ABSTRACT
MLLT10 (previously called AF10) is a moderately common MLL fusion partner predominantly occurring in acute monoblastic leukemia (AML-M5). 10;11 rearrangements require at least three breaks in order to generate an in-frame MLL-MLLT10 fusion as a result of the opposite orientations of both genes on the respective chromosome arms. In this study, we describe a detailed molecular cytogenetic analysis of MLL-MLLT10 positive 10;11 rearrangements in two patients. We observed an as yet unreported chromosomal mechanism with at least four breakpoints, leading to MLL-MLLT10 gene fusion in a 24-year-old male. An inversion of 11q13-q23 with a breakpoint in the MLL gene was followed by an additional break 3' of MLL prior to insertion of the 11q segment into MLLT10. In a second patient, a 37-year-old male with AML-M5b, molecular cytogenetic analysis of an apparent 10;11 reciprocal translocation showed an intrachromosomal inversion of 3'MLLT10followed by a reciprocal translocation between 10p12 and 11q23. Review of the literature showed that all cases were the result of an inversion of either 10p or 11q followed by translocation 10p;11q or insertion of the inverted segment into MLLT10 or MLL.
Subject(s)
Chromosomes, Human, Pair 10/genetics , Chromosomes, Human, Pair 11/genetics , DNA-Binding Proteins/genetics , Gene Rearrangement , Leukemia, Myeloid/genetics , Acute Disease , Adult , Aged , Artificial Gene Fusion , Child , Child, Preschool , Chromosome Aberrations , Cloning, Molecular , DNA, Neoplasm/genetics , Gene Expression , Humans , In Situ Hybridization, Fluorescence , Infant , Infant, Newborn , Karyotyping , Male , Middle Aged , Reverse Transcriptase Polymerase Chain Reaction , Transcription Factors/metabolism , Translocation, GeneticABSTRACT
Cancer cell lines are essential gene discovery tools and have often served as models in genetic and functional studies of particular tumor types. One of the future challenges is comparison and interpretation of gene expression data with the available knowledge on the genomic abnormalities in these cell lines. In this context, accurate description of these genomic abnormalities is required. Here, we show that a combination of M-FISH with banding analysis, standard FISH, and CGH allowed a detailed description of the genetic alterations in 16 neuroblastoma cell lines. In total, 14 cryptic chromosome rearrangements were detected, including a balanced t(2;4)(p24.3;q34.3) translocation in cell line NBL-S, with the 2p24 breakpoint located at about 40 kb from MYCN. The chromosomal origin of 22 marker chromosomes and 41 cytogenetically undefined translocated segments was determined. Chromosome arm 2 short arm translocations were observed in six cell lines (38%) with and five (31%) without MYCN amplification, leading to partial chromosome arm 2p gain in all but one cell line and loss of material in the various partner chromosomes, including 1p and 11q. These 2p gains were often masked in the GGH profiles due to MYCN amplification. The commonly overrepresented region was chromosome segment 2pter-2p22, which contains the MYCN gene, and five out of eleven 2p breakpoints clustered to the interface of chromosome bands 2p16 and 2p21. In neuroblastoma cell line SJNB-12, with double minutes (dmins) but no MYCN amplification, the dmins were shown to be derived from 16q22-q23 sequences. The ATBF1 gene, an AT-binding transcription factor involved in normal neurogenesis and located at 16q22.2, was shown to be present in the amplicon. This is the first report describing the possible implication of ATBF1 in neuroblastoma cells. We conclude that a combined approach of M-FISH, cytogenetics, and CGH allowed a more complete and accurate description of the genetic alterations occurring in the investigated cell lines.
Subject(s)
Chromosome Painting/methods , In Situ Hybridization, Fluorescence/methods , Neuroblastoma/genetics , Nucleic Acid Hybridization , Female , Humans , Karyotyping , Male , Nucleic Acid Hybridization/methods , Tumor Cells, CulturedABSTRACT
Bloom syndrome (BS) predisposes affected individuals to a wide variety of neoplasms including hematological malignancies. Thus far, cytogenetic findings in hematological neoplasms have been reported in only a few BS patients. We present the karyotypic findings in a BS patient diagnosed with acute myeloid leukemia (AML), FAB subtype M1, and a review of the literature, showing the preferential occurrence of total or partial loss of chromosome 7 in BS patients with AML or myelodysplastic syndromes (MDS).
Subject(s)
Bloom Syndrome/genetics , Chromosome Aberrations , Chromosomes, Human, Pair 7/genetics , Leukemia, Myeloid/genetics , Myelodysplastic Syndromes/genetics , Acute Disease , Adolescent , Adult , Child , Female , Humans , In Situ Hybridization, Fluorescence , Karyotyping , MaleABSTRACT
Rearrangements of 12p, resulting from deletions or translocations, are common findings in hematologic malignancies. In many cases, these rearrangements target the ETV6 gene (previously called TEL) located at 12p13. Various partner genes have been implicated in the formation of fusion genes with ETV6. These include PDGFRB, JAK2, NTRK3, ABL2, and ABL1, each of which encodes for proteins with tyrosine kinase activity. To date, ETV6/ABL1 transcripts have been detected in only four patients with a leukemic disorder. Here, we describe one adult with chronic myeloid leukemia and a child with T-cell acute lymphocytic leukemia with ETV6/ABL1. Molecular cytogenetic analysis confirmed that formation of an ETV6/ABL1 fusion in these patients required at least three chromosomal breaks and showed that each of these translocations is the result of a complex chromosomal rearrangement. Molecular analysis showed the presence of two fusion transcripts in both patients as the result of alternative splicing, questioning the suggested role of these transcripts in the lineage specificity. Clinical findings of these patients were compared to those of previously reported cases, and the possible clinical and biological similarities between ETV6/ABL1 and other fusion genes leading to increased tyrosine kinase activity are discussed.
Subject(s)
DNA-Binding Proteins/genetics , Genes, abl/genetics , Karyotyping , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics , Leukemia-Lymphoma, Adult T-Cell/genetics , Oncogene Proteins, Fusion/genetics , Repressor Proteins , Transcription Factors/genetics , Child, Preschool , Chromosome Deletion , Humans , In Situ Hybridization, Fluorescence , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/blood , Leukemia-Lymphoma, Adult T-Cell/blood , Male , Middle Aged , Proto-Oncogene Proteins c-ets , Reverse Transcriptase Polymerase Chain Reaction , Translocation, Genetic/genetics , ETS Translocation Variant 6 ProteinABSTRACT
PROCEDURE: M-FISH analysis was performed on 18 neuroblastoma cell lines, which were previously studied with cytogenetic, standard FISH and CGH data. RESULTS: One of the most striking findings of this study was the detection of chromosome 2 short arm rearrangements in 61% of the investigated cell lines. These rearrangements resulted from translocations with various partner chromosomes. All translocations, except one were unbalanced, leading to the consistent gain of chromosome segment 2pter-p22. A cryptic balanced translocation t(2;4) was observed with a breakpoint located in the vicinity of MYCN in cell line NBL-S. CONCLUSIONS: Combination of M-FISH results together with cytogenetic, standard FISH and CGH data yielded the most comprehensive description of chromosome 2 short arm rearrangements, leading to a consistent gain of chromosome 2 short arm material.
