematopoiesis, suggest their potential causal relationships.
authors.forename: Karolina
authors.initials: K
authors.lastname: Skvarova Kramarzova
authors.forename: Karel
authors.initials: K
authors.lastname: Fiser
authors.forename: Ester
authors.initials: E
authors.lastname: Mejstrikova
authors.forename: Katerina
authors.initials: K
authors.lastname: Rejlova
authors.forename: Marketa
authors.initials: M
authors.lastname: Zaliova
authors.forename: Maarten
authors.initials: M
authors.lastname: Fornerod
authors.forename: Harry A
authors.initials: HA
authors.lastname: Drabkin
authors.forename: Marry M
authors.initials: MM
authors.lastname: van den Heuvel-Eibrink
authors.forename: Jan
authors.initials: J
authors.lastname: Stary
authors.forename: Jan
authors.initials: J
authors.lastname: Trka
authors.forename: Julia
authors.initials: J
authors.lastname: Starkova
mesh_terms: D001854:Bone Marrow Cells / Q000473:pathology; D002648:Child; D002869:Chromosome Aberrations; D016000:Cluster Analysis; D004252:DNA Mutational Analysis; D005260:Female; D015973:Gene Expression Regulation, Leukemic / Q000235:genetics*; D005801:Genes, Homeobox / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics*; D008297:Male; D038042:Myelopoiesis / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D059467:Transcriptome
chemical_list: D018398:Homeodomain Proteins