RESUMEN
Interferon-gamma (IFN-γ) has pleiotropic effects on cancer immune checkpoint blockade (ICB), including roles in ICB resistance. We analyzed gene expression in ICB-sensitive versus ICB-resistant tumor cells and identified a strong association between interferon-mediated resistance and expression of Ripk1, a regulator of tumor necrosis factor (TNF) superfamily receptors. Genetic interaction screening revealed that in cancer cells, RIPK1 diverted TNF signaling through NF-κB and away from its role in cell death. This promoted an immunosuppressive chemokine program by cancer cells, enhanced cancer cell survival, and decreased infiltration of T and NK cells expressing TNF superfamily ligands. Deletion of RIPK1 in cancer cells compromised chemokine secretion, decreased ARG1+ suppressive myeloid cells linked to ICB failure in mice and humans, and improved ICB response driven by CASP8-killing and dependent on T and NK cells. RIPK1-mediated resistance required its ubiquitin scaffolding but not kinase function. Thus, cancer cells co-opt RIPK1 to promote cell-intrinsic and cell-extrinsic resistance to immunotherapy.
Asunto(s)
Resistencia a Antineoplásicos , Inhibidores de Puntos de Control Inmunológico , Interferones , Neoplasias , Proteína Serina-Treonina Quinasas de Interacción con Receptores , Animales , Inmunoterapia , Interferón gamma/metabolismo , Interferones/metabolismo , Ratones , FN-kappa B/metabolismo , Neoplasias/genética , Proteína Serina-Treonina Quinasas de Interacción con Receptores/genética , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismoRESUMEN
Several rRNA-modifying enzymes install rRNA modifications while participating in ribosome assembly. Here, we show that 18S rRNA methyltransferase DIMT1 is essential for acute myeloid leukemia (AML) proliferation through a noncatalytic function. We reveal that targeting a positively charged cleft of DIMT1, remote from the catalytic site, weakens the binding of DIMT1 to rRNA and mislocalizes DIMT1 to the nucleoplasm, in contrast to the primarily nucleolar localization of wild-type DIMT1. Mechanistically, rRNA binding is required for DIMT1 to undergo liquid-liquid phase separation, which explains the distinct nucleoplasm localization of the rRNA binding-deficient DIMT1. Re-expression of wild-type or a catalytically inactive mutant E85A, but not the rRNA binding-deficient DIMT1, supports AML cell proliferation. This study provides a new strategy to target DIMT1-regulated AML proliferation via targeting this essential noncatalytic region.
Asunto(s)
Leucemia Mieloide Aguda , Metiltransferasas , Humanos , Nucléolo Celular/metabolismo , Núcleo Celular/metabolismo , Leucemia Mieloide Aguda/genética , Metiltransferasas/metabolismo , Procesamiento Postranscripcional del ARN , ARN Ribosómico 18S/metabolismoRESUMEN
The transformed state in acute leukemia requires gene regulatory programs involving transcription factors and chromatin modulators. Here, we uncover an IRF8-MEF2D transcriptional circuit as an acute myeloid leukemia (AML)-biased dependency. We discover and characterize the mechanism by which the chromatin "reader" ZMYND8 directly activates IRF8 in parallel with the MYC proto-oncogene through their lineage-specific enhancers. ZMYND8 is essential for AML proliferation in vitro and in vivo and associates with MYC and IRF8 enhancer elements that we define in cell lines and in patient samples. ZMYND8 occupancy at IRF8 and MYC enhancers requires BRD4, a transcription coactivator also necessary for AML proliferation. We show that ZMYND8 binds to the ET domain of BRD4 via its chromatin reader cassette, which in turn is required for proper chromatin occupancy and maintenance of leukemic growth in vivo. Our results rationalize ZMYND8 as a potential therapeutic target for modulating essential transcriptional programs in AML.
Asunto(s)
Factores Reguladores del Interferón/metabolismo , Leucemia Mieloide Aguda/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Proteínas de Ciclo Celular/metabolismo , Línea Celular , Línea Celular Tumoral , Proliferación Celular/genética , Cromatina/genética , Elementos de Facilitación Genéticos/genética , Regulación Neoplásica de la Expresión Génica/genética , Humanos , Factores Reguladores del Interferón/genética , Leucemia Mieloide Aguda/genética , Proteínas Nucleares/metabolismo , Regiones Promotoras Genéticas/genética , Proto-Oncogenes Mas , Factores de Transcripción/metabolismo , Transcripción Genética/genética , Proteínas Supresoras de Tumor/genéticaRESUMEN
Gain-of-function mutations in the histone acetylation 'reader' ENL, found in AML and Wilms tumor, are known to drive condensate formation and gene activation in cellular systems. However, their role in tumorigenesis remains unclear. Using a conditional knock-in mouse model, we show that mutant ENL perturbs normal hematopoiesis, induces aberrant expansion of myeloid progenitors, and triggers rapid onset of aggressive AML. Mutant ENL alters developmental and inflammatory gene programs in part by remodeling histone modifications. Mutant ENL forms condensates in hematopoietic stem/progenitor cells at key leukemogenic genes, and disrupting condensate formation via mutagenesis impairs its chromatin and oncogenic function. Moreover, treatment with an acetyl-binding inhibitor of mutant ENL displaces these condensates from target loci, inhibits mutant ENL-induced chromatin changes, and delays AML initiation and progression in vivo. Our study elucidates the function of ENL mutations in chromatin regulation and tumorigenesis, and demonstrates the potential of targeting pathogenic condensates in cancer treatment.
RESUMEN
Cellular plasticity describes the ability of cells to transition from one set of phenotypes to another. In melanoma, transient fluctuations in the molecular state of tumor cells mark the formation of rare cells primed to survive BRAF inhibition and reprogram into a stably drug-resistant fate. However, the biological processes governing cellular priming remain unknown. We used CRISPR-Cas9 genetic screens to identify genes that affect cell fate decisions by altering cellular plasticity. We found that many factors can independently affect cellular priming and fate decisions. We discovered a new plasticity-based mode of increasing resistance to BRAF inhibition that pushes cells towards a more differentiated state. Manipulating cellular plasticity through inhibition of DOT1L before the addition of the BRAF inhibitor resulted in more therapy resistance than concurrent administration. Our results indicate that modulating cellular plasticity can alter cell fate decisions and may prove useful for treating drug resistance in other cancers.
Asunto(s)
Plasticidad de la Célula/genética , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Pruebas Genéticas , Neoplasias/genética , Neoplasias/patología , Animales , Sistemas CRISPR-Cas/genética , Diferenciación Celular/genética , Línea Celular Tumoral , Proliferación Celular/genética , N-Metiltransferasa de Histona-Lisina/genética , Humanos , Melanoma/tratamiento farmacológico , Melanoma/genética , Melanoma/patología , Ratones Endogámicos NOD , Ratones SCID , Modelos Biológicos , Terapia Molecular Dirigida , Neoplasias/tratamiento farmacológico , Proteínas Proto-Oncogénicas B-raf/genética , Transcripción GenéticaRESUMEN
CRISPR-based genetic screening has revolutionized cancer drug target discovery, yet reliable, multiplex gene editing to reveal synergies between gene targets remains a major challenge. Here, we present a simple and robust CRISPR-Cas12a-based approach for combinatorial genetic screening in cancer cells. By engineering the CRISPR-AsCas12a system with key modifications to the Cas protein and its CRISPR RNA (crRNA), we can achieve high efficiency combinatorial genetic screening. We demonstrate the performance of our optimized AsCas12a (opAsCas12a) through double knockout screening against epigenetic regulators. This screen reveals synthetic sick interactions between Brd9&Jmjd6, Kat6a&Jmjd6, and Brpf1&Jmjd6 in leukemia cells.