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Demarest JF, Kienle M, Boytz R, Ayres M, Kim EJ, Patten JJ, Chung D, Gandhi V, Davey R, Sykes DB, Shohdy N, Pottage JC, Kumar VS. Brequinar and dipyridamole in combination exhibits synergistic antiviral activity against SARS-CoV-2 in vitro: Rationale for a host-acting antiviral treatment strategy for COVID-19. Antiviral Res 2022; 206:105403. [PMID: 36041646 PMCID: PMC9420051 DOI: 10.1016/j.antiviral.2022.105403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 07/28/2022] [Accepted: 08/23/2022] [Indexed: 11/25/2022]
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19) and the associated global pandemic resulting in >400 million infections worldwide and several million deaths. The continued evolution of SARS-CoV-2 to potentially evade vaccines and monoclonal antibody (mAb)-based therapies and the limited number of authorized small-molecule antivirals necessitates the need for development of new drug treatments. There remains an unmet medical need for effective and convenient treatment options for SARS-CoV-2 infection. SARS-CoV-2 is an RNA virus that depends on host intracellular ribonucleotide pools for its replication. Dihydroorotate dehydrogenase (DHODH) is a ubiquitous host enzyme that is required for de novo pyrimidine synthesis. The inhibition of DHODH leads to a depletion of intracellular pyrimidines, thereby impacting viral replication in vitro. Brequinar (BRQ) is an orally available, selective, and potent low nanomolar inhibitor of human DHODH that has been shown to exhibit broad spectrum inhibition of RNA virus replication. However, host cell nucleotide salvage pathways can maintain intracellular pyrimidine levels and compensate for BRQ-mediated DHODH inhibition. In this report, we show that the combination of BRQ and the salvage pathway inhibitor dipyridamole (DPY) exhibits strong synergistic antiviral activity in vitro against SARS-CoV-2 by enhanced depletion of the cellular pyrimidine nucleotide pool. The combination of BRQ and DPY showed antiviral activity against the prototype SARS-CoV-2 as well as the Beta (B.1.351) and Delta (B.1.617.2) variants. These data support the continued evaluation of the combination of BRQ and DPY as a broad-spectrum, host-acting antiviral strategy to treat SARS-CoV-2 and potentially other RNA virus infections.
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Affiliation(s)
| | | | | | - Mary Ayres
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX, USA
| | | | | | | | - Varsha Gandhi
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX, USA
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Walter M, Herr P. Re-Discovery of Pyrimidine Salvage as Target in Cancer Therapy. Cells 2022; 11:cells11040739. [PMID: 35203388 PMCID: PMC8870348 DOI: 10.3390/cells11040739] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/10/2022] [Accepted: 02/18/2022] [Indexed: 02/06/2023] Open
Abstract
Nucleotides are synthesized through two distinct pathways: de novo synthesis and nucleoside salvage. Whereas the de novo pathway synthesizes nucleotides from amino acids and glucose, the salvage pathway recovers nucleosides or bases formed during DNA or RNA degradation. In contrast to high proliferating non-malignant cells, which are highly dependent on the de novo synthesis, cancer cells can switch to the nucleoside salvage pathways to maintain efficient DNA replication. Pyrimidine de novo synthesis remains the target of interest in cancer therapy and several inhibitors showed promising results in cancer cells and in vivo models. In the 1980s and 1990s, poor responses were however observed in clinical trials with several of the currently existing pyrimidine synthesis inhibitors. To overcome the observed limitations in clinical trials, targeting pyrimidine salvage alone or in combination with pyrimidine de novo inhibitors was suggested. Even though this approach showed initially promising results, it received fresh attention only recently. Here we discuss the re-discovery of targeting pyrimidine salvage pathways for DNA replication alone or in combination with inhibitors of pyrimidine de novo synthesis to overcome limitations of commonly used antimetabolites in various preclinical cancer models and clinical trials. We also highlight newly emerged targets in pyrimidine synthesis as well as pyrimidine salvage as a promising target in immunotherapy.
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Liu Y, Xie C, Zhai Z, Deng ZY, De Jonge HR, Wu X, Ruan Z. Uridine attenuates obesity, ameliorates hepatic lipid accumulation and modifies the gut microbiota composition in mice fed with a high-fat diet. Food Funct 2021; 12:1829-1840. [PMID: 33527946 DOI: 10.1039/d0fo02533j] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Uridine (UR) is a pyrimidine nucleoside that plays an important role in regulating glucose and lipid metabolism. The aim of this study was to investigate the effect of UR on obesity, fat accumulation in liver, and gut microbiota composition in high-fat diet (HFD)-fed mice. ICR mice were, respectively, divided into 3 groups for 8 weeks, that is, control (CON, n = 12), high fat diet (HFD, n = 16), and HFD + UR groups (0.4 mg mL-1 in drinking water, n = 16). UR supplementation significantly reduced the body weight and suppressed the accumulation of subcutaneous, epididymal, and mesenteric WAT in HFD-fed mice (P < 0.05). Meanwhile, UR also decreased the lipid droplet accumulation in the liver and liver organoids (P < 0.05). In addition, UR supplementation increased bacterial diversity and Bacteroidetes abundance, and decreased the Firmicutes-to-Bacteroidetes ratio in HFD-fed mice significantly (P < 0.05). UR promoted the growth of butyrate-producing bacteria of Odoribacter, unidentified-Ruminococcaceae, Intestinimonas, Ruminiclostridium, and unidentified-Lachnospiraceae. A close correlation between several specific bacterial phyla or genera and the levels of WAT weight, hepatic TC, or hepatic TG genera was revealed through Spearman's correlation analysis. These results demonstrated that UR supplementation could be beneficial by attenuating HFD-induced obesity and nonalcoholic fatty liver disease.
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Affiliation(s)
- Yilin Liu
- School of Food Science and Technology, State Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China. and Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, the Chinese Academy of Sciences, Changsha 410125, China.
| | - Chunyan Xie
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China and Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, Rotterdam, Netherlands
| | - Zhenya Zhai
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, the Chinese Academy of Sciences, Changsha 410125, China.
| | - Ze-Yuan Deng
- School of Food Science and Technology, State Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China.
| | - Hugo R De Jonge
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, Rotterdam, Netherlands
| | - Xin Wu
- School of Food Science and Technology, State Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China. and Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, the Chinese Academy of Sciences, Changsha 410125, China. and Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Zheng Ruan
- School of Food Science and Technology, State Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China.
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Human Safety, Tolerability, and Pharmacokinetics of Molnupiravir, a Novel Broad-Spectrum Oral Antiviral Agent with Activity Against SARS-CoV-2. Antimicrob Agents Chemother 2021; 65:AAC.02428-20. [PMID: 33649113 PMCID: PMC8092915 DOI: 10.1128/aac.02428-20] [Citation(s) in RCA: 230] [Impact Index Per Article: 76.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Molnupiravir, EIDD-2801/MK-4482, the prodrug of the active antiviral ribonucleoside analog ß-d-N4-hydroxycytidine (NHC; EIDD-1931), has activity against a number of RNA viruses including severe acute respiratory syndrome coronavirus 2, severe acute respiratory syndrome coronavirus, Middle East respiratory syndrome coronavirus, and seasonal and pandemic influenza viruses.Single and multiple doses of molnupiravir were evaluated in this first-in-human, phase 1, randomized, double-blind, placebo-controlled study in healthy volunteers, which included evaluation of the effect of food on pharmacokinetics.EIDD-1931 appeared rapidly in plasma, with a median time of maximum observed concentration of 1.00 to 1.75 hours, and declined with a geometric half-life of approximately 1 hour, with a slower elimination phase apparent following multiple doses or higher single doses (7.1 hours at the highest dose tested). Mean maximum observed concentration and area under the concentration versus time curve increased in a dose-proportional manner, and there was no accumulation following multiple doses. When administered in a fed state, there was a decrease in the rate of absorption, but no decrease in overall exposure.Molnupiravir was well tolerated. Fewer than half of subjects reported an adverse event, the incidence of adverse events was higher following administration of placebo, and 93.3% of adverse events were mild. One discontinued early due to rash. There were no serious adverse events and there were no clinically significant findings in clinical laboratory, vital signs, or electrocardiography. Plasma exposures exceeded expected efficacious doses based on scaling from animal models; therefore, dose escalations were discontinued before a maximum tolerated dose was reached.
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Gaidano V, Houshmand M, Vitale N, Carrà G, Morotti A, Tenace V, Rapelli S, Sainas S, Pippione AC, Giorgis M, Boschi D, Lolli ML, Cilloni D, Cignetti A, Saglio G, Circosta P. The Synergism between DHODH Inhibitors and Dipyridamole Leads to Metabolic Lethality in Acute Myeloid Leukemia. Cancers (Basel) 2021; 13:1003. [PMID: 33670894 PMCID: PMC7957697 DOI: 10.3390/cancers13051003] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/15/2021] [Accepted: 02/22/2021] [Indexed: 12/20/2022] Open
Abstract
Dihydroorotate Dehydrogenase (DHODH) is a key enzyme of the de novo pyrimidine biosynthesis, whose inhibition can induce differentiation and apoptosis in acute myeloid leukemia (AML). DHODH inhibitors had shown promising in vitro and in vivo activity on solid tumors, but their effectiveness was not confirmed in clinical trials, probably because cancer cells exploited the pyrimidine salvage pathway to survive. Here, we investigated the antileukemic activity of MEDS433, the DHODH inhibitor developed by our group, against AML. Learning from previous failures, we mimicked human conditions (performing experiments in the presence of physiological uridine plasma levels) and looked for synergic combinations to boost apoptosis, including classical antileukemic drugs and dipyridamole, a blocker of the pyrimidine salvage pathway. MEDS433 induced apoptosis in multiple AML cell lines, not only as a consequence of differentiation, but also directly. Its combination with antileukemic agents further increased the apoptotic rate, but when experiments were performed in the presence of physiological uridine concentrations, results were less impressive. Conversely, the combination of MEDS433 with dipyridamole induced metabolic lethality and differentiation in all AML cell lines; this extraordinary synergism was confirmed on AML primary cells with different genetic backgrounds and was unaffected by physiological uridine concentrations, predicting in human activity.
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Affiliation(s)
- Valentina Gaidano
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, 10043 Turin, Italy; (M.H.); (G.C.); (A.M.); (D.C.); (G.S.); (P.C.)
- Division of Hematology, A.O. SS Antonio e Biagio e Cesare Arrigo, 15121 Alessandria, Italy
| | - Mohammad Houshmand
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, 10043 Turin, Italy; (M.H.); (G.C.); (A.M.); (D.C.); (G.S.); (P.C.)
- Molecular Biotechnology Center, University of Turin, 10126 Turin, Italy;
| | - Nicoletta Vitale
- Molecular Biotechnology Center, University of Turin, 10126 Turin, Italy;
- Department of Medical Sciences, University of Turin, 10124 Turin, Italy
| | - Giovanna Carrà
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, 10043 Turin, Italy; (M.H.); (G.C.); (A.M.); (D.C.); (G.S.); (P.C.)
- Molecular Biotechnology Center, University of Turin, 10126 Turin, Italy;
| | - Alessandro Morotti
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, 10043 Turin, Italy; (M.H.); (G.C.); (A.M.); (D.C.); (G.S.); (P.C.)
| | - Valerio Tenace
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84112, USA;
| | - Stefania Rapelli
- Department of Life Sciences and System Biology, University of Turin, 10124 Turin, Italy;
| | - Stefano Sainas
- Department of Drug Science and Technology, University of Turin, 10124 Turin, Italy; (S.S.); (A.C.P.); (M.G.); (D.B.); (M.L.L.)
| | - Agnese Chiara Pippione
- Department of Drug Science and Technology, University of Turin, 10124 Turin, Italy; (S.S.); (A.C.P.); (M.G.); (D.B.); (M.L.L.)
| | - Marta Giorgis
- Department of Drug Science and Technology, University of Turin, 10124 Turin, Italy; (S.S.); (A.C.P.); (M.G.); (D.B.); (M.L.L.)
| | - Donatella Boschi
- Department of Drug Science and Technology, University of Turin, 10124 Turin, Italy; (S.S.); (A.C.P.); (M.G.); (D.B.); (M.L.L.)
| | - Marco Lucio Lolli
- Department of Drug Science and Technology, University of Turin, 10124 Turin, Italy; (S.S.); (A.C.P.); (M.G.); (D.B.); (M.L.L.)
| | - Daniela Cilloni
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, 10043 Turin, Italy; (M.H.); (G.C.); (A.M.); (D.C.); (G.S.); (P.C.)
- University Division of Hematology and Cell Therapy, A.O. Ordine Mauriziano, University of Turin, 10128 Turin, Italy;
| | - Alessandro Cignetti
- University Division of Hematology and Cell Therapy, A.O. Ordine Mauriziano, University of Turin, 10128 Turin, Italy;
| | - Giuseppe Saglio
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, 10043 Turin, Italy; (M.H.); (G.C.); (A.M.); (D.C.); (G.S.); (P.C.)
- University Division of Hematology and Cell Therapy, A.O. Ordine Mauriziano, University of Turin, 10128 Turin, Italy;
| | - Paola Circosta
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, 10043 Turin, Italy; (M.H.); (G.C.); (A.M.); (D.C.); (G.S.); (P.C.)
- Molecular Biotechnology Center, University of Turin, 10126 Turin, Italy;
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Cuthbertson CR, Guo H, Kyani A, Madak JT, Arabzada Z, Neamati N. The Dihydroorotate Dehydrogenase Inhibitor Brequinar Is Synergistic with ENT1/2 Inhibitors. ACS Pharmacol Transl Sci 2020; 3:1242-1252. [PMID: 33344900 DOI: 10.1021/acsptsci.0c00124] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Indexed: 02/06/2023]
Abstract
The dihydroorotate dehydrogenase (DHODH) inhibitor brequinar failed all clinical trials for solid tumors. To investigate mechanisms to increase brequinar's efficacy, we employed a combination strategy to simultaneously inhibit the nucleotide salvage pathways. Brequinar is synergistic with the equilibrative nucleoside transporter (ENT) inhibitor dipyridamole, but not the concentrative nucleoside transporter inhibitor phlorizin. This synergy carries over to ENT1/2 inhibition, but not ENT4. Our previously described brequinar analogue 41 was also synergistic with dipyridamole as were the FDA-approved DHODH inhibitors leflunomide and teriflunomide but the latter required much higher concentrations than brequinar. Therefore, a combination of brequinar and ENT inhibitors presents a potential anti-cancer strategy in select tumors.
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Affiliation(s)
- Christine R Cuthbertson
- Department of Medicinal Chemistry, College of Pharmacy and the Rogel Cancer Center, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, Michigan 48109, United States
| | - Hui Guo
- Department of Medicinal Chemistry, College of Pharmacy and the Rogel Cancer Center, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, Michigan 48109, United States
| | - Armita Kyani
- Department of Medicinal Chemistry, College of Pharmacy and the Rogel Cancer Center, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, Michigan 48109, United States
| | - Joseph T Madak
- Department of Medicinal Chemistry, College of Pharmacy and the Rogel Cancer Center, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, Michigan 48109, United States
| | - Zahra Arabzada
- Department of Medicinal Chemistry, College of Pharmacy and the Rogel Cancer Center, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, Michigan 48109, United States
| | - Nouri Neamati
- Department of Medicinal Chemistry, College of Pharmacy and the Rogel Cancer Center, University of Michigan, North Campus Research Complex, 1600 Huron Parkway, Ann Arbor, Michigan 48109, United States
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Metabolic engineering generates a transgene-free safety switch for cell therapy. Nat Biotechnol 2020; 38:1441-1450. [PMID: 32661439 DOI: 10.1038/s41587-020-0580-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 05/27/2020] [Indexed: 12/28/2022]
Abstract
Safeguard mechanisms can ameliorate the potential risks associated with cell therapies but currently rely on the introduction of transgenes. This limits their application owing to immunogenicity or transgene silencing. We aimed to create a control mechanism for human cells that is not mediated by a transgene. Using genome editing methods, we disrupt uridine monophosphate synthetase (UMPS) in the pyrimidine de novo synthesis pathway in cell lines, pluripotent cells and primary human T cells. We show that this makes proliferation dependent on external uridine and enables us to control cell growth by modulating the uridine supply, both in vitro and in vivo after transplantation in xenograft models. Additionally, disrupting this pathway creates resistance to 5-fluoroorotic acid, which enables positive selection of UMPS-knockout cells. We envision that this approach will add an additional level of safety to cell therapies and therefore enable the development of approaches with higher risks, especially those that are intended for limited treatment durations.
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Biglarnia AR, Lorant T, Lee HS, Tufveson G, Tötsch M, Malagó M. Liver regeneration is impaired by FK778 in partially hepatectomized rats, while supplemental uridine restores both liver growth and hepatocyte proliferation. Hepatol Res 2009; 39:86-92. [PMID: 18713276 DOI: 10.1111/j.1872-034x.2008.00402.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM The impact of mandatory immunosuppression on liver regeneration after segmental liver transplantation is of clinical importance. FK778, a novel immunosuppressant, inhibits pyrimidine biosynthesis and prevents rejection after organ transplantation in a dose-dependent manner. We investigated the effect of FK778 at a highly effective dose on liver regeneration in a small animal model. METHODS Inbred Lewis rats were subjected to 70% partial hepatectomy (PH) and treated with saline (n = 28), uridine (n = 16), FK778 alone (n = 28) or in combination with uridine (n = 16). FK778 was given intravenously daily at a dose of 25 mg/kg bodyweight (bw) and uridine was given daily intraperitoneally at a dose of 250 mg/kg bw. Liver bodyweight ratio (LBR), hepatocyte proliferation index (PI), blood chemistry and morphological analysis were incorporated. PI was determined by Ki-67 immunostaining. De Ritis ratio was calculated to assess the extent of liver damage. RESULTS In FK778-treated animals PI was decreased at 24 h and 72 h and LBR was lower at 48 h and 72 h (P < 0.05) after the PH. In addition, morphological analysis showed confluent central lobular necrosis at 72 h in four of seven animals. Uridine supplementation restored PI, LBR and the de Ritis ratio in FK778-treated animals and no confluent necroses were observed. CONCLUSION FK778 is antihepatotrophic as well as antiproliferative during rat liver regeneration. Both liver growth and hepatocyte proliferation are completely restored by supplementation with uridine. In addition, supplemental uridine markedly reduces the severity of morphological abnormalities consistent with FK778 toxicity.
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Affiliation(s)
- Ali-Reza Biglarnia
- Department of Surgical Sciences, Section of Transplantation Surgery, Uppsala University Hospital, Uppsala, Sweden
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9
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Cansev M, Watkins CJ, van der Beek EM, Wurtman RJ. Oral uridine-5'-monophosphate (UMP) increases brain CDP-choline levels in gerbils. Brain Res 2005; 1058:101-8. [PMID: 16126180 DOI: 10.1016/j.brainres.2005.07.054] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2005] [Revised: 07/27/2005] [Accepted: 07/27/2005] [Indexed: 11/21/2022]
Abstract
We examined the biochemical pathways whereby oral uridine-5'-monophosphate (UMP) increases membrane phosphatide synthesis in brains of gerbils. We previously showed that supplementing PC12 cells with uridine caused concentration-related increases in CDP-choline levels, and that this effect was mediated by elevations in intracellular uridine triphosphate (UTP) and cytidine triphosphate (CTP). In the present study, adult gerbils received UMP (1 mmol/kg), a constituent of human breast milk and infant formulas, by gavage, and plasma samples and brains were collected for assay between 5 min and 8 h thereafter. Thirty minutes after gavage, plasma uridine levels were increased from 6.6 +/- 0.58 to 32.7 +/- 1.85 microM (P < 0.001), and brain uridine from 22.6 +/- 2.9 to 89.1 +/- 8.82 pmol/mg tissue (P < 0.001). UMP also significantly increased plasma and brain cytidine levels; however, both basally and following UMP, these levels were much lower than those of uridine. Brain UTP, CTP, and CDP-choline were all elevated 15 min after UMP (from 254 +/- 31.9 to 417 +/- 50.2, [P < 0.05]; 56.8 +/- 1.8 to 71.7 +/- 1.8, [P < 0.001]; and 11.3 +/- 0.5 to 16.4 +/- 1, [P < 0.001] pmol/mg tissue, respectively), returning to basal levels after 20 and 30 min. The smallest UMP dose that significantly increased brain CDP-choline was 0.05 mmol/kg. These results show that oral UMP, a uridine source, enhances the synthesis of CDP-choline, the immediate precursor of PC, in gerbil brain.
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Affiliation(s)
- Mehmet Cansev
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, E25-604, MIT, Cambridge, MA 02139, USA
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Gray JH, Owen RP, Giacomini KM. The concentrative nucleoside transporter family, SLC28. Pflugers Arch 2004; 447:728-34. [PMID: 12856181 DOI: 10.1007/s00424-003-1107-y] [Citation(s) in RCA: 306] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2003] [Revised: 05/04/2003] [Accepted: 05/04/2003] [Indexed: 10/26/2022]
Abstract
The SLC28 family consists of three subtypes of sodium-dependent, concentrative nucleoside transporters, CNT1, CNT2, and CNT3 (SLC28A1, SLC28A2, and SLC28A3, respectively), that transport both naturally occurring nucleosides and synthetic nucleoside analogs used in the treatment of various diseases. These subtypes differ in their substrate specificities: CNT1 is pyrimidine-nucleoside preferring, CNT2 is purine-nucleoside preferring, and CNT3 transports both pyrimidine and purine nucleosides. Recent studies have identified key amino acid residues that are determinants of pyrimidine and purine specificity of CNT1 and CNT2. The tissue distributions of the CNTs vary: CNT1 is localized primarily in epithelia, whereas CNT2 and CNT3 have more generalized distributions. Nucleoside transporters in the SLC28 and SLC29 families play critical roles in nucleoside salvage pathways where they mediate the first step of nucleotide biosynthesis. In addition, these transporters work in concert to terminate adenosine signaling. SLC28 family members are crucial determinants of response to a variety of anticancer and antiviral nucleoside analogs, as they modulate the entry of these analogs into target tissues. Further, this family is involved in the absorption and disposition of many nucleoside analogs. Several CNT single nucleoside polymorphisms (SNPs) have been identified, but have yet to be characterized.
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Affiliation(s)
- Jennifer H Gray
- Department of Biopharmaceutical Sciences, University of California-San Francisco, 513 Parnassus Ave., S-926, San Francisco, CA 94143-0446, USA.
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Chong AS, Huang W, Liu W, Luo J, Shen J, Xu W, Ma L, Blinder L, Xiao F, Xu X, Clardy C, Foster P, Williams JA. In vivo activity of leflunomide: pharmacokinetic analyses and mechanism of immunosuppression. Transplantation 1999; 68:100-9. [PMID: 10428276 DOI: 10.1097/00007890-199907150-00020] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Leflunomide is an experimental drug with demonstrated ability to prevent and reverse acute allograft and xenograft rejection. The two biochemical activities reported for the active metabolite of leflunomide, A77 1726, are inhibition of tyrosine phosphorylation and inhibition of dihydroorotate dehydrogenase, an enzyme necessary for de novo pyrimidine synthesis. These activities can be distinctly separated in vitro by the use of uridine, which reverses the anti-proliferative effects of A77 1726 caused by inhibition of de novo pyrimidine synthesis. We report the effect of uridine on the in vivo immunosuppressive activities of leflunomide. METHODS We first quantified the serum levels of A77 1726, the active metabolite of leflunomide, after a single treatment of leflunomide (5, 15, and 35 mg/kg). Additionally, we quantified the levels of serum uridine and of nucleotide triphosphates in the liver, spleen, and lymph nodes of Lewis rats after the administration of a single dose of uridine (500 mg/kg; i.p.). Lewis rats heterotopically transplanted with brown Norway or Golden Syrian hamster hearts were treated for 50 or 75 days with leflunomide (5, 15, and 35 mg/kg/day; gavage) alone or in combination with uridine (500 mg/ kg/day; i.p.). Hematocrits were determined and the levels of alloreactive or xenoreactive immunoglobulin (Ig)M and IgG were determined by flow cytometric analysis. The allograft and xenografts, small bowel, liver, kidney, and spleen were subjected to pathological examination. RESULTS A linear relationship was observed between the serum A77 1726 concentrations in Lewis rats and the dose of leflunomide administered. Peak A77 1726 concentrations were 20.9, 71.8 and 129.3 mg/l (77.5, 266.1 and 478.8 microM) for the 5, 15, and 35 mg/kg doses of leflunomide, respectively. The concentration of uridine in the serum of normal Lewis rats is 6.5 microM; after i.p. administration of 500 mg/kg uridine, the serum uridine concentrations peaked at 384.1 microM in 15-30 min. The rapid elimination of uridine was not reflected in the lymphoid compartments, and the pharmacokinetics of pyrimidine nucleotides in the spleen resembled that of A77 1726. This dose of uridine, when administered daily (500 mg/kg/day, i.p.), weakly antagonized the immunosuppressive activities of leflunomide (5, 15, and 35 mg/kg/day) in the allotransplantation model. In contrast, in the xenotransplantation model, the same concentration of uridine completely antagonized the immunosuppressive activities of low-dose leflunomide (15 mg/kg/day) and partially antagonized the immunosuppressive activities of high-dose leflunomide (35 mg/kg/day). Toxicities associated with high-dose leflunomide (35 mg/kg/day) were anemia, diarrhea, and pathological changes in the small bowel and liver. These toxicities were significantly reduced by uridine co-administration. CONCLUSION These studies reveal that the blood levels of A77 1726 in Lewis rats satisfy in vitro requirements for both inhibition of de novo pyrimidine synthesis and protein tyrosine kinase activity. Our data also illustrate that the in vivo mechanism of immunosuppression by leflunomide is complex and is affected by at least the following four factors: type and vigor of the immune response, availability of uridine for salvage by proliferating lymphocytes, species being investigated, and concentration of serum A77 1726.
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Affiliation(s)
- A S Chong
- Department of General Surgery, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA.
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Xu X, Williams JW, Shen J, Gong H, Yin DP, Blinder L, Elder RT, Sankary H, Finnegan A, Chong ASF. In Vitro and In Vivo Mechanisms of Action of the Antiproliferative and Immunosuppressive Agent, Brequinar Sodium. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.2.846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Intracellular pyrimidine nucleotides (PyN) can be synthesized de novo from glutamine, CO2, and ATP, or they can be salvaged from preformed pyrimidine nucleosides. The antiproliferative and immunosuppressive activities of brequinar sodium (BQR) are thought to be due to the inhibition of the activity of dihydroorotate dehydrogenase, which results in a suppression of de novo pyrimidine synthesis. Here we describe the effects of the pyrimidine nucleoSide, uridine, on the antiproliferative and immunosuppressive activities of BQR. In vitro reduction of PyN levels in Con A-stimulated T cells and inhibition of cell proliferation by low concentrations of BQR (≤65 μM) are reversed by uridine. However, uridine is unable to reverse the effects of high concentrations of BQR (≥65 μM). The ability of BQR to induce anemia in BALB/c mice is prevented by the coadministration of uridine. In contrast, the immunosuppressive activity of BQR is unaffected by similar doses of uridine. PyN levels in the bone marrow, but not in the spleen, are depressed in mice treated with BQR. These observations suggest that the induction of anemia by BQR is due to depletion of intracellular PyN in hemopoietic stem cells located in the bone marrow. They also suggest that the mechanism of immunosuppression by BQR may be only marginally dependent on depletion of intracellular PyN in lymphocytes located in the periphery. We report a novel activity of BQR: inhibition of tyrosine phosphorylation, and hypothesize that the immunosuppressive activity may be due, in part, to this unsuspected ability of BQR to inhibit tyrosine phosphorylation in lymphocytes.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Alison Finnegan
- †Immunology/Microbiology and
- ‡Section of Rheumatology, Department of Internal Medicine, Rush Medical College, Chicago, IL 60612
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Ashour OM, Naguib FN, el Kouni MH. 5-(m-Benzyloxybenzyl)barbituric acid acyclonucleoside, a uridine phosphorylase inhibitor, and 2',3',5'-tri-O-acetyluridine, a prodrug of uridine, as modulators of plasma uridine concentration. Implications for chemotherapy. Biochem Pharmacol 1996; 51:1601-11. [PMID: 8687475 DOI: 10.1016/0006-2952(96)00102-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
5-(m-Benzyloxybenzyl)barbituric acid acyclonucleoside (BBBA), the most potent inhibitor known of uridine phosphorylase (UrdPase, EC 2.4.2.3), the enzyme responsible for uridine catabolism, and 2',3',5'-tri-O-acetyluridine (TAU), a prodrug of uridine, were used to investigate the possibility of improving the bioavailability of oral uridine in mice. Oral BBBA administered at 30, 60, 120, and 240 mg/kg increased the concentration of plasma uridine (2.6 +/- 0.7 microM) by 3.2-, 4.6-, 5.4-, and 7.2-fold, respectively. After administration of 120 and 240 mg/kg BBBA, plasma uridine concentration remained 3- and 6-fold, respectively, higher than the plasma concentration at zero time (C0) for over 8 hr. On the other hand, BBBA did not change the concentration of plasma uracil. TAU was far more superior than uridine in improving the bioavailability of plasma uridine. The relative bioavailability of plasma uridine released from oral TAU (53%) was 7-fold higher than that (7.7%) obtained by oral uridine. Oral TAU at 460, 1000, and 2000 mg/kg achieved area under the curve (AUC) values of plasma uridine of 82, 288, and 754 mumol.hr/L, respectively. Coadministration of BBBA with uridine or TAU further improved the bioavailability of plasma uridine resulting from the administration of either alone and reduced the Cmax and AUC of plasma uracil. Coadministration of BBBA at 30, 60, and 120 mg/kg improved the relative bioavailability of uridine released from 2000 mg/kg TAU (53%) by 1.7-, 2.7-, and 3.9-fold, respectively, while coadministration of the same doses of BBBA with an equimolar dose of uridine (1320 mg/kg) increased the relative bioavailability of oral uridine (7.7%) by 4.1-, 5.3-, and 7.8-fold, respectively. Moreover, the AUC and Cmax of plasma uridine after BBBA (120 mg/kg) coadministration with TAU were 3.5- and 11.5-fold, respectively, higher than those obtained from coadministration of BBBA with an equimolar dose of uridine. The exceptional effectiveness of the BBBA plus TAU combination in elevating and sustaining high plasma uridine concentration can be useful in the management of medical disorders that are remedied by administration of uridine as well as to rescue or protect from host-toxicities of various chemotherapeutic pyrimidine analogues.
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Affiliation(s)
- O M Ashour
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham 35294, USA
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15
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Abstract
The classical 'hypnotoxin theory' was followed by extensive search for an endogenous sleep substance. Brain tissues and body fluids of sleeping and sleep-deprived animals contained active sleep-inducing factors like the sleep-promoting substance (SPS). Uridine and oxidized glutathione (GSSG), two components of SPS, seem to regulate physiological sleep differentially. Uridine may facilitate the inhibitory neurotransmission at the synaptic level of the GABAA-uridine receptor complex. In contrast, GSSG may inhibit the excitatory neurotransmission at the synaptic level of the glutamate receptor. Thus, the two SPS components promote sleep by exerting a complementary action on the two major neurotransmitter systems in the brain that have mutually reciprocal functions. Further, among multidimensional functions of sleep, uridine may contribute to recover the activity of neurons, while glutathione may counteract excitotoxic events. Hence sleep at the behavioral level is a process of neuronal restitution and detoxification at the cellular level. Such a concept can be regarded as a modern version of the Ishimori-Piéron's hypnotoxin theory proposed early in this century.
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Affiliation(s)
- S Inoué
- Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Japan
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16
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Cysyk RL, Malinowski N, Marquez V, Zaharevitz D, August EM, Moyer JD. Cyclopentenyl uracil: an effective inhibitor of uridine salvage in vivo. Biochem Pharmacol 1995; 49:203-7. [PMID: 7840797 DOI: 10.1016/0006-2952(94)00470-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cyclopentenyl uracil, a non-cytotoxic inhibitor of uridine kinase, was found to effectively block the salvage of circulating uridine by host and tumor tissues in the intact mouse. Dose-response characteristics of the inhibition were determined. Large doses (1 g/kg) of cyclopentenyl uracil were required, and the effect of a single dose fell rapidly over a 24-hr period. A sustained inhibition of uridine salvage of > 64-79% could be maintained by multiple doses of 1 g/kg given on an every 8-hr schedule. Mice given cyclopentenyl uracil (1 g/kg) every 8 hr for 5 days continued to gain weight and showed no signs of toxicity; however, the combination of cyclopentenyl uracil with a non-toxic dose of N-(phosphonacetyl)-L-aspartic acid (PALA; 200 mg/kg daily for 5 days) was lethal to mice, indicating that circulating uridine modifies the toxicity of agents that act on enzymes of the de novo pyrimidine pathway. Although the duration of action and potency of cyclopentenyl uracil are not ideal, this is the first demonstration of an effective inhibition of uridine salvage in the intact mouse with a non-cytotoxic agent. This makes possible the evaluation of concurrent inhibition of de novo and salvage routes to pyrimidine nucleotides as an approach to chemotherapy.
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Affiliation(s)
- R L Cysyk
- Laboratory of Medicinal Chemistry, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
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17
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Abstract
The concentrations of bases, nucleosides, and nucleosides mono-, di- and tri-phosphate are compared for about 600 published values. The data are predominantly from mammalian cells and fluids. For the most important ribonucleotides, average concentrations +/- SD (microM) are: ATP, 3,152 +/- 1,698; GTP, 468 +/- 224; UTP, 567 +/- 460 and CTP, 278 +/- 242. For deoxynucleosides-triphosphate (dNTP), the concentrations in dividing cells are: dATP, 24 +/- 22; dGTP, 5.2 +/- 4.5; dCTP, 29 +/- 19 and dTTP 37 +/- 30. By comparison, dUTP is usually about 0.2 microM. For the 4 dNTPs, tumor cells have concentrations of 6-11 fold over normal cells, and for the 4 NTPs, tumor cells also have concentrations 1.2-5 fold over the normal cells. By comparison, the concentrations of NTPs are significantly lower in various types of blood cells. The average concentration of bases and nucleosides in plasma and other extracellular fluids is generally in the range of 0.4-6 microM; these values are usually lower than corresponding intracellular concentrations. For phosphate compounds, average cellular concentrations are: Pi, 4400; ribose-1-P, 55; ribose-5-P, 70 and P-ribose-PP, 9.0. The metal ion magnesium, important for coordinating phosphates in nucleotides, has values (mM) of: free Mg2+, 1.1; complexed-Mg, 8.0. Consideration of experiments on the intracellular compartmentation of nucleotides shows support for this process between the cytoplasm and mitochondria, but not between the cytoplasm and the nucleus.
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Affiliation(s)
- T W Traut
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill 27599-7260
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Hotta T, Asai K, Takeda N, Tatematsu A, Nakanishi K, Eksioglu YZ, Isobe I, Kato T. Neuroblastoma growth factors derived from neurofibroma (NF1): participation of uridine in a neuroblastoma growth. J Neurochem 1993; 60:312-9. [PMID: 8417151 DOI: 10.1111/j.1471-4159.1993.tb05853.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Human glioma cell extracts were found to elicit a marked growth-promoting activity on human neuroblastoma cells. This activity was also detected in the extracts of neurofibroma type 1 (NF1; von Recklinghausen neurofibromatosis) comprising aberrant Schwann cell growth. The purified substance from the NF1 extracts by HPLC on ODS columns was identical to a pyrimidine nucleoside, uridine, the chemical structure of which was identified by gas chromatography-mass spectrometry. The authentic uridine showed a strong growth-promoting activity on human neuroblastoma cells. Other purine or pyrimidine nucleotides, their derivatives, and ribose sources for their syntheses were employed to test the activity; a purine nucleoside, adenosine, showed a stronger activity than uridine. The current study raises the possibility that human neuroblastoma cells may be affected by dysfunctions of the de novo pathway of both purine and pyrimidine nucleotide biosyntheses.
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Affiliation(s)
- T Hotta
- Department of Bioregulation Research, Nagoya City University Medical School, Japan
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20
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Abstract
A new approach in the treatment of gastrointestinal tumors with 5-fluorouracil involves the infusion of high doses of uridine to improve the chemotherapeutic efficiency of the former. High amounts of uracil formed from uridine can interfere with the hepatic catabolism of 5-fluorouracil and thus increase its bioavailability and toxicity. In our study, we analysed the metabolite pattern of uridine in the effluent of isolated perfused rat livers in relation to portal uridine levels. The livers were perfused hemoglobin-free without recirculation at a constant flow. In the perfusate, uridine was changed from 0.5 to 100 mumol/l. The complete degradation of [2-14C]uridine and [2-14C]uracil was monitored via the release of labeled CO2. Radioactive catabolites of uridine including uracil and the sum of dihydrouracil and beta-ureidopropionate were separated by high-performance liquid chromatography and counted using a radioactivity flow monitor. Portal uridine concentrations were increased from 0.5 to 100 mumol/l and were accompanied by a rise in the relative amount of non-metabolized uridine in the effluent from 13 to 78%. At uridine concentrations above 50 mumol/l, there was a constant release of uracil into the effluent, indicating saturation of uridine phosphorolysis or transport. The amount of 14CO2 formed by the liver reflecting complete uridine breakdown was higher than any other uridine metabolite when uridine concentration varied from 0.5 to 15 mumol/l. Saturation of 14CO2 formation was achieved at a uridine concentration of 25 mumol/l. Higher peak values of 14CO2 release were observed after direct infusion of equivalent amounts of uracil into the portal vein.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A Holstege
- Department of Internal Medicine, University of Freiburg, Federal Republic of Germany
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21
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Zinkewich-Péotti K, Parent M, Morais R. On the tumorigenicity of mitochondrial DNA-depleted avian cells. Cancer Lett 1991; 59:119-24. [PMID: 1884368 DOI: 10.1016/0304-3835(91)90175-h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have examined the tumorigenic potential of mitochondrial DNA-depleted (mtDNA-) cells derived from the tumorigenic chicken cell line DU24. The mtDNA- cells were unable to proliferate in the wing web of day-old chicks. Cytoplasmic hybrids resulting from crosses between the mtDNA- whole cells and cytoplasts from enucleated parental cells (mtDNA+) recover both mtDNA and tumorigenicity. These results are in accordance with those obtained in prior experiments where mtDNA was shown to modulate the anchorage-independent phenotype of transformed avian cells.
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Affiliation(s)
- K Zinkewich-Péotti
- Department of Biochemistry, Faculty of Medicine, University of Montreal, Quebec, Canada
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22
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Chapter 3 Ribonucleosides in Body Fluids: On-Line Chromato-Graphic Cleanup and Analysis by A Column Switching Technique. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0301-4770(08)61541-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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23
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Heideman RL, Roth JS, Ford H, Kinnard RD, Litterst CL, Kelley JA. Reverse Phase HPLC Determination and Murine Pharmacokinetics of Arabinosyl-5-azacytosine. ACTA ACUST UNITED AC 1989. [DOI: 10.1080/01483918908049530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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24
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McDermott PJ, Morgan HE. Contraction modulates the capacity for protein synthesis during growth of neonatal heart cells in culture. Circ Res 1989; 64:542-53. [PMID: 2465098 DOI: 10.1161/01.res.64.3.542] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Neonatal ventricular myocytes that were incubated in a well-defined serum-free medium containing 50 mM KCl did not contract and maintained stable cell size, as assessed by the protein/DNA ratio. The present study utilized KCl-arrested cells to examine the effect of constant rates of synchronous contraction in normal [K+]o (4 mM) as a physiological stimulus for myocyte growth. Cell growth increased following the onset of contraction when measured over 3 days. The rate of protein synthesis was accelerated in parallel by contraction, but the rate of protein degradation remained similar to rates in noncontracting cells. The capacity for protein synthesis was estimated by total RNA content and was increased in contracting as compared with KCl-arrested cells. This increase was accompanied by faster rates of RNA synthesis as determined from the incorporation of [3H]uridine into RNA and the specific activity of the cellular UTP pool. The rate of RNA degradation was accelerated during contraction but the difference between the rates of RNA synthesis and degradation resulted in net RNA accumulation of 49% after 3 days. These data demonstrated that 1) contractile activity stimulated myocyte growth through an increased capacity for protein synthesis and 2) the increased capacity for protein synthesis involved acceleration of the rate of RNA synthesis. Since enhancement of protein synthetic capacity is a common feature of myocyte hypertrophy in vivo and in vitro, this model can be used to examine the regulation of ribosome synthesis during hypertrophic growth.
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Affiliation(s)
- P J McDermott
- Sigfried and Janet Weis Center for Research, Geisinger Clinic, Danville, PA 17822
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25
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Klubes P, Leyland-Jones B. Enhancement of the antitumor activity of 5-fluorouracil by uridine rescue. Pharmacol Ther 1989; 41:289-302. [PMID: 2652153 DOI: 10.1016/0163-7258(89)90111-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- P Klubes
- Department of Pharmacology, George Washington University Medical Center, Washington, DC 20037
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26
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Olivares J, Verdys M. Isocratic high-performance liquid chromatographic method for studying the metabolism of blood plasma pyrimidine nucleosides and bases: concentration and radioactivity measurements. JOURNAL OF CHROMATOGRAPHY 1988; 434:111-21. [PMID: 3243806 DOI: 10.1016/0378-4347(88)80066-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A rapid and efficient isocratic high-performance liquid chromatographic method for studying the metabolism of blood plasma cytosine, uracil, thymine, cytidine, deoxycytidine and uridine has been elaborated. For each compound this method can measure concentrations in the range 0.5-200 microM and determine radioactivity. All the pyrimidine compounds can be eluted in less than 18 min, and the total time elapsed between collection of the blood and completion of the analysis need not exceed 3 h. All measurements can be performed on 0.025-ml blood samples. Blood plasma pyrimidine concentrations were determined for the rat, the rabbit, the guinea pig, the dog and the healthy human. This method could be well applied to experimentation on small animals using radiolabelled pyrimidine derivatives, in order to study the metabolic pathways of nucleotides and nucleic acids. It could also be used to characterize certain illnesses or cases of toxicity created by a chemotherapy affecting the plasma level of pyrimidine bases or nucleosides.
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Affiliation(s)
- J Olivares
- Université Joseph Fourier, Grenoble, Laboratoire de Physiologie Cellulaire Cardiaque (URA CNRS 632), France
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27
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Boos KS, Wilmers B, Schlimme E, Sauerbrey R. On-line sample processing and analysis of diol compounds in biological fluids. J Chromatogr A 1988; 456:93-104. [PMID: 3243873 DOI: 10.1016/0021-9673(86)80009-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We developed a coupled dual column system with an optional post-column derivatization for on-line sample processing, trace enrichment and analysis of aromatic 1,2-diol and aliphatic cis-diol biomolecules (e.g. catecholamines, ribonucleosides). The fully automated high-performance liquid chromatography analyzer tolerates the direct injection of proteinaceous fluids by use of a unique bonded-phase precolumn material which allows the simultaneous performance of covalent affinity and size-exclusion chromatography.
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Affiliation(s)
- K S Boos
- Laboratory for Biological Chemistry, University, Paderborn, F.R.G
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28
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Dumler F, Cortes P. Uracil ribonucleotide metabolism in rat and human glomerular epithelial and mesangial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1988; 255:C712-8. [PMID: 3202145 DOI: 10.1152/ajpcell.1988.255.6.c712] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Uridine diphosphosugars (UDP-sugars: UDP-N-acetylglucosamine, UDP-glucose, and UDP-glucuronic acid) are essential coenzymes for the synthesis of glomerular basement membrane and mesangial matrix (GBM-MM). This study has characterized UDP-sugar metabolism in rat and human glomerular cells in tissue culture. Culture of rat mesangial cells in medium containing dialyzed fetal calf serum resulted in UTP loss (28 +/- 4 nmol.mg DNA-1.h-1); the addition of 2 microM orotate to this medium resulted in net UTP accretion (5.42 +/- 0.06 nmol.mg DNA-1.h-1). Rat mesangial cells demonstrated 16- and 29- to 46-fold greater UTP and UDP-sugar pools, respectively, than whole glomeruli. In human mesangial cells, 6-azauridine (500 microM) decreased UDP-sugar pools by 48% (P less than 0.05), whereas uridine (50 microM) produced a 2.5-fold increase. Human and rat mesangial cells had greater (1.8- to 6.1-fold) UDP-sugar pools than epithelial cells and 1.7-3.4 times greater labeled precursor incorporation into UDP-sugars. In conclusion, glomerular cells utilize both exogenous orotate and uridine for ribonucleotide synthesis, and the extracellular concentration of these precursors markedly influence the formation and cellular content of UDP-sugars. Prominent differences exist between separate glomerular cell populations in their metabolism of UDP-sugars. This may represent diverse activity of glycosylating reactions.
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Affiliation(s)
- F Dumler
- Department of Medicine, Henry Ford Hospital, Detroit, Michigan 48202
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29
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King MP, Attardi G. Injection of mitochondria into human cells leads to a rapid replacement of the endogenous mitochondrial DNA. Cell 1988; 52:811-9. [PMID: 3349520 DOI: 10.1016/0092-8674(88)90423-0] [Citation(s) in RCA: 197] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Isolated human mitochondria containing a mitochondrial DNA (mtDNA) coded chloramphenicol resistance marker were injected into cells from two different human sensitive cell lines, 143BTK- and HT1080-6TG, which had been partially depleted of their mtDNA by ethidium bromide treatment. On the basis of the available evidence concerning the tolerance of introduced volumes into mammalian cells, it is estimated that, on the average, less than one mitochondrion was introduced into each cell. Under selective conditions, the mitochondria became established in the recipient cells with a frequency greater than 2-3 x 10(-3). An analysis of multiple mtDNA and nuclear DNA polymorphisms revealed a rapid replacement of the resident mtDNA by the exogenous mtDNA. Six to ten weeks after microinjection, this replacement was complete in all but one of the HT1080-6TG transformants, and nearly complete in the majority of the 143BTK- transformants. The quantitative behavior of the mtDNA of the transformants at very early stages of selection strongly suggests that intracellular mtDNA selection played a crucial role in this replacement, with significant implications for mitochondrial genetics.
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Affiliation(s)
- M P King
- Division of Biology, California Institute of Technology, Pasadena 91125
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30
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Blau PA, Hines JW, Voyksner RD. Application of high-performance liquid chromatography and thermospray high-performance liquid chromatography-mass spectrometry to the analysis and identification of 2',3'-dideoxyadenosine and its metabolite in biological media. JOURNAL OF CHROMATOGRAPHY 1987; 420:1-12. [PMID: 3499445 DOI: 10.1016/0378-4347(87)80149-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Reversed-phase high-performance liquid chromatographic (HPLC) procedures are described for determining the stability of 2',3'-dideoxyadenosine (DDA) in biological fluids at therapeutic dosages. The validated methodology uses both direct injection and solid-phase extraction techniques. Deamination of DDA to 2',3'-dideoxyinosine (DDI) in plasma by adenosine deaminase was monitored by HPLC, and the identification of DDI verified by thermospray HPLC-mass spectrometry. This methodology should prove useful in future studies concerning the stability and metabolism of dideoxynucleosides.
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Affiliation(s)
- P A Blau
- Analytical and Chemical Sciences, Research Triangle Institute, NC 27709
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31
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Paroni R, Sirtori CR, Borghi C, Kienle MG. High-performance liquid chromatographic determination of ribavirin in serum and urine and of its urinary metabolite 1,2,4-triazole-3-carboxamide. JOURNAL OF CHROMATOGRAPHY 1987; 420:189-96. [PMID: 3667820 DOI: 10.1016/0378-4347(87)80172-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- R Paroni
- Department of Medical Chemistry and Biochemistry, University of Milan, Italy
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32
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Olivares J, Rossi A. [Effect of D-galactosamine on nucleotides in the rat heart. Effects of cytidine and uridine administration]. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE ET DE BIOCHIMIE 1987; 95:1-11. [PMID: 2441669 DOI: 10.3109/13813458709075019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The treatment of rats by galactosamine (2 mmol/kg i.p.), which dramatically alters the metabolism of pyrimidine nucleotides in the liver, has been used to investigate the dynamics of pyrimidine nucleotides in the rat heart. Six hours after administration of the drug, the UTP and UDPG myocardial contents were decreased by respectively 40 and 52% while the sum of uracil nucleotides was increased by 66% and that of cytosine nucleotides by 15%. When administered 5 h after galactosamine treatment, cytidine (750 nmol/rat i.v.) induced a further increase in cytosine nucleotides (46% above control value 1 h later) without however effect on uracil nucleotides. On the other hand, the administration of uridine (250 nmol/rat, i.v. 5 h after galactosamine), while restoring UTP, UDPG and the pool of uracil nucleotides, provoked a decrease in cytosine nucleotide level (-17%). In the absence of galactosamine treatment, the administration of uridine and cytidine did not induce changes in nucleotide levels despite a rise in blood cytidine concentration. All these observations support the hypothesis that: 1. the pathway for cytosine nucleotide synthesis predominant in the heart is that utilizing preformed exogenous cytidine and 2. this pathway is mainly controlled by the intracellular concentration of UTP rather than that of CTP.
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33
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Markman M, Chan TC, Cleary S, Howell SB. Phase I trial of combination therapy of cancer with N-phosphonacetyl-L-aspartic acid and dipyridamole. Cancer Chemother Pharmacol 1987; 19:80-3. [PMID: 3815730 DOI: 10.1007/bf00296262] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
While N-phosphonacetyl-L-aspartic acid (PALA), an inhibitor of de novo pyrimidine biosynthesis, demonstrated a unique spectrum of activity during preclinical drug evaluation, multiple clinical trials have shown it to possess minimal clinical activity. One explanation for the disappointing results is the possibility that tumor cells are able to utilize circulating uridine in the synthesis of pyrimidines (salvage pathway). Dipyridamole, an inhibitor of nucleoside transport, has been demonstrated experimentally to potentiate the cytotoxicity of PALA significantly. In addition, this agent has a long safety record when used clinically in man. A phase I trial of this two-drug combination was therefore conducted, with a fixed oral dose of dipyridamole (50 mg/m2 every 6 h) and an escalating i.v. dose of PALA administered every 3 weeks. The dose-limiting toxicity with this schedule was diarrhea and abdominal cramping pain at a PALA dose of 3900-4200 mg/m2. Among the 65 patients participating in this trial 4 objective responses (2 partial, 2 minimal) were observed. Because of the potential for unique clinical synergy between PALA and dipyridamole further investigation should be considered.
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34
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Simpson RC, Brown PR. High-performance liquid chromatographic profiling of nucleic acid components in physiological samples. JOURNAL OF CHROMATOGRAPHY 1986; 379:269-311. [PMID: 3525591 DOI: 10.1016/s0378-4347(00)80687-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The papers reviewed represent recent progress in HPLC profiling of nucleic acid components in physiological samples. Each method was designed for a particular application and possesses certain inherent advantages and/or disadvantages. Many methods are simply modifications of previous procedures. Although some methodologies appear to be superior to others, there is no "best" method for universal usage. The analyst must use the procedure which is best suited for the particular application at hand. This review is meant to be a starting point for the chromatographer who is comparing and evaluating HPLC methods for a given application.
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Koshida K, Harmenberg J, Borgström E, Wahren B, Andersson L. Pseudouridine and uridine in normal kidney and kidney cancer tissues. UROLOGICAL RESEARCH 1985; 13:219-21. [PMID: 4060365 DOI: 10.1007/bf00261579] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The tissue concentrations of a modified nucleoside, pseudouridine, and a normal nucleoside, uridine, were measured with high-performance liquid chromatography. Human kidneys were obtained from five patients with renal cell carcinoma and divided into a noncancerous part and a cancerous part. The pseudouridine concentration in the cancerous part of the kidneys ranged between less than 2-2.8 nmoles/g and in the noncancerous part 4.3-19.4 nmoles/g (mean 10,9 nmoles/g). The uridine concentration in the cancerous and noncancerous parts of the kidney ranged between 19.6-179.1 nmoles/g (mean 110.7 nmoles/g) and 117.5-235.6 nmoles/g (mean 191.5 nmoles/g), respectively. The pseudouridine concentration appeared to be approximately seven times higher in the noncancerous part as compared to the cancerous part of the kidney. In the case of uridine, the difference was less pronounced.
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Holstege A, Leser HG, Pausch J, Gerok W. Uridine catabolism in Kupffer cells, endothelial cells, and hepatocytes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 149:169-73. [PMID: 3922756 DOI: 10.1111/j.1432-1033.1985.tb08907.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Kupffer cells, endothelial cells, and hepatocytes were separated by centrifugal elutriation. The rate of uracil formation from [2-14C]uridine, the first step in uridine catabolism, was monitored in suspensions of the three different liver cell types. Kupffer cells demonstrated the highest rate of uridine phosphorolysis. 15 min after the addition of the nucleoside the label in uracil amounted to 51%, 13%, and 19% of total radioactivity in the medium of Kupffer cells, endothelial cells, and hepatocytes, respectively. If corrected for Kupffer cell contamination, hepatocyte suspensions demonstrated similar activities as endothelial cells. In contrast to non-parenchymal cells, hepatocytes continuously cleared uracil from the incubation medium. The lack of uracil consumption by Kupffer cells and endothelial cells points to uracil as the end-product of uridine catabolism in these cells. Kupffer cells and endothelial cells did not produce radioactive CO2 upon incubation in the presence of [2-14C]uridine. Hepatocytes, however, were able to degrade uridine into CO2, beta-alanine, and ammonia as demonstrated by active formation of volatile radioactivity from the labeled nucleoside. There was almost no detectable formation of thymine from thymidine or of cytosine, uracil, or uridine from cytidine by any of the different cell types tested. These results are in line with low thymidine phosphorolysis and cytidine deamination in rat liver. Our studies suggest a co-operation of Kupffer cells, endothelial cells, and hepatocytes in the breakdown of uridine from portal vein blood with uridine phosphorolysis predominantly occurring in Kupffer cells and with uracil catabolism restricted to parenchymal liver cells.
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Moyer JD, Malinowski N, Ayers O. Salvage of circulating pyrimidine nucleosides by tissues of the mouse. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89436-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Moyer JD, Henderson JF. Salvage of uridine in the mouse. Effect of uridine phosphorylase pretreatment. Biochem Pharmacol 1985; 34:101-5. [PMID: 3966913 DOI: 10.1016/0006-2952(85)90107-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Salvage of circulating nucleosides provides an alternative to de novo synthesis of nucleotides and may modify response to antimetabolites. We have investigated treatment with uridine phosphorylase as a means of inhibiting salvage of uridine in vivo. Examination of the metabolism of intravenous [3H] uridine in mice revealed that 30-40% was salvaged by conversion to uracil nucleotides and the remainder was catabolized. In contrast, less than 0.3% of intravenous [3H]uracil was salvaged. Addition of partially purified bacterial uridine phosphorylase to plasma produced a rapid phosphorolysis of uridine. In vivo, 1.5 hr after intravenous injection of 9 units of uridine phosphorylase, plasma activity (1.3 units/ml) was 65-fold greater than that of control mice. Pretreatment with uridine phosphorylase prior to administration of [3H]uridine produced a marked (65-92%) but incomplete inhibition of salvage of uridine in all tissues examined. The dose required to produce 50% inhibition of uridine salvage at 1 hr was 2 to 2.5 units/mouse. The inhibition of nucleoside salvage by this approach may permit an evaluation of the role of nucleoside salvage in the supply of cellular nucleotides and the effects of concurrent inhibition of de novo and salvage pathways for nucleotide synthesis.
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Monks A, Chisena CA, Cysyk RL. Influence of ammonium ions on hepatic de novo pyrimidine biosynthesis. Arch Biochem Biophys 1985; 236:1-10. [PMID: 2981502 DOI: 10.1016/0003-9861(85)90599-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Carbamyl phosphate (CP) is synthesized in the liver by two separate enzymes, CPS I and CPS II. CPS I, an intramitochondrial enzyme involved in ureogenesis, has a relative activity of 500- to 1000-fold greater than CPS II, a cytoplasmic enzyme which initiates the sequence of reactions for pyrimidine biosynthesis. The contributions of NH4Cl (substrate for CPS I) ang glutamine (substrate for CPS II) as precursors for pyrimidine biosynthesis in isolated hepatocytes were compared by measuring their effect on uracil nucleotide pool size, the incorporation of NaH14CO3 into these pools, and the accumulation of orotic acid. Physiological concentrations of NH4Cl caused a marked stimulation of incorporation of radioactivity into uracil nucleotides (6-fold increase at 0.5 mM NH4Cl), and radioactive orotate appeared in both the cells and the medium. In contrast, glutamine (at concentrations up to 10 mM) had no effect on the incorporation of radioactivity into uracil nucleotides, and no orotic acid was detected. Uracil nucleotide pools were expanded up to 50% by low levels of NH4Cl, but there was no expansion of this pool in the presence of added glutamine. NH4Cl-driven pyrimidine de novo biosynthesis was insensitive to feedback inhibition by an expanded uracil nucleotide pool, to galactosamine treatment, and to acivicin treatment, indicating that NH+4 stimulated pyrimidine biosynthesis as a result of CP synthesis by mitochondrial CPS I. The consequence of intramitochondrially produced CP being available for pyrimidine biosynthesis is that the controlling step of this pathway (CPS II) is bypassed. The appearance of orotic acid following NH4Cl stimulation indicated that the rate-controlling step of hepatic de novo pyrimidine synthesis under these conditions was orotate phosphoribosyl transferase. These data indicate that, at physiological concentrations of NH+4, the majority of uracil nucleotides synthesized in isolated rat hepatocytes was derived from intramitochondrially generated CP. The effect of NH4Cl on the output of uridine by the isolated perfused rat liver was examined. In the presence of a single addition of 20 mM NH4Cl, the excretion of uridine was increased from 100-200 to 375 nmol h-1 g-1 liver and orotic acid was released into the circulating perfusate reaching a maximum of 2 microM (in 220 ml of perfusate) after 2 h. With 40 mM NH4Cl, uridine export was increased to 450 nmol h-1 g-1 and a maximum of 5 microM orotic acid was released into the perfusate after 2 h.(ABSTRACT TRUNCATED AT 400 WORDS)
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Erlichman C, Vidgen D. Antitumor activity of N-phosphonacetyl-L-aspartic acid in combination with nitrobenzylthioinosine. Biochem Pharmacol 1984; 33:3177-81. [PMID: 6487365 DOI: 10.1016/0006-2952(84)90074-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
N-Phosphonacetyl-L-aspartic acid (PALA) resistance may be due to the ability of tumor cells to utilize preformed circulating pyrimidine nucleosides, thereby overcoming the block of de novo pyrimidine biosynthesis which PALA causes. To test this hypothesis we examined the effects of PALA and nitrobenzylthioinosine (NBMPR) alone and in combination on B16 melanoma cells in vitro using a clonogenic assay and in vivo using growth delay. In medium containing purine and pyrimidine nucleosides at a final concentration of 28 microM, exposure to PALA (100 microM) alone or to NBMPR (10 microM) alone for periods up to 72 hr did not result in any cytotoxicity. However, exposures to PALA (100 microM) plus NBMPR (10 microM) resulted in a decrease in clonogenic survival to 0.011 at 72 hr. In medium without nucleosides, PALA (100 microM) exposure for 72 hr caused a similar decrease in survival to 0.015, whereas NBMPR (10 microM) had no effect on survival. The addition of uridine resulted in a concentration-dependent reversal of the cytotoxic effects of PALA. C57 Bl female mice bearing B16 melanoma were treated intraperitoneally daily for 4 days with PALA, the phosphate of NBMPR (NBMPR-P), or PALA plus NBMPR-P. PALA, 300 mg/kg daily X 4, resulted in a 6-day tumor growth delay but NBMPR-P, 100 mg/kg daily X 4, had no effect. PALA, 150 mg/kg daily X 4, plus NBMPR, 50 or 100 mg/kg daily X 4, resulted in a 6-day tumor growth delay also. These studies demonstrate that: (1) circulating pyrimidine nucleosides are determinants of the cytotoxic effects of PALA; (2) in vitro PALA and NBMPR combine to cause significant cytotoxicity whereas either agent alone has no effect; (3) in vivo the combination of PALA and NBMPR-P results in the same antitumor affect as PALA alone at twice the dose; and (4) due to an increase in animal toxicity, no therapeutic advantage could be demonstrated for the combination over PALA alone in vivo. We conclude that the cytotoxic effect of PALA is modulated by the levels of the preformed circulating nucleosides and that combining PALA with an inhibitor of salvage pyrimidine uptake would not increase the therapeutic efficacy of PALA because of an increase in toxicity.
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Eells JT, Spector R, Huntoon S. Nucleoside and oxypurine homeostasis in adult rabbit cerebrospinal fluid and plasma. J Neurochem 1984; 42:1620-4. [PMID: 6726230 DOI: 10.1111/j.1471-4159.1984.tb12751.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In adult New Zealand white rabbits, the effects of food deprivation and of massive elevations of plasma uridine or thymidine concentrations on CSF and plasma nucleoside and oxypurine concentrations were studied. Nucleoside and oxypurine levels were determined by high performance liquid chromatography using unequivocal methods of compound identification. After 48 and 96 h of food deprivation, the concentrations of uridine, cytidine, inosine, thymidine, deoxycytidine, deoxyuridine, hypoxanthine, xanthine, and uric acid in CSF and plasma were not different than in controls, except at 96 h, when the plasma uridine concentration was 35% lower (p less than 0.05). After elevation of the plasma and CSF thymidine concentrations to approximately 200 and 100 microM, respectively, with intravenous thymidine for 5 h, there was a large increase in CSF and plasma thymidine to approximately 100 microM and a smaller increase in plasma and CSF deoxyuridine concentrations. After elevation of the plasma and CSF uridine concentrations to 0.6 and 0.2 mM, respectively, there was a large increase in CSF and plasma uracil and a smaller increase in plasma and CSF deoxyuridine concentrations. Elevated plasma concentration of thymidine and uridine significantly decreased the CSF to plasma ratios of deoxyuridine and thymidine; however, only elevated plasma uridine concentrations decreased the CSF to plasma ratio of uridine. These results document the powerful homeostatic mechanisms that regulate the concentrations of the principal nucleosides and oxypurine bases in CSF.
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Holstege A, Manglitz D, Gerok W. Depletion of blood plasma cytidine due to increased hepatocellular salvage in D-galactosamine-treated rats. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 141:339-44. [PMID: 6734601 DOI: 10.1111/j.1432-1033.1984.tb08197.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Pyrimidine nucleosides in blood plasma of rats were identified by different procedures, including chemical peak shift methods, before their quantification by reversed-phase high-performance liquid chromatography. The concentrations of uridine, cytidine, and deoxycytidine were 1.0 +/- 0.2, 10.6 +/- 1.9, and 33.4 +/- 5.4 mumol/l, respectively. Six hours after the administration of D-galactosamine, the level of circulating cytidine was severely depressed to 25% of control values; uridine decreased to 54% while deoxycytidine remained unchanged. 24 h after the dose of the amino sugar, the levels of cytidine and uridine returned to control values in blood plasma. Total acid-soluble uridine, cytidine, guanosine, and adenosine was determined by reversed-phase HPLC after treatment of the neutralized acid-soluble supernatant of freeze-clamped rat livers with phosphodiesterase and alkaline phosphatase. Six hours after its administration, D-galactosamine induced a 2.2-fold and a 1.6-fold rise in total acid-soluble uridine and cytidine, respectively. Co-administration of N-(phosphonoacetyl)-L-aspartate, an inhibitor of de novo pyrimidine synthesis, suppressed the increase in total acid-soluble uridine observed after D-galactosamine alone, but was without effect on the enhancement of total cytidine. Three hours after D-galactosamine and 15 min after [2-14C] cytidine, there was a rapid fall of the labeled nucleoside in blood plasma to 49% of control animals accompanied by a 2.8-fold rise in the total radioactivity of rat liver homogenates. From these results it can be concluded that the hepatocellular rise in total acid-soluble cytidine after D-galactosamine, in contrast to the increase in total acid-soluble uridine, originates from the phosphorylation of blood plasma cytidine via the salvage pathway. The depletion of circulating cytidine in the presence of hepatocellular UTP deficiency points to the importance of the liver and the hepatic UTP level for the clearance of blood plasma cytidine.
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Karle JM, Anderson LW, Cysyk RL. Effect of plasma concentrations of uridine on pyrimidine biosynthesis in cultured L1210 cells. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43622-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Monks A, Anderson LW, Strong J, Cysyk RL. Flux through the de novo pyrimidine pathway in vivo. Effect of N-phosphonacetyl-L-aspartate, a potent inhibitor of aspartate transcarbamylase. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)43951-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Eells JT, Spector R. Determination of ribonucleosides, deoxyribonucleosides, and purine and pyrimidine bases in adult rabbit cerebrospinal fluid and plasma. Neurochem Res 1983; 8:1307-20. [PMID: 6656989 DOI: 10.1007/bf00964000] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Purine and pyrimidine base and nucleoside levels were measured in adult rabbit cisternal CSF and plasma by reversed-phase high-performance liquid chromatography. The concentrations of bases, nucleosides, and nucleoside phosphates were similar in plasma and CSF except for the adenosine phosphates and uracil which were higher in the plasma. In plasma and CSF, adenosine levels were low (0.12 microM) and guanosine, deoxyadenosine, deoxyguanosine, and deoxyinosine were not detectable (less than 0.1 microM); inosine and xanthine concentrations were 1-2 microM and hypoxanthine concentrations were approximately 5 microM; uridine (approximately 8 microM), cytidine (2-3 microM), and thymidine, deoxyuridine, and deoxycytidine (0.5-1.4 microM) were easily detectable. In both plasma and CSF, guanine, and thymine were undetectable (less than 0.1 microM), adenine and cytosine were less than 0.2 microM, but uracil was present (greater than 1 microM). Adenosine, inosine, and guanosine phosphates were also detectable at low concentrations in CSF and plasma. These results are consistent with the hypothesis that purine deoxyribonucleosides are synthesized in situ in the adult rabbit brain. In contrast, pyrimidine deoxyribonucleosides and ribonucleosides, and purine and pyrimidine bases are available in the CSF for use by the brain.
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Strong JM, Anderson LW, Monks A, Chisena CA, Cysyk RL. A 13C tracer method for quantitating de novo pyrimidine biosynthesis in vitro and in vivo. Anal Biochem 1983; 132:243-53. [PMID: 6414331 DOI: 10.1016/0003-2697(83)90003-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Gas chromatographic/mass spectrometric methods for the measurement of the flux through the de novo pyrimidine biosynthetic pathway by quantitating the incorporation of [13C]bicarbonate and 13CO2 into the uracil nucleotide pool in L1210 tumors are reported. Simultaneous measurements of the incorporation of [13C]bicarbonate and the more commonly used [14C]bicarbonate into uridine of L1210 cells in vitro showed that the two methods were comparable. A modification of the method was applied to in vivo studies where the incorporation of 13CO2 into the uracil nucleotide pool of L1210 tumors in mice was quantitated. The measurements were used to determine changes in the flux through the de novo pyrimidine pathway in animals pretreated with known inhibitors of the pathway. A comparison of control animals with those pretreated with 6-azauridine, acivicin, and pyrazofurin resulted in mean percentage inhibitions of 87, 95, and 94%, respectively. This technique should allow investigation of the respective contributions of salvage and de novo synthesis in the formation of pyrimidines in vivo and the effects of agents designed as enzyme inhibitors of the de novo pathway.
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Monks A, Ayers O, Cysyk RL. Effect of 5-benzylacyclouridine, a potent inhibitor of uridine phosphorylase, on the metabolism of circulating uridine by the isolated rat liver. Biochem Pharmacol 1983; 32:2003-9. [PMID: 6870929 DOI: 10.1016/0006-2952(83)90419-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
5-Benzylacyclouridine (BAU) is a specific inhibitor of uridine phosphorylase, the first enzyme in the catabolism of uridine. It was found that 20 and 100 microM BAU dramatically reduced the rapid clearance of trace amounts of either [14C]uridine or hyperphysiologic concentrations of non-labeled uridine by the isolated rat liver perfused with an artificial oxygen carrier. In the absence of exogenously added uridine, non-treated livers maintained circulating concentrations of 1-2 microM uridine. In the presence of 20 microM BAU, these concentrations were increased 2- to 3-fold higher than physiologic levels (1.4 +/- 0.6 microM) and remained elevated for the duration of the experiment (120-160 min). In the presence of 100 microM BAU, uridine concentrations rose continuously at rates of between 80 and 150 nmoles per hr per g of liver, and the clearance of a single radioactive spike of uridine was reduced extensively. The half-life of a uridine spike was extended 2-fold in the presence of 20 microM BAU and 5- to 6-fold in the presence of 100 microM BAU. Exogenously added uridine (15 and 40 microM) was cleared rapidly by nontreated livers, with a half-life of approximately 10 min. However, BAU at a concentration of 20 microM increased the half-life of 15 or 40 microM uridine added to the perfusate by approximately 10-fold. A 100 microM concentration of BAU inhibited the removal of 40 microM circulating uridine, but with 15 microM uridine there was a continuous increase in the circulating concentration similar to that seen in the absence of added uridine. We conclude that extensive inhibition of uridine phosphorylase occurs at 100 microM BAU and partial inhibition at 20 microM BAU. These data indicate independent catabolic and excretory functions of the rat liver with respect to uridine.
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Colonna A, Russo T, Esposito F, Salvatore F, Cimino F. Determination of pseudouridine and other nucleosides in human blood serum by high-performance liquid chromatography. Anal Biochem 1983; 130:19-26. [PMID: 6869800 DOI: 10.1016/0003-2697(83)90644-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A specific, sensitive, and rapid method to measure pseudouridine in human blood serum is described. The method is based on the following steps: (i) deproteinization of serum samples by filtration on membrane cones or by acetonitrile; (ii) purification of nucleosides and concentration of the sample by affinity chromatography on phenylboronate gel followed by lyophilization; and (iii) separation of nucleosides and their quantitation by reverse-phase high-performance liquid chromatography. The pseudouridine mean value in 30 normal subjects was 2.52 +/- 0.28 nmol/ml. The procedure also allows the identification of inosine, uridine, guanosine, and adenosine. Nevertheless, the presence in human blood serum of enzymatic activities which convert adenosine to inosine and cytidine to uridine prevents the precise quantitation of these nucleosides. All the compounds were identified by comparing their retention times and absorbance ratios (A280/A254) with those of pure compounds, as well as by cochromatography.
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Salvatore F, Colonna A, Costanzo F, Russo T, Esposito F, Cimino F. Modified nucleosides in body fluids of tumor-bearing patients. Recent Results Cancer Res 1983; 84:360-77. [PMID: 6844698 DOI: 10.1007/978-3-642-81947-6_27] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The catabolism of nucleic acids, particularly tRNA, produces a variety of modified nucleosides which are not reutilized by mammalian cells. Investigation of these compounds in body fluids, mainly urine, has recently provided evidence of altered metabolic situations in tumor-bearing patients. The factors involved in the alterations of modified nucleosides formation are connected with altered tRNA-modifying enzymes and/or altered turnover of subpopulations of tRNA. A common pattern in tumor cells or tissues is the presence of isoaccepting tRNA species containing aberrant nucleoside modifications. Several modified nucleosides have been detected and quantitated by HPLC analysis of the urine of normal subjects and cancer patients. Results obtained, in the authors' laboratory, among others, indicate a possible correlation between urinary excretion of these compounds and the course of the disease, with implications for the follow-up of therapeutic treatment. Particular reference should be made to psi, which appears to be a suitable marker for monitoring these subjects. The data from the authors' laboratory also show that the analysis of modified nucleosides in blood may be considered a useful tool in the search for proper markers associated with the cancer status. In this respect psi is suggested as a biochemical indicator for cancer patients.
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Zakaria M, Brown PR, Farnes MP, Barker BE. HPLC analysis of aromatic amino acids, nucleosides, and bases in plasma of acute lymphocytic leukemia on chemotherapy. Clin Chim Acta 1982; 126:69-80. [PMID: 6959747 DOI: 10.1016/0009-8981(82)90362-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Plasma chromatograms--obtained by the reversed-phase mode of high performance liquid chromatography (HPLC)--of 19 subjects with acute lymphocytic leukemia (ALL) were compared to those of 19 normal individuals. ALL patients were in remission and on a methotrexate and 6-mercaptopurine maintenance regimen. The concentrations of the aromatic amino acids L-phenylalanine and L-tyrosine, the nucleosides uridine, adenosine, inosine, and guanosine, as well as the bases hypoxanthine and xanthine, were elevated in the leukemic in comparison to the normal chromatograms. Highest inosine levels corresponded to leukemic subjects whose condition severely deteriorated with time. Patients with lower inosine levels are still in continuous remission.
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