Analysis of t(9;11) chromosomal breakpoint sequences in childhood acute leukemia: almost identical MLL breakpoints in therapy-related AML after treatment without etoposides.
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.
Langer
Thorsten
T
Hospital for Children and Adolescents, University of Erlangen, Erlangen, Germany.
Metzler
Markus
M
Reinhardt
Dirk
D
Viehmann
Susanne
S
Borkhardt
Arndt
A
Reichel
Martin
M
Stanulla
Martin
M
Schrappe
Martin
M
Creutzig
Ursula
U
Ritter
Jörg
J
Leis
Thomas
T
Jacobs
Ulla
U
Harbott
Jochen
J
Beck
Jörn D
JD
Rascher
Wolfgang
W
Repp
Reinald
R
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
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