期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：51
页码：E8247-E8256
DOI：10.1073/pnas.1610921114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceGlioblastoma, the most common primary malignant brain tumor in adults, remains challenging despite multimodality therapy, necessitating the discovery of new therapies. Nicotinamide adenine dinucleotide (NAD+) plays a pivotal role in cancer cell metabolism, but how NAD+ impacts functional signaling events in glioblastoma is not well understood. We provide clinical evidence that high expression of NAMPT, the rate-limiting step in NAD+ biosynthesis, in glioblastoma tumors is associated with poor overall survival in patients, and demonstrate NAMPT and NAD+ are required for the maintenance of patient-derived glioblastoma stem-like cells (GSCs). Moreover, we delineate a NAD+-dependent transcriptional program that governs GSC self-renewal and dictates the radiation resistance of these cells. These findings identify potential new therapeutic avenues for the treatment of glioblastoma. 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.
