Nicotinamide phosphoribosyltransferase promotes epithelial-to-mesenchymal transition as a soluble factor independent of its enzymatic activity

Nicotinamide adenine dinucleotide biosynthesis promotes liver regeneration

The regenerative capacity of the liver is essential for recovery from surgical resection or injuries induced by trauma or toxins. During liver regeneration, the concentration of nicotinamide adenine dinucleotide (NAD) falls, at least in part due to metabolic competition for precursors. To test whether NAD availability restricts the rate of liver regeneration, we supplied nicotinamide riboside (NR), an NAD precursor, in the drinking water of mice subjected to partial hepatectomy. NR increased DNA synthesis, mitotic index, and mass restoration in the regenerating livers. Intriguingly, NR also ameliorated the steatosis that normally accompanies liver regeneration. To distinguish the role of hepatocyte NAD levels from any systemic effects of NR, we generated mice overexpressing nicotinamide phosphoribosyltransferase, a rate-limiting enzyme for NAD synthesis, specifically in the liver. Nicotinamide phosphoribosyltransferase overexpressing mice were mildly hyperglycemic at baseline and, similar to mice treated with NR, exhibited enhanced liver regeneration and reduced steatosis following partial hepatectomy. Conversely, mice lacking nicotinamide phosphoribosyltransferase in hepatocytes exhibited impaired regenerative capacity that was completely rescued by administering NR.

CONCLUSION

NAD availability is limiting during liver regeneration, and supplementation with precursors such as NR may be therapeutic in settings of acute liver injury. (Hepatology 2017;65:616-630).

Novel p21-Activated Kinase 4 (PAK4) Allosteric Modulators Overcome Drug Resistance and Stemness in Pancreatic Ductal Adenocarcinoma

The p21-activated kinase 4 (PAK4) is a key downstream effector of the Rho family GTPases and is found to be overexpressed in pancreatic ductal adenocarcinoma (PDAC) cells but not in normal human pancreatic ductal epithelia (HPDE). Gene copy number amplification studies in PDAC patient cohorts confirmed PAK4 amplification making it an attractive therapeutic target in PDAC. We investigated the antitumor activity of novel PAK4 allosteric modulators (PAM) on a panel of PDAC cell lines and chemotherapy-resistant flow-sorted PDAC cancer stem cells (CSC). The toxicity and efficacy of PAMs were evaluated in multiple subcutaneous mouse models of PDAC. PAMs (KPT-7523, KPT-7189, KPT-8752, KPT-9307, and KPT-9274) show antiproliferative activity in vitro against different PDAC cell lines while sparing normal HPDE. Cell growth inhibition was concurrent with apoptosis induction and suppression of colony formation in PDAC. PAMs inhibited proliferation and antiapoptotic signals downstream of PAK4. Co-immunoprecipitation experiments showed disruption of PAK4 complexes containing vimentin. PAMs disrupted CSC spheroid formation through suppression of PAK4. Moreover, PAMs synergize with gemcitabine and oxaliplatin in vitro KPT-9274, currently in a phase I clinical trial (clinicaltrials.gov; NCT02702492), possesses desirable pharmacokinetic properties and is well tolerated in mice with the absence of any signs of toxicity when 200 mg/kg daily is administered either intravenously or orally. KPT-9274 as a single agent showed remarkable antitumor activity in subcutaneous xenograft models of PDAC cell lines and CSCs. These proof-of-concept studies demonstrated the antiproliferative effects of novel PAMs in PDAC and warrant further clinical investigations. Mol Cancer Ther; 16(1); 76-87. ©2016 AACR.

Visfatin triggers the in vitro migration of osteosarcoma cells via activation of NF-κB/IL-6 signals

Pulmonary metastasis is the major challenge for clinical treatment of osteosarcoma patients. Recent studies indicated that visfatin, a 52kDa adipocytokine, can trigger the cell motility of various cancers, while its role in the progression of osteosarcoma remains not clear. Our present study revealed that visfatin can significantly promote the in vitro migration and invasion of osteosarcoma MG-63 and HOS cells and up regulate the expression of matrix metalloproteinase-2 (MMP-2) and fibronectin (FN). Furthermore, visfatin treatment also increased the expression of IL-6 in both MG-63 and HOS cells via a time dependent manner, while anti-IL-6 antibody can significantly attenuate visfatin induced cell invasion and up regulation of MMP-2 and FN. It suggested that up regulation of IL-6 mediated visfatin induced in vitro motility of osteosarcoma cells. Visfatin treatment can increase the phosphorylation of both p65 and ERK1/2 in MG-63 and HOS cells, while only the inhibitor of NF-κB, BAY 11-7082, can abolish visfatin induced up regulation of IL-6. BAY 11-7082 also attenuated visfatin induced upregulation of MMP-2 and FN in MG-63 cells. Western blot analysis revealed that visfatin treatment can significantly increase the phosphorylation of IκBα and IKKβ in MG-63 cells. ACHP, the inhibitor of IKK-β, blocked visfatin induced expression of IL-6 mRNA in both MG-63 and HOS cells. Collectively, our data suggested that visfatin can increase the motility of osteosarcoma cells via up regulation of NF-κB/IL-6 signals. It indicated that visfatin might be a potential therapeutic target of osteosarcoma treatment.

Visfatin stimulates endometrial cancer cell proliferation via activation of PI3K/Akt and MAPK/ERK1/2 signalling pathways

OBJECTIVE

Endometrial carcinoma is one of the most common malignancies of the female reproductive system, but the aetiology and pathogenesis are not well understood, although adipokines such as visfatin may be involved. Our study provides insight into the mechanism underlying the tumorigenic effects of visfatin in endometrial carcinoma.

METHODS

We investigated the effect of visfatin on endometrial carcinoma cell proliferation, cell cycle, and apoptosis using well-differentiated Ishikawa cells and poorly differentiated KLE cells. We also assessed the effect of visfatin on tumour growth in vivo.

RESULTS

Visfatin stimulated the proliferation of both Ishikawa and KLE cells, and visfatin treatment promoted G1/S phase progression and inhibited endometrial carcinoma cell apoptosis. Visfatin promoted endometrial carcinoma tumour growth in BALB/c-nu mice. Transplanted tumour tissues from an endometrial carcinoma mouse model were analysed using immunohistochemical staining, which revealed much stronger positive signals for Ki-67 with over-abundant visfatin. Western blot analysis revealed that insulin receptor (IR), insulin receptor substrate (IRS)1/2 and key components of the phosphoinositide 3-kinase (PI3K)/AKT and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK)1/2 signalling pathways were highly expressed in endometrial carcinoma cells exposed to visfatin. Treated cells showed increased C-MYC and cyclin D1 and reduced caspase-3 expression. The effects of visfatin on proliferation and apoptosis were abrogated by treatment with the PI3K inhibitor LY294002 and MEK inhibitor U0126.

CONCLUSIONS

Visfatin promotes the malignant progression of endometrial carcinoma via activation of IR and PI3K/Akt and MAPK/ERK signalling. Visfatin may serve as a therapeutic target in the treatment of endometrial carcinoma.

Visfatin Triggers the Cell Motility of Non-Small Cell Lung Cancer via Up-Regulation of Matrix Metalloproteinases

High levels of visfatin are correlated with worse clinical prognosis of various cancers. Still, the effects and mechanisms of visfatin on progression of non-small cell lung cancer (NSCLC) remain unclear. This study revealed that plasma levels of visfatin in patients with NSCLC (585 ± 287 pg/ml) were significantly (p < 0.01) higher than those in healthy people (142 ± 61.1 pg/ml). The high level of plasma visfatin was found to be significantly (p < 0.05) correlated with TNM stage, lymph node metastasis and distant metastasis. Visfatin treatment can increase the migration and invasion of NSCLC cells via up-regulation of metalloproteinase-2 (MMP-2) and MMP-9. Both si-MMP-2 and si-MMP-9 attenuated visfatin-induced migration of NSCLC cells. The inhibitor of NF-κB, while not ERK1/2, p38-MAPK or PI3K/Akt, can significantly abolish visfatin-induced migration of A549 cells and up-regulation of MMP-2 and MMP-9. Furthermore, visfatin can increase the phosphorylation of IκBα and p65 and the transcription activities of NF-κB in NSCLC cells. ACHP, the inhibitor of IKK-β, blocked visfatin-induced activation of p65 and up-regulation of MMP-2 and MMP-9. Collectively, our data revealed that visfatin can trigger the in vitro migration and invasion of NSCLC cells via up-regulation of MMPs through activation of NF-κB.

Nicotinamide phosphoribosyltransferase (Nampt) in carcinogenesis: new clinical opportunities

INTRODUCTION

Nicotinamide phosphoribosyltransferase (Nampt) is the rate-limiting enzyme that catalyzes the first step in the mammalian nicotinamide adenine dinucleotide (NAD) salvage pathway. Aberrant NAD metabolism was associated with oncogenic signal transduction, suggesting the critical roles of Nampt in tumorigenesis and metastasis. Additionally, Nampt can be secreted out of the cell, and this extracellular form of Nampt (eNampt) was shown to induce inflammation and angiogenesis due to its cytokine activity, which may also be involved in carcinogenesis.

AREAS COVERED

This article reviews recent advances in the studies of Nampt in carcinogenesis, with a special highlight on Nampt inhibitors and future clinical application, including cancer diagnosis, prognosis and therapy. Expert commentary: Nampt not only maintains the balance of cellular metabolism, but also has a profound influence on multiple aspects of carcinogenesis. Therefore, elucidation of these mechanisms opens the door for future clinical applications targeting this protein. Additional studies are needed to address important questions including the relationship between extracellular Nampt and carcinogenesis.

Increased plasma nicotinamide phosphoribosyltransferase is associated with a hyperproliferative phenotype and restrains disease progression in MPN-associated myelofibrosis

Myeloproliferative neoplasm (MPN)-associated myelofibrosis is a clonal, neoplastic disorder of the hematopoietic stem cells, in which inflammation and immune dysregulation play an important role. Extracellular nicotinamide phosphoribosyltransferase (eNAMPT), also known as visfatin, is a cytokine implicated in a number of inflammatory and neoplastic diseases. Here plasma levels of eNAMPT in patients with MPN-associated myelofibrosis and their effects on disease phenotype and outcomes were examined. The concordance of eNAMPT levels with the marker of general inflammation high-sensitivity C-reactive protein (hs-CRP) was also studied. A total of 333 MPN-associated myelofibrosis patients (187 males and 146 females) and 31 age- and gender-matched normal-weight healthy subjects were enrolled in the study main body. Levels of eNAMPT and hs-CRP were simultaneously assayed in 209 MPN-associated myelofibrosis patients. Twenty-four polycythemia vera or essential thrombocythemia patients were used as controls. eNAMPT was over expressed in MPN-associated myelofibrosis, and eNAMPT expression was correlated with higher white blood cell count, higher hemoglobin, and higher platelet count, suggesting that eNAMPT is an indispensable permissive agent for myeloproliferation of MPN-associated myelofibrosis. The lack of correlation between eNAMPT and hs-CRP revealed that eNAMPT in MPN-associated myelofibrosis does not behave as a canonical inflammatory cytokine. In addition, higher levels of eNAMPT predicted longer time to blast transformation, and protected against progression toward thrombocytopenia and large splenomegaly. In conclusion, in MPN-associated myelofibrosis high levels of eNAMPT mark the myeloproliferative potential and, at variance with a high number of cancers, are protective against disease progression. Am. J. Hematol. 91:709-713, 2016. © 2016 Wiley Periodicals, Inc.

Extracellular nicotinamide phosphoribosyltransferase, a new cancer metabokine

In this review, we focus on the secreted form of nicotinamide phosphoribosyltransferase (NAMPT); extracellular NAMPT (eNAMPT), also known as pre-B cell colony-enhancing factor or visfatin. Although intracellular NAMPT is a key enzyme in controlling NAD metabolism, eNAMPT has been reported to function as a cytokine, with many roles in physiology and pathology. Circulating eNAMPT has been associated with several metabolic and inflammatory disorders, including cancer. Because cytokines produced in the tumour micro-environment play an important role in cancer pathogenesis, in part by reprogramming cellular metabolism, future improvements in cancer immunotherapy will require a better understanding of the crosstalk between cytokine action and tumour biology. In this review, the knowledge of eNAMPT in cancer will be discussed, focusing on its immunometabolic function as a metabokine, its secretion, its mechanism of action and possible roles in the cancer micro-environment.

Visfatin is involved in promotion of colorectal carcinoma malignancy through an inducing EMT mechanism

Increasing evidences suggested visfatin, a newly discovered obesity-induced adipocytokine, is involved in promotion of cancer malignancy and correlated with worse clinical prognosis. While its effects and mechanisms on progression of colorectal cancer (CRC) remain unclear. Our clinical data show that visfatin protein is over expressed, positive associated with lymph node metastasis, high-grade tumor, and poor prognosis in 87 CRC patients. The levels of plasma visfatin are significantly upregulated in Stage IV colon cancer. Visfatin can significantly promote the in vitro migration and invasion of CRC cells via induction epithelial mesenchymal transition (EMT). It can increase the expression and nuclear translocation of Snail, a key transcription factor in regulating EMT. While silencing of Snail attenuates visfatin induced EMT. Further studies reveal visfatin can inhibit the association of Snail with GSK-3β and subsequently suppress ubiquitylation of Snail. In addition, visfatin can increase the expression and nuclear translocation of β-catenin, elevate its binding with Snail promoter, and then increase the transcription of Snail. While inhibitor of PI3K/Akt, LY294002, abolishes visfatin induced up regulation of Snail, Vimentin (Vim), β-catenin, and phosphorylated GSK-3β. In summary, our data suggest that increased expression of visfatin are associated with a more aggressive phenotype of CRC patients. It can trigger the EMT of CRC cells via Akt/GSK-3β/β-catenin signals.

Evaluation of Adipokines, Inflammatory Markers, and Sex Hormones in Simple and Complex Breast Cysts' Fluid

Objective. The aim of the study was to analyze the association between levels of adipokines in the breast cyst fluid and in the circulation in relation to the type of cysts. Material and Measurements. A cross-sectional study involved 86 women with breast cysts (42 with simple cysts and 44 with complex cysts). Plasma and breast cyst fluid leptin, adiponectin, visfatin/NAMPT, resistin, TNF-α, and IL-6 levels, in addition to serum levels of estradiol, progesterone and prolactin, and anthropometric parameters and body composition (by bioimpedance method), were measured. Results. The levels of leptin, adiponectin, and resistin were significantly lower in breast cyst fluid than in plasma regardless of the cyst type. Contrarily, the levels of visfatin/NAMPT and TNF-α were significantly increased, and IL-6 levels were similar in the breast cyst fluid and plasma in both study groups. There was no correlation between corresponding levels of leptin, adiponectin, resistin, visfatin/NAMPT, TNF-α, and IL-6 in breast cyst fluid and plasma. Conclusions. Higher levels of visfatin/NAMPT and TNF-α in the fluid from simple and complex breast cysts than in plasma suggest that their local production is related to inflammation.

Extracellular Visfatin-Promoted Malignant Behavior in Breast Cancer Is Mediated Through c-Abl and STAT3 Activation

PURPOSE

Visfatin is an adipocytokine involved in cellular metabolism, inflammation, and cancer. This study investigated the roles of extracellular visfatin in breast cancer, and explored underlying mechanisms in clinical and experimental settings.

EXPERIMENTAL DESIGN

Associations of serum visfatin with clinicopathologic characteristics and patient survival were assessed with Cox regression models and Kaplan-Meier analyses. Effects of extracellular visfatin on cultured breast cancer cells were examined, followed by in vivo investigation of tumor growth and metastasis in xenograft animal models. Imatinib and Stattic were used to inhibit c-Abl and STAT3 activation, respectively.

RESULTS

Breast cancer patients with high serum visfatin levels were associated with advanced tumor stage, increased tumor size and lymph node metastasis, and poor survival. Elevated phosphorylation of c-Abl and STAT3 in breast tumor tissues were correlated with high serum visfatin levels in patients. Visfatin-promoted in vitro cell viability and metastatic capability were suppressed by imatinib (c-Abl inhibitor) and Stattic (STAT3 inhibitor). Increased in vivo cell invasiveness was observed in zebrafish xenografted with visfatin-pretreated breast cancer cells. Tumor growth and lung metastasis occurred in visfatin-administered mice xenografted with breast cancer cells. Tail vein-injected mice with visfatin-pretreated breast cancer cells showed increased lung metastasis, which was suppressed by imatinib.

CONCLUSIONS

Serum visfatin levels in breast cancer patients reveal potential prognostic values, and our findings that visfatin promoted breast cancer through activation of c-Abl and STAT3 may provide an important molecular basis for future design of targeted therapies that take into account different serum visfatin levels in breast cancer. Clin Cancer Res; 22(17); 4478-90. ©2016 AACR.

EIF2A-dependent translational arrest protects leukemia cells from the energetic stress induced by NAMPT inhibition

Background

Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in NAD⁺ biosynthesis from nicotinamide, is one of the major factors regulating cancer cells metabolism and is considered a promising target for treating cancer. The prototypical NAMPT inhibitor FK866 effectively lowers NAD⁺ levels in cancer cells, reducing the activity of NAD⁺-dependent enzymes, lowering intracellular ATP, and promoting cell death.

Results

We show that FK866 induces a translational arrest in leukemia cells through inhibition of MTOR/4EBP1 signaling and of the initiation factors EIF4E and EIF2A. Specifically, treatment with FK866 is shown to induce 5′AMP-activated protein kinase (AMPK) activation, which, together with EIF2A phosphorylation, is responsible for the inhibition of protein synthesis. Notably, such an effect was also observed in patients’ derived primary leukemia cells including T-cell Acute Lymphoblastic Leukemia. Jurkat cells in which AMPK or LKB1 expression was silenced or in which a non-phosphorylatable EIF2A mutant was ectopically expressed showed enhanced sensitivity to the NAMPT inhibitor, confirming a key role for the LKB1-AMPK-EIF2A axis in cell fate determination in response to energetic stress via NAD⁺ depletion.

Conclusions

We identified EIF2A phosphorylation as a novel early molecular event occurring in response to NAMPT inhibition and mediating protein synthesis arrest. In addition, our data suggest that tumors exhibiting an impaired LBK1- AMPK- EIF2A response may be especially susceptible to NAMPT inhibitors and thus become an elective indication for this type of agents.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1845-1) contains supplementary material, which is available to authorized users.

APO866 Increases Antitumor Activity of Cyclosporin-A by Inducing Mitochondrial and Endoplasmic Reticulum Stress in Leukemia Cells

PURPOSE

The nicotinamide phosphoribosyltransferase (NAMPT) inhibitor, APO866, has been previously shown to have antileukemic activity in preclinical models, but its cytotoxicity in primary leukemia cells is frequently limited. The success of current antileukemic treatments is reduced by the occurrence of multidrug resistance, which, in turn, is mediated by membrane transport proteins, such as P-glycoprotein-1 (Pgp). Here, we evaluated the antileukemic effects of APO866 in combination with Pgp inhibitors and studied the mechanisms underlying the interaction between these two types of agents.

EXPERIMENTAL DESIGN

The effects of APO866 with or without Pgp inhibitors were tested on the viability of leukemia cell lines, primary leukemia cells (AML, n = 6; B-CLL, n = 19), and healthy leukocytes. Intracellular nicotinamide adenine dinucleotide (NAD(+)) and ATP levels, mitochondrial transmembrane potential (ΔΨ(m)), markers of apoptosis and of endoplasmic reticulum (ER) stress were evaluated.

RESULTS

The combination of APO866 with Pgp inhibitors resulted in a synergistic cytotoxic effect in leukemia cells, while sparing normal CD34(+) progenitor cells and peripheral blood mononuclear cells. Combining Pgp inhibitors with APO866 led to increased intracellular APO866 levels, compounded NAD(+) and ATP shortage, and induced ΔΨ(m) dissipation. Notably, APO866, Pgp inhibitors and, to a much higher extent, their combination induced ER stress and ER stress inhibition strongly reduced the activity of these treatments.

CONCLUSIONS

APO866 and Pgp inhibitors show a strong synergistic cooperation in leukemia cells, including acute myelogenous leukemia (AML) and B-cell chronic lymphocytic leukemia (B-CLL) samples. Further evaluations of the combination of these agents in clinical setting should be considered.

Physiological and pathophysiological roles of NAMPT and NAD metabolism

Nicotinamide phosphoribosyltransferase (NAMPT) is a regulator of the intracellular nicotinamide adenine dinucleotide (NAD) pool. NAD is an essential coenzyme involved in cellular redox reactions and is a substrate for NAD-dependent enzymes. In various metabolic disorders and during ageing, levels of NAD are decreased. Through its NAD-biosynthetic activity, NAMPT influences the activity of NAD-dependent enzymes, thereby regulating cellular metabolism. In addition to its enzymatic function, extracellular NAMPT (eNAMPT) has cytokine-like activity. Abnormal levels of eNAMPT are associated with various metabolic disorders. NAMPT is able to modulate processes involved in the pathogenesis of obesity and related disorders such as nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) by influencing the oxidative stress response, apoptosis, lipid and glucose metabolism, inflammation and insulin resistance. NAMPT also has a crucial role in cancer cell metabolism, is often overexpressed in tumour tissues and is an experimental target for antitumour therapies. In this Review, we discuss current understanding of the functions of NAMPT and highlight progress made in identifying the physiological role of NAMPT and its relevance in various human diseases and conditions, such as obesity, NAFLD, T2DM, cancer and ageing.

Regulative Effect of Nampt on Tumor Progression and Cell Viability in Human Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer disease. Here we examined Nampt expression in patients with CRC and the effect of Nampt on cell viability in CRC cells. Nampt protein was overexpressed in colorectal adenoma as well as colorectal carcinoma. The immunoreactive staining of Nampt was negative in the adjacent normal colorectal tissue, weak in colorectal adenoma, and strong in colorectal carcinoma, which may represent tumor progression. Further evaluation of clinical data showed that Nampt expression was not correlated with the clinicopathological characteristics of CRC. Additionally, our in vitro studies demonstrated that Nampt promotes CRC cell viability, whereas the Nampt inhibitor FK866 suppressed CRC cell viability, which was in concordance with the previous studies in other cancer cells. Treatment with Nampt-siRNA reduced the Nampt protein expression resulting in the inhibition of the cell viability of HCT116 and Caco2. Thus, the involvement of Nampt in cell growth indicates that Nampt may play an important role in colorectal tumorigenesis. As a consequence, our results suggest that Nampt may be considered as a progression marker of colorectal tumor and a potentially therapeutic target for the treatment of CRC.