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Nicotinamide phosphoribosyltransferase (NAMPT) is the key enzyme in the salvaging synthesis pathway of the nicotinamide adenine dinucleotide (NAD). Both NAMPT and NAD progressively decline upon aging and neurodegenerative diseases. The depletion of NAMPT induces mitochondrial dysfunction in motor neurons and causes bioenergetic stress in neurons. However, the roles of NAMPT in hippocampus neurons need to be further studied. Using floxed Nampt (Namptflox/flox) mice, we knocked out Nampt specifically in the hippocampus CA1 neurons by injecting rAAV-hSyn-Cre-APRE-pA. The depletion of NAMPT in hippocampus neurons induced cognitive deficiency in mice. Nevertheless, no morphological change of hippocampus neurons was observed with immunofluorescent imaging. Under the transmission electron microscope, we observed mitochondrial swollen and mitochondrial number decreasing in the cell body and the neurites of hippocampus neurons. In addition, we found the intracellular Aβ (6E10) increased in the hippocampus CA1 region. The intensity of Aβ42 remained unchanged, but it tended to aggregate. The GFAP level, an astrocyte marker, and the Iba1 level, a microglia marker, significantly increased in the mouse hippocampus. In the primary cultured rat neurons, NAMPT inhibition by FK866 decreased the NAD level of neurons at > 10−9 M. FK866 dropped the mitochondrial membrane potential in the cell body of neurons at > 10−9 M and in the dendrite of neurons at > 10−8 M. FK866 decreased the number and shortened the length of branches of neurons at > 10−7 M. Together, likely due to the injury of mitochondria, the decline of NAMPT level can be a critical risk factor for neurodegeneration. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

Tumour cells modify their cellular metabolism with the aim to sustain uncontrolled proliferation. Cancer cells necessitate adequate amounts of NAD and NADPH to support several enzymes that are usually overexpressed and/or overactivated. Nicotinamide adenine dinucleotide (NAD) is an essential cofactor and substrate of several NAD-consuming enzymes, such as PARPs and sirtuins, while NADPH is important in the regulation of the redox status in cells. The present review explores the rationale for targeting the key enzymes that maintain the cellular NAD/NADPH pool in colorectal cancer and the enzymes that consume or use NADP(H).

Tumour cells modify their cellular metabolism with the aim to sustain uncontrolled proliferation. Cancer cells necessitate adequate amounts of NAD and NADPH to support several enzymes that are usually overexpressed and/or overactivated. Nicotinamide adenine dinucleotide (NAD) is an essential cofactor and substrate of several NAD-consuming enzymes, such as PARPs and sirtuins, while NADPH is important in the regulation of the redox status in cells. The present review explores the rationale for targeting the key enzymes that maintain the cellular NAD/NADPH pool in colorectal cancer and the enzymes that consume or use NADP(H). [ABSTRACT FROM AUTHOR]

Bladder cancer (BLCA) is one of the most prevalent malignancies worldwide with a high mortality rate and poor response to immunotherapy in patients expressing lower programmed death ligand 1 (PD-L1) levels. Nicotinamide phosphoribosyltransferase (NAMPT), a rate-limiting enzyme responsible for the biosynthesis of nicotinamide adenine dinucleotide (NAD+) from nicotinamide was reported to be overexpressed in various cancers; however, the role of NAMPT in BLCA is obscure. Immunohistochemistry of tissue microarrays, a real-time polymerase chain reaction, Western blotting, proliferation assay, NAD+ quantification, transwell-migration assay, and colony-formation assay were performed to measure NAMPT and PD-L1 expression levels in patients and the effect of NAMPT inhibition on T24 cells. Our study revealed that NAMPT expression was upregulated in BLCA patients with different grades and associated with poor T-cell infiltration. Notably, FK866-mediated NAMPT inhibition decreased cell viability by depleting NAD+, and reducing the migration ability and colony-formation ability of T24 cells. Interestingly, NAMPT negatively regulated PD-L1 under an interferon (IFN)-γ-mediated microenvironment. However, exogenous NAMPT activator has no effect on PD-L1. NAD+ supplementation also only increased PD-L1 in the absence of IFN-γ. Conclusively, NAMPT is crucial for BLCA tumorigenic properties, and it regulates expression of the PD-L1 immune checkpoint protein. NAMPT could be considered a target for modulating sensitivity to immunotherapy. • NAMPT is highly expressed in patients with different grades of BLCA. • NAMPT inhibition by FK866 reduces BLCA migration and stemness in vitro. • NAMPT is associated with low immune infiltration in BLCA patients and regulates the PD-L1 immune checkpoint protein. • NAD+ supplementation increases the PD-L1 protein level under a non-inflammatory condition. [ABSTRACT FROM AUTHOR]

Nicotinamide Phosphoribosyltransferase (NAMPT) is a rate-limiting enzyme in the biosynthesis of NAD. Cancer cells have elevated poly [ADP-Ribose] polymerase 1 (PARP) activity as well as the immense necessity of ATP: thereby consuming NAD at a higher rate than normal tissues. The perturbation of these intracellular processes is more sensitive and highly dependent on NAMPT to maintain the required NAD levels. Functional inhibition of NAMPT is, therefore, a promising drug target in therapeutic oncology. In this study, the importance of intermolecular contacts was realized based on contact occupancy and favorable energetic from molecular dynamic simulation to discern non-critical contacts of four different classes of potential NAMPT inhibitor bound complexes. Further, pharmacophore modeling, molecular docking, a quantum mechanical properties and MD simulation, as well as active site residual network communication were employed to identify potential leads. Present studies identified two leads, 2 and 3 which have better binding free energy compared to known inhibitors and showed stable hydrogen bonding and hydrophobic contacts with β barrel cavity lining residues in the active site of the dimer interface (A'B). Lead 2 containing fluorene as central core and lead 3 having phenyl-benzamide as a core showed stable moiety which was observed from electronic property analysis. Active site residual communication in identified leads bound complex also showed similarity to known inhibitor complexes. Compounds containing these moieties were not reported until now against NAMPT inhibition and can be considered as novel cores for future development of drugs to inhibit NAMPT function.