RESUMO
Merlin/NF2 is a bona fide tumor suppressor whose mutations underlie inherited tumor syndrome neurofibromatosis type 2 (NF2), as well as various sporadic cancers including kidney cancer. Multiple Merlin/NF2 effector pathways including the Hippo-YAP/TAZ pathway have been identified. However, the molecular mechanisms underpinning the growth and survival of NF2-mutant tumors remain poorly understood. Using an inducible orthotopic kidney tumor model, we demonstrate that YAP/TAZ silencing is sufficient to induce regression of pre-established NF2-deficient tumors. Mechanistically, YAP/TAZ depletion diminishes glycolysis-dependent growth and increases mitochondrial respiration and reactive oxygen species (ROS) buildup, resulting in oxidative-stress-induced cell death when challenged by nutrient stress. Furthermore, we identify lysosome-mediated cAMP-PKA/EPAC-dependent activation of RAF-MEK-ERK signaling as a resistance mechanism to YAP/TAZ inhibition. Finally, unbiased analysis of TCGA primary kidney tumor transcriptomes confirms a positive correlation of a YAP/TAZ signature with glycolysis and inverse correlations with oxidative phosphorylation and lysosomal gene expression, supporting the clinical relevance of our findings.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Carcinoma de Células Renais/metabolismo , Neoplasias Renais/metabolismo , Neurofibromina 2/deficiência , Fatores de Transcrição/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/antagonistas & inibidores , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Carcinoma de Células Renais/genética , Carcinoma de Células Renais/patologia , Linhagem Celular Tumoral , Glicólise , Xenoenxertos , Humanos , Neoplasias Renais/genética , Neoplasias Renais/patologia , Sistema de Sinalização das MAP Quinases , Camundongos , Camundongos SCID , Neurofibromatose 2/genética , Neurofibromatose 2/metabolismo , Neurofibromatose 2/patologia , Neurofibromina 2/genética , Neurofibromina 2/metabolismo , Fosforilação Oxidativa , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Transativadores , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/genética , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional , Proteínas de Sinalização YAPRESUMO
Melanoma patients with oncogenic BRAF(V600E) mutation have poor prognoses. While the role of BRAF(V600E) in tumorigenesis is well established, its involvement in metastasis that is clinically observed in melanoma patients remains a topic of debate. Here, we show that BRAF(V600E) melanoma cells have extensive invasion activity as assayed by the generation of F-actin and cortactin foci that mediate membrane protrusion, and degradation of the extracellular matrix (ECM). Inhibition of BRAF(V600E) blocks melanoma cell invasion. In a BRAF(V600E)-driven murine melanoma model or in patients' tumor biopsies, cortactin foci decrease upon inhibitor treatment. In addition, genome-wide expression analysis shows that a number of invadopodia-related genes are downregulated after BRAF(V600E) inhibition. Mechanistically, BRAF(V600E) induces phosphorylation of cortactin and the exocyst subunit Exo70 through ERK, which regulates actin dynamics and matrix metalloprotease secretion, respectively. Our results provide support for the role of BRAF(V600E) in metastasis and suggest that inhibiting invasion is a potential therapeutic strategy against melanoma.
