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: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: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:Protein tyrosine phosphorylation (pY) is central to many cellular signaling pathways. Deregulation of pY can lead to malignancies such as leukemia. Thus, assigning kinase-substrate relations is imperative to understand disease alterations. However, such efforts are complicated by kinase redundancy, overlapping specificity and magnitude differences in enzymatic activity. BCR/ABL, the predominant oncogene in leukemia, drives malignant transformation by deregulated tyrosine kinase activity. In this study, phosphorylation activity and specificity of human ABL1 and BCR/ABL have been examined in yeast by state-of-the-art phosphoproteomics. Linear sequence motif scores were generated and used for cross-kingdom (fungi to metazoa) phosphorylation analysis. Phosphoproteomic analysis of ABL1 and BCR/ABL yielded a high-confidence pY-dataset of 1186 peptides covering 1127 sites on 821 proteins. Motif scores generated from this dataset allow for examination of ABL1 and BCR/ABL kinase activity in human cell lines, and clearly identified BCR/ABL p210 in the chronic myeloid leukemia cell line K562. This cross-kingdom approach offers valuable insights into the human phosphoproteome.
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:We examine the oncogenic function of the Far Upstream Element Binding Protein 1 (FUBP1) in leukemia-initiating cells. For this perpose we performed knockdown of Fubp1 in CML cells in our mouse model. Here, we transduce donor bone marrow cell with the oncogene BCR-ABL1 and Fubp1 or scrambled shRNA and transplanted in recipient mice. Lineage- BCR-ABL1+ shRNA+ cells were then sorted from diseased mice and analyzed by RNA sequencing. We compare the gene expression of the Fubp1 shRNA expressing CML cells versus the control (scrambled shRNA expressing) cells in order to identify the relevant Fubp1 target genes.
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: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: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.