title: Analysis of t(9;11) chromosomal breakpoint sequences in childhood acute leukemia: almost identical MLL breakpoints in therapy-related AML after treatment without etoposides.
abstract: The translocation t(9;11)(p22;q23) is a recurring chromosomal abnormality in acute myeloid leukemia (AML) fusing two genes designated as MLL and AF9. Within MLL, almost all rearrangements cluster in an 8.3-kb restricted region and fuse 5' portions of MLL to a variety of heterologous genes in various 11q23 translocations. AF9 is one of the most common fusion partners of MLL. It spans more than 100 kb, and two breakpoint cluster regions (BCRs) have been identified in a telomeric region of intron 4 (BCR1) and within introns 7 and 8 (BCR2). We investigated 11 children's bone marrow or peripheral blood samples (3 AML, 5 t-AML, 2 ALL, 1 ALL relapse) and two cell lines (THP-1 and Mono-Mac-6) with cytogenetically diagnosed translocations t(9;11). By use of an optimized multiplex nested long-range PCR assay, a breakpoint-spanning DNA fragment from each sample was amplified and directly sequenced. In four patients and two cell lines, the AF9 breakpoints were located within BCR1 and in two patients within BCR2, respectively. However, in five patients the AF9 breakpoints were found outside the previously described BCRs within the centromeric region of intron 4 and even within intron 3 in one case. All five patients with a secondary AML, who had not received etoposides during treatment of the primary malignant disease, revealed almost identical MLL breakpoints very close to a breakage hot spot inducible by topoisomerase II inhibitors or apoptotic triggers in vitro. Sequence patterns around the breakpoints indicated involvement of a "damage-repair mechanism" in the development of t(9;11) similar to t(4;11) in infants' acute leukemia.
authors.affiliation: Hospital for Children and Adolescents, University of Erlangen, Erlangen, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Langer
authors.forename: Markus
authors.initials: M
authors.lastname: Metzler
authors.forename: Dirk
authors.initials: D
authors.lastname: Reinhardt
authors.forename: Susanne
authors.initials: S
authors.lastname: Viehmann
authors.forename: Arndt
authors.initials: A
authors.lastname: Borkhardt
authors.forename: Martin
authors.initials: M
authors.lastname: Reichel
authors.forename: Martin
authors.initials: M
authors.lastname: Stanulla
authors.forename: Martin
authors.initials: M
authors.lastname: Schrappe
authors.forename: Ursula
authors.initials: U
authors.lastname: Creutzig
authors.forename: Jörg
authors.initials: J
authors.lastname: Ritter
authors.forename: Thomas
authors.initials: T
authors.lastname: Leis
authors.forename: Ulla
authors.initials: U
authors.lastname: Jacobs
authors.forename: Jochen
authors.initials: J
authors.lastname: Harbott
authors.forename: Jörn D
authors.initials: JD
authors.lastname: Beck
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rascher
authors.forename: Reinald
authors.initials: R
authors.lastname: Repp
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000595:Amino Acid Sequence; D002648:Child; D002675:Child, Preschool; D019457:Chromosome Breakage / Q000235:genetics*; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics*; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005047:Etoposide / Q000627:therapeutic use*; D005260:Female; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D007223:Infant; D007951:Leukemia, Myeloid / Q000139:chemically induced* / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D051788:Myeloid-Lymphoid Leukemia Protein; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000235:genetics; D016609:Neoplasms, Second Primary / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis / Q000235:genetics*; D011519:Proto-Oncogenes; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; C497422:KMT2A protein, human; C489901:MLLT3 protein, human; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; D014157:Transcription Factors; D051788:Myeloid-Lymphoid Leukemia Protein; D005047:Etoposide; D011495:Histone-Lysine N-Methyltransferase