RESUMEN
The key myeloid transcription factor (TF), CEBPA, is frequently mutated in acute myeloid leukemia (AML), but the direct molecular effects of this leukemic driver mutation remain elusive. To investigate CEBPA mutant AML, we performed microscale, in vivo chromatin immunoprecipitation sequencing and identified a set of aberrantly activated enhancers, exclusively occupied by the leukemia-associated CEBPA-p30 isoform. Comparing gene expression changes in human CEBPA mutant AML and the corresponding Cebpa Lp30 mouse model, we identified Nt5e, encoding CD73, as a cross-species AML gene with an upstream leukemic enhancer physically and functionally linked to the gene. Increased expression of CD73, mediated by the CEBPA-p30 isoform, sustained leukemic growth via the CD73/A2AR axis. Notably, targeting of this pathway enhanced survival of AML-transplanted mice. Our data thus indicate a first-in-class link between a cancer driver mutation in a TF and a druggable, direct transcriptional target.
Asunto(s)
5'-Nucleotidasa/genética , Proteínas Potenciadoras de Unión a CCAAT/genética , Regulación Leucémica de la Expresión Génica , Leucemia Mieloide Aguda/genética , Mutación , Animales , Sitios de Unión , Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Elementos de Facilitación Genéticos , Epigénesis Genética , Proteínas Ligadas a GPI/genética , Perfilación de la Expresión Génica , Humanos , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/mortalidad , Leucemia Mieloide Aguda/patología , Ratones , Motivos de Nucleótidos , Pronóstico , Regiones Promotoras Genéticas , Unión Proteica , Isoformas de Proteínas/genéticaRESUMEN
Transcription factors are key regulators of hematopoietic stem cells (HSCs) and act through their ability to bind DNA and impact on gene transcription. Their functions are interpreted in the complex landscape of chromatin, but current knowledge on how this is achieved is very limited. C/EBPα is an important transcriptional regulator of hematopoiesis, but its potential functions in HSCs have remained elusive. Here we report that C/EBPα serves to protect adult HSCs from apoptosis and to maintain their quiescent state. Consequently, deletion of Cebpa is associated with loss of self-renewal and HSC exhaustion. By combining gene expression analysis with genome-wide assessment of C/EBPα binding and epigenetic configurations, we show that C/EBPα acts to modulate the epigenetic states of genes belonging to molecular pathways important for HSC function. Moreover, our data suggest that C/EBPα acts as a priming factor at the HSC level where it actively promotes myeloid differentiation and counteracts lymphoid lineage choice. Taken together, our results show that C/EBPα is a key regulator of HSC biology, which influences the epigenetic landscape of HSCs in order to balance different cell fate options.