Rearrangements and amplification of IER3 (IEX-1) represent a novel and recurrent molecular abnormality in myelodysplastic syndromes.
IER3 (formerly IEX-1) encodes a 27-kDa glycoprotein that regulates death receptor-induced apoptosis, interacts with NF-kappaB pathways, and increases expression rapidly in response to cellular stresses such as irradiation. Animal models, gene expression microarray experiments, and functional studies in cell lines have suggested a potential role for IER3 in oncogenesis, but, to date, no abnormalities of IER3 at the DNA level have been reported in patients with neoplasia. Here, we describe breakpoint cloning of a t(6;9)(p21;q34) translocation from a patient with a myelodysplastic syndrome (MDS), facilitated by conversion technology and array-based comparative genomic hybridization, which revealed a rearrangement translocating the IER3 coding region away from critical flanking/regulatory elements and to a transcript-poor chromosomal region, markedly decreasing expression. Using split-signal and locus-specific fluorescence in situ hybridization (FISH) probes, we analyzed 204 patients with diverse hematological malignancies accompanied by clonal chromosome 6p21 abnormalities, and found 8 additional patients with MDS with IER3 rearrangements (translocations or amplification). Although FISH studies on 157 additional samples from patients with MDS and a normal-karyotype were unrevealing, and sequencing the IER3 coding and proximal promoter regions of 74 MDS patients disclosed no point mutations, reverse transcription-PCR results suggested that dysregulated expression of IER3 is common in MDS (61% >4-fold increase or decrease in expression with decreased expression primarily in early MDS and increased expression primarily in later MDS progressing toward leukemia), consistent with findings in previous microarray experiments. These data support involvement of IER3 in the pathobiology of MDS.
Steensma
David P
DP
Mayo Clinic, Rochester, MN 55905, USA. Steensma.david@mayo.edu
Neiger
Jessemy D
JD
Porcher
Julie C
JC
Keats
J Jonathan
JJ
Bergsagel
P Leif
PL
Dennis
Thomas R
TR
Knudson
Ryan A
RA
Jenkins
Robert B
RB
Santana-Davila
Rafael
R
Kumar
Rajiv
R
Ketterling
Rhett P
RP
D000368:Aged; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics*; D001483:Base Sequence; D002896:Chromosomes, Human, Pair 6; D002899:Chromosomes, Human, Pair 9; D055028:Comparative Genomic Hybridization; D005784:Gene Amplification; D015321:Gene Rearrangement; D006412:Hematopoietic Stem Cells / Q000166:cytology; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009190:Myelodysplastic Syndromes / Q000235:genetics*; D017354:Point Mutation; D011110:Polymorphism, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction
D051017:Apoptosis Regulatory Proteins; C099815:IER3 protein, human; D008565:Membrane Proteins