RESUMEN
Neuroblastoma is an embryonic solid tumor of neural crest origin and accounts for 11% of all cancer-related deaths in children. Novel therapeutic strategies are therefore urgently required. MYCN oncogene amplification, which occurs in 20% of neuroblastomas, is a hallmark of high risk. Here, we aimed to exploit molecular mechanisms that can be pharmacologically addressed with epigenetically modifying drugs, such as histone deacetylase (HDAC) inhibitors. Grainyhead-like 1 (GRHL1), a gene critical for Drosophila neural development, belonged to the genes most strongly responding to HDAC inhibitor treatment of neuroblastoma cells in a genome-wide screen. An increase in the histone H4 pan-acetylation associated with its promoter preceded transcriptional activation. Physically adjacent, HDAC3 and MYCN colocalized to the GRHL1 promoter and repressed its transcription. High-level GRHL1 expression in primary neuroblastomas correlated on transcriptional and translational levels with favorable patient survival and established clinical and molecular markers for favorable tumor biology, including lack of MYCN amplification. Enforced GRHL1 expression in MYCN-amplified neuroblastoma cells with low endogenous GRHL1 levels abrogated anchorage-independent colony formation, inhibited proliferation, and retarded xenograft growth in mice. GRHL1 knockdown in MYCN single-copy cells with high endogenous GRHL1 levels promoted colony formation. GRHL1 regulated 170 genes genome-wide, and most were involved in pathways regulated during neuroblastomagenesis, including nervous system development, proliferation, cell-cell adhesion, cell spreading, and cellular differentiation. In summary, the data presented here indicate a significant role of HDAC3 in the MYCN-mediated repression of GRHL1 and suggest drugs that block HDAC3 activity and suppress MYCN expression as promising candidates for novel treatment strategies of high-risk neuroblastoma.
Asunto(s)
Histona Desacetilasas/fisiología , Neuroblastoma/genética , Proteínas Nucleares/fisiología , Proteínas Oncogénicas/fisiología , Proteínas Represoras/genética , Animales , Antineoplásicos/farmacología , Línea Celular Tumoral , Proliferación Celular , Supervivencia sin Enfermedad , Femenino , Regulación Neoplásica de la Expresión Génica , Silenciador del Gen , Genes Supresores de Tumor , Inhibidores de Histona Desacetilasas/farmacología , Humanos , Ácidos Hidroxámicos/farmacología , Indoles/farmacología , Lactante , Estimación de Kaplan-Meier , Ratones , Ratones SCID , Proteína Proto-Oncogénica N-Myc , Trasplante de Neoplasias , Neuroblastoma/metabolismo , Neuroblastoma/mortalidad , Neuroblastoma/patología , Panobinostat , Proteínas Represoras/metabolismo , Transcripción Genética , Carga TumoralRESUMEN
MYCN is a master regulator controlling many processes necessary for tumor cell survival. Here, we unravel a microRNA network that causes tumor suppressive effects in MYCN-amplified neuroblastoma cells. In profiling studies, histone deacetylase (HDAC) inhibitor treatment most strongly induced miR-183. Enforced miR-183 expression triggered apoptosis, and inhibited anchorage-independent colony formation in vitro and xenograft growth in mice. Furthermore, the mechanism of miR-183 induction was found to contribute to the cell death phenotype induced by HDAC inhibitors. Experiments to identify the HDAC(s) involved in miR-183 transcriptional regulation showed that HDAC2 depletion induced miR-183. HDAC2 overexpression reduced miR-183 levels and counteracted the induction caused by HDAC2 depletion or HDAC inhibitor treatment. MYCN was found to recruit HDAC2 in the same complexes to the miR-183 promoter, and HDAC2 depletion enhanced promoter-associated histone H4 pan-acetylation, suggesting epigenetic changes preceded transcriptional activation. These data reveal miR-183 tumor suppressive properties in neuroblastoma that are jointly repressed by MYCN and HDAC2, and suggest a novel way to bypass MYCN function.
Asunto(s)
Histona Desacetilasa 2/metabolismo , MicroARNs/metabolismo , Neuroblastoma/genética , Proteínas Nucleares/metabolismo , Proteínas Oncogénicas/metabolismo , Animales , Muerte Celular , Línea Celular Tumoral , Inhibidores de Histona Desacetilasas/farmacología , Humanos , Ratones , MicroARNs/antagonistas & inhibidores , MicroARNs/genética , Proteína Proto-Oncogénica N-Myc , Neuroblastoma/metabolismo , Neuroblastoma/patología , Regiones Promotoras Genéticas , Transducción de SeñalRESUMEN
Inhibition of histone deacetylase (HDAC) activity as stand-alone or combination therapy represents a promising therapeutic approach in oncology. The pan- or class I HDAC inhibitors (HDACi) currently approved or in clinical studies for oncology give rise to dose-limiting toxicities, presumably because of the inhibition of several HDACs. This could potentially be overcome by selective blockade of single HDAC family members. Here we report that HDAC11, the most recently identified zinc-dependent HDAC, is overexpressed in several carcinomas as compared to corresponding healthy tissues. HDAC11 depletion is sufficient to cause cell death and to inhibit metabolic activity in HCT-116 colon, PC-3 prostate, MCF-7 breast and SK-OV-3 ovarian cancer cell lines. The antitumoral effect induced can be mimicked by enforced expression of a catalytically impaired HDAC11 variant, suggesting that inhibition of the enzymatic activity of HDAC11 by small molecules could trigger the desired phenotypic changes. HDAC11 depletion in normal cells causes no changes in metabolic activity and viability, strongly suggesting that tumor-selective effects can be achieved. Altogether, our data show that HDAC11 plays a critical role in cancer cell survival and may represent a novel drug target in oncology.