Gamma-catenin (junction plakoglobin, Jup) dependent signals mediate the progression of BCR-ABL1+ B-ALL
ABSTRACT: 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: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: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:We screened TKI-treated-CML-samples in different-phases based on < or >10% copies of BCR-ABL, undetected and control-samples for generating transcriptomics-profile. Transcriptionally, three clusters were identified which showed correlation with BCR-ABL transcript-levels i.e. <10% copies (I-cluster) , undetectable (II-cluster) and >10% copies (III-cluster). CML-new cases as well as Tyrosine kinase treated-different phases of CML
Project description:Mass spectrometry‐based in vitro kinase screens play an essential role in the discovery of kinase substrates, however, many suffer from biological and technical noise or necessitate genetically‐altered enzymecofactor systems. We describe a method that combines stable γ‐[18O2]‐ATP with classical in vitro kinase assays within a contemporary quantitative proteomic workflow. Our approach improved detection of known substrates of the non‐receptor tyrosine kinase ABL1; and identified potential, new in vitro substrates.
Project description:We screened TKI-treated-CML-samples in different-phases based on < or >10% copies of BCR-ABL, undetected and control-samples for generating transcriptomics-profile. Transcriptionally, three clusters were identified which showed correlation with BCR-ABL transcript-levels i.e. <10% copies (I-cluster) , undetectable (II-cluster) and >10% copies (III-cluster). CML-new cases as well as Tyrosiine kinase treated-different phases of CML
Project description:To elucidate the mechanism of BCL6-mediated pre-B cell survival signaling, we investigated the gene expression pattern in BCR-ABL1-transformed BCL6+/+ and BCL6-/- B cell precursors. Pharmacological inhibition of BCR-ABL1 was performed with the BCR-ABL1 kinase inhibitor STI571 (Imatinib). BCR-ABL1 transformed B cell precursors of BCL6 wildtype and BCL6 knockout mice were either treated with 10µM STI571 (Imatinib) for 16 hours or cultured in absence of STI571. Three samples for each condition were processed.
Project description:We previously demonstrated that Alox5 deficiency impairs the function of LSCs and prevents the initiation of BCR-ABL-induced CML. To identify the pathways in which Alox5 gene regulates function of LSCs, we performed a comparative DNA microarray analysis using total RNA isolated from non-BCR-ABL-expressing Lin-Sca-1+c-Kit+, BCR-ABL-expressing wild type LSCs and BCR-ABL-expressing Alox5-/- LSCs. The result was validated by quantitative real-time PCR analysis of non-BCR-ABL-expressing Lin-Sca-1+c-Kit+, BCR-ABL-expressing wild type LSCs and BCR-ABL-expressing Alox5-/- LSCs. We have shown that Alox5 is a critical regulator of leukemia stem cells (LSCs) in a BCR-ABL-induced chronic myeloid leukemia (CML) mouse model, and we hypothesize that the Alox5 pathway represents a major molecular network that regulates LSC function. Therefore, we sought to further dissect this pathway by comparing the gene expression profiles of wild type and Alox5-/- LSCs derived from our mouse model for BCR-ABL-induced CML. DNA microarray analysis revealed a small group of candidate genes that exhibited changes in the levels of transcription in the absence of Alox5 expression. In particular, we noted that the expression of the Msr1 gene was up-regulated in Alox5-/- LSCs, suggesting that Msr1 might suppress the proliferation of LSCs. Using our CML mouse model, we show that Msr1 is down-regulated by BCR-ABL and this down-regulation is partially restored by Alox5 deletion, and that Msr1 deletion causes acceleration of CML development. Moreover, Msr1 deletion markedly increases LSC function through its effects on cell cycle progression and apoptosis. We also show that Msr1 affects CML development by regulating the PI3K-AKT pathway and β-Catenin. Together, these results demonstrate that Msr1 suppresses LSCs and CML development. The enhancement of Msr1 function may be of significance in the development of novel therapeutic strategies targeting CML. To identify genes that are regulated by BCR-ABL in LSCs and LSCs without Alox5 gene, we compared the gene profile between wild type(WT) LSCs or Alox5-/- LSCs.
Project description:Memory B cell responses are more rapid and of greater magnitude than are primary antibody responses. The mechanisms by which these secondary responses are eventually attenuated remain unknown. We demonstrate that the transcription factor ZBTB32 limits the rapidity and duration of antibody recall responses. ZBTB32 is highly expressed by mouse and human memory B cells, but not by their naïve counterparts. Zbtb32-/- mice mount normal primary antibody responses to T-dependent antigens. However, Zbtb32-/- memory B cell-mediated recall responses occur more rapidly and persist longer than do control responses. Microarray analyses demonstrate that Zbtb32-/- secondary bone marrow plasma cells display elevated expression of genes that promote cell cycle progression and mitochondrial function relative to wild-type controls. BrdU labeling and adoptive transfer experiments confirm more rapid production and a cell-intrinsic survival advantage of Zbtb32-/- secondary plasma cells relative to wild-type counterparts. ZBTB32 is therefore a novel negative regulator of antibody recall responses. CD45.2 wild type and Zbtb32-/- splenocytes from NP-CGG-immune donors were transferred into CD45.1 recipients and challenged with NP-CGG. CD45.2 donor NP-specific plasma cells B cells were isolated from the bone marrow 7 days later. 6 biological replicates of each genotype were performed.
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.