RESUMEN

Malignant peripheral nerve sheath tumors (MPNSTs) develop sporadically or in the context of neurofibromatosis type 1. Epidermal growth factor receptor (EGFR) overexpression has been implicated in MPNST formation, but its precise role and relevant signaling pathways remain unknown. We found that EGFR overexpression promotes mouse neurofibroma transformation to aggressive MPNST (GEM-PNST). Immunohistochemistry demonstrated phosphorylated STAT3 (Tyr705) in both human MPNST and mouse GEM-PNST. A specific JAK2/STAT3 inhibitor FLLL32 delayed MPNST formation in an MPNST xenograft nude mouse model. STAT3 knockdown by shRNA prevented MPNST formation in vivo. Finally, reducing EGFR activity strongly reduced pSTAT3 in vivo. Thus, an EGFR-STAT3 pathway is necessary for MPNST transformation and establishment of MPNST xenografts growth but not for tumor maintenance. Efficacy of the FLLL32 pharmacological inhibitor in delaying MPNST growth suggests that combination therapies targeting JAK/STAT3 might be useful therapeutics.

Asunto(s)

Receptores ErbB/fisiología , Neoplasias de la Vaina del Nervio/etiología , Factor de Transcripción STAT3/fisiología , Transducción de Señal/fisiología , Animales , Células Cultivadas , Curcumina/análogos & derivados , Curcumina/farmacología , Genes de Neurofibromatosis 1 , Humanos , Janus Quinasa 2/fisiología , Ratones , Ratones Endogámicos C57BL , Factor de Transcripción STAT3/antagonistas & inhibidores , Sarcoma/etiología

RESUMEN

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas without effective therapeutics. Bioinformatics was used to identify potential therapeutic targets. Paired Box (PAX), Eyes Absent (EYA), Dachsund (DACH) and Sine Oculis (SIX) genes, which form a regulatory interactive network in Drosophila, were found to be dysregulated in human MPNST cell lines and solid tumors. We identified a decrease in DACH1 expression, and increases in the expressions of PAX6, EYA1, EYA2, EYA4, and SIX1-4 genes. Consistent with the observation that half of MPNSTs develop in neurofibromatosis type 1 (NF1) patients, subsequent to NF1 mutation, we found that exogenous expression of the NF1-GTPase activating protein-related domain normalized DACH1 expression. EYA4 mRNA was elevated more than 100-fold as estimated by quantitative real-time PCR in most MPNST cell lines. In vitro, suppression of EYA4 expression using short hairpin RNA reduced cell adhesion and migration and caused cellular necrosis without affecting cell proliferation or apoptotic cell death. MPNST cells expressing shEYA4 either failed to form tumors in nude mice or formed very small tumors, with extensive necrosis but similar levels of proliferation and apoptosis as control cells. Our findings identify a role of EYA4 and possibly interacting SIX and DACH proteins in MPNSTs and suggest the EYA4 pathway as a rational therapeutic target.

Asunto(s)

Neoplasias Experimentales/genética , Neoplasias de la Vaina del Nervio/genética , Interferencia de ARN , Transactivadores/genética , Animales , Western Blotting , Línea Celular Tumoral , Células Cultivadas , Análisis por Conglomerados , Proteínas del Ojo/genética , Proteínas del Ojo/metabolismo , Femenino , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones , Ratones Desnudos , Necrosis , Neoplasias Experimentales/metabolismo , Neoplasias Experimentales/patología , Neoplasias de la Vaina del Nervio/metabolismo , Neoplasias de la Vaina del Nervio/patología , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Factor de Transcripción PAX6 , Factores de Transcripción Paired Box/genética , Factores de Transcripción Paired Box/metabolismo , Proteínas Tirosina Fosfatasas/genética , Proteínas Tirosina Fosfatasas/metabolismo , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transactivadores/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Trasplante Heterólogo