Project description:BCR-ABL1 lymphoblastic leukaemia is characterized by the deletion of Ikaros. The Philadelphia chromosome, encoding BCR-ABL1, is the defining lesion of chronic myelogenous leukemia (CML) and a subset of acute lymphoblastic leukemia (ALL) cases. To define oncogenic lesions that cooperate with BCR-ABL1 to induce ALL, we performed genome-wide analysis of leukemic samples from 23 CML cases and 304 ALL cases, including 43 BCR-ABL1 B-ALL cases. IKZF1 (encoding the transcription factor Ikaros) was deleted in 83.7% of BCR-ABL1 B-ALL cases, but not in chronic phase CML. Deletion of IKZF1 was also identified as an acquired lesion in lymphoid blast crisis of CML. The IKZF1 deletions resulted in haploinsufficiency, expression of a dominant negative Ikaros isoform or the complete loss of Ikaros expression. Sequencing of IKZF1 deletion breakpoints suggested that aberrant V(D)J recombination is responsible for the deletions. These findings suggest that genetic lesions resulting in the loss of Ikaros function are a key event in the development of BCR-ABL1 ALL. *** Due to privacy concerns, the primary SNP array data is no longer available with unrestricted access. Individuals wishing to obtain this data for research purposes may request access using the Web links below. *** This SuperSeries is composed of the SubSeries listed below.
Project description:The BCR-ABL1 translocation product is the cause of Chronic Myeloid Leukemia (CML) and of a significant fraction of adult-onset B-Acute Lymphoblastic Leukemia (B-ALL) cases. Here we identify an essential role for gamma-catenin (junction plakoglobin) in B lineage restricted cells for the progression of B-ALL in a mouse model. The array analysis of preleukemic B cells aimed at identifying genes that explain the deficient B-ALL progression in the absence gamma-catenin. Total bone marrow cells from chimeric mice expressing or lacking gamma-catenin in the hematopoietic compartment were transduced with BCR-ABL1+ IRES GFP retrovirus before transplantation into lethally irradiated wild type recipients. Three weeks later, GFP+ (BCR-ABL1+) B220+ BP-1+ B cells were flow sorted from the bone marrow of preleukemic recipient mice. The analysis includes 3 replicates for gamma-catenin WT and 3 replicates for gamma-catenin KO BCR-ABL1+ BP1+ B cells.
Project description:This comparative genomic hybridization (CGH) study investigated the effect of BCL6 on clonal evolution in BCR-ABL1-driven acute lymphoblastic leukemia (ALL). The frequencies of copy number alterations in BCR-ABL1-transformed BCL6+/+ and BCL6-/- leukemias were determined.
Project description:The BCR-ABL1 translocation product is the cause of Chronic Myeloid Leukemia (CML) and of a significant fraction of adult-onset B-Acute Lymphoblastic Leukemia (B-ALL) cases. Here we identify an essential role for gamma-catenin (junction plakoglobin) in B lineage restricted cells for the progression of B-ALL in a mouse model. The array analysis of preleukemic B cells aimed at identifying genes that explain the deficient B-ALL progression in the absence gamma-catenin. Total bone marrow cells from chimeric mice expressing or lacking gamma-catenin in the hematopoietic compartment were transduced with BCR-ABL1+ IRES GFP retrovirus before transplantation into lethally irradiated wild type recipients. Three weeks later, GFP+ (BCR-ABL1+) B220+ BP-1+ B cells were flow sorted from the bone marrow of preleukemic recipient mice.
Project description:Traditional response criteria in MDS and AML are based on bone marrow morphology and may not accurately reflect tumor burden in patients treated with hypomethylating agents. We used massively parallel sequencing of serial bone marrow samples to monitor MDS and AML tumor burden during treatment with epigenetic therapy (decitabine and panobinostat). Serial bone marrow samples (and skin as a source of normal DNA) from 25 MDS and AML patients were sequenced . We observed that responders, including those in complete remission (CR), can have persistent measurable tumor burden for at least one year without disease progression. Using an ultra-sensitive barcode sequencing approach, we detected extremely rare mutations months to years prior to disease relapse. While patients can live with persistent clonal hematopoiesis in a CR or stable disease, ultimately we find evidence that expansion of a rare subclone can drive relapse or progression. Digital sequencing provides an alternative measure of tumor burden and disease response which may augment traditional clinical response criteria in patients treated with hypomethylating agents and its use should be explored in future clinical trials. BCR-ABL1 lymphoblastic leukaemia is characterized by the deletion of Ikaros. The Philadelphia chromosome, encoding BCR-ABL1, is the defining lesion of chronic myelogenous leukemia (CML) and a subset of acute lymphoblastic leukemia (ALL) cases. To define oncogenic lesions that cooperate with BCR-ABL1 to induce ALL, we performed genome-wide analysis of leukemic samples from 23 CML cases and 304 ALL cases, including 43 BCR-ABL1 B-ALL cases. IKZF1 (encoding the transcription factor Ikaros) was deleted in 83.7% of BCR-ABL1 B-ALL cases, but not in chronic phase CML. Deletion of IKZF1 was also identified as an acquired lesion in lymphoid blast crisis of CML. The IKZF1 deletions resulted in haploinsufficiency, expression of a dominant negative Ikaros isoform or the complete loss of Ikaros expression. Sequencing of IKZF1 deletion breakpoints suggested that aberrant V(D)J recombination is responsible for the deletions. These findings suggest that genetic lesions resulting in the loss of Ikaros function are a key event in the development of BCR-ABL1 ALL.
Project description:The Philadelphia chromosome (Ph) encodes the oncogenic BCR-ABL1 tyrosine kinase, which defines a subset of acute lymphoblastic leukemia (ALL) with a particularly unfavorable prognosis. Tyrosine kinase inhibitors (TKI) are widely used to treat patients with leukemia driven by BCR-ABL1 and other oncogenic tyrosine kinases. In response to TKI-treatment, BCR-ABL1 ALL cells upregulate BCL6 protein levels by ~90-fold, i.e. to similar levels as in diffuse large B cell lymphoma (DLBCL) with BCL6 translocations. In this study, we used genome tiling arrays to identify BCL6 target genes with specific recruitment of BCL6.
Project description:This comparative genomic hybridization (CGH) study investigated the effect of BCL6 on clonal evolution in BCR-ABL1-driven acute lymphoblastic leukemia (ALL). The frequencies of copy number alterations in BCR-ABL1-transformed BCL6+/+ and BCL6-/- leukemias were determined. Three BCR-ABL1-transformed BCL6+/+ and BCL6-/- ALL samples derived from mice were maintained for 4 month in cell culture and were subjected to CGH analysis. As control samples, normal untransformed splenoytes were used.
Project description:In this study, using a murine model of Ph+ acute lymphoblastic leukemia (Ph+ ALL), a combined pharmacological profile and drug selection experimental approach identified distinct stages of tumor clonal evolution with vulnerabilities to sets of small molecules. Through genotypic, phenotypic, signaling, and binding measurements, we identified the mutation V299L in the ABL1 kinase domain as mediator for an on-target ABL1 inhibition and hence the sensitization phenotype. To further rule out any off-target effects, we performed RNA-seq analysis of select derived cell lines. Variant calls suggest that although there were other mutations, the only mutation shared among cell lines with the sensitization phenotype and that went from 0% to 100% variant allele frequency was c.895G>C, leading to BCR-ABL1 V299L. In addition, transcriptional profile does not suggest functional changes in BCR-ABL1 V299L and WT cell lines. RNA-seq of parental murine Ph+ acute lymphoblastic leukemia (Ph+ ALL) cell line and derived cell lines (via dose escalating concentrations of dasatinib or DMSO vehicle control).
Project description:Alterations of IKZF1, encoding the lymphoid transcription factor IKAROS, are a hallmark of high risk acute lymphoblastic leukemia (ALL), however the role of IKZF1 alterations in ALL pathogenesis is poorly understood. Here we show that in mouse models of BCR-ABL1 leukemia, Ikzf1 and Arf alterations synergistically promote the development of an aggressive lymphoid leukemia. Ikzf1 alterations were associated with acquisition of stem cell-like features, including self-renewal and increased bone marrow stromal adhesion. Rexinoid receptor agonists reversed this phenotype, in part by inducing expression of IKZF1, resulting in abrogation of adhesion and self-renewal, cell cycle arrest and attenuation of proliferation without direct cytotoxicity. Retinoids potentiated the activity of dasatinib in mouse and human BCR-ABL1 ALL, providing a new therapeutic option in IKZF1-mutated ALL. Significance: The outcome of therapy for high-risk acute lymphoblastic leukemia remains suboptimal despite contemporary chemotherapy and the advent of targeted therapeutic approaches. Recent genomic studies have identified deletions or mutations of IKZF1 as a hallmark of high-risk ALL, but an understanding of how IKZF1 alteration contribute to leukemia development are lacking. Here we show that IKZF1 alterations drive lymphoid lineage, a stem cell-like phenotype, abnormal bone marrow adhesion, and poor responsiveness to tyrosine kinase inhibitor (TKI) therapy. Using a high-content screen, we show that retinoids reverse this phenotype in part by inducing expression of wild type IKZF1, and increase responsiveness to TKIs. These findings provide new insight into the pathogenesis of high-risk ALL and potential new therapeutic approaches. Pre-B mRNA profiles of p185 MIG and IK6 cells, DMSO or drug treated, in 3 or 4 replicates, using Illumina HiSeq 2500.
Project description:Activation-Induced Cytidine Deaminase (AID) is required for somatic hypermutation and immunoglobulin (Ig) class switch recombination in germinal center B lymphocytes. Occasionally, AID targets non-Ig genes, thereby contributing to B cell lymphomagenesis. We recently reported aberrant expression of AID in BCR-ABL1-driven acute lymphoblastic leukemia (ALL). To elucidate the biological significance of aberrant AID expression, we studied loss of AID function in a murine model of BCR-ABL1 ALL. Mice transplanted with BCR-ABL1-transduced AID-/- bone marrow had prolonged survival as compared to mice transplanted with leukemia cells generated from AID+/+ bone marrow. Consistent with a causative role of AID in genetic instability, AID-/- leukemia had a decreased frequency of amplifications, deletions and a lower frequency of mutations in non-Ig genes including Pax5 and Rhoh as compared to AID+/+ leukemias. AID-/- and AID+/+ ALL cells showed a markedly distinct gene expression pattern as determined by principle component analysis, with 2,365 genes differentially expressed. In contrast to AID+/+ leukemia, AID-/- ALL cells failed to downregulate a number of tumor suppressor genes such as Rhoh, Cdkn1a (p21), and Blnk (SLP65). We conclude that AID accelerates clonal evolution in BCR-ABL1 ALL by enhancing genetic instability, aberrant somatic hypermutation, and by transcriptional inactivation of tumor suppressor genes. Experiment Overall Design: We used microarrays to detect differences in gene expression profiles between AID expressing leukemia and AID deficient leukemia