Targeting signaling rewiring and resistant subpopulations in Philadelphia Chromosome-like Acute Lymphoblastic Leukemia [Bulk RNA-seq]
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ABSTRACT: Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a common high-risk leukemia subtype defined by a kinase-activated gene expression pattern and chemoresistance, with low overall survival rates in both children and adults. Clinical responses of patients with Ph-like ALL to tyrosine kinase inhibitor (TKI)-based therapies are incomplete, suggesting partial oncogene addiction and highlighting the need to elucidate alternative biologic dependencies to cure patients. Herein, we report integrated bulk and single-cell multiomics studies of Ph-like ALL cells treated in vitro and in vivo with targeted agents to comprehensively define signaling adaptations and resistant subpopulations. Characterizing residual/resistant human ALL cells harvested from murine spleens revealed transcriptional regulatory network changes and kinase signaling adaptations. We identified key transcription factors including c-MYC and AP1 that mediate transcriptional rewiring associated with therapeutic escape, and demonstrate a specific MYC dependency in Ph-like ALL cells. We found a sub-population of leukemia blasts that have high senescence-associated stem cell-like features that is effectively eradicated only with combined STAT and BCL-2 inhibition. This is clinically significant since both conventional chemotherapy and ruxolitinib are ineffective against senescent stem-like blasts, which may mediate therapeutic tolerance and repopulate relapse. Our findings demonstrate that systems level discovery of key oncogenic dependencies and escape pathways can be exploited for co-targeting or sequential treatment to optimally eradicate blasts and cure this high-risk leukemia subtype.
Project description:Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a common high-risk leukemia subtype defined by a kinase-activated gene expression pattern and chemoresistance, with low overall survival rates in both children and adults. Clinical responses of patients with Ph-like ALL to tyrosine kinase inhibitor (TKI)-based therapies are incomplete, suggesting partial oncogene addiction and highlighting the need to elucidate alternative biologic dependencies to cure patients. Herein, we report integrated bulk and single-cell multiomics studies of Ph-like ALL cells treated in vitro and in vivo with targeted agents to comprehensively define signaling adaptations and resistant subpopulations. Characterizing residual/resistant human ALL cells harvested from murine spleens revealed transcriptional regulatory network changes and kinase signaling adaptations. We identified key transcription factors including c-MYC and AP1 that mediate transcriptional rewiring associated with therapeutic escape, and demonstrate a specific MYC dependency in Ph-like ALL cells. We found a sub-population of leukemia blasts that have high senescence-associated stem cell-like features that is effectively eradicated only with combined STAT and BCL-2 inhibition. This is clinically significant since both conventional chemotherapy and ruxolitinib are ineffective against senescent stem-like blasts, which may mediate therapeutic tolerance and repopulate relapse. Our findings demonstrate that systems level discovery of key oncogenic dependencies and escape pathways can be exploited for co-targeting or sequential treatment to optimally eradicate blasts and cure this high-risk leukemia subtype.
Project description:Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a common high-risk leukemia subtype defined by a kinase-activated gene expression pattern and chemoresistance, with low overall survival rates in both children and adults. Clinical responses of patients with Ph-like ALL to tyrosine kinase inhibitor (TKI)-based therapies are incomplete, suggesting partial oncogene addiction and highlighting the need to elucidate alternative biologic dependencies to cure patients. Herein, we report integrated bulk and single-cell multiomics studies of Ph-like ALL cells treated in vitro and in vivo with targeted agents to comprehensively define signaling adaptations and resistant subpopulations. Characterizing residual/resistant human ALL cells harvested from murine spleens revealed transcriptional regulatory network changes and kinase signaling adaptations. We identified key transcription factors including c-MYC and AP1 that mediate transcriptional rewiring associated with therapeutic escape, and demonstrate a specific MYC dependency in Ph-like ALL cells. We found a sub-population of leukemia blasts that have high senescence-associated stem cell-like features that is effectively eradicated only with combined STAT and BCL-2 inhibition. This is clinically significant since both conventional chemotherapy and ruxolitinib are ineffective against senescent stem-like blasts, which may mediate therapeutic tolerance and repopulate relapse. Our findings demonstrate that systems level discovery of key oncogenic dependencies and escape pathways can be exploited for co-targeting or sequential treatment to optimally eradicate blasts and cure this high-risk leukemia subtype.
Project description:Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a common high-risk leukemia subtype defined by a kinase-activated gene expression pattern and chemoresistance, with low overall survival rates in both children and adults. Clinical responses of patients with Ph-like ALL to tyrosine kinase inhibitor (TKI)-based therapies are incomplete, suggesting partial oncogene addiction and highlighting the need to elucidate alternative biologic dependencies to cure patients. Herein, we report integrated bulk and single-cell multiomics studies of Ph-like ALL cells treated in vitro and in vivo with targeted agents to comprehensively define signaling adaptations and resistant subpopulations. Characterizing residual/resistant human ALL cells harvested from murine spleens revealed transcriptional regulatory network changes and kinase signaling adaptations. We identified key transcription factors including c-MYC and AP1 that mediate transcriptional rewiring associated with therapeutic escape, and demonstrate a specific MYC dependency in Ph-like ALL cells. We found a sub-population of leukemia blasts that have high senescence-associated stem cell-like features that is effectively eradicated only with combined STAT and BCL-2 inhibition. This is clinically significant since both conventional chemotherapy and ruxolitinib are ineffective against senescent stem-like blasts, which may mediate therapeutic tolerance and repopulate relapse. Our findings demonstrate that systems level discovery of key oncogenic dependencies and escape pathways can be exploited for co-targeting or sequential treatment to optimally eradicate blasts and cure this high-risk leukemia subtype.
Project description:Philadelphia chromosome-like B-cell acute lymphoblastic leukemia (Ph-like ALL) is driven by genetic alterations that induce constitutive kinase signaling and is associated with chemoresistance and high relapse risk in children and adults. Preclinical studies in the most common CRLF2-rearranged/JAK pathway-activated Ph-like ALL subtype suggest incomplete oncogene addiction and partial response to tyrosine kinase inhibitor (TKI)-based therapies, highlighting a need to elucidate alternative biologic dependencies and therapeutic vulnerabilities, although the ABL-class Ph-like ALL subtype may be preferentially TKI-sensitive. Using bulk and single-cell multiomics analyses, we profiled residual cells from Ph-like ALL xenograft models treated in vivo with inhibitors to identify mechanisms of potential therapeutic escape. We identified a specific MYC dependency in Ph-like ALL and defined a leukemia cell subpopulation with senescence-associated stem cell-like features regulated by AP-1 transcription factors. This dormant ALL subpopulation could be eradicated by dual pharmacologic inhibition of JAK/STAT and BCL-2, providing mechanistic rationale for alternative therapeutic approaches.
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:BCR-ABL1 gene fusion is an essential driver lesion in both chronic myeloid leukemia (CML) and Philadelphia-positive (Ph+) B-cell acute lymphoblastic leukemia (B-ALL). While tyrosine kinase inhibitors (TKIs) cure up to 95% of CML patients, 50 % of Ph+ B-ALL cases do not respond to treatment or relapse. This calls for new therapeutic approaches for Ph+ B-ALL. Dysregulated redox homeostasis manifested by the increased reactive oxygen species (ROS) levels and the upregulation of the thioredoxin (TXN) antioxidant system has been previously shown in B-ALL. Pharmacological inhibition of the TXN system with auranofin (AUR) efficiently kills B-ALL cells, indicating that the TXN system plays a major role in maintaining redox homeostasis in B-ALL cells. Here we show that peroxiredoxin-1 (PRDX1), one of the enzymes of the TXN system responsible for scavenging H2O2, is upregulated in Ph+ lymphoid as compared to Ph+ myeloid cells. The genomic knockout of PRDX1 negatively affects the viability of Ph+ B-ALL cells and sensitizes them to TKIs, while no such effects occur in myeloid cells. By analyzing global changes in gene expression in PRDX1-deficient cells treated with imatinib we discover non-homologous end-joining (NHEJ) DNA repair pathways as a novel vulnerability of Ph+ B-ALL cells. Accordingly, pharmacologic inhibition of the TXN system diminishes the viability of Ph+ B-ALL cells and enhances their sensitivity to TKIs and NHEJ inhibitors. Finally, we propose a novel combination of TKIs, TXN inhibitors, and NHEJ inhibitors as a potential therapeutic approach for the treatment of Ph+ B-ALL.
Project description:Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a distinct subtype of B-ALL with a poor prognosis. Rearrangement of LYN is a recurrent genetic abnormality in Ph-like ALL, but functional analysis of LYN-related fusion genes identified in ALL has not been reported. In this study, we performed functional analysis of the NCOR1-LYN fusion gene identified in a pediatric Ph-like ALL patient to establish its potential for molecular targeted therapy. Retroviral transduction of interleukin (IL)-3-dependent Ba/F3 cells with NCOR1-LYN enabled IL-3-independent proliferation, with constitutive phosphorylation of the tyrosine residues of the LYN kinase domain in the fusion protein. Replacing tyrosine residues with phenylalanine in the LYN kinase domain abolished IL-3 independence. Tyrosine kinase inhibitor dasatinib killed Ba/F3 cells expressing NCOR1-LYN in vitro accompanied by dephosphorylation of the tyrosine residues of the LYN kinase domain in the fusion protein. In a patient-derived xenograft (PDX) mouse model, generated using leukemic cells from the NCOR1-LYN positive Ph-like ALL patient, dasatinib controlled the growth of leukemic cells in vivo and significantly extended the survival time of the PDX mice (p=0.03). Our data demonstrate that, like other kinase fusions identified in Ph-like ALL, the NCOR1-LYN rearrangement has proliferative activity, and that tyrosine phosphorylation of the LYN kinase domain is critical for IL-3 independent growth. Furthermore, in a preclinical model we demonstrate the efficacy in vivo of dasatinib as therapy for Ph-like ALL with a LYN rearrangement.
Project description:Cure rates for patients with acute myeloid leukemia (AML) remain low despite ever-increasing dose intensity of cytotoxic therapy. In an effort to identify novel approaches to AML therapy, we recently reported a new method of chemical screening based on the modulation of a gene expression signature of interest. We applied this approach to the discovery of AML-differentiation-promoting compounds. Among the compounds inducing neutrophilic differentiation was DAPH1 (4,5-dianilinophthalimide), previously reported to inhibit epidermal growth factor receptor (EGFR) kinase activity. Here we report that the Food and Drug Administration (FDA)-approved EGFR inhibitor gefitinib similarly promotes the differentiation of AML cell lines and primary patient-derived AML blasts in vitro. Gefitinib induced differentiation based on morphologic assessment, nitro-blue tetrazolium reduction, cell-surface markers, genome-wide patterns of gene expression, and inhibition of proliferation at clinically achievable doses. Importantly, EGFR expression was not detected in AML cells, indicating that gefitinib functions through a previously unrecognized EGFR-independent mechanism. These studies indicate that clinical trials testing the efficacy of gefitinib in patients with AML are warranted. golub-00392 Assay Type: Gene Expression Provider: Affymetrix Array Designs: HG-U133A, HG-U133A_2 Organism: Homo sapiens (ncbitax) Material Types: cell, total_RNA, synthetic_RNA, organism_part, whole_organism*Cell Types: Disease States: Acute Myeloid Leukemia, Normal, Acute Myeloid Leukemia
Project description:Acute myeloid leukemia (AML) with chromosomal rearrangements involving the H3K4 methyltransferase mixed-lineage leukemia (MLL) is an aggressive subtype with low overall survival. MLL rearrangements rapidly transform hematological stem and progenitor cell (HSPC) to leukemia stem cell (LSC). Bortezomib (Velcade) is used widely in hematological malignancies. However, it is still unknown whether bortezomib possesses anti-self-renewal and anti-leukemogenesis of LSC in AML with MLL rearrangements. Here, we found that bortezomib inhibited cell proliferation, induced apoptosis, and decreased colony formation in leukemic cell lines, primary AML blasts, and MLL-AF9-transformed murine leukemic blasts. Besides, bortezomib reduced the frequency and function of LSC, inhibited the progression, and prolonged