Loss of DKM6A confers drug resistance in acute myeloid leukemia (ChIP-seq of AML cell lines K562 and THP-1)
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ABSTRACT: Acute myeloid leukemia (AML) is an aggressive hematologic neoplasm resulting from the malignant transformation of myeloid progenitors. Despite intensive chemotherapy leading to initial treatment responses, relapse caused by intrinsic or acquired drug resistance represents a major challenge. Here, we report that histone 3 lysine 27 demethylase KDM6A (UTX) is targeted by inactivating mutations and mutation-independent regulation in relapsed AML. Analyses of matched diagnosis and relapse specimens from individuals with KDM6A mutations showed an outgrowth of the KDM6A mutated tumor population at relapse. KDM6A-null myeloid leukemia cells were more resistant to treatment with the chemotherapeutic agents cytarabine (AraC) and daunorubicin. Inducible re-expression of KDM6A in KDM6A-null cell lines suppressed proliferation and sensitized cells again to AraC treatment. RNA expression analysis and functional studies revealed that resistance to AraC was conferred by downregulation of the nucleoside membrane transporter ENT1 (SLC29A1). Our results show that loss of KDM6A provides cells with a selective advantage during chemotherapy, which ultimately leads to the observed outgrowth of clones with KDM6A mutations or reduced KDM6A expression at relapse.
Project description:Acute myeloid leukemia (AML) is an aggressive hematologic neoplasm resulting from the malignant transformation of myeloid progenitors. Despite intensive chemotherapy leading to initial treatment responses, relapse caused by intrinsic or acquired drug resistance represents a major challenge. Here, we report that histone 3 lysine 27 demethylase KDM6A (UTX) is targeted by inactivating mutations and mutation-independent regulation in relapsed AML. Analyses of matched diagnosis and relapse specimens from individuals with KDM6A mutations showed an outgrowth of the KDM6A mutated tumor population at relapse. KDM6A-null myeloid leukemia cells were more resistant to treatment with the chemotherapeutic agents cytarabine (AraC) and daunorubicin. Inducible re-expression of KDM6A in KDM6A-null cell lines suppressed proliferation and sensitized cells again to AraC treatment. RNA expression analysis and functional studies revealed that resistance to AraC was conferred by downregulation of the nucleoside membrane transporter ENT1 (SLC29A1). Our results show that loss of KDM6A provides cells with a selective advantage during chemotherapy, which ultimately leads to the observed outgrowth of clones with KDM6A mutations or reduced KDM6A expression at relapse.
Project description:In acute myeloid leukemias (AML), chemotherapy is frequently followed by disease relapse, yet the mechanism by which AML reemerges is not fully understood. We hypothesized that chemotherapy induces senescence-like dormancy that facilitates survival to genotoxic exposure, allowing AML cells to endure treatment in a transiently dormant state while retaining potential for leukemic repopulation. Here, we show that primary AML cells exhibit hallmark senescence features following treatment with cytarabine (AraC), including growth arrest, increased cellular granularity, senescence-associated-β-galactosidase (SA-β-gal) activity, and senescence-associated transcriptomic alterations. Induction of AraC-induced premature senescence was regulated by the ATR kinase activity and mediated stress-survival. High-throughput single cell RNA (scRNA)-seq analysis of primary AML cells ex vivo and in vivo following chemotherapy suggest active transcriptional programming towards senescent-like dormancy instead of enrichment for leukemia stem cells (LSCs). scRNA-seq of sorted AraC-induced premature senescent AML cells demonstrated a heterogenous population including a fraction of cells with simultaneous expression of dormancy- and senescence-associated gene signatures. Xenotransplantation of AraC-induced premature senescent AML cells into mice demonstrated that senescent-like AML cells maintain leukemia-repopulating potential. Altogether, we propose a mechanism of AML relapse whereby AML cells tolerate chemotherapy via acquisition of a transient senescent-like state.
Project description:In acute myeloid leukemias (AML), chemotherapy is frequently followed by disease relapse, yet the mechanism by which AML reemerges is not fully understood. We hypothesized that chemotherapy induces senescence-like dormancy that facilitates survival to genotoxic exposure, allowing AML cells to endure treatment in a transiently dormant state while retaining potential for leukemic repopulation. Here, we show that primary AML cells exhibit hallmark senescence features following treatment with cytarabine (AraC), including growth arrest, increased cellular granularity, senescence-associated-β-galactosidase (SA-β-gal) activity, and senescence-associated transcriptomic alterations. Induction of AraC-induced premature senescence was regulated by the ATR kinase activity and mediated stress-survival. High-throughput single cell RNA (scRNA)-seq analysis of primary AML cells ex vivo and in vivo following chemotherapy suggest active transcriptional programming towards senescent-like dormancy instead of enrichment for leukemia stem cells (LSCs). scRNA-seq of sorted AraC-induced premature senescent AML cells demonstrated a heterogenous population including a fraction of cells with simultaneous expression of dormancy- and senescence-associated gene signatures. Xenotransplantation of AraC-induced premature senescent AML cells into mice demonstrated that senescent-like AML cells maintain leukemia-repopulating potential. Altogether, we propose a mechanism of AML relapse whereby AML cells tolerate chemotherapy via acquisition of a transient senescent-like state.
Project description:In acute myeloid leukemias (AML), chemotherapy is frequently followed by disease relapse, yet the mechanism by which AML reemerges is not fully understood. We hypothesized that chemotherapy induces senescence-like dormancy that facilitates survival to genotoxic exposure, allowing AML cells to endure treatment in a transiently dormant state while retaining potential for leukemic repopulation. Here, we show that primary AML cells exhibit hallmark senescence features following treatment with cytarabine (AraC), including growth arrest, increased cellular granularity, senescence-associated-β-galactosidase (SA-β-gal) activity, and senescence-associated transcriptomic alterations. Induction of AraC-induced premature senescence was regulated by the ATR kinase activity and mediated stress-survival. High-throughput single cell RNA (scRNA)-seq analysis of primary AML cells ex vivo and in vivo following chemotherapy suggest active transcriptional programming towards senescent-like dormancy instead of enrichment for leukemia stem cells (LSCs). scRNA-seq of sorted AraC-induced premature senescent AML cells demonstrated a heterogenous population including a fraction of cells with simultaneous expression of dormancy- and senescence-associated gene signatures. Xenotransplantation of AraC-induced premature senescent AML cells into mice demonstrated that senescent-like AML cells maintain leukemia-repopulating potential. Altogether, we propose a mechanism of AML relapse whereby AML cells tolerate chemotherapy via acquisition of a transient senescent-like state.
Project description:In acute myeloid leukemias (AML), chemotherapy is frequently followed by disease relapse, yet the mechanism by which AML reemerges is not fully understood. We hypothesized that chemotherapy induces senescence-like dormancy that facilitates survival to genotoxic exposure, allowing AML cells to endure treatment in a transiently dormant state while retaining potential for leukemic repopulation. Here, we show that primary AML cells exhibit hallmark senescence features following treatment with cytarabine (AraC), including growth arrest, increased cellular granularity, senescence-associated-β-galactosidase (SA-β-gal) activity, and senescence-associated transcriptomic alterations. Induction of AraC-induced premature senescence was regulated by the ATR kinase activity and mediated stress-survival. High-throughput single cell RNA (scRNA)-seq analysis of primary AML cells ex vivo and in vivo following chemotherapy suggest active transcriptional programming towards senescent-like dormancy instead of enrichment for leukemia stem cells (LSCs). scRNA-seq of sorted AraC-induced premature senescent AML cells demonstrated a heterogenous population including a fraction of cells with simultaneous expression of dormancy- and senescence-associated gene signatures. Xenotransplantation of AraC-induced premature senescent AML cells into mice demonstrated that senescent-like AML cells maintain leukemia-repopulating potential. Altogether, we propose a mechanism of AML relapse whereby AML cells tolerate chemotherapy via acquisition of a transient senescent-like state.
Project description:Acute Myeloid Leukaemia (AML) carries a 5 year survival rate of just 24%. Toxic chemotherapy regimens remain the backbone of standard of care for AML. The FLT3 tyrosine kinase is a recognised AML oncogene, with FLT3 activating mutations occurring in approximately one third of all AML patients. However, therapeutic targeting of FLT3 has proven difficult as monotherapy, with the development of drug resistance and relapse. Characterisation of the signalling pathways regulated by mutant FLT3 is required to identify better therapeutic strategies.
Project description:Relapse, associated with therapy resistance, is a major clinical problem in acute myeloid leukemia (AML), yet little is known about the underlying molecular mechanisms. Using genome wide gene expression profiling on 11 paired samples from diagnosis and relapse, we show that the expression of a substantial number of genes was altered in a highly consistent manner between these disease stages. Furthermore, the relapse associated gene expression profile was significantly enriched for leukemia stem cell (LSC) genes, indicating that recurring AML is characterized by increased stemness, and supporting the concept that it is due to the outgrowth of chemotherapy resistant LSCs. Paired peripheral blood samples from the times of diagnosis and relapse were obtained from 11 patients with cytogenetically normal AML. cRNA was hybridized to Affymetrix human ST1.1 arrays.
Project description:It has been hypothesized that chemotherapy resistant human acute myeloid leukemia (AML) cells are enriched in an immature phenotype, cellular quiescence and leukemic initiating cells (LICs). However, these hypotheses have never been validated completely in vivo. We have developed a physiologically relevant chemotherapeutic approach with cytosine arabinoside AraC using patient-derived xenograft (PDX) models. AraC-treated AML cells are not consistently enriched for either immature cells or quiescent cells. AraC treatment does not enrich for LICs as measured by limiting dilution in secondary transplantations. Rather chemotherapy resistant cells in vivo have high levels of reactive oxygen species (ROS) and a gene signature consistent with oxidative phosphorylation (OXPHOS). Treatment of human HIGH OXPHOS but not LOW OXPHOS AML cell lines showed chemotherapy resistance in vivo, showing that essential mitochondrial functions make significant contributions to AraC resistance in AML. Accordingly, targeting mitochondrial OXPHOS metabolism through the inhibition of mitochondrial protein synthesis, the electron transfer chain or fatty acid oxidation induced an energetic shift towards LOW OXPHOS and strongly enhanced anti-leukemic effects of AraC in AML cells. These results demonstrate that chemotherapy resistance in AML is not necessarily associated with stemness but is highly dependent on a distinct oxidative metabolism, and that the HIGH OXPHOS gene signature is a robust hallmark of the AraC response in PDX and a promising therapeutic avenue to treat AML residual disease.
Project description:It has been hypothesized that chemotherapy resistant human acute myeloid leukemia (AML) cells are enriched in an immature phenotype, cellular quiescence and leukemic initiating cells (LICs). However, these hypotheses have never been validated completely in vivo. We have developed a physiologically relevant chemotherapeutic approach with cytosine arabinoside AraC using patient-derived xenograft (PDX) models. AraC-treated AML cells are not consistently enriched for either immature cells or quiescent cells. AraC treatment does not enrich for LICs as measured by limiting dilution in secondary transplantations. Rather chemotherapy resistant cells in vivo have high levels of reactive oxygen species (ROS) and a gene signature consistent with oxidative phosphorylation (OXPHOS). Treatment of human HIGH OXPHOS but not LOW OXPHOS AML cell lines showed chemotherapy resistance in vivo, showing that essential mitochondrial functions make significant contributions to AraC resistance in AML. Accordingly, targeting mitochondrial OXPHOS metabolism through the inhibition of mitochondrial protein synthesis, the electron transfer chain or fatty acid oxidation induced an energetic shift towards LOW OXPHOS and strongly enhanced anti-leukemic effects of AraC in AML cells. These results demonstrate that chemotherapy resistance in AML is not necessarily associated with stemness but is highly dependent on a distinct oxidative metabolism, and that the HIGH OXPHOS gene signature is a robust hallmark of the AraC response in PDX and a promising therapeutic avenue to treat AML residual disease.
Project description:In acute myeloid leukemia (AML), malignant cells surviving chemotherapy rely on high mRNA translation and their microenvironmental metabolic support to drive relapse. However, the role of translational reprogramming in the niche is unclear. Here we found that relapsing AML cells increase translation in their bone marrow (BM) niches, where BM mesenchymal stromal cells (BMSCs) become a source of eIF4A-cap-dependent translation machinery that is transferred to AML cells via extracellular vesicles (EVs), to meet their translational demands. In two independent models of highly chemo-resistant AML driven by MLL-AF9 or FLT3-ITD;NPMc mutations, protein synthesis levels increase in refractory AML dependently on nestin+ BMSCs. Inhibiting cap-dependent translation in BMSCs abolishes their chemoprotective ability, while EVs from BMSCs carrying eIF4A boost AML cell translation and survival. Consequently, eIF4A inhibition synergizes with conventional chemotherapy. Together, these results suggest that AML cells rely on BMSCs to maintain an oncogenic translational program required for relapse.