Project description:Pharmacological inhibition of chromatin co-regulatory factors represents a clinically validated strategy to modulate oncogenic signaling through selective attenuation of gene expression. Here, we demonstrate that CBP/EP300 bromodomain inhibition preferentially abrogates the viability of multiple myeloma cell lines. Phenotypic effects are preceded by the direct transcriptional suppression of the lymphocyte-specific transcription factor IRF4 and the subsequent down-regulation of the IRF4 transcriptional program. Ectopic expression of IRF4 antagonizes the phenotypic effects of CBP/EP300 bromodomain inhibition and prevents the suppression of the IRF4 target c-MYC. These findings suggest that CBP/EP300 bromodomain inhibition represents a viable therapeutic strategy for targeting multiple myeloma and other lymphoid malignancies dependent on the IRF4 network. A total of 13 ChIP-seq samples were sequenced. Samples were treated with control (DMSO) or test compound (2.5 uM SGC-CBP30 or 0.25uM CPI267203) for 6 hours. Signal from input samples was included to subtract background signal from each ChIP-seq sample. Antibodies used were against p300, H3K18ac, H3K27ac, or BRD4.
Project description:Immunomodulatory agents (IMiDs) and the next-generation Cereblon (CRBN) E3 ligase modulators (CeLMoDs), targeting the Ikaros/Aiolos-IRF4-MYC axis, are effective therapies for multiple myeloma (MM) across all stages of disease. Resistance to treatment can be acquired following exposure, but a subset of patients have primary resistance, with both states necessitating the development of alternative treatment strategies. Enhancer of zeste homolog 2 (EZH2) has been shown to have increased expression at myeloma relapse and higher expression is associated with a shorter progression free survival from diagnosis. EZH2 inhibitors have been studied as a single agent in myeloma and in combination treatments to overcome drug resistant in other malignancies. In this study KMS11 and RPMI-8226 myeloma cell lines are used as models of primary IMID resistance, with persistent Interferon regulatory factor 4 (IRF4) expression after IMiDs/CeLMoDs exposure without loss of cell viability. The combination of Tazemetostat, an FDA-approved EZH2 inhibitor, with IMiDs/CeLMoDs significantly reduces IRF4 expression, induces apoptosis, and leads to synergistic cell death in these resistant cell lines. Further investigations reveal that the synergistic effect of EZH2 inhibition is specific to IMiDs/CeLMoDs, is CRBN-dependent and rescued by IRF4 over-expression. Mechanistically, Tazemetostat appears to reduce Ikaros binding to the IRF4 promoter, explaining how the combination with IMiDs/CeLMoDs which also have this effect can reach the threshold required to suppress IRF4 expression and ultimately inhibit MM cell growth in resistant cell lines. Our findings highlight a potential strategy for treating MM patients with IMiD resistance.
Project description:The goal of this gene expression study was to identify genes whose expression depends on the transription factor IRF4 by knocking down it's expression using shRNA in two IRF4+ myeloma cell lines. Keywords: time series design Two myeloma lines were analyzed over a time course of IRF4-targeted shRNA induction. There are 3 time courses: two using KMS12 (biological replicates) and one with SKMM1. Within each time course there are technical replicates.
Project description:Despite being recognized as a major mesenchymal cell type and a key accomplice in myeloma progression, the precise roles of adipocytes in distinct stages of myeloma pathogenesis remain elusive. Here, we elucidate a critical role of adipocyte-derived β-hydroxybutyrate (β-OHB) in enabling myeloma cells to overcome glucose metabolic stress by sustaining the stability of interferon regulatory factor 4 (IRF4), a master oncoprotein essential for myeloma survival. Under glucose deprivation conditions, AMP-activated protein kinase (AMPK) activation disrupts the IRF4-heat shock protein 90 (HSP90) interaction, enabling the E3 ligase TRIM21-mediated IRF4 ubiquitination and proteasomal degradation. Adipocytes-secreted β-OHB counteracts this process by fueling 3-oxoacid CoA-transferase 1 (OXCT1)-dependent ketolysis and activating N- acetyltransferase 10 (NAT10) to acetylate IRF4 at lysine 87, thereby restoring IRF4-HSP90 binding and blocking TRIM21-mediated IRF4 degradation. Notably, pharmacological inhibition of OXCT1 or NAT10, combined with AMPK activator, synergistically suppresses myeloma growth in vitro and in vivo. Our study thus positions adipocytes-derived β-OHB as a critical metabolic adaptor that empowers myeloma cells to circumvent glucose metabolic stress and highlights a promising therapeutic avenue for targeting metabolic vulnerabilities in multiple myeloma.
Project description:Despite being recognized as a major mesenchymal cell type and a key accomplice in myeloma progression, the precise roles of adipocytes in distinct stages of myeloma pathogenesis remain elusive. Here, we elucidate a critical role of adipocyte-derived β-hydroxybutyrate (β-OHB) in enabling myeloma cells to overcome glucose metabolic stress by sustaining the stability of interferon regulatory factor 4 (IRF4), a master oncoprotein essential for myeloma survival. Under glucose deprivation conditions, AMP-activated protein kinase (AMPK) activation disrupts the IRF4-heat shock protein 90 (HSP90) interaction, enabling the E3 ligase TRIM21-mediated IRF4 ubiquitination and proteasomal degradation. Adipocytes-secreted β-OHB counteracts this process by fueling 3-oxoacid CoA-transferase 1 (OXCT1)-dependent ketolysis and activating N- acetyltransferase 10 (NAT10) to acetylate IRF4 at lysine 87, thereby restoring IRF4-HSP90 binding and blocking TRIM21-mediated IRF4 degradation. Notably, pharmacological inhibition of OXCT1 or NAT10, combined with AMPK activator, synergistically suppresses myeloma growth in vitro and in vivo. Our study thus positions adipocytes-derived β-OHB as a critical metabolic adaptor that empowers myeloma cells to circumvent glucose metabolic stress and highlights a promising therapeutic avenue for targeting metabolic vulnerabilities in multiple myeloma.
Project description:Despite being recognized as a major mesenchymal cell type and a key accomplice in myeloma progression, the precise roles of adipocytes in distinct stages of myeloma pathogenesis remain elusive. Here, we elucidate a critical role of adipocyte-derived β-hydroxybutyrate (β-OHB) in enabling myeloma cells to overcome glucose metabolic stress by sustaining the stability of interferon regulatory factor 4 (IRF4), a master oncoprotein essential for myeloma survival. Under glucose deprivation conditions, AMP-activated protein kinase (AMPK) activation disrupts the IRF4-heat shock protein 90 (HSP90) interaction, enabling the E3 ligase TRIM21-mediated IRF4 ubiquitination and proteasomal degradation. Adipocytes-secreted β-OHB counteracts this process by fueling 3-oxoacid CoA-transferase 1 (OXCT1)-dependent ketolysis and activating N- acetyltransferase 10 (NAT10) to acetylate IRF4 at lysine 87, thereby restoring IRF4-HSP90 binding and blocking TRIM21-mediated IRF4 degradation. Notably, pharmacological inhibition of OXCT1 or NAT10, combined with AMPK activator, synergistically suppresses myeloma growth in vitro and in vivo. Our study thus positions adipocytes-derived β-OHB as a critical metabolic adaptor that empowers myeloma cells to circumvent glucose metabolic stress and highlights a promising therapeutic avenue for targeting metabolic vulnerabilities in multiple myeloma.
Project description:Pharmacological inhibition of chromatin co-regulatory factors represents a clinically validated strategy to modulate oncogenic signaling through selective attenuation of gene expression. Here, we demonstrate that CBP/EP300 bromodomain inhibition preferentially abrogates the viability of multiple myeloma cell lines. Phenotypic effects are preceded by the direct transcriptional suppression of the lymphocyte-specific transcription factor IRF4 and the subsequent down-regulation of the IRF4 transcriptional program. Ectopic expression of IRF4 antagonizes the phenotypic effects of CBP/EP300 bromodomain inhibition and prevents the suppression of the IRF4 target c-MYC. These findings suggest that CBP/EP300 bromodomain inhibition represents a viable therapeutic strategy for targeting multiple myeloma and other lymphoid malignancies dependent on the IRF4 network.