Project description:We quantitatively evaluated H2Bub and H3K79me2 epigenetic marks genome wide in a KMT2A rearranged B lineage acute lymphoblastic leukemia cell line after treatment with bortezomib over a 6 hour time course by ChIP-Rx. We identified rapid and concordant depletion of these epigenetic marks within two hours. To look at gene expression changes, RNA sequencing was performed on KMT2A rearranged B lineage acute lymphoblastic leukemia patient samples in the presence and absence of bortezomib exposure.
Project description:Analysis of the coordinated transcriptional reponse to proteasome inhibition mRNA profiles of NIH3T3 cells which stably expressing DD-sfGFP were generated by deep sequencing using Illumina HiSeq. The samples were collected from indicated timepoints after exposed to proteasome inhibition by Bortezomib.
Project description:Pharmacologic targeting of epigenetic protein complexes has shown significant in vitro responses in acute myeloid leukemia (AML). Early clinical trials in KMT2A-rearranged leukemia indicate rather transient responses and development of resistance. In an effort to define functional dependencies of KMT2A-fusions in AML, we identify the catalytic immunoproteasome subunit PSMB8 as a KMT2A-complex-specific vulnerability. Genetic and pharmacologic inactivation of PSMB8 results in impaired proliferation of murine and human leukemic cells while normal hematopoietic cells remain unaffected. Disruption of immunoproteasome function results in cellular enrichment of transcription factor BASP1, and consecutive repression of KMT2A-target genes. Pharmacologic targeting of PSMB8 improves efficacy of Menin-inhibitors, eradicates leukemia in primary human xenografts and shows preserved activity against Menin-inhibitor resistance mutations. This identifies and validates a cell-intrinsic mechanism whereby selective disruption of proteostasis results in altered transcription factor abundance and repression of oncogene-specific transcriptional networks. Therapeutic targeting of PSMB8-dependent transcription in combination with Menin-inhibition could thus eradicate KMT2A-complex driven AML.
Project description:The KMT2A rearranged B lineage infant ALL cell line SEM was treated with the proteasome inhibitor bortezomib followed by a multiplexed mass spectrometry-based proteomic analysis at multiple time points (0, 6, 12, 16, and 20 hours) over 20 hours to further understand the cellular response of these cells to proteasome inhibition.
Project description:Environmental stresses that disrupt protein homeostasis induce phosphorylation of eIF2, triggering repression of global protein synthesis coincident with preferential translation of ATF4, a transcriptional activator of the Integrated stress response (ISR). Depending on the extent of protein disruption, ATF4 may not be able to restore proteostatic control and instead switch to a terminal outcome that features elevated expression of the transcription factor CHOP (GADD153/DDIT3). The focus of this study was to define the mechanisms by which CHOP directs gene regulatory networks that determine cell fate. We find that in response to proteasome inhibition, CHOP induces the expression of a collection of genes encoding transcription regulators, including ATF5, which is preferentially translated during eIF2 phosphorylation. Transcriptional expression of ATF5 is directly activated by both CHOP and ATF4. Knock-down of ATF5 increased cell survival in response to proteasome inhibition, supporting the idea that both ATF5 and CHOP have pro-apoptotic functions. Transcriptome analyses of ATF5-dependent genes revealed targets involved in apoptosis, including, NOXA, which is important for inducing cell death during proteasome inhibition. This study suggests that the ISR features a feed-forward loop of stress induced transcriptional regulators, each subject to transcriptional and translational control that can switch cell fate towards apoptosis. 8 plates (10cm) of WT and and 8 plates (10cm) of ATF5-KD MEF cells were subject to no stress (4 each for a total of 8) or treated for 8 hours with 1uM MG132 (4 each for a total of 8). Unstressed cells were harvested at the same time as the stressed cells
Project description:Environmental stresses that disrupt protein homeostasis induce phosphorylation of eIF2, triggering repression of global protein synthesis coincident with preferential translation of ATF4, a transcriptional activator of the Integrated stress response (ISR). Depending on the extent of protein disruption, ATF4 may not be able to restore proteostatic control and instead switch to a terminal outcome that features elevated expression of the transcription factor CHOP (GADD153/DDIT3). The focus of this study was to define the mechanisms by which CHOP directs gene regulatory networks that determine cell fate. We find that in response to proteasome inhibition, CHOP induces the expression of a collection of genes encoding transcription regulators, including ATF5, which is preferentially translated during eIF2 phosphorylation. Transcriptional expression of ATF5 is directly activated by both CHOP and ATF4. Knock-down of ATF5 increased cell survival in response to proteasome inhibition, supporting the idea that both ATF5 and CHOP have pro-apoptotic functions. Transcriptome analyses of ATF5-dependent genes revealed targets involved in apoptosis, including, NOXA, which is important for inducing cell death during proteasome inhibition. This study suggests that the ISR features a feed-forward loop of stress induced transcriptional regulators, each subject to transcriptional and translational control that can switch cell fate towards apoptosis. 8 plates (10cm) of WT and and 8 plates (10cm) of CHOP-/- MEF cells were subject to no stress (4 each for a total of 8) or treated for 8 hours with 1uM MG132 (4 each for a total of 8). Unstressed cells were harvested at the same time as the stressed cells
Project description:KMT2A-rearranged acute lymphoblastic leukemia (ALL) is an aggressive type of leukemia which represents the most common form diagnosed in infancy. Oncogenic KMT2A-fusion proteins recruit histone methyltransferase DOT1L which leads to misplaced H3K79 methylation inducing an abnormal transcriptomic landscape that favors leukemia development. Hence, inhibition of DOT1L represents an attractive therapeutic strategy. Unfortunately, the first-in-class DOT1L inhibitor pinometostat resulted in the development of resistance. To understand this resistance we established acquired resistance to DOT1L inhibition in a pediatric KMT2A::AFF1+ B-ALL cell line model that stably became ~35-fold more resistant to pinometostat. Interestingly, while becoming almost completely independent of DOT1L-mediated H3K79 methylation, these cells remained fully dependent on the physical presence of DOT1L, HOXA9, as well as the KMT2A::AFF1 fusion protein. Further characterization of these cells using RNA-, ChIP-, and ATAC-sequencing analyses revealed that acquired resistance to DOT1L inhibition leads to a selective loss of KMT2A-fusion driven epigenetic regulation and expression of genes such as PROM1 (encoding the hematopoietic/leukemia stem cell marker CD133) and its enhancer TAPT1, as well as other putative KMT2A::AFF1 target genes such as RUNX2, PRSS12, ZC3H12, and GNAQ. In contrast, the levels of H3K79me2 and expression of other KMT2A::AFF1 target genes, including HOXA9, MEIS1, and CDK6 remained unaffected. Concomitantly, pinometostat-resistant KMT2A::AFF1+ B-ALL cells showed upregulation of genes associated with a myeloid immunophenotype, including CD33, LILRB4/CD85k, MPEG1, CCL5, and LIMK1. Taken together, we here present a valuable model to study the adaptive potential of KMT2A-rearranged ALL upon losing dependency on one of its main oncogenic properties.
Project description:KMT2A-rearranged acute lymphoblastic leukemia (ALL) is an aggressive type of leukemia which represents the most common form diagnosed in infancy. Oncogenic KMT2A-fusion proteins recruit histone methyltransferase DOT1L which leads to misplaced H3K79 methylation inducing an abnormal transcriptomic landscape that favors leukemia development. Hence, inhibition of DOT1L represents an attractive therapeutic strategy. Unfortunately, the first-in-class DOT1L inhibitor pinometostat resulted in the development of resistance. To understand this resistance we established acquired resistance to DOT1L inhibition in a pediatric KMT2A::AFF1+ B-ALL cell line model that stably became ~35-fold more resistant to pinometostat. Interestingly, while becoming almost completely independent of DOT1L-mediated H3K79 methylation, these cells remained fully dependent on the physical presence of DOT1L, HOXA9, as well as the KMT2A::AFF1 fusion protein. Further characterization of these cells using RNA-, ChIP-, and ATAC-sequencing analyses revealed that acquired resistance to DOT1L inhibition leads to a selective loss of KMT2A-fusion driven epigenetic regulation and expression of genes such as PROM1 (encoding the hematopoietic/leukemia stem cell marker CD133) and its enhancer TAPT1, as well as other putative KMT2A::AFF1 target genes such as RUNX2, PRSS12, ZC3H12, and GNAQ. In contrast, the levels of H3K79me2 and expression of other KMT2A::AFF1 target genes, including HOXA9, MEIS1, and CDK6 remained unaffected. Concomitantly, pinometostat-resistant KMT2A::AFF1+ B-ALL cells showed upregulation of genes associated with a myeloid immunophenotype, including CD33, LILRB4/CD85k, MPEG1, CCL5, and LIMK1. Taken together, we here present a valuable model to study the adaptive potential of KMT2A-rearranged ALL upon losing dependency on one of its main oncogenic properties.
Project description:KMT2A-rearranged acute lymphoblastic leukemia (ALL) is an aggressive type of leukemia which represents the most common form diagnosed in infancy. Oncogenic KMT2A-fusion proteins recruit histone methyltransferase DOT1L which leads to misplaced H3K79 methylation inducing an abnormal transcriptomic landscape that favors leukemia development. Hence, inhibition of DOT1L represents an attractive therapeutic strategy. Unfortunately, the first-in-class DOT1L inhibitor pinometostat resulted in the development of resistance. To understand this resistance we established acquired resistance to DOT1L inhibition in a pediatric KMT2A::AFF1+ B-ALL cell line model that stably became ~35-fold more resistant to pinometostat. Interestingly, while becoming almost completely independent of DOT1L-mediated H3K79 methylation, these cells remained fully dependent on the physical presence of DOT1L, HOXA9, as well as the KMT2A::AFF1 fusion protein. Further characterization of these cells using RNA-, ChIP-, and ATAC-sequencing analyses revealed that acquired resistance to DOT1L inhibition leads to a selective loss of KMT2A-fusion driven epigenetic regulation and expression of genes such as PROM1 (encoding the hematopoietic/leukemia stem cell marker CD133) and its enhancer TAPT1, as well as other putative KMT2A::AFF1 target genes such as RUNX2, PRSS12, ZC3H12, and GNAQ. In contrast, the levels of H3K79me2 and expression of other KMT2A::AFF1 target genes, including HOXA9, MEIS1, and CDK6 remained unaffected. Concomitantly, pinometostat-resistant KMT2A::AFF1+ B-ALL cells showed upregulation of genes associated with a myeloid immunophenotype, including CD33, LILRB4/CD85k, MPEG1, CCL5, and LIMK1. Taken together, we here present a valuable model to study the adaptive potential of KMT2A-rearranged ALL upon losing dependency on one of its main oncogenic properties.