Project description:Philadelphia (Ph) chromosome-positive leukemia is characterized by the BCR/ABL1 fusion protein that affects a wide range of signal transduction pathways. The knowledge about its downstream target genes is, however, still quite limited. To identify novel BCR/ABL1-regulated genes we used global gene expression profiling of several Ph-positive and Ph-negative cell lines treated with imatinib. Following imatinib treatment, the Ph-positive cells showed decreased growth, viability, and reduced phosphorylation of BCR/ABL1 and STAT5. In total, 142 genes were identified as being dependent on BCR/ABL1-mediated signaling, mainly including genes involved in signal transduction, e.g. the JAK/STAT, MAPK, TGFB and insulin signaling pathways, and in regulation of metabolism. Interestingly, BCR/ABL1 was found to activate several genes involved in negative feedback regulation (CISH, SOCS2, SOCS3, PIM1, DUSP6, and TNFAIP3), which may act to indirectly suppress the tumor promoting effects exerted by BCR/ABL1. In addition, several genes identified as deregulated upon BCR/ABL1 expression could be assigned to the TGFB and NFkB signaling pathways, as well as to reflect the metabolic adjustments needed for rapidly growing cells. Apart from providing important pathogenetic insights into BCR/ABL1-mediated leukemogenesis, the present study also provides a number of pathways/individual genes that may provide attractive targets for future development of targeted therapies. Keywords: global gene expression profiling, Ph chromosome, BCR/ABL1, imatinib mesylate
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
Project description:Coordinated BCR-ABL1 kinase-dependent and -independent mechanisms convert p27 from a nuclear tumor suppressor to a cytoplasmic oncogene. Persistence of oncogenic p27 functions despite effective inhibition of BCR-ABL1 may contribute to resistance to tyrosine kinase inhibitors. BCR-ABL1 induced p27 versus knockout, controlling with Empty vector p27 versus knock out
Project description:Philadelphia chromosome-positive B-cell acute lymphoblastic leukaemia (Ph+B-ALL), characterised by the BCR-ABL1 fusion gene, remains a poor prognosis cancer that needs new therapeutic approaches. Transcriptomic profiling and pathway analysis identified up-regulation of the oncogenic transcription factors ERG and c-MYC, with enrichment of genes involved in metabolic processes including ribosome biogenesis.
Project description:This analysis focused on identifying factors that protect pre-B cells against DNA double strand break (DSB)-mediated DNA damage stress during pre-B cell differentiation. Differentiation of pre-B cells including immunoglobulin light chain gene recombination were performed by withdrawal of interleukin-7 (IL-7) from IL-7-dependent murine pre-B cells or by inhibition of the BCR-ABL1 kinase activity in BCR-ABL1-transformed pre-B cells. The BCR-ABL1 kinase inhibitor STI571 (Imatinib) was used for the inhibition of BCR-ABL1. IL-7-dependent murine pre-B cells were either cultured in IL-7 (10 ng/ml) or induced to differentiate by withdrawal of IL-7. BCR-ABL1-transformed pre-B cells were either treated with 10 µM STI571 (in absence or presence of 10 ng/ml IL-7) for 16 hours or cultured without STI571. Three samples for each condition were processed.
Project description:This analysis focused on identifying factors that protect pre-B cells against DNA double strand break (DSB)-mediated DNA damage stress during pre-B cell differentiation. Differentiation of pre-B cells including immunoglobulin light chain gene recombination were performed by withdrawal of interleukin-7 (IL-7) from IL-7-dependent murine pre-B cells or by inhibition of the BCR-ABL1 kinase activity in BCR-ABL1-transformed pre-B cells. The BCR-ABL1 kinase inhibitor STI571 (Imatinib) was used for the inhibition of BCR-ABL1.
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:Coordinated BCR-ABL1 kinase-dependent and -independent mechanisms convert p27 from a nuclear tumor suppressor to a cytoplasmic oncogene. Persistence of oncogenic p27 functions despite effective inhibition of BCR-ABL1 may contribute to resistance to tyrosine kinase inhibitors.
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