1
|
Parisot D, Malet-Martino MC, Martino R, Crasnier P. F Nuclear Magnetic Resonance Analysis of 5-Fluorouracil Metabolism in Four Differently Pigmented Strains of Nectria haematococca. Appl Environ Microbiol 2010; 57:3605-12. [PMID: 16348609 PMCID: PMC184020 DOI: 10.1128/aem.57.12.3605-3612.1991] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
F nuclear magnetic resonance spectroscopy was used to study the metabolism of 5-fluorouracil in four strains of Nectria haematococca which displayed similar sensitivities to growth inhibition by this compound but differed in their pigmentation. The major metabolites, 5-fluorouridine and alpha-fluoro-beta-alanine, were excreted into the medium by all four strains. The classical ribofluoronucleotides (5-fluorouridine-5'-monophosphate, -diphosphate, and -triphosphate) and alpha-fluoro-beta-alanine were identified in the acid-soluble fraction of perchloric acid extracts of mycelia. Two hydrolysis products of 5-fluorouracil incorporated into RNA were found in the acid-insoluble pool. They were unambiguously assigned to 5-fluorouridine-2'-monophosphate and 3'-monophosphate with specific hydrolysis reactions on isolated RNA. The lack of fluorodeoxyribonucleotides and the fact that the four strains incorporated similar amounts of fluororibonucleotides into their RNAs strongly suggest an RNA-directed mechanism of cytotoxicity for 5-fluorouracil. The heavily pigmented wild type differed from the three low-pigmented strains in its low uptake of 5-fluorouracil and, consequently, in its reduced biosynthesis of 5-fluorouridine and alpha-fluoro-beta-alanine. At present, it is not clear whether this change in 5-fluorouracil metabolism is a side effect of pigment production or results from another event.
Collapse
Affiliation(s)
- D Parisot
- Laboratoire de Cryptogamie, Bâtiment 400, Faculté des Sciences, 91405 Orsay Cédex, and Groupe de RMN Biomédicale, Laboratoire des IMRCP, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cédex, France
| | | | | | | |
Collapse
|
2
|
Stegman LD, Rehemtulla A, Beattie B, Kievit E, Lawrence TS, Blasberg RG, Tjuvajev JG, Ross BD. Noninvasive quantitation of cytosine deaminase transgene expression in human tumor xenografts with in vivo magnetic resonance spectroscopy. Proc Natl Acad Sci U S A 1999; 96:9821-6. [PMID: 10449778 PMCID: PMC22294 DOI: 10.1073/pnas.96.17.9821] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Analysis of transgene expression in vivo currently requires destructive and invasive molecular assays of tissue specimens. Noninvasive methodology for assessing the location, magnitude, and duration of transgene expression in vivo will facilitate subject-by-subject correlation of therapeutic outcomes with transgene expression and will be useful in vector development. Cytosine deaminase (CD) is a microbial gene undergoing clinical trials in gene-directed enzyme prodrug gene therapy. We hypothesized that in vivo magnetic resonance spectroscopy could be used to measure CD transgene expression in genetically modified tumors by directly observing the CD-catalyzed conversion of the 5-fluorocytosine (5-FC) prodrug to the chemotherapeutic agent 5-fluorouracil (5-FU). The feasibility of this approach is demonstrated in subcutaneous human colorectal carcinoma xenografts in nude mice by using yeast CD (yCD). A three-compartment model was used to analyze the metabolic fluxes of 5-FC and its metabolites. The rate constants for yCD-catalyzed prodrug conversion (k(1)(app)), 5-FU efflux from the observable tumor volume (k(2)(app)), and formation of cytotoxic fluorinated nucleotides from 5-FU (k(3)(app)) were 0.49 +/- 0.27 min(-1), 0.766 +/- 0.006 min(-1), and 0.0023 +/- 0.0007 min(-1), respectively. The best fits of the 5-FU concentration data assumed first-order kinetics, suggesting that yCD was not saturated in vivo in the presence of measured intratumoral 5-FC concentrations well above the in vitro K(m). These results demonstrate the feasibility of using magnetic resonance spectroscopy to noninvasively monitor therapeutic transgene expression in tumors. This capability provides an approach for measuring gene expression that will be useful in clinical gene therapy trials.
Collapse
Affiliation(s)
- L D Stegman
- Department of Radiology and Biological Chemistry, University of Michigan Medical School, 1150 West Medical Center Drive, MSRBIII Room 9301 Ann Arbor, MI 48109-0648, USA
| | | | | | | | | | | | | | | |
Collapse
|
3
|
Malet-Martino MC, Martino R. Magnetic resonance spectroscopy: a powerful tool for drug metabolism studies. Biochimie 1992; 74:785-800. [PMID: 1467338 DOI: 10.1016/0300-9084(92)90061-i] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Studies on the metabolism and disposition of drugs using nuclear magnetic resonance spectroscopy (MRS) as the analytical technique are reviewed. An overview of the main studies classed in terms of the observed magnetic nucleus (1H, 2H, 7Li, 13C, 19F, 31P, 77Se) is followed by some typical examples of the way in which 19F and 31P MRS can be profitably employed to gain more understanding about the metabolism and disposition of the anticancer fluoropyrimidines (5-fluorouracil (FU) and its prodrugs) and ifosfamide (IF). The results of three recent studies carried out in our laboratory are developed. They concern the direct quantitative monitoring of the hepatic metabolism of FU in the isolated perfused mouse liver, the elucidation of the origin of the cardiotoxicity of FU and the metabolism of IF from an analysis of biofluids of patients. Finally, the advantages and limitations of MRS for investigations on drug metabolism are discussed.
Collapse
Affiliation(s)
- M C Malet-Martino
- Laboratoire des IMRCP, URA CNRS 470, Université Paul Sabatier, Toulouse, France
| | | |
Collapse
|
4
|
|
5
|
Fasoli MO, Kerridge D, Morris PG, Torosantucci A. 19F nuclear magnetic resonance study of fluoropyrimidine metabolism in strains of Candida glabrata with specific defects in pyrimidine metabolism. Antimicrob Agents Chemother 1990; 34:1996-2006. [PMID: 2291666 PMCID: PMC171978 DOI: 10.1128/aac.34.10.1996] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Flucytosine (5-FC)-resistant strains were isolated from the haploid opportunistic pathogen Candida glabrata by UV-induced mutation and fluoropyrimidine selection. These strains were characterized biochemically, and the metabolism of fluorinated pyrimidines was studied by 19F nuclear magnetic resonance spectroscopy. No evidence was obtained from these studies for degradative metabolism of the fluorinated derivatives. In the parental susceptible strain of C. glabrata, 5-fluorouracil but not 5-FC was detected within the cells. 5-Fluorouracil was also present in the culture supernatant after incubation of the cells with 5-FC. The distribution of fluorinated derivatives within the 5-FC-resistant strains was consistent with their genotype. Two strains of C. glabrata which had only a partial loss of cytosine deaminase and UMP pyrophosphorylase activity had high levels of resistance to 5-FC. Both C. glabrata and Candida albicans were susceptible to 5-fluorouridine. This compound but not the anticancer drug 5-fluoro-2-deoxyuridine was shown to be transported into susceptible cells by a specific uridine permease.
Collapse
Affiliation(s)
- M O Fasoli
- Department of Biochemistry, Cambridge CB2 1QW, United Kingdom
| | | | | | | |
Collapse
|
6
|
Chouini-Lalanne N, Malet-Martino MC, Martino R, Michel G. Study of the metabolism of flucytosine in Aspergillus species by 19F nuclear magnetic resonance spectroscopy. Antimicrob Agents Chemother 1989; 33:1939-45. [PMID: 2610505 PMCID: PMC172792 DOI: 10.1128/aac.33.11.1939] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The metabolism of flucytosine (5FC) in two Aspergillus species (Aspergillus fumigatus and A. niger) was investigated by 19F nuclear magnetic resonance spectroscopy. In intact mycelia, 5FC was found to be deaminated to 5-fluorouracil and then transformed into fluoronucleotides; the catabolite alpha-fluoro-beta-alanine was also detected in A. fumigatus. Neither 5-fluoroorotic acid nor 5-fluoro-2'-deoxyuridine-5'-monophosphate was detected in perchloric acid extracts after any incubation with 5FC. 5FC, 5-fluorouracil, and the classical fluoronucleotides 5-fluorouridine-5'-mono-, di-, and triphosphates were identified in the acid-soluble pool. Two hydrolysis products of 5-fluorouracil incorporated into RNA, 5-fluorouridine-2'-monophosphate and 5-fluorouridine-3'-monophosphate, were found in the acid-insoluble pool. No significant differences in the metabolic transformation of 5FC were noted in the two species of Aspergillus. The main pathway of 5FC metabolism in the two species of Aspergillus studied is thus the biotransformation into ribofluoronucleotides and the subsequent incorporation of 5-fluorouridine-5'-triphosphate into RNA.
Collapse
|
7
|
Parisot D, Malet-Martino MC, Crasnier P, Martino R. 19F nuclear magnetic resonance analysis of 5-fluorouracil metabolism in wild-type and 5-fluorouracil-resistant Nectria haematococca. Appl Environ Microbiol 1989; 55:2474-9. [PMID: 2604390 PMCID: PMC203107 DOI: 10.1128/aem.55.10.2474-2479.1989] [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: 01/01/2023] Open
Abstract
A mutant (furA3) was isolated from the S1 wild-type strain of Nectria haematococca on the basis of its resistance to 5-fluorouracil (5FU). This mutant has greatly reduced activity of uracil phosphoribosyltransferase, a pyrimidine salvage enzyme catalyzing the synthesis of UMP from uracil. The metabolism of 5FU was examined in both strains by using 19F nuclear magnetic resonance spectroscopy. In the S1 strain, 5FU appears to be metabolized by two pathways operating simultaneously: (i) conversion to fluoronucleotides and (ii) degradation into alpha-fluoro-beta-alanine. The furA3 mutant shows metabolic changes consistent with a uracil phosphoribosyltransferase lesion, since it takes up 5FU and forms a small amount of alpha-fluoro-beta-alanine but does not synthesize fluoronucleotides. Since pigment synthesis is strongly enhanced by 5FU in the S1 wild-type strain but not in the furA3 mutant, these results support the hypothesis that 5FU stimulation of secondary metabolism in N. haematococca is not mediated by the drug itself but involves a phosphorylated anabolite.
Collapse
Affiliation(s)
- D Parisot
- Laboratoire de Cryptogamie, Bâtiment 400, Faculté des Sciences, Orsay, France
| | | | | | | |
Collapse
|
8
|
Malet-Martino MC, Martino R. The application of nuclear magnetic resonance spectroscopy to drug metabolism studies. Xenobiotica 1989; 19:583-607. [PMID: 2669361 DOI: 10.3109/00498258909042297] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
1. The applications of n.m.r. spectroscopy studies to drug metabolism, both in vitro (biofluids, isolated cells, excised tissue samples, isolated organs) and in vivo (animals, humans) are reviewed. 2. N.m.r. is a relatively insensitive technique, but it has the great advantage of being non-invasive and non-destructive, i.e. it allows a direct study of intact biological samples. 3. The majority of studies examined deal with 19F-n.m.r. spectroscopy mainly because of the favourable n.m.r. characteristics of this nucleus, and the low level of endogenous fluorine which gives no detectable 19F signal. However, the potential utility of 1H-31P- and 13C-n.m.r. is also emphasized.
Collapse
Affiliation(s)
- M C Malet-Martino
- Groupe de RMN Biomédicale, Laboratoire des IMRCP, Université Paul Sabatier, Toulouse, France
| | | |
Collapse
|
9
|
Mobashery S, Lerner SA, Johnston M. Monitoring beta-lactamase activity in vivo by 13C nuclear magnetic resonance spectroscopy. Antimicrob Agents Chemother 1988; 32:1196-203. [PMID: 3056254 PMCID: PMC172376 DOI: 10.1128/aac.32.8.1196] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
A 13C-labeled cephalothin, 7 beta-(2-thienylacetamido)-3-[acetoxy-13C1]methyl-3-cephem-4- carboxylate (compound 1), has been prepared and used to monitor beta-lactamase activities by 13C nuclear magnetic resonance spectroscopy. Time-elapsed spectral analysis of the reaction of the labeled cephalothin with the TEM-2 beta-lactamase purified from Escherichia coli revealed the progressive loss of the cephalothin acetyl resonance at 176.8 ppm and accumulation of an acetate signal at 184.3 ppm. Spectral results identical to those observed in the in vitro experiment were obtained when compound 1 was incubated with cell suspensions of E. coli JSR-O (pBR322), which contains the plasmid-encoded TEM-2 beta-lactamase, and Enterobacter cloacae strains that contain a class I chromosomal beta-lactamase. Pseudo-first-order rate constants for the lactamase-catalyzed formation of acetate from cephalothin in vivo were obtained by integration of the 13C-acetyl resonances of compound 1 during timed incubations with cell preparations. These results constitute the first demonstration of the ability to monitor beta-lactamase activity in viable cells by nuclear magnetic resonance spectroscopy.
Collapse
Affiliation(s)
- S Mobashery
- Department of Chemistry, Searle Chemistry Laboratory, University of Chicago, Illinois 60637
| | | | | |
Collapse
|
10
|
Whelan WL. The genetic basis of resistance to 5-fluorocytosine in Candida species and Cryptococcus neoformans. Crit Rev Microbiol 1987; 15:45-56. [PMID: 3319420 DOI: 10.3109/10408418709104447] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In terms of genetically determined susceptibility to the clinical antifungal agent 5-fluorocytosine (5-FC), Candida albicans may be homozygous sensitive (FCY/FCY), homozygous resistant (fcy/fcy), or heterozygous (fcy/FCY). Although heterozygotes are only slightly resistant, they occur at significant frequency among clinical strains and carry preexisting resistance determinants which may be responsible, following homozygosis, for treatment failures. There are two resistance genes (FCY1 and FCY2) known. Resistance in fcy1/fcy1 strains was associated with decreased UMP pyrophosphorylase activity, whereas resistance in fcy2/fcy2 strains was associated with decreased cytosine deaminase activity. These results were confirmed and extended in a 19F nuclear magnetic resonance study of 5-FC uptake and metabolism in genetically defined strains. By means of hybridization via spheroplast fusion, a complementation test was devised to test allelism of resistance determinants. Resistance to 5-FC was employed as a useful genetic marker in basic studies. In tetraploid hybrids which bore appropriate fcy markers, it was possible to select for reduction in ploidy by selecting for increased resistance to 5-FC; a novel parasexual system was thus generated (2n x 2n----4n----2n). In linkage studies, the gene FCY1 was shown to be linked to the gene HIS. Reciprocal mitotic recombination was demonstrated repeatedly with fcy1 and his alleles in cis and in trans configurations and evidence for nonreciprocal recombination (mitotic gene conversion) was also obtained. In Cryptococcus neoformans, mutation in either of two genes (FCY1, FCY2) is sufficient to confer resistance. These genes behave as simple Mendelian determinants which recombine freely. Diploid C. neoformans heterozygous for resistance (FCY/fcy) provided useful strains in which to develop genetic mapping methodology based on mitotic recombination.
Collapse
Affiliation(s)
- W L Whelan
- Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
| |
Collapse
|
11
|
Abstract
The present review is concerned with recent progress in basic genetic investigations with a variety of fungi which are pathogenic for man and animals. The principles and strategies involved in undertaking genetic investigations of sexual species and of asexual species are discussed. Progress in genetic analysis of Cryptococcus neoformans made possible by the discovery of its sexual phase is described in detail, as is progress in development of parasexual methods of analysis in Candida albicans. The genetic bases of virulence and drug resistance are discussed for those few species in which these phenotypes have been investigated. Suggestions for future research, including the application of recent advances in molecular biology to the study of pathogenic fungi, are presented.
Collapse
|
12
|
Vialaneix JP, Chouini N, Malet-Martino MC, Martino R, Michel G, Lepargneur JP. Noninvasive and quantitative 19F nuclear magnetic resonance study of flucytosine metabolism in Candida strains. Antimicrob Agents Chemother 1986; 30:756-62. [PMID: 3800351 PMCID: PMC176527 DOI: 10.1128/aac.30.5.756] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
19F nuclear magnetic resonance was used for a noninvasive and quantitative study of flucytosine (FC; 5-fluorocytosine) metabolism in two strains of Candida albicans and one strain of Candida tropicalis with various susceptibilities to FC. Three intracellular fluorinated metabolites were detected in the highly susceptible strain, F-nucleotides (Fnt), F-nucleosides, and 5-fluorouracil (5FU). Fnt were partially converted into 5FU when the spectra of the yeasts were recorded at 37 degrees C without perfusion, but the intensities of the signals were not modified at 4 or 37 degrees C if the cells were perfused. In the acid extract, the Fnt signal was resolved into three distinct peaks; none of them was attributable to 5-fluoro-2'-deoxyuridine-5'-monophosphate. The same signals were detected in the partially resistant strain, but only 5FU was observed in the highly resistant strain; the resistance of the latter strain therefore was primarily due to a defect in UMP pyrophosphorylase. At the end of the incubation period, only FC and released 5FU were present in the culture media. The concentration of the intracellular fluorinated metabolites was increased if the strain was susceptible to FC. The total amount of metabolized FC was very similar for the highly susceptible and the partially resistant strains, but the percentage of Fnt was much higher in the former (38%) than in the latter (8%); the mild resistance of the partially resistant strain therefore was attributed to the decreased activity of UMP pyrophosphorylase.
Collapse
|