Inhibitors of nicotinamide phosphoribosyltransferase have recently been validated as therapeutic targets in leukemia, but the mechanism of leukemogenic transformation downstream of this enzyme is unclear.
Design and Methods
Here, we evaluated whether nicotinamide phosphoribosyltransferase’s effects on aberrant proliferation and survival of myeloid leukemic cells are dependent on sirtuin and delineated the downstream signaling pathways operating during this process.
Results
We identified significant upregulation of sirtuin 2 and nicotinamide phosphoribosyltransferase levels in primary acute myeloid leukemia blasts compared to in hematopoietic progenitor cells from healthy individuals. Importantly, specific inhibition of nicotinamide phosphoribosyltransferase or sirtuin 2 significantly reduced proliferation and induced apoptosis in human acute myeloid leukemia cell lines and primary blasts. Intriguingly, we found that protein kinase B/AKT could be deacetylated by nicotinamide phosphoribosyltransferase and sirtuin 2. The anti-leukemic effects of the inhibition of nicotinamide phosphoribosyltransferase or sirtuin 2 were accompanied by acetylation of protein kinase B/AKT with subsequent inhibition by dephosphorylation. This leads to activation of glycogen synthase kinase-3 β via diminished phosphorylation and, ultimately, inactivation of β-catenin by phosphorylation.
Conclusions
Our results provide strong evidence that nicotinamide phosphoribosyltransferase and sirtuin 2 participate in the aberrant proliferation and survival of leukemic cells, and suggest that the protein kinase B/AKT/ glycogen synthase kinase-3 β/β-catenin pathway is a target for inhibition of nicotinamide phosphoribosyltransferase or sirtuin 2 and, thereby, leukemia cell proliferation. 相似文献
Visfatin, a newly discovered adipocytokine, is a pro-inflammatory cytokine. This study aimed to evaluate the predictive value of visfatin on prognosis of patients with upper tract urothelial carcinoma. One-hundred and five patients (median age=64, range=24-84 years) were included in this study. Visfatin expression in upper tract urothelial carcinoma tissues was analyzed by immunohistochemistry. Visfatin expression was correlated with clinicopathologic variables using the χ2 test. The prognostic value of visfatin for recurrence-free and cancer-specific survival was evaluated by Kaplan-Meier estimates, and the significance of differences between curves was evaluated by the log-rank test. Cox regression model was also used to evaluate the hazard ratios of visfatin on survival. High visfatin expression in upper tract urothelial carcinoma tissues was significantly correlated with tumor stage (P=0.001), grade (P=0.007) and p53 expression (P=0.07). High visfatin expression was associated with poor recurrence-free and cancer-specific survival. Cox regression analysis also revealed that visfatin is an independent predictor of recurrence-free (HR=3.22, P=0.009) and cancer-specific survival (HR=5.74, P=0.023). Our findings indicated that higher visfatin expression is a potential biomarker to predict patient survival. Further study is necessary to investigate the role of visfatin in the carcinogenesis of upper tract urothelial carcinoma. 相似文献
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. 相似文献