NAMPT Inhibition Induces Neuroblastoma Cell Death and Blocks Tumor Growth

Abstract

High-risk neuroblastoma (NB) portends very poor prognoses in children. Targeting tumor metabolism has emerged as a novel therapeutic strategy. High levels of nicotinamide-adenine-dinucleotide (NAD+) are required for rapid cell proliferation. Nicotinamide phosphoribosyl transferase (NAMPT) is the rate-limiting enzyme for NAD+ salvage and is overexpressed in several cancers. Here, we determine the potential of NAMPT as a therapeutic target for NB treatment. NAMPT inhibition cytotoxicity was determined by trypan blue exclusion and LDH assays. Neuroblastoma stem cell self-renewal was evaluated by neurosphere assay. Protein expression was evaluated via Western blot. The effect of targeting NAMPT in vivo was determined using an NB1691-xenografted mouse model. Robust NAMPT expression was demonstrated in multiple N-MYC amplified, high-risk neuroblastoma cell lines. NAMPT inhibition with STF-118804 (STF) decreased ATP, induced apoptosis, and reduced NB stem cell neurosphere formation. STF treatment down-regulated N-MYC levels and abrogated AKT activation. AKT and glycolytic pathway inhibitors in combination with NAMPT inhibition induced robust, greater-than-additive neuroblastoma cell death. Lastly, STF treatment blocked neuroblastoma tumor growth in mouse xenograft models. NAMPT is a valid therapeutic target as inhibition promoted neuroblastoma cell death in vitro and prevented tumor growth in vivo. Further investigation is warranted to establish this therapy’s role as an adjunctive modality.

Targeting NAD+ metabolism: dual roles in cancer treatment

“…NAMPT upregulation has been reported to be associated with the phosphorylation of AKT ( 48 ). NAMPT inhibition suppressed N-MYC expression and reduced the phosphorylation levels of AKT and GSK3 ( 49 ). Similarly, NAMPTi decreased the dephosphorylation rate of the EGFR, ERK1/2, MEK1/2, and Akt in NSCLC ( 50 ).…”

NAD+ associated genes as potential biomarkers for predicting the prognosis of gastric cancer

“…Cancer cells constantly reprogram their metabolism to support the high proliferation rates, such as the Warburg effect of aerobic glycolysis [12][13][14], a critical metabolic hallmark in cancer. NAD+ levels and the NAD+/NADH (nicotinamide adenine dinucleotide) ratio are much higher in cancer cells than in normal cells, suggesting the vital role of NAD+ in cancer cell metabolism [12].…”

“…It has also been reported that NAD+ can strongly induce highly proinflammatory senescence-associated secretory phenotype (SASP) and accelerate cancer progression [10]. Several studies have shown that targeting NAD+ synthesis induces cancer cell cytotoxicity upon NAMPT inhibitor in vitro and in vivo [11,[13][14][15][16][17]. Although previous clinical trials of NAD+ inhibitors showed no effect on remission of advanced solid tumor [18][19][20][21][22], NAD+ is still an intriguing target for cancer therapy and a better understanding of its role in cancer may show some clinical success.…”