<p>Supplementary Figure S1. Nampt inhibitor effects in glioblastoma tumorsphere cells. Supplementary Figure S2. Characterization of Nampt inhibitor effects in MYC/MYCN driven glioblastoma cells. Supplementary Figure S3. Characterization of NAD+-synthesis pathways in glioblastoma cells. Supplementary Figure S4. Nampt inhibitors induce apoptosis and disrupt intracellular metabolism pathways in MYC/MYCN amplified glioblastoma cells. Supplementary Figure S5. Fluorescent in situ hybridization (FISH) for MYC and MYCN in standard cancer cell lines. Supplementary Figure S6. Effect of Nampt inhibitors in Myc-driven standard cancer cell lines. Supplementary Figure S7. In vivo efficacy of Nampt inhibitor in MYC amplified H1975 xenografts. Supplementary Figure S8. NAMPT inhibitors were well tolerated in SCID mice bearing flank or orthotopic xenografts.</p>
ARTICLE ABSTRACT
Purpose: Deregulated Myc drives an oncogenic metabolic state, including pseudohypoxic glycolysis, adapted for the constitutive production of biomolecular precursors to feed rapid tumor cell growth. In glioblastoma, Myc facilitates renewal of the tumor-initiating cell reservoir contributing to tumor maintenance. We investigated whether targeting the Myc-driven metabolic state could be a selectively toxic therapeutic strategy for glioblastoma.Experimental Design: The glycolytic dependency of Myc-driven glioblastoma was tested using 13C metabolic flux analysis, glucose-limiting culture assays, and glycolysis inhibitors, including inhibitors of the NAD+ salvage enzyme nicotinamide phosphoribosyl-transferase (NAMPT), in MYC and MYCN shRNA knockdown and lentivirus overexpression systems and in patient-derived glioblastoma tumorspheres with and without MYC/MYCN amplification. The in vivo efficacy of glycolyic inhibition was tested using NAMPT inhibitors in MYCN-amplified patient-derived glioblastoma orthotopic xenograft mouse models.Results: Enforced Myc overexpression increased glucose flux and expression of glycolytic enzymes in glioblastoma cells. Myc and N-Myc knockdown and Myc overexpression systems demonstrated that Myc activity determined sensitivity and resistance to inhibition of glycolysis. Small-molecule inhibitors of glycolysis, particularly NAMPT inhibitors, were selectively toxic to MYC/MYCN–amplified patient-derived glioblastoma tumorspheres. NAMPT inhibitors were potently cytotoxic, inducing apoptosis and significantly extended the survival of mice bearing MYCN-amplified patient-derived glioblastoma orthotopic xenografts.Conclusions: Myc activation in glioblastoma generates a dependency on glycolysis and an addiction to metabolites required for glycolysis. Glycolytic inhibition via NAMPT inhibition represents a novel metabolically targeted therapeutic strategy for MYC or MYCN-amplified glioblastoma and potentially other cancers genetically driven by Myc. Clin Cancer Res; 22(17); 4452–65. ©2016 AACR.
