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Liu Y, Zhang L, Wang L, Tang X, Wan S, Huang Q, Ran M, Shen H, Yang Y, Chiampanichayakul S, Tima S, Anuchapreeda S, Wu J. Targeting CD38/ ADP-ribosyl cyclase as a novel therapeutic strategy for identification of three potent agonists for leukopenia treatment. Pharmacol Res 2024; 200:107068. [PMID: 38232908 DOI: 10.1016/j.phrs.2024.107068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/24/2023] [Accepted: 01/08/2024] [Indexed: 01/19/2024]
Abstract
Leukopenia is the most common side effect of chemotherapy and radiotherapy. It potentially deteriorates into a life-threatening complication in cancer patients. Despite several agents being approved for clinical administration, there are still high incidences of pathogen-related disease due to a lack of functional immune cells. ADP-ribosyl cyclase of CD38 displays a regulatory effect on leukopoiesis and the immune system. To explore whether the ADP-ribosyl cyclase was a potential therapeutic target of leukopenia. We established a drug screening model based on an ADP-ribosyl cyclase-based pharmacophore generation algorithm and discovered three novel ADP-ribosyl cyclase agonists: ziyuglycoside II (ZGSII), brevifolincarboxylic acid (BA), and 3,4-dihydroxy-5-methoxybenzoic acid (DMA). Then, in vitro experiments demonstrated that these three natural compounds significantly promoted myeloid differentiation and antibacterial activity in NB4 cells. In vivo, experiments confirmed that the compounds also stimulated the recovery of leukocytes in irradiation-induced mice and zebrafish. The mechanism was investigated by network pharmacology, and the top 12 biological processes and the top 20 signaling pathways were obtained by intersecting target genes among ZGSII, BA, DMA, and leukopenia. The potential signaling molecules involved were further explored through experiments. Finally, the ADP-ribosyl cyclase agonists (ZGSII, BA, and DMA) has been found to regenerate microbicidal myeloid cells to effectively ameliorate leukopenia-associated infection by activating CD38/ADP-ribosyl cyclase-Ca2+-NFAT. In summary, this study constructs a drug screening model to discover active compounds against leukopenia, reveals the critical roles of ADP-ribosyl cyclase in promoting myeloid differentiation and the immune response, and provides a promising strategy for the treatment of radiation-induced leukopenia.
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Affiliation(s)
- Yuanzhi Liu
- Division of Clinical Microscopy, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; Department of Pharmacy, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan 646000, China; School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Linwei Zhang
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 611137, China
| | - Long Wang
- School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China; Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Xiaoqin Tang
- School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China; Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Shengli Wan
- Department of Pharmacy, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan 646000, China; School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Qianqian Huang
- School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China; Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Mei Ran
- School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China; Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Hongping Shen
- The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Yan Yang
- Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Sawitree Chiampanichayakul
- Division of Clinical Microscopy, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence in Pharmaceutical Nanotechnology, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Singkome Tima
- Division of Clinical Microscopy, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence in Pharmaceutical Nanotechnology, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Songyot Anuchapreeda
- Division of Clinical Microscopy, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence in Pharmaceutical Nanotechnology, Chiang Mai University, Chiang Mai 50200, Thailand.
| | - Jianming Wu
- School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan 646000, China; Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, Southwest Medical University, Luzhou, Sichuan 646000, China.
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Zhou H, Liu S, Zhang N, Fang K, Zong J, An Y, Chang X. Downregulation of Sirt6 by CD38 promotes cell senescence and aging. Aging (Albany NY) 2022; 14:9730-9757. [PMID: 36490326 PMCID: PMC9792202 DOI: 10.18632/aging.204425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/17/2022] [Indexed: 12/12/2022]
Abstract
Decreased nicotinamide adenine dinucleotide (NAD+) levels accompany aging. CD38 is the main cellular NADase. Cyanidin-3-O-glucoside (C3G), a natural inhibitor of CD38, is a well-known drug that extends the human lifespan. We investigated mechanisms of CD38 in cell senescence and C3G in antiaging. Myocardial H9c2 cells were induced to senescence with D-gal. CD38 siRNA, C3G and UBCS039 (a chemical activator of Sirt6) inhibited D-gal-induced senescence by reducing reactive oxygen species, hexokinase 2 and SA-β-galactosidase levels. These activators also stimulated cell proliferation and telomerase reverse transcriptase levels, while OSS-128167 (a chemical inhibitor of Sirt6) and Sirt6 siRNA exacerbated the senescent process. H9c2 cells that underwent D-gal-induced cell senescence increased CD38 expression and decreased Sirt6 expression; CD38 siRNA and C3G decreased CD38 expression and increased Sirt6 expression, respectively; and Sirt6 siRNA stimulated cell senescence in the presence of C3G and CD38 siRNA. In D-gal-induced acute aging mice, CD38 and Sirt6 exhibited increased and decreased expression, respectively, in myocardial tissues, and C3G treatment decreased CD38 expression and increased Sirt6 expression in the tissues. C3G also reduced IL-1β, IL-6, IL-17A, TNF-α levels and restored NAD+ and NK cell levels in the animals. We suggest that CD38 downregulates Sirt6 expression to promote cell senescence and C3G exerts an antiaging effect through CD38-Sirt6 signaling.
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Affiliation(s)
- Hongji Zhou
- Medical Research Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China,Department of Cardiovascular Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - Shihai Liu
- Medical Research Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - NanYang Zhang
- Medical Research Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - Kehua Fang
- Medical Research Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - Jinbao Zong
- Clinical Laboratory and Central Laboratory, The Affiliated Qingdao Hiser Hospital of Qingdao University, Qingdao, Shandong 266033, P.R. China
| | - Yi An
- Department of Cardiovascular Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - Xiaotian Chang
- Medical Research Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
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Zhao J, Guo Y, Li Q, Chen J, Niu D, Liu J. Reconstruction of a Cofactor Self-Sufficient Whole-Cell Biocatalyst System for Efficient Biosynthesis of Allitol from d-Glucose. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:3775-3784. [PMID: 35298165 DOI: 10.1021/acs.jafc.2c00440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The combined catalysis of glucose isomerase (GI), d-psicose 3-epimerase (DPEase), ribitol dehydrogenase (RDH), and formate dehydrogenase (FDH) provides a convenient route for the biosynthesis of allitol from d-glucose; however, the low catalytic efficiency restricts its industrial applications. Here, the supplementation of 0.32 g/L NAD+ significantly promoted the cell catalytic activity by 1.18-fold, suggesting that the insufficient intracellular NAD(H) content was a limiting factor in allitol production. Glucose dehydrogenase (GDH) with 18.13-fold higher activity than FDH was used for reconstructing a cofactor self-sufficient system, which was combined with the overexpression of the rate-limiting genes involved in NAD+ salvage metabolic flow to expand the available intracellular NAD(H) pool. Then, the multienzyme self-assembly system with SpyTag and SpyCatcher effectively channeled intermediates, leading to an 81.1% increase in allitol titer to 15.03 g/L from 25 g/L d-glucose. This study provided a facilitated strategy for large-scale and efficient biosynthesis of allitol from a low-cost substrate.
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Affiliation(s)
- Jingyi Zhao
- College of Light Industry and Food Engineering, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
| | - Yan Guo
- College of Light Industry and Food Engineering, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
| | - Qiufeng Li
- College of Light Industry and Food Engineering, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
| | - Jing Chen
- South Subtropical Agricultural Scientific Research Institute of Guangxi, Longzhou, Guangxi 532415, China
| | - Debao Niu
- College of Light Industry and Food Engineering, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
| | - Jidong Liu
- College of Light Industry and Food Engineering, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
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Wang H, Li S, Zhang G, Wu H, Chang X. Potential therapeutic effects of cyanidin-3-O-glucoside on rheumatoid arthritis by relieving inhibition of CD38+ NK cells on Treg cell differentiation. Arthritis Res Ther 2019; 21:220. [PMID: 31661005 PMCID: PMC6819496 DOI: 10.1186/s13075-019-2001-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 09/10/2019] [Indexed: 12/19/2022] Open
Abstract
Background CD38+ NK cells are overabundant in rheumatoid arthritis (RA). Cyanidin-3-O-glucoside (C3G) is an inhibitor of CD38. This study investigated the pathogenic role of CD38+ NK cells and the effect of C3G on RA. Methods Rats with bovine type II collagen-induced arthritis (CIA) were injected with C3G. RA synovial fibroblasts (RASFs) or mononuclear cells (MNCs) were cultured with C3G. MNCs were also cocultured with CD38+ NK cells following C3G pretreatment. Results C3G injection significantly alleviated CIA. C3G also significantly increased the level of interleukin (IL)-10 and the regulatory T (Treg) cell proportion, and it decreased the interleukin (IL)-6 and interferon (IFN)-γ levels and CD38+ NK cell proportion in rat peripheral blood and synovial fluid. Additionally, C3G significantly increased RASF apoptosis and decreased RASF proliferation and IL-6 production in the culture medium. Furthermore, C3G stimulated MNCs to increase IL-2 and IL-10 production and the Treg cell proportion, and it caused MNCs to decrease IL-6 and IFN-γ production and the CD38+ NK cell proportion. Although CD38+ NK cells significantly decreased the Treg cell proportion and IL-10 level in MNCs, CD38+ NK cells that had been pretreated with C3G increased the proportion of Treg cells and IL-10 levels and decreased the IL-6 and IFN-γ levels in the coculture. In CD38+ NK cells, C3G significantly increased Sirtuin 6 (Sirt6) expression and the tumor necrosis factor (TNF)-α level, and it decreased natural killer group 2D (NKG2D) expression and the IFN-γ level. However, when CD38+ NK cells were treated with Sirt6 siRNA, C3G did not change the NKG2D expression, the TNF-α level sharply decreased, and the IFN-γ level increased. When MNCs were cocultured with C3G-pretreated CD38+ NK cells in the presence of TNF-α and an anti-IFN-γ antibody, the IL-10+ Treg cell proportion significantly increased. When MNCs were cocultured with C3G-pretreated CD38+ NK cells in the presence of IFN-γ and an anti-TNF-α antibody, the IL-10+ Treg cell proportion sharply decreased. When CIA rats were injected with both C3G and the Sirt6 inhibitor OSS_128167, the rats exhibited joint inflammation and a low Treg cell proportion, but the CD38+ NK proportion was still low. Conclusion C3G has therapeutic effects on CIA and RA. C3G decreased the proportion of CD38+ cells, RASF proliferation, and proinflammatory cytokine secretion, and it increased the Treg cell proportion. C3G also elevated Sirt6 expression to suppress NKG2D expression, increase TNF-α secretion, and decrease IFN-γ secretion in CD38+ NK cells, which stimulates MNCs to differentiate into Treg cells. This study also demonstrates that the inhibition of Treg cell differentiation in MNCs by CD38+ NK cells is a potential cause of the immune imbalance in RA and CIA.
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Affiliation(s)
- Hongxing Wang
- Shandong Provincial Qianfoshan Hospital, Shandong University, Jingshi Road 16766, Jinan, 250014, Shandong, People's Republic of China
| | - Shutong Li
- Shandong Provincial Qianfoshan Hospital, Shandong University, Jingshi Road 16766, Jinan, 250014, Shandong, People's Republic of China
| | - Guoqing Zhang
- Medical Research Center of The Affiliated Hospital of Qingdao University, Wutaishan Road 1677, Qingdao, 266000, Shandong, People's Republic of China
| | - Hui Wu
- Shandong Provincial Qianfoshan Hospital, Shandong University, Jingshi Road 16766, Jinan, 250014, Shandong, People's Republic of China
| | - Xiaotian Chang
- Medical Research Center of The Affiliated Hospital of Qingdao University, Wutaishan Road 1677, Qingdao, 266000, Shandong, People's Republic of China. .,Qingdao Engineering Technology Center For Major Disease Marker, Wutaishan Road 1677, Qingdao, 266000, Shandong, People's Republic of China.
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Deshpande DA, Guedes AGP, Lund FE, Subramanian S, Walseth TF, Kannan MS. CD38 in the pathogenesis of allergic airway disease: Potential therapeutic targets. Pharmacol Ther 2016; 172:116-126. [PMID: 27939939 DOI: 10.1016/j.pharmthera.2016.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
CD38 is an ectoenzyme that catalyzes the conversion of β-nicotinamide adenine dinucleotide (β-NAD) to cyclic adenosine diphosphoribose (cADPR) and adenosine diphosphoribose (ADPR) and NADP to nicotinic acid adenine dinucleotide phosphate (NAADP) and adenosine diphosphoribose-2'-phosphate (ADPR-P). The metabolites of NAD and NADP have roles in calcium signaling in different cell types including airway smooth muscle (ASM) cells. In ASM cells, inflammatory cytokines augment CD38 expression and to a greater magnitude in cells from asthmatics, indicating a greater capacity for the generation of cADPR and ADPR in ASM from asthmatics. CD38 deficient mice develop attenuated airway responsiveness to inhaled methacholine following allergen sensitization and challenge compared to wild-type mice indicating its potential role in asthma. Regulation of CD38 expression in ASM cells is achieved by mitogen activated protein kinases, specific isoforms of PI3 kinases, the transcription factors NF-κB and AP-1, and post-transcriptionally by microRNAs. This review will focus on the role of CD38 in intracellular calcium regulation in ASM, contribution to airway inflammation and airway hyperresponsiveness in mouse models of allergic airway inflammation, the transcriptional and post-transcriptional mechanisms of regulation of expression, and outline approaches to inhibit its expression and activity.
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Affiliation(s)
| | - Alonso G P Guedes
- Department of Veterinary Clinical Sciences, University of Minnesota at Twin Cities, USA
| | - Frances E Lund
- Department of Microbiology, University of Alabama at Birmingham, USA
| | | | - Timothy F Walseth
- Department of Pharmacology, University of Minnesota at Twin Cities, USA
| | - Mathur S Kannan
- Department of Veterinary and Biomedical Sciences, University of Minnesota at Twin Cities, USA.
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Intracellular NAD+ levels are associated with LPS-induced TNF-α release in pro-inflammatory macrophages. Biosci Rep 2016; 36:e00301. [PMID: 26764408 PMCID: PMC4770305 DOI: 10.1042/bsr20150247] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 01/04/2016] [Indexed: 02/02/2023] Open
Abstract
Bacterial lipopolysaccharide induces changes in intracellular NAD+ levels in a pro-inflammatory, but not an anti-inflammatory, macrophage model that are correlated with the release of the pro-inflammatory cytokine tumour necrosis factor-α (TNF-α). Metabolism and immune responses have been shown to be closely linked and as our understanding increases, so do the intricacies of the level of linkage. NAD+ has previously been shown to regulate tumour necrosis factor-α (TNF-α) synthesis and TNF-α has been shown to regulate NAD+ homoeostasis providing a link between a pro-inflammatory response and redox status. In the present study, we have used THP-1 differentiation into pro- (M1-like) and anti- (M2-like) inflammatory macrophage subset models to investigate this link further. Pro- and anti-inflammatory macrophages showed different resting NAD+ levels and expression levels of NAD+ homoeostasis enzymes. Challenge with bacterial lipopolysaccharide, a pro-inflammatory stimulus for macrophages, caused a large, biphasic and transient increase in NAD+ levels in pro- but not anti-inflammatory macrophages that were correlated with TNF-α release and inhibition of certain NAD+ synthesis pathways blocked TNF-α release. Lipopolysaccharide stimulation also caused changes in mRNA levels of some NAD+ homoeostasis enzymes in M1-like cells. Surprisingly, despite M2-like cells not releasing TNF-α or changing NAD+ levels in response to lipopolysaccharide, they showed similar mRNA changes compared with M1-like cells. These data further strengthen the link between pro-inflammatory responses in macrophages and NAD+. The agonist-induced rise in NAD+ shows striking parallels to well-known second messengers and raises the possibility that NAD+ is acting in a similar manner in this model.
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Ruggieri S, Orsomando G, Sorci L, Raffaelli N. Regulation of NAD biosynthetic enzymes modulates NAD-sensing processes to shape mammalian cell physiology under varying biological cues. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1138-49. [PMID: 25770681 DOI: 10.1016/j.bbapap.2015.02.021] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 12/25/2022]
Abstract
In addition to its role as a redox coenzyme, NAD is a substrate of various enzymes that split the molecule to either catalyze covalent modifications of target proteins or convert NAD into biologically active metabolites. The coenzyme bioavailability may be significantly affected by these reactions, with ensuing major impact on energy metabolism, cell survival, and aging. Moreover, through the activity of the NAD-dependent deacetylating sirtuins, NAD behaves as a beacon molecule that reports the cell metabolic state, and accordingly modulates transcriptional responses and metabolic adaptations. In this view, NAD biosynthesis emerges as a highly regulated process: it enables cells to preserve NAD homeostasis in response to significant NAD-consuming events and it can be modulated by various stimuli to induce, via NAD level changes, suitable NAD-mediated metabolic responses. Here we review the current knowledge on the regulation of mammalian NAD biosynthesis, with focus on the relevant rate-limiting enzymes. This article is part of a Special Issue entitled: Cofactor-dependent proteins: evolution, chemical diversity and bio-applications.
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Affiliation(s)
- Silverio Ruggieri
- Department of Agricultural, Food and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Giuseppe Orsomando
- Department of Clinical Sciences, Section of Biochemistry, Polytechnic University of Marche, Ancona, Italy
| | - Leonardo Sorci
- Department of Clinical Sciences, Section of Biochemistry, Polytechnic University of Marche, Ancona, Italy
| | - Nadia Raffaelli
- Department of Agricultural, Food and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy.
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The enzymatic activities of CD38 enhance CLL growth and trafficking: implications for therapeutic targeting. Leukemia 2014; 29:356-68. [PMID: 24990614 DOI: 10.1038/leu.2014.207] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/20/2014] [Accepted: 06/24/2014] [Indexed: 12/25/2022]
Abstract
The ecto-enzyme CD38 is gaining momentum as a novel therapeutic target for patients with hematological malignancies, with several anti-CD38 monoclonal antibodies in clinical trials with promising results. In chronic lymphocytic leukemia (CLL) CD38 is a marker of unfavorable prognosis and a central factor in the pathogenetic network underlying the disease: activation of CD38 regulates genetic pathways involved in proliferation and movement. Here we show that CD38 is enzymatically active in primary CLL cells and that its forced expression increases disease aggressiveness in a xenograft model. The effect is completely lost when using an enzyme-deficient version of CD38 with a single amino-acid mutation. Through the enzymatic conversion of NAD into ADPR (ADP-ribose) and cADPR (cyclic ADP-ribose), CD38 increases cytoplasmic Ca(2+) concentrations, positively influencing proliferation and signaling mediated via chemokine receptors or integrins. Consistently, inhibition of the enzymatic activities of CD38 using the flavonoid kuromanin blocks CLL chemotaxis, adhesion and in vivo homing. In a short-term xenograft model using primary cells, kuromanin treatment traps CLL cells in the blood, thereby increasing responses to chemotherapy. These results suggest that monoclonal antibodies that block the enzymatic activities of CD38 or enzyme inhibitors may prove therapeutically useful.
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