Role Of Nicotinamide Phosphoribosyltransferase Research Articles

The role of nicotinamide adenine dinucleotide salvage enzymes in cardioprotection.

The increasing trend of cardiac diseases is becoming a major threat globally. Cardiac activities are based on integrated action potential through electronic flux changes within intra- and extracellular molecular activities. Nicotinamide adenine dinucleotide (NAD) is a major electron carrier present in almost all living cells and creates gated potential by electron exchange from one chemical to another in terms of oxidation (NAD+) and reduction (NADH) reactions. NAD+ plays an important role directly or indirectly in protecting against various cardiovascular diseases, including heart failure, occlusion, ischemia-reperfusion (IR) injury, arrhythmia, myocardial infarction (MI), rhythmic disorder, and a higher order of cardiovascular complexity. Nicotinamide phosphoribosyl transferase (NAMPT) is well known as a rate-limiting enzyme in this pathway except for de-novo NAD synthesis and directly involved in the cardioprotective activity. There are two more enzymes - nicotinate phosphoribosyl transferase (NAPRT) and nicotinamide riboside kinase (NRK) - which also work as rate-limiting factors in the NAD+ synthesis pathway. This study concentrated on the role of NAMPT, NAPRT, and NRK in cardioprotective activity and prospective cardiac health.

A Review on the Role of Nicotinamide Phosphoribosyl Transferase in the Adipose Tissue

A Review on the Role of Nicotinamide Phosphoribosyl Transferase in the Adipose Tissue

Role of nicotinamide phosphoribosyltransferase in delaying smooth muscle cell senescence and protecting abdominal aortic aneurysm

To investigate the protective effect of nicotinamide phosphoribosyltransferase (NAMPT) on abdominal aortic aneurysm by delaying the senescence of aortic vascular smooth muscle cells (VSMC). The primary VSMC cells from normal and patients with abdominal aortic aneurysm were cultured by tissue adherence method. Cells were divided into normal human-derived VSMC group (Ctrl-VSMC group), abdominal aortic aneurysm patient-derived VSMC group (AAA-VSMC group), and angiotensin II (Ang II) in vitro abdominal aortic aneurysm model group (Ang II-VSMC group, 100 nmol/L Ang II treated normal human-derived VSMC for 48 hours), Ang II + P7C3 group and AAA + P7C3 group after NAMPT agonist P7C3 intervention (adding 5 μmol/L P7C3 on the basis of Ang II-VSMC group and AAA-VSMC group, respectively). Immunofluorescence staining was used to identify VSMC; cell proliferation-associated antigen Ki67 staining was used to detect cell proliferation; senescence associated β-galactosidase (SA-β-gal) staining was used to detect cell senescence in each group; Western blotting was used to detect the protein expression levels of senescence-related proteins p21, p16 and NAMPT in each group. Compared with the Ctrl-VSMC group, the positive rate of SA-β-gal staining and the expression levels of senescence-related proteins p21 and p16 in the AAA-VSMC group and Ang II-VSMC group were significantly increased [SA-β-gal staining positive rate: (74.1±4.4)%, (68.6±5.5)% vs. (36.8±10.3)%, p21/GAPDH: 0.61±0.07, 0.51±0.03 vs. 0.31±0.03, p16/GAPDH: 0.77±0.03, 0.72±0.06 vs. 0.33±0.26, all P < 0.01]. However, the expression of NAMPT was significantly decreased (NAMPT/GAPDH: 0.88±0.07, 0.79±0.14 vs. 1.29±0.02, both P < 0.01). Compared with the Ang II-VSMC group, the positive rate of SA-β-gal staining and the expressions levels of senescence-related proteins p21 and p16 in the Ang II + P7C3 group were significantly lower [SA-β-gal staining positive rate: (49.1±3.2)% vs. (68.6±5.5)%, p21/GAPDH: 0.35±0.06 vs. 0.51±0.03, p16/GAPDH: 0.47±0.08 vs. 0.72±0.06, all P < 0.05], while the expression of NAMPT was significantly increased (NAMPT/GAPDH: 1.15±0.06 vs. 0.79±0.14, P < 0.01). Compared with the AAA-VSMC group, the positive rate of SA-β-gal staining and the expression levels of senescence-related proteins p21 and p16 in the AAA+P7C3 group were significantly lower [SA-β-gal staining positive rate: (54.1±6.0)% vs. (74.1±4.4)%, p21/GAPDH: 0.38±0.02 vs. 0.61±0.07, p16/GAPDH: 0.50±0.13 vs. 0.77±0.03, all P < 0.05], but the expression of NAMPT was significantly increased (NAMPT/GAPDH: 1.25±0.28 vs. 0.88±0.07, P < 0.01). NAMPT agonist P7C3 can delay the senescence of VSMC and play a protective role in abdominal aortic aneurysm.

Is eNAMPT/visfatin a potential serum marker of papillary thyroid cancer?

Purpose:The role of nicotinamide phosphoribosyltransferase (NAMPT)/visfatin in a more aggressive course of many malignancies has been proven. Previous studies have noticed the importance of visfatin in thyroid neoplastic tissue, but the diagnostic and prognostic value of its serum concentration has not been investigated so far. Our study aimed to consider whether extracellular NAMPT (eNAMPT) could be a potential serum marker in recurrent papillary thyroid cancer (PTC).Methods:It was a prospective observational study with consecutive enrolment. We recruited 100 patients with PTC after thyroidectomy with postoperative 131I ablation and 100 healthy controls. Also, 50 randomly selected patients underwent laboratory assessment (including eNAMPT serum concentration by ELISA Assay Kit, TSH, free thyroid hormones, TSH-stimulated thyroglobulin Tg, antibodies – TgAbs, TPOAb) and body composition analysis twice: at admission and 6 months after being on suppressive levothyroxine doses. TSH-stimulated Tg of 1 ng/ml was defined as the cutoff value for predicting disease status as complete remission (n = 55) and recurrent or persistent structural disease (n = 45).Results:The visfatin serum concentrations in patients diagnosed with PTC and in healthy subjects were not statistically significantly different (p = 0.9425). The eNAMPT levels were also similar in disease-free patients and the ones with tumour relapse. Besides, ROC curve analysis did not detect eNAMPT as a biomarker of PTC.Conclusion:We have not found visfatin as a potential serum marker of papillary thyroid cancer. Also, eNAMPT has no prognostic value in assessing the risk of disease recurrence or metastasis in PTC management.

NAMPT reduction-induced NAD+ insufficiency contributes to the compromised oocyte quality from obese mice.

Maternal obesity is associated with multiple adverse reproductive outcomes, whereas the underlying molecular mechanisms are still not fully understood. Here, we found the reduced nicotinamide phosphoribosyl transferase (NAMPT) expression and lowered nicotinamide adenine dinucleotide (NAD+) content in oocytes from obese mice. Next, by performing morpholino knockdown assay and pharmacological inhibition, we revealed that NAMPT deficiency not only severely disrupts maturational progression and meiotic apparatus, but also induces the metabolic dysfunction in oocytes. Furthermore, overexpression analysis demonstrated that NAMPT insufficiency induced NAD+ loss contributes to the compromised developmental potential of oocytes and early embryos from obese mice. Importantly, in vitro supplement and in vivo administration of nicotinic acid (NA) was able to ameliorate the obesity‐associated meiotic defects and oxidative stress in oocytes. Our results indicate a role of NAMPT in modulating oocyte meiosis and metabolism, and uncover the beneficial effects of NA treatment on oocyte quality from obese mice.

Dual Roles of Nicotinamide Phosphoribosyltransferase as a Promising Target for Cancer Radiotherapy.

Nicotinamide phosphoribosyltransferase (NAMPT) is the key rate-limiting enzyme in the regulation of nicotinamide adenine dinucleotide (NAD) biosynthesis, and its activity is critical for the replenishment of NAD level as well as cell survival or death. As one of the most important components in the electron transport chain of complex I in mitochondrion, sustained supply of NAD is essential to the maintenance of energy metabolism both in normal and cancer cells. Recent research showed that X-ray radiation sharply downregulated the expression of NAMPT, which may be the main cause of radiation damage in salivary gland. Consistently, upregulation of NAMPT by phenylephrine restored the function and tissue structure of salivary gland, indicating the cytoprotective role of NAMPT in preventing radiation damage in normal tissues of patients with head and neck cancer during radiotherapy. On the other hand, NAMPT downregulation and NAD depletion could induce cell death in oral squamous cell cancer, suggesting that a combination of NAMPT inhibitor and radiotherapy presents a promising therapeutic strategy for cancer treatment. Based on our and other's studies, NAMPT may have dual roles in cancer radiotherapy: the upregulation of NAMPT could serve to suppress radiotherapy complications such as radiation sialadenitis, and combination regimens that involve NAMPT inhibitors may enhance efficacy of radiotherapy for cancer treatment.

Lipopolysaccharide-Induced Microglial Neuroinflammation: Attenuation by FK866.

Alleviating microglia-mediated neuroinflammation bears great promise to reduce neurodegeneration. Nicotinamide phosphoribosyltransferase (NAMPT) may exert cytokine-like effect in the brain. However, it remains unclear about role of NAMPT in microglial inflammation. Also, it remains unknown about effect of NAMPT inhibition on microglial inflammation. In the present study, we observed that FK866 (a specific noncompetitive NAMPT inhibitor) dose-dependently inhibited lipopolysaccharide (LPS)-induced proinflammatory mediator (interleukin (IL)-6, IL-1β, inducible nitric oxide synthase, nitric oxide and reactive species) level increase in BV2 microglia cultures. FK866 also significantly inhibited LPS-induced polarization change in microglia. Furthermore, LPS significantly increased NAMPT expression and nuclear factor kappa B (NF-κB) phosphorylation in microglia. FK866 significantly decreased NAMPT expression and NF-κB phosphorylation in LPS-treated microglia. Finally, conditioned medium from microglia cultures co-treated with FK866 and LPS significantly increased SH-SY5Y and PC12 cell viability compared with conditioned medium from microglia cultures treated with LPS alone. Our study strongly indicates that NAMPT may be a promising target for microglia modulation and NAMPT inhibition may attenuate microglial inflammation.

The Pivotal Role of Nicotinamide Phosphoribosyl Transferase in Chronic Myeloid Leukemia Cells Under Hypoxic Condition

Introduction: ABL tyrosine kinase inhibitors (TKIs) improved outcomes for patients with chronic myeloid leukemia (CML) and Philadelphia chromosome (Ph)-positive leukemia. However, ABL TKIs do not eliminate the leukemia stem cells (LSCs) in the bone marrow, which may represent the most important event in leukemia relapse after TKI discontinuation. Bone marrow is also considered a tissue with limited oxygen supply. Therefore, new approach against leukemia stem cells, which is presented in bone marrow under hypoxia, may improve the outcome of CML patients. Nicotinamide phosphoribosyl transferase (NAMPT) is the rate limiting enzyme of the primary pathway for maintaining cellular NAD+ and that regulates intracellular adenosine triphosphate (ATP) levels in mammalian cells. It has been reported that NAMPT expression is upregulated in several human cancers. Materials and methods: In this study, we established ABL TKI resistantin vitrocell line models (K562 imatinib-R, K562 nilotinib-R, K562 ponatinib-R and Ba/F3 T315I) and used Ph-positive leukemia cell lines. We also investigated whether NAMPT inhibitor could suppress Ph-positive leukemia cells including T315I mutation and ABL TKI resistant under hypoxic condition. Results: In chemical library screen of compounds, NAMPT inhibitor, CHS828 is selected the candidate drug for ABL TKI resistant cells under hypoxic condition. Drug repositioning and repurposing can be an important part of any drug discovery. Therefore, we examined NAMPT efficacy by using Ph-positive leukemia cell lines. We first investigated the NAMPT expression by microarray gene expression data from the online Gene Expression Omnibus (GEO). Gene expression of NAMPT is increased in CML patients compared to normal samples from the public microarray datasets of GSE13159. Protein expression of NAMPT is found in Ph-positive leukemia cell lines including ABL TKI resistant cells. In hypoxia, gene expression of NAMPT was increased in Ph-positive cells compare to normoxic condition. We next examined efficacy of NAMPT inhibitor, CHS828 in Ph-positive leukemia cell lines. We found that CHS828 treatment for 72 h decreased cell viability of Ph-positive cell lines in a dose dependent manner. We also found that CHS828 inhibited the proliferation of ABL TKI resistant cells (K562 imatinib-R, K562 nilotinib-R, K562 ponatinib-R) and T315I mutant Ba/F3 cells under hypoxic condition. The rate of cell cycle progression was delayed and cells were blocked in G2/M phase. Nuclear factor-kappaB (NF-kB) is also implicated in cancer development. CHS828 inhibited constitutive NF-kB activity in the time and dose dependent manner. Intracellular ATP, which is the most important source of energy for cellular reactions, was drastically decreased after CHS828 treatment. NAD+ plays a vital role in diverse cellular processes that govern human health and disease. Intracellular NAD+ was decreased after CHS828 treatment. The wound healing effect was evaluated at 0, 24, 48, and 72 h by using NIH3T3 cells. In wound healing results, CHS828 treatment inhibited cellular migration of NIH3T3 cells. We next investigated the efficacy of ABL TKI and CHS828 against Ph-positive leukemia cell lines. ABL TKI and CHS828 treatment induced cellular growth inhibition compared with each drug alone. Caspase 3/7 activity was also increased after ABL TKIs and CHS828 treatment. ABL TKI and CHS828 reduced the colony formation ability of Ph-positive cells under hypoxic condition. Thein vivoefficacies of one of ABL TKI, ponatinib and CHS828 were evaluated in a mouse xenograft model. Ponatinib and CHS828 inhibited the growth of T315I mutant Ba/F3 cellsin vivomore than the control vehicle. We also found that co-treatment with ponatinib and CHS828 increased mouse survival. Combination treatment with ponatinib and CHS828 was also well tolerated, with no animal deaths in the treated mice. Conclusion: The results of our study indicate that the ABL TKI and CHS828 may be a powerful strategy against Ph-positive cells including ABL TKI resistant cells and provide the promising clinical relevance as a candidate drug for treatment of CML stem cells of the bone marrow microenvironment under hypoxic condition. Disclosures No relevant conflicts of interest to declare.

Targeting the NAD+ salvage pathway suppresses APC mutation-driven colorectal cancer growth and Wnt/\u03b2-catenin signaling via increasing Axin level

BackgroundThe role and mechanism of the nicotinamide adenine dinucleotide (NAD+) salvage pathway in cancer cell proliferation is poorly understood. Nicotinamide phosphoribosyltransferase (NAMPT), which converts nicotinamide into NAD+, is the rate-limiting enzyme in the NAD+ salvage pathway. Here, we assessed the role of NAMPT in the proliferation of colorectal cancer.MethodsReal-time PCR, immunohistochemistry, western blotting, and analyses of datasets from Oncomine and Gene Expression Omnibus were conducted to assess the expression of NAMPT at the mRNA and protein levels in colorectal cancer. The Kaplan Meier plotter online tool was used to evaluate the prognostic role of NAMPT. Knockdown of NAMPT was performed to assess the role of NAMPT in colorectal cancer cell proliferation and tumorigenesis both in vitro and in vivo. Overexpression of NAMPT was used to evaluate impact of NAMPT on colorectal cancer cell proliferation in vitro. NAD+ quantitation, immunofluorescence, dual luciferase assay and western blot were used to explore the mechanism of colorectal cancer proliferation. Transwell migration and invasion assays were conducted to assess the role of NAMPT in cell migration and invasion abilities of colorectal cancer cells.ResultsOur study indicated that the inhibition of NAMPT decreased proliferation capacity of colorectal cancer cells both in vitro and in vivo. Conversely, overexpression of NAMPT could promote cell proliferation in vitro. NAMPT inhibition induced β-catenin degradation by increasing Axin expression levels; this resulted in the inhibition of Wnt/β-catenin signaling and cell proliferation in colorectal cancer. The addition of nicotinamide mononucleotide, the enzymatic product of NAMPT, effectively reversed β-catenin protein degradation and inhibited growth. Similarly, the knockdown of Axin also decreased the cell death induced by the inhibition of NAMPT. In addition, we showed that colorectal cancer tissues harbored significantly higher levels of NAMPT than the levels harbored by paired normal tissues, especially in colorectal cancer stages I and II. And the overexpression of NAMPT was associated with unfavorable survival results.ConclusionsOur findings reveal that NAMPT plays an important role in colorectal cancer proliferation via Wnt/β-catenin pathway, which could have vital implications for the diagnosis, prognosis and treatment of colorectal cancer.

The Role of Nicotinamide Phosphoribosyltransferase in Pregnancy: A Review.

Nicotinamide phosphoribosyltransferase (NAMPT) was first reported in 1994 and has been explored in various human disease processes. However, until recently, very little has been done to define the role of NAMPT in pregnancy. NAMPT is a 52 kDa protein that has diverse functions in the human body, acting as a growth factor, cytokine, an enzyme, and an insulinomimetic agent. Initial studies examined NAMPT expression in fetal membranes and its effects on the amnion. Later research in nonpregnant studies showed an insulinomimetic effect, and attention focused on its role in gestational diabetes. In addition, as studies revealed NAMPT's function as an inflammatory cytokine, studies examined NAMPT in preeclampsia and fetal growth restriction. Several studies have confirmed that NAMPT is a marker of systemic infectious processes such as pyelonephritis and intrauterine infection. In this review, we present the current understanding of NAMPT's role in various pregnancy-related conditions as well as possible directions for future research.

NAMPT protects against 6-hydroxydopamine-induced neurotoxicity in PC12 cells through modulating SIRT1 activity.

Parkinson's disease (PD) is the second most common progressive neurodegenerative movement disorder. Nicotinamide phosphoribosyltransferase (NAMPT) catalyzes the first rate‑limiting step in the nicotinamide adenine dinucleotide (NAD+) biosynthetic pathway in mammals, is a substrate for NAD+‑dependent enzymes, such as sirtuin1 (SIRT1), and contributes to cell fate decisions. However, the role of NAMPT in PD has remained to be fully elucidated. In the present study, PC12 cells were treated with the neurotoxin 6-hydroxydopamine (6‑OHDA) to establish an invitro model of PD, following which an obvious inhibitory effect on the levels of NAMPT and NAD+ as well as the NAD+/NADH ratio was detected. In addition, pre‑incubation with FK866, a highly specific NAMPT inhibitor, enhanced the inhibitory effects of 6‑OHDA on the viability of PC12, while pre‑incubation with nicotinamide mononucleotide (NMN), am enzymatic product of NAMPT, had the opposite effect. Furthermore, it was revealed that NMN markedly attenuated 6‑OHDA‑induced decreases in superoxide dismutase activity and glutathione levels, as well as 6‑OHDA‑induced increases in malondialdehyde and lactate dehydrogenase in PC12 cells. Furthermore, 6‑OHDA significantly reduced SIRT1 activity in PC12 cells, which was inhibited by NMN. The pharmacological activator resveratrol also significantly inhibited 6‑OHDA‑mediated decreases in PC12 cell viability while reversing 6‑OHDA‑induced decreases in SIRT1 levels. The results of the present study suggested that NMT protected against 6‑OHDA‑induced decreases in PC12 cell viability, and that SIRT1 activation had a role in this process. Treatment with NMN to activate SIRT1 may represent a novel therapeutic strategy for treating PD.

The Role of Nicotinamide Phosphoribosyltransferase in Cerebral Ischemia.

As recombinant tissue plasminogen activator is the only drug approved for the clinical treatment of acute ischemic stroke, there is an urgent unmet need for novel stroke treatments. Endogenous defense mechanisms against stroke may hold the key to new therapies for stroke. A large number of studies suggest that nicotinamide phosphoribosyl-transferase (NAMPT is an attractive candidate to improve post-stroke recovery. NAMPT is a multifunctional protein and plays important roles in immunity, metabolism, aging, inflammation, and stress responses. NAMPT exists in both the intracellular and extracellular space. As a rate-limiting enzyme, the intracellular form (iNAMPT catalyzes the first step in the biosynthesis of nicotinamide adenine dinucleotide (NAD from nicotinamide. iNAMPT closely regulates energy metabolism, enhancing the proliferation of endothelial cells, inhibiting apoptosis, regulating vascular tone, and stimulating autophagy in disease conditions such as stroke. Extracellular NAMPT (eNAMPT is also known as visfatin (visceral fat-derived adipokine and has pleotropic effects. It is widely believed that the diverse biological functions of eNAMPT are attributed to its NAMPT enzymatic activity. However, the effects of eNAMPT on ischemic injury are still controversial. Some authors have argued that eNAMPT exacerbates ischemic neuronal injury non-enzymatically by triggering the release of TNF-α from glial cells. In addition, NAMPT also participates in several pathophysiological processes such as hypertension, atherosclerosis, and ischemic heart disease. Thus, it remains unclear under what conditions NAMPT is beneficial or destructive. Recent work using in vitro and in vivo genetic/ pharmacologic manipulations, including our own studies, has greatly improved our understanding of NAMPT. This review focuses on the multifaceted and complex roles of NAMPT under both normal and ischemic conditions.

Abstract 1770: A role of nicotinamide phosphoribosyltransferase in growth of KRAS mutant non-small cell lung cancer

Abstract Background: KRAS mutations are frequently found in non-small cell lung cancer (NSCLC). The KRAS mutations could be predictive of resistance to targeted therapy like epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) or a prognostic factor in NSCLC. No successful targeted therapy currently exists to treat patients with KRAS mutant NSCLC, and novel therapeutic strategies are needed to prolong survival in patients with KRAS mutant NSCLC. Nicotinamide phosphoribosyltransferase (nampt) is a rate-limiting enzyme in NAD+ salvage, and we previously reported that nampt is a potent therapeutic target in NSCLC. Based on the analysis result of GEO database, we found that expression of nampt is associated with RAS-MAPK signaling pathway in NSCLC, and we therefore, conducted an in vitro study to evaluate a role of nampt in growth of KRAS mutant NSCLC. Methods: We used a panel of KRAS mutant NSCLC cell lines (A427, A549, H157, H23, H1792, H2009, H358, H441, Calu6, Calu1). The cells were treated with a nampt inhibitor, FK866, and acid phosphatase (APH) assay (Thermo SCIENTIFIC) was used to evaluate cell viability of the KRAS mutant cells. Changes in expression of MAPK signaling pathway and BCL2 family proteins (antibodies from Cell Signaling and Santa Cruz) were evaluated by western blot. Apoptosis of the cells treated with FK866 was detected using an Annexin V FITC apoptosis detection kit (BD Biosciences). FACS analysis was performed using a BD FACSAria II cytometer (BD Bioscience). Autophagic proteolysis was studied by Cyto-ID autophagy detection kit (Cosmo Bio), and the expression of the fluorescent signal was visualized by a FV1000 confocal microscope (OLYMPUS JAPAN). Results: We found that the sensitivity to FK866 was different among the KRAS mutant cell lines, and for instance, A427 cells were sensitive while H157 cells were resistant. FK866 suppressed growth of KRAS mutant NSCLC and decreased expression of p-ERK expression in the cell line sensitive to FK866. We will report alteration of apoptosis and autophagy in the KRAS mutant NSCLC treated with FK866. Conclusion: Nampt could be a potent therapeutic target in KRAS mutant NSCLC. Citation Format: Shunsuke Okumura, Takaaki Sasaki, Yoshinobu Ohsaki. A role of nicotinamide phosphoribosyltransferase in growth of KRAS mutant non-small cell lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1770. doi:10.1158/1538-7445.AM2015-1770

Abstract 393: Nicotinamide phosphoribosyl transferase (NAMPT) inhibitors: novel modulators of antitumor immunity

Abstract Nicotinamide phosphoribosyltransferase (NAMPT), an essential enzyme involved in NAD metabolism, is a pleiotropic player in cell signalling and is implicated in a number of diseases, including cancer, inflammatory and metabolic disorders. NAMPT inhibitors (e.g. FK866 and CHS828) have been shown to be potentially effective in cancer therapy and have entered clinical trials in oncology. NAMPT could represent a putative link between metabolism, inflammation and cancer. This study investigated the role of NAMPT in cancer-related inflammation. A mouse model of transplantable MNMCA1 fibrosarcoma was utilized. WT Mice or NAMPTflox CrelysM+/- mice were injected with 10^4 MN-MNCA1 or G217R MNMCA1 (NAMPT inhibitors resistant cell line) cells and subsequently treated or not with 10 mg/kg of NAMPT inhibitors. Next, tumor growth, metastasis formation, tumor angiogenesis and the inflammatory infiltrate were estimated. In addition, monocytic (M-MDSCs) and granulocytic (G-MDSCs) myeloid derived-suppressor cells (MDSCs), isolated from the spleen of tumour bearing mice (untreated and treated with NAMPT inhibitors), or differentiated in vitro from bone marrow precursors, were analysed for their suppressive activity, nitric oxide (NO) production, gene profile and expression of enzymes involved in cancer-associated immunosuppression (e.g. iNOS, ARG1, NOX2). In the fibrosarcoma mouse model, NAMPT inhibitors inhibited tumor growth, tumor vessel formation and delay metastasis formation. Phenotypic analysis of the immune infiltrate revealed that the number of macrophages and dendritic cells was not affected by NAMPT inhibition. However MDSCs displayed a marked decreased in blood, spleen and primary tumour, which was associated with an increase number of both CD4+ and CD8+ T lymphocytes. On the contrary an increase number of MDSCs have been found in the bone marrow. A detail analysis of CXCR4 expression revealed that NAMPT inhibitors affect MDSCs migration in vivo. Moreover, in NAMPTflox CrelysM+/- mice fibrosarcoma growth is reduced. Expression analysis revealed that NAMPT was up-regulated in MDSCs in response to M1-stimulation, suggesting a role of this enzyme during inflammatory process. Moreover, NAMPT inhibitors blocked the NO-mediated T cell suppressive activity induced by IFNγ in M-MDSC. Preliminary evidences indicate a role of both AMPK and SIRT 1/3 in the inhibition of M-MDSC suppressive activity operated by NAMPT inhibitors. Furthermore, both M-MDSCs isolated from spleen of NAMPT inhibitors treated mice and MDSCs isolated from NAMPTflox CrelysM+/- mice display a reduced T-cell suppression activity. Here, we demonstrate for the first time a role of NAMPT metabolism in the functional differentiation of suppressive M-MDSCs associated with cancer development and suggest that pharmacological inhibition of NAMPT may prevent cancer-associated immunosuppression, restoring adaptive antitumor immunity. Citation Format: Cristina Travelli, Sara Morlacchi, Ubaldina Galli, Gian Cesare Tron, Armando A Genazzani, Antonio Sica. Nicotinamide phosphoribosyl transferase (NAMPT) inhibitors: novel modulators of antitumor immunity. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 393. doi:10.1158/1538-7445.AM2015-393

Role of nicotinamide phosphoribosyltransferase in lipopolysaccharide-induced myocardial injury in rats

Objective To evaluate the role of nicotinamide phosphoribosyltransferase (Nampt in lipopolysaccharide (LPS)-induced myocardial injury in rats.Methods Forty male Sprague-Dawley rats,aged 12 weeks,weighing 210-230 g,were randomly divided into 3 groups (n =10 each) using a random number table:control group (group C),LPS group and FK866 (specific Nampt inhibitor) group (group F).LPS 4 mg/kg was injected intraperitoneally in LPS and F groups,and then FK866 10 mg/kg was injected intraperitoneally in group F.At 6 h after the end of administration,the blood samples were taken from the abdominal aorta for determination of serum concentrations of cardiac troponin Ⅰ (cTnI).Then the animals were sacrificed and myocardial specimens were removed for determination of tumor necrosis factor-α (TNF-α),interleukin-6 (IL-6),and malondialdehyde (MDA) contents,glutathion (GSH)/oxidized glutathione (GSSG) ratio,caspase-3 activity and apoptosis rate.Results Compared with group C,the levels of cTnI,TNF-α,IL-6,MDA and caspase-3 were significantly increased,and GSH/GSSG ratio was decreased in LPS and F groups.Compared with group LPS,the levels of cTnI,TNF-α,IL-6,MDA and caspase-3 were significantly decreased,and GSH/GSSG ratio was increased in group F.There was no significant difference in apoptosis rate among the 3 groups.Conelusion Nampt activation can induce inflammatory responses and oxidative damage and promote cell apoptosis,thus being involved in LPS-induced myocardial injury in rats. Key words: Nicotinamide phosphoribosyltransferase ; Endotoxemia ; Myocardium

NAMPT-mediated salvage synthesis of NAD+ controls morphofunctional changes of macrophages.

Functional morphodynamic behavior of differentiated macrophages is strongly controlled by actin cytoskeleton rearrangements, a process in which also metabolic cofactors ATP and NAD(H) (i.e. NAD+ and NADH) and NADP(H) (i.e. NADP+ and NADPH) play an essential role. Whereas the link to intracellular ATP availability has been studied extensively, much less is known about the relationship between actin cytoskeleton dynamics and intracellular redox state and NAD+-supply. Here, we focus on the role of nicotinamide phosphoribosyltransferase (NAMPT), found in extracellular form as a cytokine and growth factor, and in intracellular form as one of the key enzymes for the production of NAD+ in macrophages. Inhibition of NAD+ salvage synthesis by the NAMPT-specific drug FK866 caused a decrease in cytosolic NAD+ levels in RAW 264.7 and Maf-DKO macrophages and led to significant downregulation of the glycolytic flux without directly affecting cell viability, proliferation, ATP production capacity or mitochondrial respiratory activity. Concomitant with these differential metabolic changes, the capacity for phagocytic ingestion of particles and also substrate adhesion of macrophages were altered. Depletion of cytoplasmic NAD+ induced cell-morphological changes and impaired early adhesion in phagocytosis of zymosan particles as well as spreading performance. Restoration of NAD+ levels by NAD+, NMN, or NADP+ supplementation reversed the inhibitory effects of FK866. We conclude that direct coupling to local, actin-based, cytoskeletal dynamics is an important aspect of NAD+’s cytosolic role in the regulation of morphofunctional characteristics of macrophages.

Endogenous NAMPT dampens chemokine expression and apoptotic responses in stressed tubular cells

Diabetic nephropathy (DN) is the most common cause of end-stage renal disease and identification of new therapeutic targets is needed. Nicotinamide phosphoribosyltransferase (NAMPT) is both an extracellular and intracellular protein. Circulating NAMPT is increased in diabetics and in chronic kidney disease patients. The role of NAMPT in renal cell biology is poorly understood. NAMPT mRNA and protein were increased in the kidneys of rats with streptozotocin-induced diabetes. Immunohistochemistry localized NAMPT to glomerular and tubular cells in diabetic rats. The inflammatory cytokine TNFα increased NAMPT mRNA, protein and NAD production in cultured kidney human tubular cells. Exogenous NAMPT increased the mRNA expression of chemokines MCP-1 and RANTES. The NAMPT enzymatic activity inhibitor FK866 prevented these effects. By contrast, FK866 boosted TNFα-induced expression of MCP-1 and RANTES mRNA and endogenous NAMPT targeting by siRNA also had a proinflammatory effect. Furthermore, FK866 promoted tubular cell apoptosis in an inflammatory milieu containing the cytokines TNFα/IFNγ. In an inflammatory environment FK866 promoted tubular cell expression of the lethal cytokine TRAIL. These data are consistent with a role of endogenous NAMPT activity as an adaptive, protective response to an inflammatory milieu that differs from the proinflammatory activity of exogenous NAMPT. Thus, disruption of endogenous NAMPT function in stressed cells promotes tubular cell death and chemokine expression. This information may be relevant for the design of novel therapeutic strategies in DN.

Abstract 1871: Targeting nicotinamide phosphoribosyltransferase (NAMPT) in cancer therapy.

Abstract Nicotinamide adenine dinucleotide (NAD) metabolism has been emerged as a new target pathway in developing new cancer therapies. NAD has principal two functions in cells: (i) cofactor in redox reactions and (ii) substrate of several classes of NAD-dependent enzymes (i.e. PARPs, sirtuins). When NAD is a redox carrier, its not consumed by cells, however NAD-utilizing enzymes degrade NAD, inducing a decrease of the intracellular NAD pool. Therefore, to re-establish NAD levels in cells, the so called “NAD salvage pathway” exists. In this pathway, nicotinamide phosphoribosyltransferase (NAMPT) plays a crucial role; this enzyme is able to convert nicotinamide (Nam), released by NAD-dependent enzymes, into nicotinamide mononucleotide (NMN), which is finally converted to NAD by NMNAT. Different expression and activity of NAMPT have been correlated with a number of pathologies, and cancer is not an exception. For example, NAMPT has been found up-regulated in several types of cancer. To date, two potent NAMPT inhibitors (FK866 and CHS828) have been discovered and are now in phase I and II of trials in different types of solid and non-solid cancers. However, the results of the trials are still unpublished. Moreover, NAMPT has been also described as a cytokine, also called visfatin, released by adipocytes and several types of activated immune cells. However the function of visfatin and the possible release of this cytokine by cancer cells are still unknown. We have investigated (i) the action of NAMPT inhibitors in two different types of cancer (neuroblastoma and melanoma) that differ in NAMPT expression and (ii) the contribution of extracellular form of NAMPT (visfatin) in tumour. We found a positive correlation between NAMPT expression and responsiveness to NAMPT inhibitors. In particular neuroblastoma cells, which express normal levels of NAMPT, are sensitive to FK866, contrary melanoma cells, which over-expressed NAMPT are refractory to FK866 treatment. Therefore, these data may suggest that in melanoma cells NAMPT may have not only an enzymatic activity but may have another function. We found that these cells are able to release NAMPT in a time-dependent manner, suggesting that NAMPT could act also as a cytokine in melanoma cell culture. Since cytokines are involved in inflammation, and that inflammation is a critical component of tumour progression, we decided to investigate the possible role of NAMPT and visfatin in tumour-related inflammation. Our preliminary results show that NAMPT altered the activity of myeloid-derived suppressor cells (MDSC), a heterogeneous population of early myeloid progenitors that facilitate tumour progression. Our results could be a starting point for future direction in targeting NAMPT to interfere with tumour-related inflammation. Citation Format: Cristina Travelli, Sara Morlacchi, Antonio Caldarelli, Antonio Sica, Armando A. Genazzani. Targeting nicotinamide phosphoribosyltransferase (NAMPT) in cancer therapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1871. doi:10.1158/1538-7445.AM2013-1871 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Abstract 5146: Nicotinamide phosphoribosyl transferase (NAMPT) is over-expressed in Melanoma

Abstract NAD is an essential coenzyme involved in numerous metabolic pathways and it has been demonstrated that a number of signalling pathways bring about its consumption. Different pathways leading to the formation of NAD are present in cells. Nicotinamide phosphoribosyl transferase (NAMPT), which forms nicotinamide mononucleotide (NMN) from nicotinamide (NM) and PRPP, plays a crucial role in cells to re-use nicotinamide released by NAD-metabolizing enzymes. Moreover, NAMPT has also been described as a cytokine released by immune cells and adipocytes, however the role of NAMPT in the extracellular space is still unclear. The link between NAMPT and cancer is rapidly strengthening. NAMPT has been shown to be involved in angiogenesis and to be up-regulated in a number of solid tumours. Moreover, an important role in tumorigenesis has been postulated for a number of NAD-utilizing enzymes and inhibitors of NAMPT, named FK866 and CHS 828 have entered clinical trails for cancer treatment. In particular, FK866 has entered phase II trial for metastatic melanoma. The aim of our work was to determine the role of NAMPT in melanoma progression and the possibility to use NAMPT inhibitors as anti-cancer agents in melanoma. We investigated the expression of NAMPT in normal nevi, dysplastic nevi and melanoma human samples. Surprisingly, in all melanoma samples and in dysplastic nevi NAMPT is over-expressed, suggesting a possible contribution of this enzyme in melanoma progression. To confirm this data, we investigated the expression of NAMPT in six different melanoma cell lines. All melanoma cells show high levels of NAMPT expression compared to melanocytes. To test if the inhibition of NAMPT was able to decrease melanoma cells viability, we capitalize the action of FK866. However, only one to six melanoma cell line is sensitive to FK866 treatment. To understand why melanoma cells are insensitive to NAMPT inhibition, we investigate MDR expression and the possibility that NAMPT is mutated. Unfortunately, verapamil was not able to increase the sensitivity to FK866 and NAMPT is not mutated in all melanoma cell lines tested, moreover the treatment with FK866 is able to decrease the intracellular NAD level, suggesting that this agent is able to enter cells but not to induce cell death. As NAMPT was described also as a cytokine, we speculate the possibility that melanoma cells are able to release NAMPT in the extracellular space. Indeed, in starvation condition NAMPT is released by melanoma cells in a time-dependent manner. In conclusion, we have demonstrated that NAMPT is over-expressed in human melanoma samples and in melanoma cells, however NAMPT inhibition is not able to affect melanoma cells growth and viability, suggesting that NAMPT up-regulation does not correlate with a pharmacological response. Moreover, NAMPT is released by melanoma cells as a cytokine, we can speculate that NAMPT has a role in the angiogenic process of melanoma progression Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5146. doi:1538-7445.AM2012-5146

Intracellular Nicotinamide Phosphoribosyltransferase Protects against Hepatocyte Apoptosis and Is Down-Regulated in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in Western and non-Western countries, but its pathogenesis is not fully understood. Based on the role of nicotinamide phosphoribosyltransferase (NAMPT) in fat and glucose metabolism and cell survival, we hypothesized a role for NAMPT/visfatin in the pathogenesis of NAFLD-related disease. We conducted clinical studies at a referral medical center in well-characterized NAFLD patients (n = 58) and healthy controls (n = 27). In addition we performed experimental in vitro studies in hepatocytes. We examined 1) the hepatic and systemic expression of NAMPT/visfatin in patients with NAFLD and control subjects, 2) the hepatic regulation of NAMPT/visfatin, and 3) the effect of NAMPT/visfatin on hepatocyte apoptosis. Our main findings were as follows. 1) Patients with NAFLD had decreased NAMPT/visfatin expression both systemically in serum and within the hepatic tissue, with no difference between simple steatosis and nonalcoholic steatohepatitis. 2) By studying the hepatic regulation of NAMPT/visfatin in wild-type and peroxisome proliferators-activated receptor (PPAR)alpha(-/-) mice as well as in hepatocytes, we showed that PPARalpha activation and glucose may be involved in the down-regulation of hepatic NAMPT/visfatin expression in NAFLD. 4) Within the liver, NAMPT/visfatin was located to hepatocytes, and our in vitro studies showed that NAMPT/visfatin exerts antiapoptotic effects in these cells, involving enzymatic synthesis of nicotinamide adenine dinucleotide. Based on these findings, we suggest a role for decreased NAMPT/visfatin levels in hepatocyte apoptosis in NAFLD-related disease.