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Jia X, Schols D, Meier C. Antiviral Activity of Lipophilic Nucleoside Tetraphosphate Compounds. J Med Chem 2024; 67:2864-2883. [PMID: 38345794 PMCID: PMC10895676 DOI: 10.1021/acs.jmedchem.3c02022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/24/2024] [Accepted: 01/31/2024] [Indexed: 02/23/2024]
Abstract
We report on the synthesis and characterization of three types of nucleoside tetraphosphate derivatives 4-9 acting as potential prodrugs of d4T nucleotides: (i) the δ-phosph(on)ate is modified by two hydrolytically stable alkyl residues 4 and 5; (ii) the δ-phosph(on)ate is esterified covalently by one biodegradable acyloxybenzyl moiety and a nonbioreversible moiety 6 and 7; or (iii) the δ-phosphate of nucleoside tetraphosphate is masked by two biodegradable prodrug groups 8 and 9. We were able to prove the efficient release of d4T triphosphate (d4TTP, (i)), δ-monoalkylated d4T tetraphosphates (20 and 24, (ii)), and d4T tetraphosphate (d4T4P, (iii)), respectively, by chemical or enzymatic processes. Surprisingly, δ-dialkylated d4T tetraphosphates, δ-monoalkylated d4T tetraphosphates, and d4T4P were substrates for HIV-RT. Remarkably, the antiviral activity of TetraPPPPro-prodrug 7 was improved by 7700-fold (SI 5700) as compared to the parent d4T in CEM/TK- cells, denoting a successful cell membrane passage of these lipophilic prodrugs and an intracellular delivery of the nucleotide metabolites.
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Affiliation(s)
- Xiao Jia
- Organic
Chemistry, Department of Chemistry, Faculty of Mathematics, Informatics
and Natural Sciences, Universität
Hamburg, Martin-Luther-King-Platz 6, Hamburg D-20146, Germany
| | - Dominique Schols
- Laboratory
of Virology and Chemotherapy, Department of Microbiology and Immunology
and Transplantation, Rega Institute for
Medical Research, KU
Leuven, Herestraat 49, Leuven B-3000, Belgium
| | - Chris Meier
- Organic
Chemistry, Department of Chemistry, Faculty of Mathematics, Informatics
and Natural Sciences, Universität
Hamburg, Martin-Luther-King-Platz 6, Hamburg D-20146, Germany
- Centre
for Structural Systems Biology (CSSB), Hamburg, DESY Campus, Notkestrasse 85, Hamburg D-22607, Germany
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2
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Jia X, Weber S, Schols D, Meier C. Membrane Permeable, Bioreversibly Modified Prodrugs of Nucleoside Diphosphate-γ-Phosphonates. J Med Chem 2020; 63:11990-12007. [PMID: 32991174 DOI: 10.1021/acs.jmedchem.0c01294] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Nucleoside reverse transcriptase inhibitors (NRTIs) are widely used as antiviral and anticancer agents, although they require intracellular phosphorylation into their antivirally active form, the triphosphorylated nucleoside analogue metabolites. We report on the synthesis and characterization of a new class of nucleoside triphosphate analogues comprising a C-alkyl-phosphonate moiety replacing the γ-phosphate. These compounds were converted into bioreversibly modified lipophilic prodrugs at the γ-phosphonate by the attachment of an acyloxybenzyl (ester) or an alkoxycarbonyloxybenzyl (carbonate) group. Such compounds formed γ-C-(alkyl)-nucleoside triphosphate analogues with high selectivity because of an enzyme-triggered delivery mechanism. The latter compounds were very stable in CD4+ T-lymphocyte (CEM cell) extracts, and they were substrates for HIV-reverse transcriptase without being substrates for DNA-polymerases α, β, and γ. In antiviral assays, the excellent antiviral activity of the prodrugs that was found in CEM/0 cells was completely kept in CEM/TK- cells. The activity was improved by 3 logs as compared to the parent nucleoside d4T.
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Affiliation(s)
- Xiao Jia
- Organic Chemistry, Department of Chemistry, Faculty of Mathematics, Informatics and Natural Sciences, Universität Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
| | - Stefan Weber
- Organic Chemistry, Department of Chemistry, Faculty of Mathematics, Informatics and Natural Sciences, Universität Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
| | - Dominique Schols
- Laboratory of Virology and Chemotherapy, Department of Microbiology and Immunology and Transplantation, Rega Institute for Medical Research, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium
| | - Chris Meier
- Organic Chemistry, Department of Chemistry, Faculty of Mathematics, Informatics and Natural Sciences, Universität Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
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3
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Virological efficacy of 24-week fozivudine-based regimen in ART-naive patients from Tanzania and Côte d'Ivoire. AIDS 2017; 31:501-509. [PMID: 27941394 PMCID: PMC5278894 DOI: 10.1097/qad.0000000000001362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Supplemental Digital Content is available in the text Objective: Use of zidovudine (ZDV) in antiretroviral therapy is limited by toxicity and twice daily (b.i.d.) dosing. Fozivudine (FZD) is a ZDV prodrug, which is activated intracellularly to ZDV-monophosphate especially in mononuclear cells but not in bone marrow cells. FZD promises improved myelotoxicity and once daily (o.d.) dosing. Design: Randomized clinical trial. Methods: We conducted an open-label, phase II, proof-of-concept trial investigating three different FZD doses (800 mg o.d., 600 mg b.i.d., 1200 mg o.d.) versus ZDV (300 mg b.i.d.) in combination with lamivudine and efavirenz in HIV-infected, ART-naive patients from Tanzania and Côte d’Ivoire. The primary objective was to demonstrate virological efficacy after 24 weeks in intent-to treat and per-protocol analysis. Secondary endpoints included safety and pharmacokinetic outcomes. Results: Of 119 participants included in the intent-to treat analysis, HIV RNA less than 50 copies/ml at 24 weeks was observed in 64 of 88 (73%) patients in the combined FZD arms versus 24 of 31 (77%) in the ZDV arm (RR 0.94, 95% confidence interval 0.75–1.18). In the per-protocol analysis, responses were 64 of 77 (87%) versus 23 of 29 (79%), respectively (RR 1.09, 95% confidence interval 0.89–1.34). Outcomes were similar between FZD arms. Overall, treatments were well tolerated. Severe or worse anaemia occurred in two cases (one related to FZD, one to ZDV), grade III/IV neutropenia was less frequent in FZD compared with ZDV arms (22 versus 42%, P = 0.035). Pharmacokinetic analysis supported o.d. administration of FZD. Conclusion: Virological 24-week efficacy was demonstrated in b.i.d. and o.d. administered FZD-based regimens. Reduced myelotoxicity of FZD needs to be confirmed in a larger trial.
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4
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Weinschenk L, Schols D, Balzarini J, Meier C. Nucleoside Diphosphate Prodrugs: Nonsymmetric DiPPro-Nucleotides. J Med Chem 2015; 58:6114-30. [PMID: 26125628 DOI: 10.1021/acs.jmedchem.5b00737] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nonsymmetric DiPPro-nucleotides are described as nucleoside diphosphate (NDP) delivery systems. The concept is to attach different bis(acyloxybenzyl) moieties at the β-phosphate moiety of a NDP. DiPPro compounds bearing two alkanoylbenzyl residues and DiPPro compounds bearing an alkanoylbenzyl or a benzoylbenzyl group as bioreversible prodrug moieties were studied. Compounds bearing short chain alkanoyl esters led to a fast hydrolysis by chemical or enzymatic means. The ester group in the second prodrug group comprised a long lipophilic aliphatic or an aromatic residue. The lipophilicity of this group enabled the prodrug to penetrate the cell membrane. The introduction of two different groups allowed a controlled stepwise removal of the prodrug moieties to achieve a highly selective delivery of the NDP in CEM cell extracts. The compounds were highly active against HIV even in thymidine kinase-deficient CEM cells. Thus, the compounds, although charged at the α-phosphate group, were taken up by the cells and released NDPs.
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Affiliation(s)
- Lina Weinschenk
- †Organic Chemistry, Department of Chemistry, Faculty of Sciences, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Dominique Schols
- ‡Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Jan Balzarini
- ‡Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Chris Meier
- †Organic Chemistry, Department of Chemistry, Faculty of Sciences, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
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5
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Weinschenk L, Gollnest T, Schols D, Balzarini J, Meier C. Bis(benzoyloxybenzyl)-DiPPro nucleoside diphosphates of anti-HIV active nucleoside analogues. ChemMedChem 2015; 10:891-900. [PMID: 25847660 DOI: 10.1002/cmdc.201500063] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Indexed: 11/08/2022]
Abstract
Nucleoside analogues are extensively used as antiviral and anticancer agents. Their efficiency is dependent on their metabolism into the ultimately active nucleoside triphosphates. Often one step or even more in the metabolism of the nucleoside to the triphosphate is inefficient. To overcome this hurdle, prodrugs of the nucleotides are needed. Bis(acyloxybenzyl)nucleoside diphosphates have been reported by us as a first example of an efficient nucleoside diphosphate prodrug (DiPPro nucleotides). Here, the synthesis and the properties of bis(benzoyloxybenzyl)nucleoside diphosphates of the nucleoside analogues d4T and AZT are disclosed. The synthesis was achieved by using a phosphoramidite/oxidation route. In chemical hydrolysis studies, most of the compounds formed a nucleoside diphosphate. This was confirmed in CEM cell extracts, although the prodrug stability in extracts was lower than in phosphate buffer. Furthermore, the stability and the amount of nucleoside diphosphate formed were dependent on the substituent in the benzoyl moiety. Some of the compounds were more active against HIV in thymidine kinase-deficient CEM/TK(-) cells than were d4T or AZT.
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Affiliation(s)
- Lina Weinschenk
- Organic Chemistry, Department of Chemistry, Faculty of Sciences, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); German Center of Infection Research (DZIF)
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6
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Pradere U, Garnier-Amblard E, Coats SJ, Amblard F, Schinazi RF. Synthesis of nucleoside phosphate and phosphonate prodrugs. Chem Rev 2014; 114:9154-218. [PMID: 25144792 PMCID: PMC4173794 DOI: 10.1021/cr5002035] [Citation(s) in RCA: 391] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Indexed: 01/29/2023]
Affiliation(s)
- Ugo Pradere
- Center
for AIDS Research, Laboratory of Biochemical Pharmacology, Department
of Pediatrics, Emory University School of
Medicine, and Veterans Affairs Medical Center, Atlanta, Georgia 30322, United States
| | | | | | - Franck Amblard
- Center
for AIDS Research, Laboratory of Biochemical Pharmacology, Department
of Pediatrics, Emory University School of
Medicine, and Veterans Affairs Medical Center, Atlanta, Georgia 30322, United States
| | - Raymond F. Schinazi
- Center
for AIDS Research, Laboratory of Biochemical Pharmacology, Department
of Pediatrics, Emory University School of
Medicine, and Veterans Affairs Medical Center, Atlanta, Georgia 30322, United States
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7
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Schulz T, Balzarini J, Meier C. The DiPPro approach: synthesis, hydrolysis, and antiviral activity of lipophilic d4T diphosphate prodrugs. ChemMedChem 2014; 9:762-75. [PMID: 24616176 DOI: 10.1002/cmdc.201300500] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Indexed: 11/09/2022]
Abstract
Bioreversible protection of the β-phosphate group of nucleoside diphosphates (NDPs) as bis(acyloxybenzyl)phosphate esters is presented. To investigate the structure-activity relationship of these potential NDP prodrugs (DiPPro drugs) a series of DiPPro compounds was synthesized bearing fatty acids of various lengths and d4T as a model nucleoside. For synthesis of the lipophilically modified diphosphate group, preformed phosphoramidites were allowed to react with nucleotides, and the β-P(III) moiety was subsequently oxidized. The chemical and enzymatic stability of these prodrugs was studied in different media such as phosphate buffer (pH 7.3) or CEM cell extracts. In all media, the hydrolysis rate was clearly dependent on the acyl moiety and decreased with increasing alkyl chain length. The compounds showed a markedly lower half-life in cell extracts than in pH 7.3 phosphate buffer due to the presence of enzyme-catalyzed cleavage. In all media, the DiPPro compounds released d4T diphosphate (d4TDP) as the main product beside d4TMP. In antiviral assays, the compounds proved to be at least as potent as d4T against HIV-1 and 2 in wild-type CEM/0 cells. As a proof of concept, compounds with longer acyl residues showed very good anti-HIV activities in thymidine-kinase-deficient cells (CEM/TK(-) ), indicating their ability to penetrate cell membranes and the delivery of phosphorylated metabolites.
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Affiliation(s)
- Tilmann Schulz
- Organic Chemistry, Department of Chemistry, Faculty of Sciences, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany)
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8
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Jessen HJ, Schulz T, Balzarini J, Meier C. Bioreversible protection of nucleoside diphosphates. Angew Chem Int Ed Engl 2009; 47:8719-22. [PMID: 18833560 DOI: 10.1002/anie.200803100] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Henning Jacob Jessen
- Organic Chemistry, Department of Chemistry, Faculty of Science, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
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9
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Jessen H, Schulz T, Balzarini J, Meier C. Bioreversible Maskierung von Nucleosiddiphosphaten. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200803100] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Carter MM, Torres SM, Cook DL, McCash CL, Yu M, Walker VE, Walker DM. Relative mutagenic potencies of several nucleoside analogs, alone or in drug pairs, at the HPRT and TK loci of human TK6 lymphoblastoid cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2007; 48:239-47. [PMID: 17358029 DOI: 10.1002/em.20282] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Experiments were performed to investigate the impact of didanosine (ddI), lamivudine (3TC), and stavudine (d4T) on cell survival and mutagenicity in two reporter genes, hypoxanthine-guanine phosphoribosyltransferase (HPRT) and thymidine kinase (TK), using a cell cloning assay for assessing the effects of individual nucleoside analogs (NRTIs)/drug combinations in human TK6 B-lymphoblastoid cells. Three-day treatments with 0, 33, 100, or 300 microM ddI, 3TC, or ddI-3TC produced positive trends for increased HPRT and TK mutant frequencies. While dose-related trends were too small to reach significance after treatments with d4T or d4T-3TC, pairwise comparisons with control cells indicated that exposure to 100 microM d4T or d4T-3TC caused significant elevations in HPRT mutants. Measurements of mutagenicity in cells exposed to d4T (or d4T-3TC) were complicated by the cytotoxicity of this NRTI. Enhanced increases in mutagenic responses to combined NRTI treatments, compared with single drug treatments, occurred as additive to synergistic effects in the HPRT gene of cells exposed to 100 microM ddI-3TC or 100 microM d4T-3TC, and in the TK gene of cells exposed to 100 or 300 microM ddI-3TC. Comparisons of these data to mutagenicity studies of other NRTIs in the same system (Meng Q et al. [2000c]: Proc Natl Acad Sci USA 97:12667-126671; Torres SM et al. [2007]: Environ Mol Mutagen) indicate that the relative mutagenic potencies for all drugs tested to date are: AZT-ddI > ddI-3TC > AZT-3TC congruent with AZT-3TC-ABC (abacavir) > AZT >/=ddI > d4T-3TC > 3TC > d4T >/= ABC. These collective data suggest that all NRTIs with antiviral activity against HIV-1 may cause host cell DNA damage and mutations, and impose a cancer risk.
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Affiliation(s)
- Meghan M Carter
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
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11
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Matsushita S, Yoshimura K, Kimura T, Kamihira A, Takano M, Eto K, Shirasaka T, Mitsuya H, Oka S. Spontaneous recovery of hemoglobin and neutrophil levels in Japanese patients on a long-term Combivir containing regimen. J Clin Virol 2004; 33:188-93. [PMID: 15911439 DOI: 10.1016/j.jcv.2004.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Accepted: 11/03/2004] [Indexed: 11/26/2022]
Abstract
OBJECTIVE In order to evaluate long-term toxicity of Combivir, we retrospectively reviewed clinical records of HIV-1 infected cases under treatment with Combivir-containing regimen and we analyzed the clinical data compared to other NRTIs-containing regimens. STUDY DESIGN A total of 55 patients who were on Combivir and 39 on a control regimen were examined. RESULTS After starting treatment with Combivir-containing regimens viral load and CD4(+) T-cell count improved as well as the control group. Rates of adverse events in Combivir group and ZDV (400 mg/day) + 3TC group were 50.9% (28/55) and 60% (12/20), respectively. Some of these Japanese patients who started Combivir regimen as a first-line HAART (primary Combivir group) showed some decrease in hemoglobin levels or neutrophil counts within 6 months. However, a significant recovery of these indices of hematological toxicities occurred in patients who continued the regimen for 18-24 months. CONCLUSION Our findings suggest that the safety of 600 mg of ZDV is similar to 400 mg/day of ZDV and the existence of mechanisms that compensate for anemia and for the neutropenia associated with long-term use of Combivir.
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Affiliation(s)
- Shuzo Matsushita
- Division of Clinical Retrovirology and Infectious Diseases, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Kumamoto 860-0811, Japan.
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Antoniou T, Gough K, Yoong D, Arbess G. Severe anemia secondary to a probable drug interaction between zidovudine and valproic acid. Clin Infect Dis 2004; 38:e38-40. [PMID: 14986271 DOI: 10.1086/381760] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2003] [Accepted: 11/20/2003] [Indexed: 11/03/2022] Open
Abstract
A 42-year-old man with human immunodeficiency virus (HIV) infection and a history of complex partial seizures developed severe anemia after the addition of valproic acid to his stable antiretroviral regimen of zidovudine, lamivudine, and abacavir. The inhibition of zidovudine glucuronidation by valproic acid and the resultant zidovudine hematologic toxicity is the proposed mechanism of the interaction.
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Affiliation(s)
- Tony Antoniou
- Department of Family and Community Medicine, St. Michael's Hospital, Toronto, Ontario, Canada,
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13
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Lilling G, Elena N, Sidi Y, Bakhanashvili M. p53-associated 3'-->5' exonuclease activity in nuclear and cytoplasmic compartments of cells. Oncogene 2003; 22:233-45. [PMID: 12527892 DOI: 10.1038/sj.onc.1206111] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The tumor suppressor protein p53 plays an important role in maintenance of the genomic integrity of cells. p53 possesses an intrinsic 3'-->5' exonuclease activity. p53 was found in the nucleus and in the cytoplasm of the cell. In order to evaluate the subcellular location and extent of p53-associated 3'--> 5' exonuclease activity, we established an in vitro experimental system of cell lines with different nuclear/cytoplasmic distribution of p53. Nuclear and cytoplasmic extracts obtained from LCC2 cells (expressing a high level of cytoplasmic wild-type p53), MCF-7 cells (expressing a high level of wild-type nuclear p53), MDA cells (expressing mutant p53) and H1299 cells (p53-null) were subjected to the analysis of exonuclease activity. Interestingly, 3'-->5' exonuclease was predominantly cytoplasmic; the nuclear extracts derived from all cell lines tested, exerted a low level of exonuclease activity. Cytoplasmic extracts of LCC2 cells, with a high level of wild-type p53, showed an enhanced exonuclease activity in comparison to those expressing either a low level of wild-type p53 (in MCF-7 cells) or the mutant p53 (in MDA cells). Evidence that exonuclease function detected in cytoplasmic extracts is attributed to the p53 is supported by several facts: First, this activity closely parallels with levels and status of endogenous cytoplasmic p53. Second, immunoprecipitation of p53 from cytoplasmic extracts of LCC2 cells markedly reduced the exonuclease activity. Third, the observed 3'-->5' exonuclease in cytoplasmic fraction of LCC2 cells displays identical biochemical properties characteristic of recombinant wild-type p53. The biochemical functions include: (a) substrate specificity; exonuclease hydrolyzes single-stranded DNA in preference to double-stranded DNA and RNA/DNA template-primers, (b) efficient excision of 3'-terminal mispairs from DNA/DNA and RNA/DNA substrates, (c) the preferential excision of purine-purine mispairs over purine-pyrimidine mispairs and (d) functional interaction with exonuclease-deficient DNA polymerase, for example, murine leukemia virus reverse transcriptase (representing a relatively low fidelity enzyme), thus enhancing the fidelity of DNA synthesis by excision of mismatched nucleotides from the nascent DNA strand. Taken together, the data demonstrate that wild-type p53 in cytoplasm, in its noninduced state, is functional; it displays intrinsic 3'-->5' exonuclease activity. The possible role of p53-associated 3'-->5' exonuclease activity in DNA repair in nucleus and cytoplasm is discussed.
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Affiliation(s)
- Gila Lilling
- Department of Medicine C, Chaim Sheba Medical Center, Tel Hashomer, Israel
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14
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Skalski V, Brown KR, Choi BY, Lin ZY, Chen S. A 3'-5' exonuclease in human leukemia cells: implications for resistance to 1-beta -D-arabinofuranosylcytosine and 9-beta -D-arabinofuranosyl-2-fluoroadenine 5'-monophosphate. J Biol Chem 2000; 275:25814-9. [PMID: 10833512 DOI: 10.1074/jbc.m001460200] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A 3'-5' exonuclease that excises the nucleotide analogs 1-beta-d-arabinofuranosylcytosine monophosphate and 9-beta-d-arabinofuranosyl-2-fluoroadenine 5'-monophosphate incorporated at 3' ends of DNA was purified from the nuclei of: 1) primary human chronic lymphocytic leukemia cells, 2) primary and established human acute myeloblastic leukemia cells, and 3) lymphocytes obtained from healthy individuals. The activity of this nuclear exonuclease (exoN) is elevated approximately 6-fold in 1-beta-d-arabinofuranosylcytosine-resistant leukemia cells as compared with drug-sensitive cells, and it differs between two healthy individuals and among three leukemia patients. exoN is a 46-kDa monomer, requires 50 mm KCl and 1 mm magnesium for optimal activity, and shows a preference for single-stranded over duplex DNA. Its physical and enzymatic properties indicate that exoN is a previously uncharacterized enzyme whose activity may confer resistance to clinical nucleoside analogs in leukemia cells.
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MESH Headings
- Antimetabolites, Antineoplastic/pharmacology
- Arabinonucleotides/pharmacology
- Cell Nucleus/enzymology
- Cells, Cultured
- Cytidine Monophosphate/analogs & derivatives
- Cytidine Monophosphate/pharmacology
- DNA-Directed DNA Polymerase/metabolism
- Drug Resistance, Neoplasm
- Exodeoxyribonuclease V
- Exodeoxyribonucleases/genetics
- Exodeoxyribonucleases/isolation & purification
- Exodeoxyribonucleases/metabolism
- Exonucleases/biosynthesis
- Exonucleases/chemistry
- Exonucleases/metabolism
- Humans
- Leukemia/enzymology
- Leukemia, Lymphocytic, Chronic, B-Cell/blood
- Leukemia, Lymphocytic, Chronic, B-Cell/enzymology
- Leukemia, Myeloid, Acute/blood
- Leukemia, Myeloid, Acute/enzymology
- Lymphocytes/enzymology
- Magnesium/metabolism
- Neoplasm Proteins
- Potassium Chloride/metabolism
- Protein Biosynthesis
- Time Factors
- Transcription, Genetic
- Tumor Cells, Cultured
- Up-Regulation
- Vidarabine Phosphate/analogs & derivatives
- Vidarabine Phosphate/pharmacology
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Affiliation(s)
- V Skalski
- Division of Experimental Therapeutics, Ontario Cancer Institute, Princess Margaret Hospital and the Department of Medical Biophysics, University of Toronto, Ontario, Canada.
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15
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Girard PM, Pegram PS, Diquet B, Anderson R, Raffi F, Tubiana R, Sereni D, Boerner D. Phase II placebo-controlled trial of fozivudine tidoxil for HIV infection: pharmacokinetics, tolerability, and efficacy. J Acquir Immune Defic Syndr 2000; 23:227-35. [PMID: 10839658 DOI: 10.1097/00126334-200003010-00003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Fozivudine tidoxil (FZD) is a thioether lipid-zidovudine (ZDV) conjugate with anti-HIV activity demonstrated in vitro and in pilot phase I studies. To assess its safety, efficacy and pharmacokinetics, we conducted a multicenter, randomized, double-blind, placebo-controlled trial of FZD monotherapy in 72 HIV-infected patients who had not previously received antiretroviral therapy. In each dosage group (200 mg daily, 400 mg daily, 200 mg twice daily, 800 mg daily, 400 mg twice daily, and 600 mg twice daily), 12 patients were randomized to receive in a 10:2 ratio either FZD or a placebo for 4 weeks. Overall, FZD was well tolerated in all dosage groups; only 1 patient discontinued the drug, because of a moderate rise in aminotransaminase activity. HIV viral load fell in all the patients who were receiving FZD, except in the 200 mg daily group. The largest decrease (-0.67 log10) was observed in the 600 mg twice daily group. The plasma half-life was significantly longer (approximately 3.8 hours) than that of the parent drug ZDV. Exposure to ZDV, as reflected by the area under the time-concentration curve, was much lower after FZD than after ZDV administration. FZD thus appears to be as effective as and potentially better tolerated than ZDV during short-term administration and has the advantage of once daily intake.
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Affiliation(s)
- P M Girard
- Service des Maladies Infectieuses et Tropicales, Assistance Publique-Hôpitaux de Paris, Hôpital Rothschild, France.
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16
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Phase II Placebo-Controlled Trial of Fozivudine Tidoxil for HIV Infection: Pharmacokinetics, Tolerability, and Efficacy. J Acquir Immune Defic Syndr 2000. [DOI: 10.1097/00042560-200003010-00003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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17
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Development and optimization of anti-HIV nucleoside analogs and prodrugs: A review of their cellular pharmacology, structure-activity relationships and pharmacokinetics. Adv Drug Deliv Rev 1999; 39:117-151. [PMID: 10837771 DOI: 10.1016/s0169-409x(99)00023-x] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Significant improvements in antiviral therapy have been realized over the past 10 years. Numerous nucleoside analogs, as well as prodrugs of active compounds, have been synthesized and tested for anti-HIV activity. In addition to the five nucleoside analogs currently used clinically for the treatment of HIV infection, a broad spectrum of anti-HIV nucleoside analogs (including 2',3'-dideoxynucleoside analogs, oxathiolanyl 2',3'-dideoxynucleoside analogs, dioxolanyl 2',3'-dideoxynucleoside analogs, carbocyclic 2',3'-dideoxynucleoside analogs and acyclic nucleoside analogs) and their prodrugs (including ester prodrugs, phospholipid prodrugs, dihydropyridine prodrugs, pronucleotides and dinucleotide analogs), targeted at HIV reverse transcriptase, are reviewed with focus on structure-activity relationships, cellular pharmacology and pharmacokinetics. Several of these anti-viral agents show promise in the treatment of AIDS.
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18
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Sim SM, Hoggard PG, Sales SD, Phiboonbanakit D, Hart CA, Back DJ. Effect of ribavirin on zidovudine efficacy and toxicity in vitro: a concentration-dependent interaction. AIDS Res Hum Retroviruses 1998; 14:1661-7. [PMID: 9870320 DOI: 10.1089/aid.1998.14.1661] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Zidovudine (ZDV) is converted to its active triphosphate (ZDVTP) by intracellular kinases. The intermediate ZDV monophosphate (ZDVMP) is believed to play a major role in ZDV toxicity. Manipulation of ZDV phosphorylation is a possible therapeutic strategy for altering the risk-benefit ratio. Here we investigate whether combining RBV with ZDV is able to modulate efficacy and toxicity of ZDV. We have measured the intracellular activation of ZDV (0.3 microM) in the absence and presence of ribavirin (RBV; 2 and 20 microM) in Molt 4 and U937 cells. MTT cytotoxicity of ZDV (10-1000 microM) was also measured with and without RBV (2 microM) in Molt 4 and U937 cells. Measurement of endogenous deoxythymidine triphosphate (dTTP) allowed investigation of the dTTP/ZDVTP ratio. The antiviral efficacy of ZDV in combination with RBV (2 microM) was assessed by HIV p24 antigen measurements. In the presence of RBV (2 and 20 microM) a decrease in total ZDV phosphates was observed, owing mainly to an effect primarily on ZDVMP rather than the active ZDVTP. RBV also increased endogenous dTTP pools in both cell types, resulting in an increase in the dTTP/ZDVTP ratio. ZDV alone significantly reduced p24 antigen production, with an IC50 of 0.34 microM. Addition of RBV increased the IC50 approximately fivefold (1.52 microM). However, at higher concentrations of ZDV (10 and 100 microM) the antagonistic effect of RBV (2 microM) on ZDV was lost. The RBV-mediated decrease in ZDVMP may explain the reduction in ZDV toxicity when combined with RBV (2 microM). Cytotoxicity of ZDV was reduced in the presence of RBV (2 microM) at all concentrations in both cell lines, probably owing to saturation of ZDVTP formation. The interaction of ZDV and RBV is concentration dependent.
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Affiliation(s)
- S M Sim
- Department of Pharmacology, University of Malaya, Kuala Lumpur, Malaysia
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19
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Lavie A, Ostermann N, Brundiers R, Goody RS, Reinstein J, Konrad M, Schlichting I. Structural basis for efficient phosphorylation of 3'-azidothymidine monophosphate by Escherichia coli thymidylate kinase. Proc Natl Acad Sci U S A 1998; 95:14045-50. [PMID: 9826650 PMCID: PMC24323 DOI: 10.1073/pnas.95.24.14045] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/1998] [Indexed: 11/18/2022] Open
Abstract
The crystal structures of Escherichia coli thymidylate kinase (TmpK) in complex with P1-(5'-adenosyl)-P5-(5'-thymidyl)pentaphosphate and P1-(5'-adenosyl)P5-[5'-(3'-azido-3'-deoxythymidine)] pentaphosphate have been solved to 2.0-A and 2.2-A resolution, respectively. The overall structure of the bacterial TmpK is very similar to that of yeast TmpK. In contrast to the human and yeast TmpKs, which phosphorylate 3'-azido-3'-deoxythymidine 5'-monophosphate (AZT-MP) at a 200-fold reduced turnover number (kcat) in comparison to the physiological substrate dTMP, reduction of kcat is only 2-fold for the bacterial enzyme. The different kinetic properties toward AZT-MP between the eukaryotic TmpKs and E. coli TmpK can be rationalized by the different ways in which these enzymes stabilize the presumed transition state and the different manner in which a carboxylic acid side chain in the P loop interacts with the deoxyribose of the monophosphate. Yeast TmpK interacts with the 3'-hydroxyl of dTMP through Asp-14 of the P loop in a bidentate manner: binding of AZT-MP results in a shift of the P loop to accommodate the larger substituent. In E. coli TmpK, the corresponding residue is Glu-12, and it interacts in a side-on fashion with the 3'-hydroxyl of dTMP. This different mode of interaction between the P loop carboxylic acid with the 3' substituent of the monophosphate deoxyribose allows the accommodation of an azido group in the case of the E. coli enzyme without significant P loop movement. In addition, although the yeast enzyme uses Arg-15 (a glycine in E. coli) to stabilize the transition state, E. coli seems to use Arg-153 from a region termed Lid instead. Thus, the binding of AZT-MP to the yeast TmpK results in the shift of a catalytic residue, which is not the case for the bacterial kinase.
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Affiliation(s)
- A Lavie
- Department of Physical Biochemistry, Max Planck Institute for Molecular Physiology, Rheinlanddamm 201, 44139 Dortmund, Germany
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20
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Goujon L, Brossette T, Dereudre-Bosquet N, Creminon C, Clayette P, Dormont D, Mioskowski C, Lebeau L, Grassi J. Monitoring of intracellular levels of 5'-monophosphate-AZT using an enzyme immunoassay. J Immunol Methods 1998; 218:19-30. [PMID: 9819120 DOI: 10.1016/s0022-1759(98)00101-x] [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: 11/28/2022]
Abstract
We have developed a competitive enzyme immunoassay suitable for routine monitoring of intracellular levels of 5'-monophosphate-AZT (AZT-MP). This assay is performed in 96-well microtiter plates coated with anti-rabbit immunoglobulin antibodies and is based on the use of rabbit polyclonal antibodies raised against an AZT-MP analog and of an AZT-MP/acetylcholinesterase conjugate as tracer. It is very sensitive, with a detection limit close to 0.1 ng/ml (0.2 pmol/ml), and precise (CV < 20% from 20 to 0.3 ng/ml). Very low cross-reactivities were observed with AZT and the corresponding di- and triphosphate derivatives as well as with other related nucleotides and nucleosides. The validity of the assay was demonstrated by measuring intracellular concentrations of AZT-MP in peripheral blood mononuclear cells (PBMCs) and in monocyte-derived macrophages (MDMs) cultured in the presence of various concentrations of AZT (from 0.01 microM to 10 microM). We observed very high levels of AZT-MP in stimulated (PHA + IL2) PBMCs (> 100 pmol/10(6) cells) while, as expected, much lower concentrations were measured in resting PBMCs or MDMs (0.1 to 2 pmol/10(6) cells). The assay constitutes a very convenient tool permitting easy, precise studies of the first step of the intracellular metabolism of AZT leading to the formation of AZT-TP in cultured cells.
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Affiliation(s)
- L Goujon
- CEA, Département de Recherche Médicale, CEA Saclay, Gif sur Yvette, France
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21
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Albengres E, Le Louët H, Tillement JP. Systemic antifungal agents. Drug interactions of clinical significance. Drug Saf 1998; 18:83-97. [PMID: 9512916 DOI: 10.2165/00002018-199818020-00001] [Citation(s) in RCA: 180] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
There are 3 main classes of systemic antifungals: the polyene macrolides (e.g. amphotericin B), the azoles (e.g. the imidazoles ketoconazole and miconazole and the triazoles itraconazole and fluconazole) and the allylamines (e.g. terbinafine). Other systemic antifungals include griseofulvin and flucytosine. Most drug-drug interactions involving systemic antifungals have negative consequences. The interactions of amphotericin B, flucytosine, griseofulvin, terbinafine and azole antifungals can be divided into the following categories: (i) additive dangerous interactions; (ii) modifications of antifungal kinetics by other drugs; and (iii) modifications of the kinetics of other drugs by antifungals. Amphotericin B and flucytosine mainly interact with other agents pharmacodynamically. Clinically important drug interactions with amphotericin B cause nephrotoxicity, hypokalaemia and blood dyscrasias. The most important drug interaction of flucytosine occurs with myelotoxic agents. Hypokalaemia can precipitate the long QT syndrome, as well as potentially lethal ventricular arrhythmias like torsade de pointes. Synergism is likely to occur when either QT interval-modifying drugs (e.g. terfenadine and astemizole) and drugs that induce hypokalaemia (e.g. amphotericin B) are coadministered. Induction and inhibition of cytochrome P450 enzymes at hepatic and extrahepatic sites are the mechanisms that underlie the most serious pharmacokinetic drug interactions of the azole antifungals. These agents have been shown to notably decrease the catabolism of numerous drugs: histamine H1 receptor antagonists, warfarin, cyclosporin, tacrolimus, digoxin, felodipine, lovastatin, midazolam, triazolam, methylprednisolone, glibenclamide (glyburide), phenytoin, rifabutin, ritonavir, saquinavir, nevirapine and nortriptyline. Non-antifungal drugs like carbamazepine, phenobarbital (phenobarbitone), phenytoin and rifampicin (rifampin) can induce the metabolism of azole antifungals. The bioavailability of ketoconazole and itraconazole is also reduced by drugs that increase gastric pH, such as H2 receptor antagonists, proton pump inhibitors, sucralfate and didanosine. Griseofulvin is an enzymatic inducer of coumarin-like drugs and estrogens, whereas terbinafine seems to have a low potential for drug interactions. Despite important advances in our understanding of the mechanisms underlying pharmacokinetic drug interactions during the 1990s, at this time they still remain difficult to predict in terms of magnitude in individual patients. This is because of the large interindividual and intraindividual variations in the catalytic activity of those metabolising enzymes that can either be induced or inhibited by various drugs. Notwithstanding these variations, increasing clinical experience is allowing pharmacokinetic interactions to be used to advantage in order to improve the tolerability of some drugs, as recently exemplified by the use of a fixed combination of ketoconazole and cyclosporin.
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Affiliation(s)
- E Albengres
- Département de Pharmacologie, Faculté de Médecine de Paris XII-Créteil, France
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22
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Guettari N, Loubière L, Brisson E, Klatzmann D. Use of herpes simplex virus thymidine kinase to improve the antiviral activity of zidovudine. Virology 1997; 235:398-405. [PMID: 9281520 DOI: 10.1006/viro.1997.8706] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Many antiviral drugs must be metabolized to their active form by cellular enzymes. Their antiviral activity may therefore be limited by an inefficient metabolism, leading to low intracellular concentration of the active form or to the accumulation of toxic intermediate metabolites. Gene transfer might be used to overcome such limitations by transducing a gene able to increase intracellular drug metabolism. To prove such a concept, we chose the well-studied paradigm of zidovudine (AZT) metabolism and anti-HIV activity. AZT-triphosphate is the active form of AZT, acting through inhibition of HIV reverse transcription. In human cells, the rate-limiting step for AZT phosphorylation is catalyzed by the thymidylate kinase. We thus tested the capacity of herpes simplex virus type 1 thymidine kinase, which possesses a thymidylate kinase activity, to improve AZT metabolism and antiviral activity. Our results show enhanced AZT phosphorylation in HSV-1 TK-expressing lymphoid and monoblastoid cells, which correlated with significantly improved antiviral activity against different strains of HIV-1. The antiviral activity of Foscarnet, another reverse transcriptase inhibitor that does not require phosphorylation, remained unchanged. These results suggest that gene transfer might be envisioned for genetic pharmacomodulation of antiviral drugs.
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Affiliation(s)
- N Guettari
- Centre National de la Recherche Scientifique, ERS 107, Hôpital de la Pitié-Salpêtrière, 83, Boulevard de l'hôpital, Paris Cedex 13, 75651, France
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23
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Lavie A, Vetter IR, Konrad M, Goody RS, Reinstein J, Schlichting I. Structure of thymidylate kinase reveals the cause behind the limiting step in AZT activation. NATURE STRUCTURAL BIOLOGY 1997; 4:601-4. [PMID: 9253404 DOI: 10.1038/nsb0897-601] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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24
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Lavie A, Schlichting I, Vetter IR, Konrad M, Reinstein J, Goody RS. The bottleneck in AZT activation. Nat Med 1997; 3:922-4. [PMID: 9256287 DOI: 10.1038/nm0897-922] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nucleoside-based inhibitors of reverse transcriptase were the first drugs to be used in the chemotherapy of AIDS. After entering the cell, these substances are activated to their triphosphate form by cellular kinases, after which they are potent chain terminators for the growing viral DNA. The two main factors limiting their efficacy are probably interrelated. These are the insufficient degree of reduction of viral load at the commencement of treatment and the emergence of resistant variants of the virus. The reason for the relatively poor suppression of viral replication appears to be inefficient metabolic activation. Thus, for the most extensively used drug, 3'-azido-3'-deoxythymidine (AZT), whereas phosphorylation to the monophosphate is facile, the product is a very poor substrate for the next kinase in the cascade, thymidylate kinase. Because of this, although high concentrations of the monophosphate can be reached in the cell, the achievable concentration of the active triphosphate is several orders of magnitude lower. Determination of the structure of thymidylate kinase as a complex with AZT monophosphate (AZTMP) together with studies on the kinetics of its phosphorylation have now led to a detailed understanding of the reasons for and consequences of the poor substrate properties.
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Affiliation(s)
- A Lavie
- Max Planck Institute for Molecular Physiology, Department of Physical Biochemistry, Dortmund, Germany
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25
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Darnowski JW, Davol PA, Goulette FA. Human recombinant interferon alpha-2a plus 3'-azido-3'-deoxythymidine. Synergistic growth inhibition with evidence of impaired DNA repair in human colon adenocarcinoma cells. Biochem Pharmacol 1997; 53:571-80. [PMID: 9105409 DOI: 10.1016/s0006-2952(96)00824-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We reported that 3'-azidothymidine-3'-deoxythymidine (AZT) plus 5-fluorouracil or methotrexate produces additive cytotoxicity in HCT-8 cells: a reflection of increased AZT metabolism when de novo thymidylate (dTMP) synthesis was inhibited. We now report that AZT plus human recombinant interferon alpha-2a (rIFN-alpha 2a) produces synergistic growth inhibition in these cells. Evaluation of the effect of rIFN-alpha 2a on dTMP metabolism revealed that exposure to rIFN-alpha 2a (+/-AZT) did not affect dTMP synthase activity significantly but increased thymidine (dThd) kinase activity significantly. Consequently, AZT nucleotide production and incorporation into DNA were increased by coexposure to rIFN-alpha 2a. This alone, however, cannot explain the observed synergism. Therefore, the effect of these agents on DNA excision/repair processes was assessed. Isotope clearance studies demonstrated that rIFN-alpha 2a did not alter the rate of [3H]AZT excision from DNA. In contrast, filter-elution studies revealed that rIFN-alpha 2a (+/-AZT) produced more DNA damage and delayed repair compared with the effects produced by AZT alone. Since DNA polymerases alpha and beta are directly involved in gap-filling repair synthesis, experiments next assessed the effect of rIFN-alpha 2a and/or 3'- azido-3'-deoxythymidine-5'-triphosphate (AZTTP) on their activities. Polymerase alpha was inhibited slightly by AZTTP but not by rIFN-alpha 2a. Polymerase beta activity, however, was inhibited dramatically by rIFN-alpha 2a + AZTTP. Finally, western analysis revealed that a 24-hr exposure to 5000 IU/mL rIFN-alpha 2a (+/-20 microM AZT) significantly reduced wild-type p53 expression compared with AZT-exposed cells. We conclude that rIFN-alpha 2a enhances AZT-induced tumor cell growth inhibition by (i) increasing AZT metabolism, and (ii) inhibiting DNA repair and p53-mediated cell cycle control processes.
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Affiliation(s)
- J W Darnowski
- Department of Medicine, Brown University, Rhode Island Hospital, Providence 02903, USA
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26
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Sailaja G, Nayak R, Antony A. Azidothymidine induces apoptosis in mouse myeloma cell line Sp2/0. Biochem Pharmacol 1996; 52:857-62. [PMID: 8781503 DOI: 10.1016/0006-2952(96)82183-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Azidothymidine (AZT), which has been extensively used as an antiviral agent in the treatment of AIDS, showed strong inhibition of growth of Sp2/0 cells in vitro. AZT-treated cells showed a decrease in viability in a dose-dependent manner. AZT specifically induced typical apoptotic cell death with DNA double-strand cleavage and subsequent formation of apoptotic bodies. The induction of DNA double-strand cleavage into the oligonucleosomal ladder by AZT was protected in the presence of thymidine or uridine. An increase in endonuclease activity from nuclear extract of AZT-treated cells was observed. The enzyme activity was found to be Ca(2+)-and Mg(2+)-dependent and was inhibited by zinc acetate. A marked enhancement of PARP activity was observed in AZT-treated cells. These observations show that AZT can trigger both morphological and biochemical changes typical of apoptosis in the mouse myeloma cell line Sp2/0.
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Affiliation(s)
- G Sailaja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
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27
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Hoetelmans RM, Burger DM, Meenhorst PL, Beijnen JH. Pharmacokinetic individualisation of zidovudine therapy. Current state of pharmacokinetic-pharmacodynamic relationships. Clin Pharmacokinet 1996; 30:314-27. [PMID: 8983861 DOI: 10.2165/00003088-199630040-00004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Zidovudine is the cornerstone of current antiretroviral treatment of human immunodeficiency virus (HIV) infection. Its use, however, frequently leads to adverse reactions, including myelosuppression. Zidovudine pharmacokinetics show large interindividual variation with indications of pharmacokinetic-pharmacodynamic relationships, but a clear therapeutic window has not yet been defined. Individualisation of zidovudine therapy with monitoring of drug concentrations might be desirable. This review considers (intracellular) monitoring of zidovudine and anabolites for individualisation of zidovudine therapy and the achievements in describing pharmacokinetic-pharmacodynamic relationships so far.
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Affiliation(s)
- R M Hoetelmans
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, Netherlands
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28
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Arts EJ, Wainberg MA. Mechanisms of nucleoside analog antiviral activity and resistance during human immunodeficiency virus reverse transcription. Antimicrob Agents Chemother 1996; 40:527-40. [PMID: 8851566 PMCID: PMC163153 DOI: 10.1128/aac.40.3.527] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- E J Arts
- McGill University AIDS Centre, Montreal, Quebec, Canada
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29
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Shaw T, Locarnini SA. Hepatic purine and pyrimidine metabolism: implications for antiviral chemotherapy of viral hepatitis. LIVER 1995; 15:169-84. [PMID: 8544639 DOI: 10.1111/j.1600-0676.1995.tb00667.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The use of nucleoside analogues as antiviral agents is expanding. For most nucleoside analogues, intracellular phosphorylation is the major prerequisite for activity. Antiviral activity may be limited by poor uptake, absence of appropriate activating enzymes, catabolism, and competition from endogenous nucleotides. Appreciation of these factors, which are species-, tissue- and cell-specific is important in the understanding of the pharmacology and toxicology of nucleoside analogues. The use of nucleoside analogues against the agents of viral hepatitis is inherently problematic for many reasons including active hepatic nucleoside catabolism, probable absence of virus-specific activating enzymes, competition from endogenous nucleotides synthesised de novo or derived from RNA turnover, and factors related to mitochondrial toxicity. Despite these drawbacks, some nucleoside analogues have been found efficacious against hepatitis B virus and it is likely that as knowledge of their mechanism of action accumulates, their efficacy can be improved both by rational drug design and by use in combination with other drugs, including interferon.
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Affiliation(s)
- T Shaw
- Macfarlane Burnet Centre for Medical Research, Fairfield Hospital, Victoria, Australia
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30
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Stretcher BN. Pharmacokinetic optimisation of antiretroviral therapy in patients with HIV infection. Clin Pharmacokinet 1995; 29:46-65. [PMID: 7586898 DOI: 10.2165/00003088-199529010-00006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
More than 7 years after the introduction of zidovudine for treatment of HIV infection, little use has been made of the pharmacokinetic properties of this or any of the subsequently approved antiretroviral agents to optimise therapy. This is partly because of the limits of technologies developed to measure clinically relevant forms and concentrations of these drugs, and partly because the clinical community has been slow to recognise the potential benefits of pharmacokinetic optimisation of nucleoside analogue therapy in any disease. Nonetheless, for some of these agents, progress in understanding the relationship between pharmacokinetics and pharmacodynamics has been made. With zidovudine, for example, even though plasma concentrations have little clinical utility, evidence suggests that concentrations of active phosphorylated forms of zidovudine inside target cells are related to disease progression and toxicity. Furthermore, a decreased ability to phosphorylate zidovudine might be a prerequisite for the emergence of zidovudine-resistant HIV strains. Measurements of phosphorylated zidovudine inside cells similarly suggest that 100 mg of oral zidovudine every 8 hours approximates the optimal initial dosage regimen in asymptomatic patients. Increased plasma didanosine concentrations have been associated with several measures of clinical improvement in patients, and may be associated with an increased risk of toxicity as well. For zalcitabine and stavudine, however, the picture is much less clear. Their pharmacokinetic and pharmacodynamic relationships have not been studied in patients. Furthermore, there is insufficient data on the effects of age, gender, race and concurrent underlying conditions on the pharmacokinetics of all of these agents. Mounting evidence suggests that monitoring of these compounds could lead to individually optimised intervention strategies. Given the marginal benefits of therapy with these agents, their proven toxic effects and the lack of proven alternatives, it is critical that the clinical community strive to make the most effective use of these agents in the treatment of their patients.
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Affiliation(s)
- B N Stretcher
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Ohio, USA
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31
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Abstract
Depending on the stage of their intervention with the viral replicative cycle, human immunodeficiency virus inhibitors could be divided into the following groups: (i) adsorption inhibitors (i.e., CD4 constructs, polysulfates, polysulfonates, polycarboxylates, and polyoxometalates), (ii) fusion inhibitors (i.e., plant lectins, succinylated or aconitylated albumins, and betulinic acid derivatives), (iii) uncoating inhibitors (i.e., bicyclams), (iv) reverse transcription inhibitors acting either competitively with the substrate binding site (i.e., dideoxynucleoside analogs and acyclic nucleoside phosphonates) or allosterically with a nonsubstrate binding site (i.e., non-nucleoside reverse transcriptase inhibitors), (v) integration inhibitors, (vi) DNA replication inhibitors, (vii) transcription inhibitors (i.e., antisense oligodeoxynucleotides and Tat antagonists), (viii) translation inhibitors (i.e., antisense oligodeoxynucleotides and ribozymes), (ix) maturation inhibitors (i.e., protease inhibitors, myristoylation inhibitors, and glycosylation inhibitors), and finally, (x) budding (assembly/release) inhibitors. Current knowledge, including the therapeutic potential, of these various inhibitors is discussed. In view of their potential clinical the utility, the problem of virus-drug resistance and possible strategies to circumvent this problem are also addressed.
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Affiliation(s)
- E De Clercq
- Rega Institute for Medical Research, Katholieke Universiteit Leuven, Belgium
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32
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Chandrasekaran B, Kute TE, Duch DS. Synchronization of cells in the S phase of the cell cycle by 3'-azido-3'-deoxythymidine: implications for cell cytotoxicity. Cancer Chemother Pharmacol 1995; 35:489-95. [PMID: 7882457 DOI: 10.1007/bf00686833] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The mechanism of synergy between 3'-azido-3'-deoxythymidine (AZT) and anticancer agents was investigated with emphasis on cell-cycle events. Exposure of exponentially growing WiDr human colon carcinoma cells to AZT resulted in synchronization of cells in the S phase of the cell cycle. Following treatment with AZT at 50 or 200 microM, 62% +/- 3% or 82% +/- 4% of the cells were in the S phase as compared with 36% +/- 2% in the control. Bromodeoxyuridine uptake studies revealed that the synchronized cells actively synthesized DNA. At concentrations of up to 200 microM, AZT produced a cytostatic rather than cytotoxic effect as indicated by viability and cell growth measurements. At 200 microM, AZT-induced synchronization was significant (P = < 0.001) after 12 h of drug exposure, reached a maximum at 24 h, and reversed to baseline levels by 72 h even in the continued presence of the drug. This indicates that AZT-induced cytostasis is a transient and reversible effect. The cell-cycle events seen with AZT in WiDr cells were also observed in eight of nine human tumor cell lines tested. Isobologram analysis of WiDr cells preexposed to AZT for 24 h and then exposed to either AZT-5-fluorouracil or AZT-methotrexate for a further 72 h revealed synergy between AZT and the anticancer agents, indicating that AZT-induced synchronization may have therapeutic benefits.
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Affiliation(s)
- B Chandrasekaran
- Division of Cell Biology, Wellcome Research Laboratories, Research Triangle Park, NC 27709
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33
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In vitro studies of the toxicity of nucleoside analogues used in the treatment of HIV infection. Toxicol In Vitro 1994; 8:677-83. [DOI: 10.1016/0887-2333(94)90042-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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34
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Stretcher BN, Pesce AJ, Frame PT, Stein DS. Pharmacokinetics of zidovudine phosphorylation in peripheral blood mononuclear cells from patients infected with human immunodeficiency virus. Antimicrob Agents Chemother 1994; 38:1541-7. [PMID: 7979286 PMCID: PMC284590 DOI: 10.1128/aac.38.7.1541] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
As part of an effort towards optimization of dosing of zidovudine (ZDV), formation and elimination of total phosphorylated ZDV (ZDVPt) in peripheral blood mononuclear cells were examined in 21 asymptomatic human immunodeficiency virus-infected patients during their first 24 weeks of therapy (AIDS Clinical Trials Group Protocol 161). Intracellular concentrations of ZDVPt were measured with a previously described and validated radioimmunoassay technique. Although ZDV phosphorylation occurred readily upon initiation of therapy, it declined with time; the area under the concentration-time curve (AUC) at week 4 (mean +/- standard deviation, 3.41 +/- 0.93 pmol.h/10(6) cells) was significantly greater than that at week 24 (2.19 +/- 1.10 pmol.h/10(6) cells). Plasma ZDV AUC did not change with time and did not correlate with ZDVPt AUC. In dose-response experiments (20 to 100 mg orally), phosphorylation did not proportionally increase with increasing plasma ZDV concentrations. Similarly, compared with a single dose, two doses of ZDV over an 8-h period resulted in little ZDVPt increase in cells relative to increase in plasma ZDV concentrations. The half-life of intracellular ZDVPt was twice that of plasma ZDV (4 versus 2 h), suggesting that an every-8-h dosing regimen is justifiable. These findings suggest that metabolism of ZDV to its active intracellular forms may be saturable in some patients, is poorly correlated with plasma concentrations, and diminishes over time. These findings have implications for future development and management of anti-human immunodeficiency virus nucleoside therapy.
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Affiliation(s)
- B N Stretcher
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Ohio 45267-0714
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Mazumder A, Cooney D, Agbaria R, Gupta M, Pommier Y. Inhibition of human immunodeficiency virus type 1 integrase by 3'-azido-3'-deoxythymidylate. Proc Natl Acad Sci U S A 1994; 91:5771-5. [PMID: 8016063 PMCID: PMC44078 DOI: 10.1073/pnas.91.13.5771] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The effects of 3'-azido-3'-deoxythymidine (AZT) and three of its intracellular metabolites, azido- thymidine mono-, di-, and triphosphates, on the human immunodeficiency virus type 1 integrase have been determined. AZT mono-, di-, and triphosphate have an IC50 for integration between 110 and 150 microM, whereas AZT does not inhibit the integrase. The inhibition by AZT monophosphate can be partially reversed by coincubation with either thymidine monophosphate or 2',3'-dideoxythymidine monophosphate, suggesting that either of these monophosphates can bind to the integrase but that the azido group at the 3' position could be responsible for the inhibition. Integrase inhibition is associated with reduced enzyme-DNA binding but does not appear to be competitive with respect to the DNA substrate. Inhibition of an integrase deletion mutant containing only amino acids 50-212 suggests that these nucleotides bind in the catalytic core. Concentrations up to 1 mM AZT monophosphate can accumulate in vivo, indicating that integrase inhibition may contribute to the antiviral effects of AZT. The increasing incidence of AZT-resistant virus strains may, therefore, be associated with mutations not only in the reverse transcriptase but also in the human immunodeficiency virus integrase. Finally, these observations suggest that additional strategies for antiviral drug development could be based upon nucleotide analogs as inhibitors of human immunodeficiency virus integrase.
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Affiliation(s)
- A Mazumder
- Laboratory of Molecular Pharmacology, National Cancer Institute, Bethesda, MD 20892
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Faraj A, Fowler DA, Bridges EG, Sommadossi JP. Effects of 2',3'-dideoxynucleosides on proliferation and differentiation of human pluripotent progenitors in liquid culture and their effects on mitochondrial DNA synthesis. Antimicrob Agents Chemother 1994; 38:924-30. [PMID: 7520683 PMCID: PMC188128 DOI: 10.1128/aac.38.5.924] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
2',3'-Dideoxynucleosides (ddNs) including 3'-azido-3'-deoxythymidine (AZT), 3'-fluoro-3'-deoxythymidine (FLT), 3'-amino-3'-deoxythymidine (AMT), 2',3'-dideoxycytidine (ddC), and 2',3'-didehydro-3'-deoxythymidine (D4T) were tested for their effects on proliferation and differentiation of pluripotent progenitor cells (CD34+) purified from human bone marrow cells grown in liquid cultures. These highly purified progenitor cells undergo extensive proliferation during 14 days, with a marked differentiation during the last 7 days. These differentiated cells exhibit normal morphological features in response to specific hematopoietic growth factors of both erythroid and granulocyte-macrophage lineages, as demonstrated by flow cytometry cell phenotyping. The potencies of these ddNs in inhibiting proliferation of granulocyte-macrophage lineage cells were in the order FLT > AMT = ddC > AZT >> D4T, and the potencies in inhibiting proliferation of erythroid lineage cultures were in the order FLT > AMT > AZT > ddC >> D4T. The toxic effects of ddNs assessed in these liquid cultures were in agreement with data obtained by using semisolid cultures, demonstrating the consistency of these two in vitro hematopoietic systems toward ddN toxicity. ddC was toxic to CD34+ progenitor cells and/or cells in the early stages of differentiation, whereas the inhibitory effect of AZT on the erythroid lineage was predominantly observed on a more mature population of erythroid progenitors during the differentiation process. Slot blot analysis of granulocyte-macrophage cultures demonstrated that exposure to ddC and FLT was associated with a decrease in total mitochondrial DNA (mtDNA) content, suggesting that these two ddNs inhibit mtDNA synthesis. In contrast, no difference in the ratio of nuclear DNA to mtDNA was observed in cells exposed to toxic concentrations of AZT and AMT is not associated with an inhibition of mtDNA synthesis. This human pluripotent progenitor liquid culture system should permit detailed investigations of the cellular and molecular events involved in ddN-induced hematological toxicity.
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Affiliation(s)
- A Faraj
- Department of Pharmacology, University of Alabama at Birmingham 35294
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