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:BCR-ABL1-targeting tyrosine kinase inhibitors (TKIs) dominate the treatment of chronic myeloid leukemia (CML) over the past decades. In this study, we reported an unexpected role of neddylation inhibitors in desensitizing the therapeutic efficacy of BCR-ABL1-targeting TKIs in CML. Unlike their function in reducing drug resistance in many solid tumors, we revealed that neddylation inhibitors counteracted the cytotoxicity of TKIs against CML cells, both in cellular experiments and in animal model. Conversely, neddylation agonist sensitized the function of TKIs. RNA sequencing data revealed that neddylation inhibitor reversed the transcriptomic changes induced by TKI. Co-immunoprecipitation (co-IP) assay identified ABL1 kinase domain as a novel substrate for neddylation. Furthermore, an artificial intelligence (AI) 3-Dimensional spatial structure binding technology was employed to predict the impact of neddylation on the structure of ABL1 kinase domain. Finally, we provided potential evidence showing that TKI therapy decreased the expression of neddylation enzymes in the bone marrow of CML patients. Hence, our study offers new insights into the post-translational modification (PTM)-mediated drug resistance, and highlights the potential clinical benefits of neddylation agonists in improving the responsiveness of BCR-ABL1 TKIs in CML.
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:Ph+ acute lymphoblastic leukemia (ALL) is characterized by the expression of an oncogenic fusion kinase termed BCR-ABL1. Here, we show that interleukin 7 receptor (IL7R) interacts with the chemokine receptor CXCR4 to recruit BCR-ABL1 and JAK kinases in close proximity. Treatment with BCR-ABL1 kinase inhibitors result in elevated expression of IL7R which enable the survival of transformed cells when IL7 was added together with the kinase inhibitors. Importantly, treatment with anti-IL7R antibodies prevents leukemia development in xenotransplantation models using patient-derived Ph+ ALL cells. Our results suggest that the association between IL7R and CXCR4 serves as molecular platform for BCR-ABL1 induced transformation and development of Ph+ ALL. Targeting this platform with anti-IL7R antibody eliminates Ph+ ALL cells including those with resistance to commonly used ABL1 kinase inhibitors. Thus, anti-IL7R antibodies may provide alternative treatment options for ALL in general and may suppress incurable drug-resistant leukemia forms.
Project description:Although the development of tyrosine kinase inhibitors (TKIs), including BCR-ABL1 targeted therapies, rendered chronic myeloid leukemia (CML) a manageable condition, acquisition of drug resistance during blast crisis (BC) progression remains a critical challenge. Here, we elucidate the significance of FLT3 signaling in the acquisition of drug resistance in BC-CML. Mechanistically, FLT3 expression in CML cells activated FLT3-JAK-STAT3-TAZ-TEAD-CD36 pathway, which conferred resistance to wide range of tyrosine kinase inhibitors (TKIs). Remarkably, a subgroup of BC-CML patients who expressed FLT3 showed strong correlation with the prognostic factors of CML independent of recurrent BCR-ABL1 mutations. We demonstrate that combining FLT3 inhibitors with BCR-ABL1 targeted therapies or single treatment with ponatinib can overcome drug resistance and promote cell death in patient-derived FLT3+ BC-CML cells and mouse xenograft models. Our findings reveal the mechanism of FLT3-mediated drug resistance in BC progression and suggest the inclusion of FLT3 as a therapeutic target for this defined group of patients.
Project description:Tyrosine kinase inhibitors (TKIs) directed against BCR-ABL1, the product of the Philadelphia (Ph) chromosome, have revolutionized treatment of patients with chronic myeloid leukemia (CML). However, acquired resistance to TKIs is a significant clinical problem in CML, and TKI therapy is much less effective against Ph+ B-cell acute lymphoblastic leukemia (B-ALL). BCR-ABL1, via phosphorylated Tyr177, recruits the adapter GAB2 as part of a GRB2/GAB2 complex. We showed previously that GAB2 is essential for BCR-ABL1-evoked myeloid transformation in vitro. Using a genetic strategy and mouse models of CML and B-ALL, we show here that GAB2 is essential for myeloid and lymphoid leukemogenesis by BCR-ABL1. In the mouse model, recipients of BCR-ABL1-transduced Gab2-/- bone marrow failed to develop CML-like myeloproliferative neoplasia. Leukemogenesis was restored by expression of GAB2 but not by GAB2 mutants lacking binding sites for its effectors PI3K or SHP2. GAB2 deficiency also attenuated BCR-ABL1-induced B-ALL, but only the SHP2 binding site was required. The SHP2 and PI3K binding sites were differentially required for signaling downstream of GAB2. Hence, GAB2 transmits critical transforming signals from Tyr177 to PI3K and SHP2 for CML pathogenesis, whereas only the GAB2-SHP2 pathway is essential for lymphoid leukemogenesis. Given that GAB2 is dispensable for normal hematopoiesis, GAB2 and its effectors PI3K and SHP2 represent promising targets for therapy in Ph+ hematologic neoplasms. RNA-Seq expression profiling of 6 mouse bone marrow samples: 3 GAB2 WT (+/+) and 3 GAB2 NULL (-/-)
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:KCL-22 is a chronic myeloid leukemia (CML) cell line derived from a patient in blast crisis phase and harbors the BCR-ABL translocation. The catalytic (ATP-competitive) BCR-ABL inhibitors imatinib and nilotinib have dramatically improved CML patient outcome, but the development of resistance remains a clinical challenge. The recent identification of allosteric BCR-ABL inhibitors, such as GNF-2, which target the enzyme by binding to the myristoyl pocket rather than catalytic site of ABL1, may provide a strategy to broadly overcome resistance to the class of ABL1 ATP competitive inhibitors. We therefore wanted to use the ClonTracer barcoding system to compare the clonal responses of KCL-22 to imatinib, nilotinib and GNF-2. RNA-seq was employed to characterize genetic alterations and gene expression signatures in the pooled cell populations resistant to BCR-ABL inhibitors as well as single clones showing differential response to the three inhibitors. mRNA profiling of the subpopulations and single clones of human CML cell line KCL-22 that contribute to BCR-ABL inhibitor resistance
Project description:Prime editing is a versatile genome-editing technique that shows great promise for the generation and repair of patient mutations. However, some genomic sites are difficult to edit and optimal design of prime-editing tools remains elusive. Here we present a fluorescent prime editing and enrichment reporter (fluoPEER), which can be tailored to any genomic target site. This system rapidly and faithfully ranks the efficiency of prime edit guide RNAs (pegRNAs) combined with any prime editor variant. We apply fluoPEER to instruct correction of pathogenic variants in patient cells and find that plasmid-editing enriches for genomic editing up to 3-fold compared to conventional enrichment strategies. DNA repair and cell cycle-related genes are enriched in the transcriptome of edited cells. Stalling cells in the G1/S boundary increases prime editing efficiency up to 30%. Together, our results show that fluoPEER can be employed for rapid and efficient correction of patient cells, selection of gene-edited cells, and elucidation of cellular mechanisms needed for successful prime editing.