RESUMEN
Accumulating evidence suggests cancer cells exhibit a dependency on metabolic pathways regulated by nicotinamide adenine dinucleotide (NAD+). Nevertheless, how the regulation of this metabolic cofactor interfaces with signal transduction networks remains poorly understood in glioblastoma. Here, we report nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting step in NAD+ synthesis, is highly expressed in glioblastoma tumors and patient-derived glioblastoma stem-like cells (GSCs). High NAMPT expression in tumors correlates with decreased patient survival. Pharmacological and genetic inhibition of NAMPT decreased NAD+ levels and GSC self-renewal capacity, and NAMPT knockdown inhibited the in vivo tumorigenicity of GSCs. Regulatory network analysis of RNA sequencing data using GSCs treated with NAMPT inhibitor identified transcription factor E2F2 as the center of a transcriptional hub in the NAD+-dependent network. Accordingly, we demonstrate E2F2 is required for GSC self-renewal. Downstream, E2F2 drives the transcription of members of the inhibitor of differentiation (ID) helix-loop-helix gene family. Finally, we find NAMPT mediates GSC radiation resistance. The identification of a NAMPT-E2F2-ID axis establishes a link between NAD+ metabolism and a self-renewal transcriptional program in glioblastoma, with therapeutic implications for this formidable cancer.
Asunto(s)
Neoplasias Encefálicas/metabolismo , Citocinas/genética , Glioblastoma/metabolismo , NAD/biosíntesis , Nicotinamida Fosforribosiltransferasa/genética , Tolerancia a Radiación , Transcripción Genética , Animales , Antineoplásicos/farmacología , Encéfalo/patología , Neoplasias Encefálicas/radioterapia , Línea Celular Tumoral , Núcleo Celular/metabolismo , Proliferación Celular , Regulación Neoplásica de la Expresión Génica , Glioblastoma/radioterapia , Humanos , Ratones , Mutación , Trasplante de Neoplasias , Interferencia de ARN , Transducción de Señal/efectos de los fármacos , Células Madre/citologíaRESUMEN
Recent molecular classification of glioblastoma (GBM) has shown that patients with a mesenchymal (MES) gene expression signature exhibit poor overall survival and treatment resistance. Using regulatory network analysis of available expression microarray data sets of GBM, including The Cancer Genome Atlas (TCGA), we identified the transcriptional coactivator with PDZ-binding motif (TAZ), to be highly associated with the MES network. TAZ expression was lower in proneural (PN) GBMs and lower-grade gliomas, which correlated with CpG island hypermethylation of the TAZ promoter compared with MES GBMs. Silencing of TAZ in MES glioma stem cells (GSCs) decreased expression of MES markers, invasion, self-renewal, and tumor formation. Conversely, overexpression of TAZ in PN GSCs as well as murine neural stem cells (NSCs) induced MES marker expression and aberrant osteoblastic and chondrocytic differentiation in a TEAD-dependent fashion. Using chromatin immunoprecipitation (ChIP), we show that TAZ is directly recruited to a majority of MES gene promoters in a complex with TEAD2. The coexpression of TAZ, but not a mutated form of TAZ that lacks TEAD binding, with platelet-derived growth factor-B (PDGF-B) resulted in high-grade tumors with MES features in a murine model of glioma. Our studies uncover a direct role for TAZ and TEAD in driving the MES differentiation of malignant glioma.
Asunto(s)
Neoplasias Encefálicas/fisiopatología , Glioma/fisiopatología , Células Madre Mesenquimatosas/citología , Células Madre Neoplásicas/citología , Factores de Transcripción/metabolismo , Aciltransferasas , Animales , Línea Celular Tumoral , Células Cultivadas , Proteínas de Unión al ADN/metabolismo , Epigenómica , Regulación Neoplásica de la Expresión Génica , Humanos , Células Madre Mesenquimatosas/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones SCID , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Factores de Transcripción de Dominio TEA , Factores de Transcripción/genética , Células Tumorales CultivadasRESUMEN
Glioblastoma harbors a dynamic subpopulation of glioblastoma stem-like cells (GSCs) that can propagate tumors in vivo and is resistant to standard chemoradiation. Identification of the cell-intrinsic mechanisms governing this clinically important cell state may lead to the discovery of therapeutic strategies for this challenging malignancy. Here, we demonstrate that the mitotic E3 ubiquitin ligase CDC20-anaphase-promoting complex (CDC20-APC) drives invasiveness and self-renewal in patient tumor-derived GSCs. Moreover, CDC20 knockdown inhibited and CDC20 overexpression increased the ability of human GSCs to generate brain tumors in an orthotopic xenograft model in vivo. CDC20-APC control of GSC invasion and self-renewal operates through pluripotency-related transcription factor SOX2. Our results identify a CDC20-APC/SOX2 signaling axis that controls key biological properties of GSCs, with implications for CDC20-APC-targeted strategies in the treatment of glioblastoma.