RESUMEN
Melanoma is a paradigm of aggressive tumors with a complex and heterogeneous genetic background. Still, melanoma cells frequently retain developmental traits that trace back to lineage specification programs. In particular, lysosome-associated vesicular trafficking is emerging as a melanoma-enriched lineage dependency. However, the contribution of other lysosomal functions such as autophagy to melanoma progression is unclear, particularly in the context of metastasis and resistance to targeted therapy. Here we mined a broad spectrum of cancers for a meta-analysis of mRNA expression, copy number variation and prognostic value of 13 core autophagy genes. This strategy identified heterozygous loss of ATG5 at chromosome band 6q21 as a distinctive feature of advanced melanomas. Importantly, partial ATG5 loss predicted poor overall patient survival in a manner not shared by other autophagy factors and not recapitulated in other tumor types. This prognostic relevance of ATG5 copy number was not evident for other 6q21 neighboring genes. Melanocyte-specific mouse models confirmed that heterozygous (but not homozygous) deletion of Atg5 enhanced melanoma metastasis and compromised the response to targeted therapy (exemplified by dabrafenib, a BRAF inhibitor in clinical use). Collectively, our results support ATG5 as a therapeutically relevant dose-dependent rheostat of melanoma progression. Moreover, these data have important translational implications in drug design, as partial blockade of autophagy genes may worsen (instead of counteracting) the malignant behavior of metastatic melanomas.
Asunto(s)
Proteína 5 Relacionada con la Autofagia/genética , Pérdida de Heterocigocidad/genética , Melanoma/genética , Melanoma/patología , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Animales , Autofagia/efectos de los fármacos , Autofagia/genética , Mapeo Cromosómico , Variaciones en el Número de Copia de ADN/genética , Metilación de ADN/genética , Modelos Animales de Enfermedad , Regulación hacia Abajo/efectos de los fármacos , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Heterocigoto , Ratones , Metástasis de la Neoplasia , Nevo/genética , Nevo/patología , Pigmentación/genética , Pronóstico , Regiones Promotoras Genéticas/genética , Proteínas Proto-Oncogénicas B-raf/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Factores de Riesgo , Análisis de SupervivenciaRESUMEN
RNA binding proteins (RBPs) modulate cancer progression through poorly understood mechanisms. Here we show that the RBP UNR/CSDE1 is overexpressed in melanoma tumors and promotes invasion and metastasis. iCLIP sequencing, RNA sequencing, and ribosome profiling combined with in silico studies unveiled sets of pro-metastatic factors coordinately regulated by UNR as part of RNA regulons. In addition to RNA steady-state levels, UNR was found to control many of its targets at the level of translation elongation/termination. Key pro-oncogenic targets of UNR included VIM and RAC1, as validated by loss- and gain-of-function studies. Our results identify UNR as an oncogenic modulator of melanoma progression, unravel the underlying molecular mechanisms, and identify potential targets for this therapeutically challenging malignancy.