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1.
Mol Microbiol ; 112(6): 1784-1797, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31532038

RESUMO

A microbe's ecological niche and biotechnological utility are determined by its specific set of co-evolved metabolic pathways. The acquisition of new pathways, through horizontal gene transfer or genetic engineering, can have unpredictable consequences. Here we show that two different pathways for coumarate catabolism failed to function when initially transferred into Escherichia coli. Using laboratory evolution, we elucidated the factors limiting activity of the newly acquired pathways and the modifications required to overcome these limitations. Both pathways required host mutations to enable effective growth with coumarate, but the necessary mutations differed. In one case, a pathway intermediate inhibited purine nucleotide biosynthesis, and this inhibition was relieved by single amino acid replacements in IMP dehydrogenase. A strain that natively contains this coumarate catabolism pathway, Acinetobacter baumannii, is resistant to inhibition by the relevant intermediate, suggesting that natural pathway transfers have faced and overcome similar challenges. Molecular dynamics simulation of the wild type and a representative single-residue mutant provide insight into the structural and dynamic changes that relieve inhibition. These results demonstrate how deleterious interactions can limit pathway transfer, that these interactions can be traced to specific molecular interactions between host and pathway, and how evolution or engineering can alleviate these limitations.


Assuntos
Ácidos Cumáricos/metabolismo , Nucleotídeos de Purina/biossíntese , Acinetobacter baumannii/metabolismo , Escherichia coli/genética , Evolução Molecular , Técnicas de Transferência de Genes , Transferência Genética Horizontal , IMP Desidrogenase/genética , IMP Desidrogenase/metabolismo , Redes e Vias Metabólicas/genética , Simulação de Dinâmica Molecular , Mutação , Nucleotídeos de Purina/antagonistas & inibidores , Nucleotídeos de Purina/genética
2.
Artigo em Inglês | MEDLINE | ID: mdl-29723133

RESUMO

The pyrimidine de novo nucleotide synthesis consists of 6 sequential steps. Various inhibitors against these enzymes have been developed and evaluated in the clinic for their potential anticancer activity: acivicin inhibits carbamoyl-phosphate-synthase-II, N-(phosphonacetyl)-L- aspartate (PALA) inhibits aspartate-transcarbamylase, Brequinar sodium and dichloroallyl-lawsone (DCL) inhibit dihydroorotate-dehydrogenase, and pyrazofurin (PF) inhibits orotate-phosphoribosyltransferase. We compared their growth inhibition against 3 cell lines from head-and-neck-cancer (HEP-2, UMSCC-14B and UMSCC-14C) and related the sensitivity to their effects on nucleotide pools. In all cell lines Brequinar and PF were the most active compounds with IC50 (50% growth inhibition) values between 0.06-0.37 µM, Acivicin was as potent (IC50s 0.26-1 µM), but DCL was 20-31-fold less active. PALA was most inactive (24-128 µM). At equitoxic concentrations, all pure antipyrimidine de novo inhibitors depleted UTP and CTP after 24 hr exposure, which was most pronounced for Brequinar (between 6-10% of UTP left, and 12-36% CTP), followed by DCL and PF, which were almost similar (6-16% UTP and 12-27% CTP), while PALA was the least active compound (10-70% UTP and 13-68% CTP). Acivicin is a multi-target inhibitor of more glutamine requiring enzymes (including GMP synthetase) and no decrease of UTP was found, but a pronounced decrease in GTP (31-72% left). In conclusion, these 5 inhibitors of the pyrimidine de novo nucleotide synthesis varied considerably in their efficacy and effect on pyrimidine nucleotide pools. Inhibitors of DHO-DH were most effective suggesting a primary role of this enzyme in controlling pyrimidine nucleotide pools.


Assuntos
Antineoplásicos/farmacologia , Compostos de Bifenilo/farmacologia , Carcinoma de Células Escamosas/metabolismo , Neoplasias de Cabeça e Pescoço/metabolismo , Nucleotídeos de Purina/antagonistas & inibidores , Nucleotídeos de Pirimidina/antagonistas & inibidores , Ribonucleosídeos/farmacologia , Amidas , Aspartato Carbamoiltransferase/antagonistas & inibidores , Ácido Aspártico/análogos & derivados , Ácido Aspártico/farmacologia , Carbamoil Fosfato Sintase (Glutamina-Hidrolizante)/antagonistas & inibidores , Linhagem Celular Tumoral , Di-Hidro-Orotato Desidrogenase , Humanos , Isoxazóis/farmacologia , Naftoquinonas/farmacologia , Orotato Fosforribosiltransferase/antagonistas & inibidores , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/antagonistas & inibidores , Ácido Fosfonoacéticos/análogos & derivados , Ácido Fosfonoacéticos/farmacologia , Nucleotídeos de Purina/biossíntese , Pirazóis , Nucleotídeos de Pirimidina/biossíntese , Ribose
3.
Biomed Pharmacother ; 101: 30-36, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29477055

RESUMO

Diabetes Mellitus (DM) is associated with an increased susceptibility to various infections, which might be attributed to changes in immune response owing to chronic hyperglycemia. Nucleoside triphosphate diphosphohydrolase (NTPDase), 5'-nucleotidase, and adenosine deaminase (ADA) are important enzymes involved in the generation of anti-aggregant and anti-inflammatory microenvironments. The aim of this study was to evaluate the effect of gallic acid (GA) on the hematological parameters and ectonucleotidase activities in platelets, lymphocytes, and serum of diabetic rats. Experimental rats were categorized into 4 groups: (i) control -saline, (ii) control - GA, (iii) diabetic -saline, and (iv) diabetic - GA. One week after induction of DM using streptozotocin (65 mg/kg), GA (30 mg/kg) or saline was orally administered to the rats for 21 days. Our results demonstrated that the concentration of mean corpuscular hemoglobin was decreased, whereas that of red cell distribution was increased in the diabetic group, however, GA could revert these alterations. Moreover, in diabetic rats, GA reverted the increase in ATP and ADP hydrolysis and ADA activity in lymphocytes, and it prevented the increase in NTPDase and ADA activities in platelets. A decrease in ATP hydrolysis and an increase in ADP and AMP hydrolysis were observed in the serum of diabetic rats; however, GA treatment could solely revert changes in ATP hydrolysis. Our study suggests that GA exhibits beneficial effects on immuno- and thrombo-regulatory responses in DM and that these effects may be related to the modulation of purinergic signaling.


Assuntos
Plaquetas/metabolismo , Diabetes Mellitus Experimental/sangue , Ácido Gálico/farmacologia , Linfócitos/metabolismo , Nucleotídeos de Purina/metabolismo , Soro/metabolismo , Animais , Plaquetas/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Ácido Gálico/uso terapêutico , Linfócitos/efeitos dos fármacos , Masculino , Agregação Plaquetária/efeitos dos fármacos , Agregação Plaquetária/fisiologia , Nucleotídeos de Purina/agonistas , Nucleotídeos de Purina/antagonistas & inibidores , Ratos , Ratos Wistar , Soro/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia
4.
J Med Chem ; 61(5): 2027-2040, 2018 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-29425443

RESUMO

Tumor-targeted specificities of 6-substituted pyrrolo[2,3- d]pyrimidine analogues of 1, where the phenyl side-chain is replaced by 3',6' (5, 8), 2',5' (6, 9), and 2',6' (7, 10) pyridyls, were analyzed. Proliferation inhibition of isogenic Chinese hamster ovary (CHO) cells expressing folate receptors (FRs) α and ß were in rank order, 6 > 9 > 5 > 7 > 8, with 10 showing no activity, and 6 > 9 > 5 > 8, with 10 and 7 being inactive, respectively. Antiproliferative effects toward FRα- and FRß-expressing cells were reflected in competitive binding with [3H]folic acid. Only compound 6 was active against proton-coupled folate receptor (PCFT)-expressing CHO cells (∼4-fold more potent than 1) and inhibited [3H]methotrexate uptake by PCFT. In KB and IGROV1 tumor cells, 6 showed <1 nM IC50, ∼2-3-fold more potent than 1. Compound 6 inhibited glycinamide ribonucleotide formyltransferase in de novo purine biosynthesis and showed potent in vivo efficacy toward subcutaneous IGROV1 tumor xenografts in SCID mice.


Assuntos
Antineoplásicos/síntese química , Antagonistas do Ácido Fólico/síntese química , Pirimidinas/farmacologia , Pirróis/farmacologia , Animais , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Células CHO , Proliferação de Células/efeitos dos fármacos , Cricetulus , Receptor 1 de Folato/análise , Receptor 1 de Folato/metabolismo , Receptor 2 de Folato/análise , Antagonistas do Ácido Fólico/farmacologia , Xenoenxertos , Humanos , Camundongos , Camundongos SCID , Transportador de Folato Acoplado a Próton/metabolismo , Nucleotídeos de Purina/antagonistas & inibidores , Pirimidinas/química , Pirimidinas/farmacocinética , Pirróis/química , Pirróis/farmacocinética
5.
J Med Chem ; 59(17): 7856-76, 2016 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-27458733

RESUMO

Targeted antifolates with heteroatom replacements of the carbon vicinal to the phenyl ring in 1 by N (4), O (8), or S (9), or with N-substituted formyl (5), acetyl (6), or trifluoroacetyl (7) moieties, were synthesized and tested for selective cellular uptake by folate receptor (FR) α and ß or the proton-coupled folate transporter. Results show increased in vitro antiproliferative activity toward engineered Chinese hamster ovary cells expressing FRs by 4-9 over the CH2 analogue 1. Compounds 4-9 inhibited de novo purine biosynthesis and glycinamide ribonucleotide formyltransferase (GARFTase). X-ray crystal structures for 4 with FRα and GARFTase showed that the bound conformations of 4 required flexibility for attachment to both FRα and GARFTase. In mice bearing IGROV1 ovarian tumor xenografts, 4 was highly efficacious. Our results establish that heteroatom substitutions in the 3-atom bridge region of 6-substituted pyrrolo[2,3-d]pyrimidines related to 1 provide targeted antifolates that warrant further evaluation as anticancer agents.


Assuntos
Antineoplásicos/química , Receptor 1 de Folato/metabolismo , Antagonistas do Ácido Fólico/química , Transportador de Folato Acoplado a Próton/metabolismo , Nucleotídeos de Purina/antagonistas & inibidores , Pirimidinas/química , Pirróis/química , Animais , Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Antagonistas do Ácido Fólico/síntese química , Antagonistas do Ácido Fólico/farmacologia , Xenoenxertos , Humanos , Camundongos SCID , Simulação de Acoplamento Molecular , Transplante de Neoplasias , Fosforribosilglicinamido Formiltransferase/antagonistas & inibidores , Nucleotídeos de Purina/biossíntese , Pirimidinas/síntese química , Pirimidinas/farmacologia , Pirróis/síntese química , Pirróis/farmacologia , Relação Estrutura-Atividade
6.
Eur J Med Chem ; 93: 142-55, 2015 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-25668494

RESUMO

A novel series of 2-amino-4-oxo-6-substituted pyrrolo[2,3-d]pyrimidines were designed and synthesized as potential nonclassical antifolates targeting both thymidylate and purine nucleotide biosynthesis. Condensation of 2,4-diamino-6-hydroxypyrimidine with ethyl-4-chloroacetoacetate and subsequent hydrolysis afforded the key intermediate, 2-amino-4-oxo-pyrrolo[2,3-d]pyrimidin-6-yl-acetic acid. Coupling with various amino acid methyl esters followed by saponification and condensation with 3-(aminomethyl)pyridine provided target compounds 1-9. The new compounds exhibited micromolar to submicromolar antiproliferative potencies against a panel of tumor cell lines including KB, A549 and HepG2. Growth inhibition of compound 2 toward KB cells resulted in cytotoxicity and G1/G2-phase accumulation, and was partially protected by excess thymidine and adenosine, but was completely reversed in the combination of thymidine and adenosine, indicating both thymidylate and de novo purine nucleotide synthesis as the targeted pathway. However, 5-aminoimidazole-4-carboxamide (AICA) protection was incomplete, suggesting inhibition of both glycinamide ribonucleotide formyltransferase (GARFTase) and AICA ribonucleotide formyltransferase (AICARFTase). The results of the docking studies show that 2 could bind and inhibit both thymidylate synthase (TS) and the two folate-dependent purine biosynthetic enzymes (GARFTase and AICARFTase), which is consistent with the results of in vitro metabolic assays. Our studies establish that compound 2 is an excellent lead analog as a multitargeted antifolate for further structure optimization.


Assuntos
Antineoplásicos/síntese química , Antagonistas do Ácido Fólico/síntese química , Nucleotídeos de Purina/antagonistas & inibidores , Pirimidinas/síntese química , Pirróis/síntese química , Timidilato Sintase/antagonistas & inibidores , Antineoplásicos/química , Antineoplásicos/farmacologia , Técnicas de Cultura de Células , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Antagonistas do Ácido Fólico/química , Antagonistas do Ácido Fólico/farmacologia , Humanos , Simulação de Acoplamento Molecular , Estrutura Molecular , Pirimidinas/química , Pirimidinas/farmacologia , Pirróis/química , Pirróis/farmacologia , Relação Estrutura-Atividade
7.
J Med Chem ; 56(21): 8684-95, 2013 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-24111942

RESUMO

A new series of 6-substituted straight side chain pyrrolo[2,3-d]pyrimidines 3a-d with varying chain lengths (n = 5-8) was designed and synthesized as part of our program to provide targeted antitumor agents with folate receptor (FR) cellular uptake specificity and glycinamide ribonucleotide formyltransferase (GARFTase) inhibition. Carboxylic acids 4a-d were converted to the acid chlorides and reacted with diazomethane, followed by 48% HBr to generate the α-bromomethylketones 5a-d. Condensation of 2,4-diamino-6-hydroxypyrimidine 6 with 5a-d afforded the 6-substituted pyrrolo[2,3-d]pyrimidines 7a-d. Hydrolysis and subsequent coupling with diethyl l-glutamate and saponification afforded target compounds 3a-d. Compounds 3b-d showed selective cellular uptake via FRα and -ß, associated with high affinity binding and inhibition of de novo purine nucleotide biosynthesis via GARFTase, resulting in potent inhibition against FR-expressing Chinese hamster cells and human KB tumor cells in culture. Our studies establish, for the first time, that a side chain benzoyl group is not essential for tumor-selective drug uptake by FRα.


Assuntos
Receptor 1 de Folato/antagonistas & inibidores , Antagonistas do Ácido Fólico/farmacologia , Ácido Fólico/metabolismo , Nucleotídeos de Purina/antagonistas & inibidores , Pirimidinas/farmacologia , Pirróis/farmacologia , Animais , Células CHO , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Cricetulus , Relação Dose-Resposta a Droga , Receptor 1 de Folato/metabolismo , Antagonistas do Ácido Fólico/síntese química , Antagonistas do Ácido Fólico/química , Humanos , Células KB , Modelos Moleculares , Estrutura Molecular , Nucleotídeos de Purina/biossíntese , Pirimidinas/síntese química , Pirimidinas/química , Pirróis/síntese química , Pirróis/química , Relação Estrutura-Atividade
8.
J Immunol ; 170(10): 4986-95, 2003 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-12734342

RESUMO

Purine and pyrimidine nucleotides play critical roles in DNA and RNA synthesis as well as in membrane lipid biosynthesis and protein glycosylation. They are necessary for the development and survival of mature T lymphocytes. Activation of T lymphocytes is associated with an increase of purine and pyrimidine pools. However, the question of how purine vs pyrimidine nucleotides regulate proliferation, cell cycle, and survival of primary T lymphocytes following activation has not yet been specifically addressed. This was investigated in the present study by using well-known purine (mycophenolic acid, 6-mercaptopurine) and pyrimidine (methotrexate, 5-fluorouracil) inhibitors, which are used in neoplastic diseases or as immunosuppressive agents. The effect of these inhibitors was analyzed according to their time of addition with respect to the initiation of mitogenic activation. We showed that synthesis of both purine and pyrimidine nucleotides is required for T cell proliferation. However, purine and pyrimidine nucleotides differentially regulate the cell cycle since purines control both G(1) to S phase transition and progression through the S phase, whereas pyrimidines only control progression from early to intermediate S phase. Furthermore, inhibition of pyrimidine synthesis induces apoptosis whatever the time of inhibitor addition whereas inhibition of purine nucleotides induces apoptosis only when applied to already cycling T cells, suggesting that both purine and pyrimidine nucleotides are required for survival of cells committed into S phase. These findings reveal a hitherto unknown role of purine and pyrimidine de novo synthesis in regulating cell cycle progression and maintaining survival of activated T lymphocytes.


Assuntos
Ciclo Celular/imunologia , Nucleotídeos de Purina/farmacologia , Nucleotídeos de Pirimidina/farmacologia , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/metabolismo , Apoptose/efeitos dos fármacos , Apoptose/imunologia , Agregação Celular/efeitos dos fármacos , Agregação Celular/imunologia , Ciclo Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Divisão Celular/imunologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/imunologia , Células Cultivadas , Fase G1/efeitos dos fármacos , Fase G1/imunologia , Inibidores do Crescimento/farmacologia , Humanos , Cinética , Ativação Linfocitária/efeitos dos fármacos , Contagem de Linfócitos , Inibidores da Síntese de Ácido Nucleico/farmacologia , Nucleotídeos de Purina/antagonistas & inibidores , Nucleotídeos de Purina/biossíntese , Nucleotídeos de Pirimidina/antagonistas & inibidores , Nucleotídeos de Pirimidina/biossíntese , Fase de Repouso do Ciclo Celular/efeitos dos fármacos , Fase de Repouso do Ciclo Celular/imunologia , Fase S/efeitos dos fármacos , Fase S/imunologia , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/imunologia
9.
Acc Chem Res ; 35(11): 961-71, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12437321

RESUMO

Potent inhibitors of enzymes catalyzing reactions in the de novo pathways for biosynthesis of purine and pyrimidine nucleotides are synthetic or natural-product analogues of pathway intermediates or, more recently, inhibitors rationally designed from a knowledge of the catalytic mechanism. Such inhibitors may be effective drugs against cancer, inflammatory disorders, or various infections. For human cancer, the purine pathway may be a better target for inhibition than the pyrimidine pathway, where toxic side effects are more apparent. Drugs such as methotrexate and 6-mercaptopurine have multiple sites of action, making it difficult to quantitatively predict their effects upon cells. Rational design of inhibitors based upon the X-ray structure of the target enzyme has the prospect of yielding drugs with only one site of action in human cells. Such a drug is VX-497, a potent inhibitor of the purine enzyme, IMP dehydrogenase.


Assuntos
Inibidores Enzimáticos/química , Nucleotídeos/antagonistas & inibidores , Nucleotídeos/biossíntese , Inibidores Enzimáticos/farmacologia , Nucleotídeos de Purina/antagonistas & inibidores , Nucleotídeos de Purina/biossíntese , Nucleotídeos de Pirimidina/antagonistas & inibidores , Nucleotídeos de Pirimidina/biossíntese
10.
Neurochem Int ; 40(5): 427-33, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11821150

RESUMO

Rat corticoencephalic cell cultures were investigated by high performance liquid chromatography for changes in the levels of adenosine 5'-triphosphate (ATP), guanosine 5'-triphosphate (GTP), uridine 5'-triphosphate (UTP), cytidine 5'-triphosphate (CTP), and the respective nucleoside diphosphates. Hypoxia was induced by gassing the incubation medium for 30 min with 100% argon. Removal of glucose was caused by washing the cultures in glucose-free medium at the beginning of the 30 min incubation period. Whereas hypoxia or glucose-deficiency alone failed to alter the nucleotide levels, the combination of these two manipulations was clearly inhibitory. Diazoxide (300 microM) an opener of ATP-dependent potassium channels (K(ATP)) did not alter the nucleotide contents either in a normoxic and glucose-containing medium, or a hypoxic and glucose-free medium. By contrast, the K(ATP) channel antagonist tolbutamide (300 microM) aggravated the hypoxic decrease of nucleotide levels in a glucose-free medium, although it was ineffective in a normoxic and glucose-containing medium. Hypoxia and glucose-deficiency decreased the ATP/ADP and UTP/UDP ratios, but failed to change the GTP/GDP ratio. Diazoxide and tolbutamide (300 microM each) had no effect on the nucleoside triphosphate/diphosphate ratios either during normoxic or during hypoxic conditions. In conclusion, corticoencephalic cultures are rather resistant to in vitro ischemia. Although they clearly respond to the blockade of plasmalemmal K(ATP) channels (plasmaK(ATP)) by tolbutamide, these channels appear to be maximally open as a consequence of the fall in intracellular nucleotides and, therefore, diazoxide has no further effect.


Assuntos
Córtex Cerebral/metabolismo , Nucleotídeos de Purina/metabolismo , Nucleotídeos de Pirimidina/metabolismo , Animais , Hipóxia Celular/fisiologia , Células Cultivadas , Córtex Cerebral/citologia , Diazóxido/farmacologia , Difosfatos/metabolismo , Embrião de Mamíferos , Feminino , Glucose/deficiência , Nucleosídeos/metabolismo , Bloqueadores dos Canais de Potássio/farmacologia , Nucleotídeos de Purina/antagonistas & inibidores , Nucleotídeos de Pirimidina/antagonistas & inibidores , Ratos , Ratos Wistar , Tolbutamida/farmacologia
12.
Biochem Pharmacol ; 58(4): 539-55, 1999 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-10413291

RESUMO

Transformed cells are characterized by imbalances in metabolic routes. In particular, different key enzymes of nucleotide metabolism and DNA biosynthesis, such as CTP synthetase, thymidylate synthase, dihydrofolate reductase, IMP dehydrogenase, ribonucleotide reductase, DNA polymerase, and DNA methyltransferase, are markedly up-regulated in certain tumor cells. Together with the concomitant down-modulation of the purine and pyrimidine degradation enzymes, the increased anabolic propensity supports the excessive proliferation of transformed cells. However, many types of cancer cells have maintained the ability to differentiate terminally into mature, non-proliferating cells not only in response to physiological receptor ligands, such as retinoic acid, vitamin D metabolites, and cytokines, but also following exposure to a wide variety of non-physiological agents such as antimetabolites. Interestingly, induction of tumor cell differentiation is often associated with reversal of the transformation-related enzyme deregulations. An important class of differentiating compounds comprises the antimetabolites of purine and pyrimidine nucleotide metabolism and nucleic acid synthesis, the majority being structural analogs of natural nucleosides. The CTP synthetase inhibitors cyclopentenylcytosine and 3-deazauridine, the thymidylate synthase inhibitor 5-fluoro-2'-deoxyuridine, the dihydrofolate reductase inhibitor methotrexate, the IMP dehydrogenase inhibitors tiazofurin, ribavirin, 5-ethynyl-1-beta-D-ribofuranosylimidazole-4-carboxamide (EICAR) and mycophenolic acid, the ribonucleotide reductase inhibitors hydroxyurea and deferoxamine, and the DNA polymerase inhibitors ara-C, 9-(2-phosphonylmethoxyethyl)adenine (PMEA), and aphidicolin, as well as several nucleoside analogs perturbing the DNA methylation pattern, have been found to induce tumor cell differentiation through impairment of DNA synthesis and/or function. Thus, by selectively targeting those anabolic enzymes that contribute to the neoplastic behavior of cancer cells, the normal cellular differentiation program may be reactivated and the malignant phenotype suppressed.


Assuntos
Antimetabólitos/farmacologia , Antineoplásicos/farmacologia , Transformação Celular Neoplásica/efeitos dos fármacos , Neoplasias/patologia , Nucleotídeos de Purina/metabolismo , Nucleotídeos de Pirimidina/metabolismo , Animais , Diferenciação Celular/efeitos dos fármacos , Humanos , Neoplasias/metabolismo , Neoplasias/terapia , Nucleotídeos de Purina/antagonistas & inibidores , Nucleotídeos de Purina/biossíntese , Nucleotídeos de Pirimidina/antagonistas & inibidores , Nucleotídeos de Pirimidina/biossíntese
13.
Arch Microbiol ; 168(6): 448-56, 1997 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9385135

RESUMO

The requirements for purine nucleotide synthesis, the effects of purine analogues, and the metabolism of adenine in the bacterium Helicobacter pylori were investigated employing cell culture techniques and one-dimensional NMR spectroscopy. Bacterial cells grew and proliferated in media lacking preformed purines, indicating that H. pylori can synthesize purine nucleotides de novo to meet its requirements. Blocking of this pathway in the absence of sufficient preformed purines for salvage nucleotide synthesis led to cell death. Analogues of purine nucleobases and nucleosides taken up by the cells were cytotoxic, suggesting that salvage routes could be exploited for therapy. Adenine or hypoxanthine were able to substitute for catalase in supporting cell growth and proliferation, suggesting a role for these bases in maintaining the microaerophilic conditions essentially required by the bacterium.


Assuntos
Helicobacter pylori/crescimento & desenvolvimento , Helicobacter pylori/metabolismo , Nucleotídeos de Purina/metabolismo , Adenina/farmacologia , Aminoidrolases/antagonistas & inibidores , Aminoidrolases/metabolismo , Aminoimidazol Carboxamida/farmacologia , Catalase/farmacologia , Meios de Cultura/metabolismo , Meios de Cultura/farmacologia , Sinergismo Farmacológico , Sequestradores de Radicais Livres/farmacologia , Inibidores do Crescimento/farmacologia , Helicobacter pylori/efeitos dos fármacos , Helicobacter pylori/enzimologia , Peróxido de Hidrogênio/farmacologia , Hipoxantina/farmacologia , Oxigênio/metabolismo , Nucleotídeos de Purina/antagonistas & inibidores , Purinas/antagonistas & inibidores , Purinas/metabolismo
14.
J Nutr ; 124(1 Suppl): 124S-127S, 1994 01.
Artigo em Inglês | MEDLINE | ID: mdl-8283301

RESUMO

Nucleotides are phosphate esters of nucleosides that contain a sugar linked through a glycosidic linkage with purine and pyrimidine bases. Purine and pyrimidine nucleotides are major components of the cells that make up the monomeric units of DNA and RNA, and they function in all cellular processes. Biosynthesis, interconversion, catabolism and other aspects of nucleotide metabolism, along with various cellular roles of nucleotides, will be discussed, and the possible use of dietary sources of preformed purines and pyrimidines will be considered.


Assuntos
Nucleotídeos de Purina/química , Nucleotídeos de Purina/metabolismo , Nucleotídeos de Pirimidina/química , Nucleotídeos de Pirimidina/fisiologia , Animais , Humanos , Nucleotídeos de Purina/antagonistas & inibidores , Nucleotídeos de Pirimidina/antagonistas & inibidores
15.
J Biol Chem ; 268(35): 26476-81, 1993 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-8253776

RESUMO

Superactivity of phosphoribosylpyrophosphate synthetase (PRS) is an X chromosome-linked disorder of purine metabolism, characterized by gout with uric acid overproduction and, in some families, neurodevelopmental impairment. Two highly homologous isoforms of PRS (PRS1 and PRS2), each encoded by a distinct X chromosome-linked locus, have been identified, and PRS1 and 2 cDNAs have been cloned. The entire 954-base pair translated regions of PRS1 and 2 cDNAs derived from cultured lymphoblasts and fibroblasts from two patients in whom purine nucleotide feedback resistance of PRS is associated with enzyme superactivity and neurodevelopmental defects were examined by direct sequencing after polymerase chain reaction amplification of PRS transcripts. Nucleotide sequences of PRS2 cDNAs from the patients and normal individuals were identical. In contrast, PRS1 cDNAs from the patients differ from normal PRS1 cDNA, each by a single base substitution. PRS1 cDNA from patient N. B. showed an A to G transition at nucleotide 341, corresponding to an asparagine to serine change at amino acid residue 113 of mature PRS1. A G to C transversion at nucleotide 547, indicating an aspartic acid to histidine change at amino acid 182, was found for PRS1 cDNA from patient S. M. Point mutations at the sites identified in the PRS1 cDNAs of the two patients were confirmed by the results of RNase mapping analysis. Normal, N. B., and S. M. PRS1 cDNAs were introduced into Escherichia coli BL21 (DE3)/pLyS, and recombinant N. B. and S. M. PRS1s showed the purine nucleotide feedback resistance phenotypes characteristic of PRS from patients' cells.


Assuntos
Ligação Genética , Isoenzimas/metabolismo , Mutação Puntual , Ribose-Fosfato Pirofosfoquinase/metabolismo , Cromossomo X , Sequência de Bases , Linhagem Celular , DNA Complementar , Escherichia coli/genética , Humanos , Isoenzimas/genética , Dados de Sequência Molecular , Nucleotídeos de Purina/antagonistas & inibidores , Ribose-Fosfato Pirofosfoquinase/genética , Análise de Sequência de DNA
18.
Tropenmed Parasitol ; 29(4): 435-8, 1978 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-105434

RESUMO

The catabolism of adenosine 5'-monophosphate in promastigotes of L. tropica suggests the presence of a parasite specific pathway. In continuing the investigation on enzymes of this pathway two purine nucleoside cleaving enzymes have been found, adenosine phosphorylase and inosine nucleosidase. Various purine nucleoside analogues inhibited the activity of both enzymes. A mode of action of the growth inhibition of L. tropica promastigotes by allopurinol has been suggested on the basis of Michaelis and inhibitor constants.


Assuntos
Alopurinol/farmacologia , Leishmaniose/metabolismo , Nucleosídeos de Purina/farmacologia , Nucleotídeos de Purina/metabolismo , Repressão Enzimática , Humanos , Leishmania/efeitos dos fármacos , Leishmania/enzimologia , Leishmania/crescimento & desenvolvimento , Morfogênese , Fosforilase Fosfatase/análise , Nucleotídeos de Purina/antagonistas & inibidores , Purina-Núcleosídeo Fosforilase/análise
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