RESUMEN
Deregulation of microRNAs' expression frequently occurs in acute myeloid leukemia (AML). Lower miR-181a expression is associated with worse outcomes, but the exact mechanisms by which miR-181a mediates this effect remain elusive. Aberrant activation of the RAS pathway contributes to myeloid leukemogenesis. Here, we report that miR-181a directly binds to 3'-untranslated regions (UTRs); downregulates KRAS, NRAS and MAPK1; and decreases AML growth. The delivery of miR-181a mimics to target AML cells using transferrin-targeting lipopolyplex nanoparticles (NP) increased mature miR-181a; downregulated KRAS, NRAS and MAPK1; and resulted in decreased phosphorylation of the downstream RAS effectors. NP-mediated upregulation of miR-181a led to reduced proliferation, impaired colony formation and increased sensitivity to chemotherapy. Ectopic expression of KRAS, NRAS and MAPK1 attenuated the anti-leukemic activity of miR-181a mimics, thereby validating the relevance of the deregulated miR-181a-RAS network in AML. Finally, treatment with miR-181a-NP in a murine AML model resulted in longer survival compared to mice treated with scramble-NP control. These data support that targeting the RAS-MAPK-pathway by miR-181a mimics represents a novel promising therapeutic approach for AML and possibly for other RAS-driven cancers.
Asunto(s)
GTP Fosfohidrolasas/genética , Leucemia Mieloide Aguda/terapia , Proteínas de la Membrana/genética , MicroARNs/genética , Proteínas Proto-Oncogénicas p21(ras)/genética , Regiones no Traducidas 3'/genética , Animales , Línea Celular Tumoral , Modelos Animales de Enfermedad , Femenino , GTP Fosfohidrolasas/metabolismo , Regulación Neoplásica de la Expresión Génica , Humanos , Leucemia Mieloide Aguda/genética , Proteínas de la Membrana/metabolismo , Ratones , Ratones SCID , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Nanopartículas , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Transducción de SeñalRESUMEN
UNLABELLED: Chromosomal aberrations and multiple genome-wide association studies (GWAS) have established a major hematopoietic quantitative trait locus in chromosome 6q23.3. The locus comprises an active enhancer region, in which some of the associated SNPs alter transcription factor binding. We now identify miR-3662 as a new functional driver contributing to the associated phenotypes. The GWAS SNPs are strongly associated with higher miR-3662 expression. Genome editing of rs66650371, a three-base-pair deletion, suggests a functional link between the SNP genotype and the abundance of miR-3662. Increasing miR-3662's abundance increases colony formation in hematopoietic progenitor cells, particularly the erythroid lineage. In contrast, miR-3662 is not expressed in acute myeloid leukemia cells, and its overexpression has potent antileukemic effects in vitro and in vivo Mechanistically, miR-3662 directly targets NF-κB-mediated transcription. Thus, miR-3662 is a new player of the hematopoietic 6q23.3 locus. SIGNIFICANCE: The characterization of miR-3662 has identified a new actor in the prominent hematopoietic quantitative trait locus in chromosome 6q23.3. The mechanistic insights into miR-3662's function may reveal novel or only partially known pathways for normal and malignant hematopoietic cell proliferation. Cancer Discov; 6(9); 1036-51. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 932.
Asunto(s)
Cromosomas Humanos Par 6 , Regulación Leucémica de la Expresión Génica , Hematopoyesis/genética , Leucemia Mieloide Aguda/genética , MicroARNs/genética , Sitios de Carácter Cuantitativo , Alelos , Animales , Sitios de Unión , Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Proliferación Celular , Supervivencia Celular/genética , Transformación Celular Neoplásica/genética , Ensayo de Unidades Formadoras de Colonias , Modelos Animales de Enfermedad , Femenino , Factor de Transcripción GATA1/metabolismo , Dosificación de Gen , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Células Madre Hematopoyéticas/metabolismo , Xenoinjertos , Humanos , Quinasa I-kappa B/genética , Quinasa I-kappa B/metabolismo , Leucemia Mieloide Aguda/metabolismo , Ratones , MicroARNs/química , Modelos Biológicos , FN-kappa B/metabolismo , Polimorfismo de Nucleótido Simple , Unión Proteica , Interferencia de ARN , Elementos de Respuesta , Transducción de SeñalRESUMEN
The B-Raf proto-oncogene serine/threonine kinase (BRAF) gene is the most frequently mutated gene in malignant melanoma (MM) and papillary thyroid cancer (PTC) and is causally involved in malignant cell transformation. Mutated BRAF is associated with an aggressive disease phenotype, thus making it a top candidate for targeted treatment strategies in MM and PTC. We show that BRAF mutations in both MM and PTC drive increased expression of oncomiR-3151, which is coactivated by the SP1/NF-κB complex. Knockdown of microRNA-3151 (miR-3151) with short hairpin RNAs reduces cell proliferation and increases apoptosis of MM and PTC cells. Using a targeted RNA sequencing approach, we mechanistically determined that miR-3151 directly targets TP53 and other members of the TP53 pathway. Reducing miR-3151's abundance increases TP53's mRNA and protein expression and favors its nuclear localization. Consequently, knockdown of miR-3151 also leads to caspase-3-dependent apoptosis. Simultaneous inhibition of aberrantly activated BRAF and knockdown of miR-3151 potentiates the effects of sole BRAF inhibition with the BRAF inhibitor vemurafenib and may provide a novel targeted therapeutic approach in BRAF-mutated MM and PTC patients. In conclusion, we identify miR-3151 as a previously unidentified player in MM and PTC pathogenesis, which is driven by BRAF-dependent and BRAF-independent mechanisms. Characterization of TP53 as a downstream effector of miR-3151 provides evidence for a causal link between BRAF mutations and TP53 inactivation.