Inhibition of TRAF3IP2 Modulates NAMPT and NAD Metabolism in Glioblastoma

Glioblastoma is a grade 4 diffuse astrocytic glioma that is the most aggressive brain malignancy, with poor treatment outcomes and median overall survival (OS) of 10-14 months. Glioblastoma is characterized by upregulation of NAD metabolism, required to maintain rapid proliferation and DNA repair. Nicotinamide phosphoribosyltransferase (NAMPT), is the rate limiting enzyme in the NAD salvage pathway, and has emerged as a promising target in the treatment of glioblastoma. Previously, we reported the crucial role of adaptor protein TRAF3IP2 in glioblastoma tumorigenesis. In this study, we aim to investigate the role of TRAF3IP2 in modulating NAMPT expression and explore its downstream impact on promoting cellular energetics in glioblastoma cells. Our results reveal that inhibition of TRAF3IP2 in glioblastoma cells attenuates metabolic activity, as evidenced by decreased expression levels of NAMPT and the mTOR complex, leading to reduction in NAD synthesis and glycolytic function, decreased expression of NAD-dependent deacetylase SIRT1, and increased presence of cellular ROS and expression of tumor suppressor p53, cumulatively resulting in decreased cell viability in glioblastoma. These outcomes elucidate that inhibition of TRAF3IP2 exerts significant anti-tumor effects on glioblastoma by reducing NAD availability and cancer-cell metabolism, highlighting the therapeutic potential of TRAF3IP2 in glioblastoma.