RESUMEN
Acute myeloid leukemia (AML) driven by the activation of EVI1 due to chromosome 3q26/MECOM rearrangements is incurable. Because transcription factors such as EVI1 are notoriously hard to target, insight into the mechanism by which EVI1 drives myeloid transformation could provide alternative avenues for therapy. Applying protein folding predictions combined with proteomics technologies, we demonstrate that interaction of EVI1 with CTBP1 and CTBP2 via a single PLDLS motif is indispensable for leukemic transformation. A 4× PLDLS repeat construct outcompetes binding of EVI1 to CTBP1 and CTBP2 and inhibits proliferation of 3q26/MECOM rearranged AML in vitro and in xenotransplant models. This proof-of-concept study opens the possibility to target one of the most incurable forms of AML with specific EVI1-CTBP inhibitors. This has important implications for other tumor types with aberrant expression of EVI1 and for cancers transformed by different CTBP-dependent oncogenic transcription factors.
Asunto(s)
Oxidorreductasas de Alcohol , Proteínas de Unión al ADN , Leucemia Mieloide Aguda , Proteína del Locus del Complejo MDS1 y EV11 , Animales , Humanos , Ratones , Oxidorreductasas de Alcohol/metabolismo , Oxidorreductasas de Alcohol/genética , Línea Celular Tumoral , Proliferación Celular , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Proteínas Co-Represoras/metabolismo , Proteínas Co-Represoras/genética , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patología , Proteína del Locus del Complejo MDS1 y EV11/metabolismo , Proteína del Locus del Complejo MDS1 y EV11/genética , Unión Proteica , Factores de Transcripción/metabolismo , Factores de Transcripción/genéticaRESUMEN
Immune checkpoint blockade (ICB) has heralded a new era in cancer therapy. Research into the mechanisms underlying response to ICB has predominantly focused on T cells; however, effective immune responses require tightly regulated crosstalk between innate and adaptive immune cells. Here, we combine unbiased analysis of blood and tumors from metastatic breast cancer patients treated with ICB with mechanistic studies in mouse models of breast cancer. We observe an increase in systemic and intratumoral eosinophils in patients and mice responding to ICB treatment. Mechanistically, ICB increased IL-5 production by CD4+ T cells, stimulating elevated eosinophil production from the bone marrow, leading to systemic eosinophil expansion. Additional induction of IL-33 by ICB-cisplatin combination or recombinant IL-33 promotes intratumoral eosinophil infiltration and eosinophil-dependent CD8+ T cell activation to enhance ICB response. This work demonstrates the critical role of eosinophils in ICB response and provides proof-of-principle for eosinophil engagement to enhance ICB efficacy.
Asunto(s)
Inhibidores de Puntos de Control Inmunológico , Neoplasias , Ratones , Animales , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Eosinófilos/patología , Interleucina-5/uso terapéutico , Interleucina-33 , Neoplasias/tratamiento farmacológico , Linfocitos T CD8-positivos , Presentación de Antígeno , Linfocitos T CD4-Positivos/patologíaRESUMEN
In acute myeloid leukemia (AML) with inv(3)(q21;q26) or t(3;3)(q21;q26), a translocated GATA2 enhancer drives oncogenic expression of EVI1. We generated an EVI1-GFP AML model and applied an unbiased CRISPR/Cas9 enhancer scan to uncover sequence motifs essential for EVI1 transcription. Using this approach, we pinpointed a single regulatory element in the translocated GATA2 enhancer that is critically required for aberrant EVI1 expression. This element contained a DNA-binding motif for the transcription factor MYB, which specifically occupied this site at the translocated allele and was dispensable for GATA2 expression. MYB knockout as well as peptidomimetic blockade of CBP/p300-dependent MYB functions resulted in downregulation of EVI1 but not of GATA2. Targeting MYB or mutating its DNA-binding motif within the GATA2 enhancer resulted in myeloid differentiation and cell death, suggesting that interference with MYB-driven EVI1 transcription provides a potential entry point for therapy of inv(3)/t(3;3) AMLs. SIGNIFICANCE: We show a novel paradigm in which chromosomal aberrations reveal critical regulatory elements that are nonfunctional at their endogenous locus. This knowledge provides a rationale to develop new compounds to selectively interfere with oncogenic enhancer activity.This article is highlighted in the In This Issue feature, p. 2659.