RESUMEN
Loss-of-function mutations of cyclic-AMP response element binding protein, binding protein (CREBBP) are prevalent in lymphoid malignancies. However, the tumour suppressor functions of CREBBP remain unclear. We demonstrate that loss of Crebbp in murine haematopoietic stem and progenitor cells (HSPCs) leads to increased development of B-cell lymphomas. This is preceded by accumulation of hyperproliferative lymphoid progenitors with a defective DNA damage response (DDR) due to a failure to acetylate p53. We identify a premalignant lymphoma stem cell population with decreased H3K27ac, which undergoes transcriptional and genetic evolution due to the altered DDR, resulting in lymphomagenesis. Importantly, when Crebbp is lost later in lymphopoiesis, cellular abnormalities are lost and tumour generation is attenuated. We also document that CREBBP mutations may occur in HSPCs from patients with CREBBP-mutated lymphoma. These data suggest that earlier loss of Crebbp is advantageous for lymphoid transformation and inform the cellular origins and subsequent evolution of lymphoid malignancies.
Asunto(s)
Proteína de Unión a CREB/deficiencia , Proteína de Unión a CREB/metabolismo , Transformación Celular Neoplásica/metabolismo , Células Progenitoras Linfoides/metabolismo , Linfoma/metabolismo , Células Madre Neoplásicas/metabolismo , Acetilación , Animales , Proteína de Unión a CREB/genética , Proliferación Celular , Autorrenovación de las Células , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/patología , Células Cultivadas , Daño del ADN , Epigénesis Genética , Regulación Neoplásica de la Expresión Génica , Predisposición Genética a la Enfermedad , Histonas/metabolismo , Linfangiogénesis , Células Progenitoras Linfoides/patología , Linfoma/genética , Linfoma/patología , Linfopoyesis , Metilación , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación , Células Madre Neoplásicas/patología , Fenotipo , Transducción de Señal , Factores de Tiempo , Transcripción Genética , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
The introduction of highly selective ABL-tyrosine kinase inhibitors (TKIs) has revolutionized therapy for chronic myeloid leukemia (CML). However, TKIs are only efficacious in the chronic phase of the disease and effective therapies for TKI-refractory CML, or after progression to blast crisis (BC), are lacking. Whereas the chronic phase of CML is dependent on BCR-ABL, additional mutations are required for progression to BC. However, the identity of these mutations and the pathways they affect are poorly understood, hampering our ability to identify therapeutic targets and improve outcomes. Here, we describe a novel mouse model that allows identification of mechanisms of BC progression in an unbiased and tractable manner, using transposon-based insertional mutagenesis on the background of chronic phase CML. Our BC model is the first to faithfully recapitulate the phenotype, cellular and molecular biology of human CML progression. We report a heterogeneous and unique pattern of insertions identifying known and novel candidate genes and demonstrate that these pathways drive disease progression and provide potential targets for novel therapeutic strategies. Our model greatly informs the biology of CML progression and provides a potent resource for the development of candidate therapies to improve the dismal outcomes in this highly aggressive disease.
Asunto(s)
Regulación Leucémica de la Expresión Génica , Leucemia Experimental/genética , Leucemia Experimental/patología , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Animales , Elementos Transponibles de ADN , Proteínas de Fusión bcr-abl/genética , Genes myb , Células Madre Hematopoyéticas/patología , Humanos , Leucemia Experimental/tratamiento farmacológico , Leucemia Experimental/mortalidad , Leucemia Mielógena Crónica BCR-ABL Positiva/mortalidad , Leucemia Mielógena Crónica BCR-ABL Positiva/patología , Ratones Transgénicos , Terapia Molecular Dirigida/métodos , Mutagénesis Insercional , Mutación , Células Tumorales Cultivadas , Factor C de Crecimiento Endotelial Vascular/genéticaRESUMEN
BACKGROUND: B-cell precursor acute lymphoblastic leukemia (B-ALL) is amongst the leading causes of childhood cancer-related mortality. Its most common chromosomal aberration is the ETV6-RUNX1 fusion gene, with ~25% of ETV6-RUNX1 patients also carrying PAX5 alterations. METHODS: We have recreated this mutation background by inter-crossing Etv6-RUNX1 (Etv6 (RUNX1-SB)) and Pax5(+/-) mice and performed an in vivo analysis to find driver genes using Sleeping Beauty transposon-mediated mutagenesis and also exome sequencing. RESULTS: Combination of Etv6-RUNX1 and Pax5(+/-) alleles generated a transplantable B220 + CD19+ B-ALL with a significant disease incidence. RNA-seq analysis showed a gene expression pattern consistent with arrest at the pre-B stage. Analysis of the transposon common insertion sites identified genes involved in B-cell development (Zfp423) and the JAK/STAT signaling pathway (Jak1, Stat5 and Il2rb), while exome sequencing revealed somatic hotspot mutations in Jak1 and Jak3 at residues analogous to those mutated in human leukemias, and also mutation of Trp53. CONCLUSIONS: Powerful synergies exists in our model suggesting STAT pathway activation and mutation of Trp53 are potent drivers of B-ALL in the context of Etv6-RUNX1;Pax5(+/-).