ABSTRACT
On current chemotherapeutic regimens, children with Philadelphia positive acute lymphoblastic leukaemia show a heterogeneous response to treatment. A few respond quickly to treatment and achieve long-term remission. Some fail to achieve remission after induction and the majority respond slowly to treatment. Relapse on treatment is common and remission is sustained in a proportion of cases only after allogeneic stem cell transplantation (allo-SCT). The use of imatinib along with conventional cytoreductive therapy, prior to allo-SCT appears to be the most promising strategy. The future lies in the molecular evaluation of response to treatment and combination targeted chemotherapy.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Antineoplastic Agents/therapeutic use , Benzamides , Child , Humans , Imatinib Mesylate , Piperazines/therapeutic use , Precursor Cell Lymphoblastic Leukemia-Lymphoma/diagnosis , Precursor Cell Lymphoblastic Leukemia-Lymphoma/immunology , Pyrimidines/therapeutic use , Remission Induction/methods , Stem Cell Transplantation , Transplantation, HomologousABSTRACT
We have prospectively analysed and correlated the gene expression profiles of children presenting with acute leukaemia to the Royal London and Great Ormond Street Hospitals with morphological diagnosis, immunophenotype and karyotype. Total RNA extracted from freshly sorted blast cells was obtained from 84 lymphoblastic [acute lymphoblastic leukaemia (ALL)], 20 myeloid [acute myeloid leukaemia (AML)] and three unclassified acute leukaemias and hybridised to the high density Affymetrix U133A oligonucleotide array. Analysis of variance and significance analysis of microarrays was used to identify discriminatory genes. A novel 50-gene set accurately identified all patients with ALL and AML and predicted for a diagnosis of AML in three patients with unclassified acute leukaemia. A unique gene set was derived for each of eight subtypes of acute leukaemia within our data set. A common profile for children with ALL with an ETV6-RUNX1 fusion, amplification or deletion of ETV6, amplification of RUNX1 or hyperdiploidy with an additional chromosome 21 was identified. This suggests that these rearrangements share a commonality in biological pathways that maintains the leukaemic state. The gene TERF2 was most highly expressed in this group of patients. Our analyses demonstrate that not only is microarray analysis the single most effective tool for the diagnosis of acute leukaemias of childhood but it has the ability to identify unique biological pathways. To further evaluate its prognostic value it needs to be incorporated into the routine diagnostic analysis for large-scale clinical trials in childhood acute leukaemias.
Subject(s)
Chromosome Aberrations , Chromosomes, Human, Pair 12 , Chromosomes, Human, Pair 21 , Gene Expression Profiling , Oligonucleotide Array Sequence Analysis , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Acute Disease , Analysis of Variance , Child , Chromosome Banding , Core Binding Factor Alpha 2 Subunit , DNA-Binding Proteins/genetics , Diagnosis, Differential , Gene Rearrangement , Humans , Immunophenotyping , In Situ Hybridization, Fluorescence , Karyotyping , Leukemia/genetics , Leukemia, Myeloid/diagnosis , Leukemia, Myeloid/genetics , Nuclear Proteins/genetics , Ploidies , Precursor Cell Lymphoblastic Leukemia-Lymphoma/diagnosis , Principal Component Analysis , Prospective Studies , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins c-ets , Repressor Proteins/genetics , Reproducibility of Results , Reverse Transcriptase Polymerase Chain Reaction , Telomeric Repeat Binding Protein 2/genetics , Transcription Factors/genetics , Translocation, Genetic , ETS Translocation Variant 6 ProteinABSTRACT
Comparative expression analysis of wild-typeETV6 in the disease state showed an absence of expression in ETV6-CBFA2 acute lymphoblastic leukaemia (ALL) when compared with non-ETV6-CBFA2 ALL and acute myeloid leukaemia. Fluorescent in-situ hybridization and loss of heterozygosity studies showed that 73% of the ETV6-CBFA2 samples had a fully or partially deleted second ETV6 allele, explaining the lack of wild-type expression in these patients. Although the second ETV6 allele was identified in the remaining patients, no ETV6 expression was detected. These observations support the hypothesis that loss of ETV6 expression is a critical secondary event for leukaemogenesis in ETV6-CBFA2 ALL.
Subject(s)
DNA-Binding Proteins/genetics , Leukemia, Myeloid/genetics , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Repressor Proteins/genetics , Acute Disease , Alleles , Child , Core Binding Factor Alpha 2 Subunit , Gene Deletion , Gene Expression , Humans , In Situ Hybridization, Fluorescence , Loss of Heterozygosity , Neoplasm Proteins/genetics , Oncogene Proteins, Fusion/genetics , Proto-Oncogene Proteins c-ets , ETS Translocation Variant 6 ProteinABSTRACT
The AF10 gene encodes a putative transcription factor containing an N-terminal LAP/PHD zinc finger motif, a functional nuclear localization signal, an AT-hook domain, and a leucine zipper toward the C-terminus. AF10 is involved in 2 distinct chromosomal translocations associated with hematologic malignancy. The chimeric fusion proteins MLL/AF10 and CALM/AF10, resulting from the t(10;11)(p12;q23) and the t(10;11)(p12;q14), respectively, consistently retain the leucine zipper motif of AF10. This part of the C-terminal region was used as bait in a yeast 2 hybrid screening of a testis complementary DNA library. The leucine zipper interacted with GAS41, a protein previously identified as the product of an amplified gene in a glioblastoma. GAS41 shows significant homology to the Saccharomyces cerevisiae protein ANC1 and to the human MLL fusion partners AF9 and ENL. The interaction was confirmed in vivo. Furthermore, the study showed by coimmunoprecipitation that GAS41 interacts with INI1 (Integrase Interactor 1) and that INI1 was present in the AF10 immunoprecipitate. INI1 is the human homologue of the yeast SNF5 protein, a component of the SWI/SNF complex, which acts to remodel chromatin and to modulate transcription. The retention of the leucine zipper in the MLL and CALM fusions suggests that a key feature of these chimeric proteins may be their ability to interfere in normal gene regulation through interaction with the adenosine triphosphate-dependent chromatinremodeling complexes.
