Project description:To investigate the mechanism driving BCR-ABL1+ B-ALL progression involves inflammatory stimulation in murine model. We then performed gene expression profiling analysis using data obtained from RNA-seq of 3 different bone marrow cells derived from BCR-ABL1+ B-ALL mice with lipopolysaccharide treatment
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
Project description:Activation-induced cytidine deaminase (AID) specific amplifications and deletions in BCR-ABL1 positive Leukemia mouse cells. Bone marrow from Balb/CJ WT and Balb/CJ AID KO mice was transduced with BCR-ABL1. The AID specific amplifications and deletions where analyzed with an Agilent 244A mouse whole Genome CGH Array.
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.
Project description:Philadelphia-like (Ph-like) acute lymphoblastic leukaemia (ALL) is a high-risk subtype of B-cell ALL characterised by a gene expression profile resembling Philadelphia Chromosome positive ALL (Ph+ ALL) in the absence of BCR-ABL1. Tyrosine kinase activating fusions, some involving ABL1, are recurrent drivers of Ph-like ALL and are targetable with tyrosine kinase inhibitors (TKIs). We identified a rare instance of SFPQ-ABL1 in a child with Ph-like ALL. SFPQ-ABL1 expressed in cytokine-dependent cell lines was sufficient to transform cells which were sensitive to ABL1-targeting TKIs. In contrast to BCR-ABL1, SFPQ-ABL1 localised to the nuclear compartment and was a weaker driver of cellular proliferation. Phosphoproteomics analysis showed upregulation of cell cycle, DNA replication and spliceosome pathways, and downregulation of signal transduction pathways, including ErbB, NF-kappa B, VEGF, and MAPK signalling in SFPQ-ABL1-, compared to BCR-ABL1-expressing cells. SFPQ-ABL1 expression did not activate PI3K/AKT signalling and was associated with phosphorylation of G2/M cell cycle proteins. SFPQ-ABL1 was sensitive to navitoclax and S-63845 and promotes cell survival through upregulation of Mcl-1 and Bcl-xL. SFPQ-ABL1 has functionally distinct mechanisms by which it drives ALL, including subcellular localisation, proliferative capacity, and activation of cellular pathways, highlighting the role that fusion partners have in mediating the function of ABL1 fusions.
Project description:The Philadelphia chromosome (Ph) encoding the oncogenic BCR-ABL1 kinase defines a subset of ALL with a particularly unfavorable prognosis. Acute lymphoblastic leukemia (ALL) cells are derived from B cell precursors in most cases and typically carry rearranged immunglobulin heavy chain (IGH) variable (V) region genes devoid of somatic mutations. Somatic hypermutation is restricted to mature germinal center B cells and depends on activation-induced cytidine deaminase (AID). Studying AID expression in 108 cases of ALL, we detected AID mRNA in 24 of 28 Ph-positive ALLs as compared to 6 of 80 Ph-negative ALLs. Forced expression of BCR-ABL1 in Ph-negative ALL cells and inhibition of the BCR-ABL1-kinase showed that aberrant expression of AID depends on BCR-ABL1 kinase activity. Consistent with aberrant AID expression in Ph-positive ALL, IGH V region genes and BCL6 were mutated in many Ph-positive but unmutated in most Ph-negative cases. In addition, AID introduced DNA-single-strand breaks within the tumor suppressor gene CDKN2B in Ph-positive ALL cells, which was sensitive to BCR-ABL1 kinase inhibition and silencing of AID expression by RNA interference. These findings identify AID as a BCR-ABL1-induced mutator in Ph-positive ALL cells, which may be relevant with respect to the particularly unfavorable prognosis of this leukemia subset. Keywords: gene expression array-based (RNA / in situ oligonucleotide)
Project description:The Philadelphia chromosome (Ph) encoding the oncogenic BCR-ABL1 kinase defines a subset of ALL with a particularly unfavorable prognosis. Acute lymphoblastic leukemia (ALL) cells are derived from B cell precursors in most cases and typically carry rearranged immunglobulin heavy chain (IGH) variable (V) region genes devoid of somatic mutations. Somatic hypermutation is restricted to mature germinal center B cells and depends on activation-induced cytidine deaminase (AID). Studying AID expression in 108 cases of ALL, we detected AID mRNA in 24 of 28 Ph-positive ALLs as compared to 6 of 80 Ph-negative ALLs. Forced expression of BCR-ABL1 in Ph-negative ALL cells and inhibition of the BCR-ABL1-kinase showed that aberrant expression of AID depends on BCR-ABL1 kinase activity. Consistent with aberrant AID expression in Ph-positive ALL, IGH V region genes and BCL6 were mutated in many Ph-positive but unmutated in most Ph-negative cases. In addition, AID introduced DNA-single-strand breaks within the tumor suppressor gene CDKN2B in Ph-positive ALL cells, which was sensitive to BCR-ABL1 kinase inhibition and silencing of AID expression by RNA interference. These findings identify AID as a BCR-ABL1-induced mutator in Ph-positive ALL cells, which may be relevant with respect to the particularly unfavorable prognosis of this leukemia subset. Experiment Overall Design: To study the gene expression profile of two Ph-positive ALL cell lines (BV173 and SUP-B15) in the presence or absence of 10 μmol/l STI571 for 16 hours
Project description:Purpose: We identified a rare instance of the SFPQ-ABL1 in a child with Ph-like ALL. The overall purpose of this study was to compare the structure and function of the SFPQ-ABL1 fusion to the well characterised BCR-ABL1 fusion. We used phosphoproteomics, transcriptomics and functional assays to determine the transforming capacity, subcellular localisation, and signalling networks of these two fusions. Given the known function of SFPQ in mRNA splicing, transcriptomic analysis was performed to analyse the effect of BCR-ABL1 or SFPQ-ABL1 expression on gene splicing. Methods: mRNA profiles of Ba/F3 cells expressing BCR-ABL1, SFPQ-ABL1, and empty vector control (MSCV) were generated by deep sequencing, in four biologically independent cell lines, using Illumina GAIIx. The sequences were aligned by subread and quantified by featureCounts. Results: In contrast to BCR-ABL1, SFPQ-ABL1 localised to the nuclear compartment and was a weaker driver of cellular proliferation. Phosphoproteomics analysis showed upregulation of cell cycle, DNA replication and spliceosome pathways, and downregulation of signal transduction pathways, including ErbB, NF-kappa B, VEGF, and MAPK signalling in SFPQ-ABL1-, compared to BCR-ABL1-expressing cells. SFPQ-ABL1 expression did not activate PI3K/AKT signalling and was associated with phosphorylation of G2/M cell cycle proteins. We identified no difference in overall splicing between cells expressing BCR-ABL1 and SFPQ-ABL1. Conclusions: SFPQ-ABL1 has functionally distinct mechanisms by which it drives ALL, including subcellular localisation, proliferative capacity, and activation of cellular pathways, highlighting the role that fusion partners have in mediating the function of ABL1 fusions.
Project description:BCR-ABL1-targeting tyrosine kinase inhibitors (TKIs) have revolutionized treatment of Philadelphia chromosome-positive (Ph+) hematologic neoplasms. Nevertheless, acquired TKI resistance remains a major problem in chronic myeloid leukemia (CML), and TKIs are less effective against Ph+ B-cell acute lymphoblastic leukemia (B-ALL). GAB2, a scaffolding adaptor that binds and activates SHP2, is essential for leukemogenesis by BCR-ABL1, and a GAB2 mutant lacking SHP2 binding cannot mediate leukemogenesis. Using a genetic loss-of-function approach and bone marrow transplantation (BMT) models for CML and BCR-ABL1+ B-ALL, we show that SHP2 is required for BCR-ABL1-evoked myeloid and lymphoid neoplasia. Ptpn11 deletion impairs initiation and maintenance of CML-like myeloproliferative neoplasm, and compromises induction of BCR-ABL1+ B-ALL. SHP2, and specifically, its SH2 domains, PTP activity and C-terminal tyrosines, is essential for BCR-ABL1+, but not WT, pre-B cell proliferation. The MEK/ERK pathway is regulated by SHP2 in WT and BCR-ABL1+ pre-B cells, but is only required for the proliferation of BCR-ABL1+ cells. SHP2 is required for SRC family kinase (SFK) activation only in BCR-ABL1+ pre-B cells. RNAseq reveals distinct SHP2-dependent transcriptional programs in BCR-ABL1+ and WT pre-B cells. Our results suggest that SHP2, via SFKs and ERK, represses MXD3/4 to facilitate a MYC-dependent proliferation program in BCR-ABL1-transformed pre-B cells.
Project description:Expression of P190 and P210 BCR/ABL1 in normal human CD34(+) cells induces similar gene expression profiles and results in a STAT5-dependent expansion of the erythroid lineage The P190 and P210 BCR/ABL1 fusion genes are mainly associated with different types of hematologic malignancies, but it is presently unclear whether they are functionally different following expression in primitive human hematopoietic cells. We investigated and systematically compared the effects of retroviral P190 BCR/ABL1 and P210 BCR/ABL1 expression on cell proliferation, differentiation, and global gene expression in human CD34(+) cells from cord blood. Expression of either P190 BCR/ABL1 or P210 BCR/ABL1 resulted in expansion of erythroid cells and stimulated erythropoietin-independent burst-forming unit-erythroid colony formation. By using a lentiviral anti-signal transducer and activator of transcription 5 (STAT5) short-hairpin RNA, we found that both P190 BCR/ABL1- and P210 BCR/ABL1-induced erythroid cell expansion were STAT5-dependent. Under in vitro conditions favoring B-cell differentiation, neither P190 nor P210 BCR/ABL1-expressing cells formed detectable levels of CD19-positive cells. Gene expression profiling revealed that P190 BCR/ABL1 and P210 BCR/ABL1 induced almost identical gene expression profiles, and we identified a common set of 222 differentially expressed genes. Our data suggest that the early cellular and transcriptional effects of P190 BCR/ABL1 and P210 BCR/ABL1 expression are very similar when they are expressed in the same human progenitor cell population, and that STAT5 is an important regulator of BCR/ABL1-induced erythroid cell expansion. Keywords: global gene expression profiling, BCR/ABL1, CD34+ cord blood cells, CML, Ph+ ALL