Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A series of folate analogs containing ornithine instead of glutamate was synthesized and tested for inhibition of folylpolyglutamate synthetase (FPGS) and other folate-dependent enzymes of human leukemia cell lines. Reduced derivatives of 2-amino-4-oxo-10-methyl-pteroyl-ornithine had dramatically increased inhibitory potency against FPGS compared to the oxidized parent. The amino-pterin analog (2,4-diamino-pteroylornithine) was a potent inhibitor of both dihydrofolate reductase and FPGS. It was a much more potent linear competitive inhibitor of human FPGS than the corresponding methotrexate derivative previously described (Ki = 0.15-0.26 and 3 microM respectively). A quinazoline folate analog, 2-amino-4-oxo-5,8-dideazapteroyl-ornithine, was a relatively poor inhibitor of isolated dihydrofolate reductase and thymidylate synthase; however, it is the most potent human FPGS inhibitor identified to date (Ki = 100-150 nM). Because of the lack of appreciable interaction with other folate-dependent enzymes, structures incorporating the 2-amino-4-oxo-5,8-dideazapteroate nucleus may thus lead to selective inhibition of FPGS. Substitution of ornithine for glutamate caused a profound decrease in cytotoxic potency for these analogs; this was apparently the result of poor transport. Together with earlier studies, these data indicate that the potency of FPGS inhibition by an analog containing ornithine closely parallels the relative substrate activity of its glutamate-containing counterpart. The substitution of ornithine apparently does not perturb the pterin specificity of FPGS. The close parallel between substrate and inhibitor specificity may thus allow the use of currently available structure-activity studies on FPGS to design more potent and more selective inhibitors of FPGS.
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PMID:Structural specificity of inhibition of human folylpolyglutamate synthetase by ornithine-containing folate analogs. 319 Jul 39

Five heretofore undescribed analogues of methotrexate (MTX) and aminopterin (AMT) were synthesized and tested as dihydrofolate reductase (DHFR) inhibitors and tumor cell growth inhibitors. The meta isomer of AMT was obtained from 2,4-diamino-6-(bromomethyl)pteridine and m-(aminobenzoyl)-L-glutamic acid, while the ortho isomer was obtained via the same route by using alpha-methyl gamma-tert-butyl o-(aminobenzoyl)-L-glutamate instead of the free acid. Analogues of MTX and AMT containing a double bond in the side chain were prepared from dimethyl D,L-2-amino-4-hexenedioate and 4-amino-4-deoxy-N10-methylpteroic acid and 4-amino-4-deoxy-N10-formylpteroic acid, respectively. Finally, a positional isomer of MTX with the CH2CH2COOH moiety moved from the alpha-carbon to the adjacent carboxamide nitrogen was synthesized from 3-[N-(carboxymethyl)amino]propanoic acid diethyl ester and 4-amino-4-deoxy-N10-methylpteroic acid. The positional isomers of AMT were weak DHFR inhibitors and showed very little growth-inhibitory activity against L1210 murine leukemia cells or the MTX-resistant L1210/R81 mutant line in culture. The MTX and AMT analogues with the CH2CH2COOH moiety replaced by a CH2CH = CHCOOH side chain showed anti-DHFR activity similar to that of the previously described saturated compound N-(4-amino-4-deoxy-N10-methylpteroyl)-L-2-aminoadipic acid, but were less potent than the parent drugs. The MTX analogue with the CH2CH2COOH side chain displaced from C to N was weakly bound to DHFR, confirming the importance of an intact CONH moiety, and showed greatly diminished cell growth inhibitory potency relative to MTX. None of the compounds was a substrate for folylpolyglutamate synthetase (FPGS) from mouse liver. Furthermore, inhibition of folic acid polyglutamylation in vitro at equimolar 500 microM concentrations of drug and substrate was negligible. The structural changes embodied in these five novel compounds are therefore too great for binding to the FPGS active site.
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PMID:Methotrexate analogues. 31. Meta and ortho isomers of aminopterin, compounds with a double bond in the side chain, and a novel analogue modified at the alpha-carbon: chemical and in vitro biological studies. 335 53

Analogues of methotrexate (MTX) and aminopterin (AMT) with aminophosphonoalkanoic, aminoalkanesulfonic, and aminoalkanephosphonic acid side chains in place of glutamate were synthesized and tested as inhibitors of folylpolyglutamate synthetase (FPGS) from mouse liver. The aminophosphonoalkanoic acid analogues were also tested as inhibitors of dihydrofolate reductase (DHFR) from L1210 murine leukemia cells and as inhibitors of the growth of MTX-sensitive (L1210) and MTX-resistant (L1210/R81) cells in culture. The optimal number of CH2 groups in aminophosphonoalkanoic acid analogues of AMT was found to be two for both enzyme inhibition and cell growth inhibition but was especially critical for activity against FPGS. Deletion of the alpha-carboxyl also led to diminished anti-FPGS activity in comparison with previously studied homocysteic acid and 2-amino-4-phosphonobutyric acid analogues. In the aminoalkanesulfonic acid analogues of MTX without an alpha-carboxyl, anti-FPGS activity was low and showed minimal variation as the number of CH2 groups between the carboxamide and sulfonate moieties was changed from one to four. In similar aminoalkanephosphonic acid analogues of MTX, anti-FPGS activity was also low, was comparable for two and three CH2 groups between the carboxamide and phosphonate moieties, and was diminished by monoesterification of the phosphonate group. These effects demonstrate that the alpha-carboxyl group of folate analogues is involved in binding to the active site of FPGS, and that an alpha-carboxyl group should be retained as part of the structure of FPGS inhibitors.
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PMID:Methotrexate analogues. 32. Chain extension, alpha-carboxyl deletion, and gamma-carboxyl replacement by sulfonate and phosphonate: effect on enzyme binding and cell-growth inhibition. 338 29

N delta-Acyl derivatives of the potent folylpolyglutamate synthetase (FPGS) inhibitor N alpha-(4-amino-4-deoxypteroyl)-L-ornithine (APA-L-Orn) were synthesized from N alpha-(4-amino-4-deoxy-N10-formylpteroyl)-L-ornithine by reaction with an N-(acyloxy)succinimide or acyl anhydride, followed by deformylation with base. The N delta-hemiphthaloyl derivative was also prepared from 4-amino-4-deoxy-N10-formylpteroic acid by reaction with persilylated N delta-phthaloyl-L-ornithine, followed by simultaneous deformylation and ring opening of the N delta-phthaloyl moiety with base. The products were potent inhibitors of purified dihydrofolate reductase (DHFR) from L1210 murine leukemia cells, with IC50's ranging from 0.027 and 0.052 microM as compared with 0.072 microM for APA-L-Orn. Several of the N delta-acyl-N10-formyl intermediates also proved to be good DHFR inhibitors. One of them, N alpha-(4-amino-4-deoxy-N10-formylpteroyl)-N delta-(4-chlorobenzoyl)-L- ornithine, had a 2-fold lower IC50 than its deformylated product, confirming that the N10-formyl group is well tolerated for DHFR binding. While N delta-acylation of APA-L-Orn did not significantly alter anti-DHFR activity, inhibition of FPGS was dramatically diminished, supporting the view that the basic NH2 on the end of the APA-L-Orn side chain is essential for the activity of this compound against FPGS. N delta-Acylation of APA-L-Orn markedly enhanced toxicity to cultured tumor cells. However, N delta-acyl derivatives also containing an N10-formyl substituent were less cytotoxic than the corresponding N10-unsubstituted analogues even though their anti-DHFR activity was the same, suggesting that N10-formylation may be unfavorable for transport. Two compounds, the N delta-benzoyl and N delta-hemiphthaloyl derivatives of APA-L-Orn, with IC50's against L1210 cells of 0.89 and 0.75 nM, respectively, were more potent than either methotrexate (MTX) or aminopterin (AMT) in this system. These compounds were also more potent than MTX against CEM human lymphoblasts and two human head and neck squamous cell carcinoma cell lines (SCC15, SCC25) in culture. Moreover, in assays against SCC15/R1 and SCC25/R1 sublines with 10-20-fold MTX resistance, the N delta-hemiphthaloyl derivative of APA-L-Orn showed potency exceeding that of MTX itself against the parental cells.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Methotrexate analogues. 33. N delta-acyl-N alpha-(4-amino-4-deoxypteroyl)-L-ornithine derivatives: synthesis and in vitro antitumor activity. 338 30

The goals of new antifolate development are: 1) improved selectivity, 2) improved penetration into pharmacologic sanctuaries, and 3) effectiveness vs. tumors either with intrinsic or acquired resistance to methotrexate (MTX). The major target for antifolate development has been dihydrofolate reductase (DHFR), but other critical folate-dependent enzymes, i.e., thymidylate synthase, methionine synthetase, and folylpolyglutamate synthetase are also important targets for new antifolate development. The possibility that DHFR from tumor tissue differs significantly from normal tissue DHFR now seems improbable, and the ideas of the late Bill Baker to design specific inhibitors of the tumor enzyme vs. the normal tissue DHFR are unlikely to succeed. However, the experience with triazinate (Baker's antifol; TZT) indicates that transport of antifols could be exploited to provide selective toxicity, as well as to provide agents effective vs. MTX-resistant cells. This work led to a second generation of "nonclassical" folate antagonists, of which trimetrexate (JB-11; TMQ) is now in clinical trial. Uptake of TMQ is via an MTX-independent membrane system, and extremely high intracellular levels of this drug are achieved in human leukemia cells.
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PMID:Design and rationale for novel antifolates. 343 93

gamma-Phosphonate analogues of methotrexate (MTX) and aminopterin (AMT) were synthesized from 4-amino-4-deoxy-N10-methylpteroic acid and 4-amino-4-deoxy-N10-formylpteroic acid, respectively, by reaction with methyl D,L-2-amino-4-phosphonobutyrate followed by gentle alkaline hydrolysis. The products were compared with the corresponding D,L-homocysteic acid derivatives as inhibitors of dihydrofolate reductase and folylpolyglutamate synthetase, and as inhibitors of cell growth in culture. The gamma-phosphonates were somewhat less active than either the gamma-sulfonates or the parent drugs as inhibitors of murine dihydrofolate reductase. The MTX gamma-sulfonate and gamma-phosphonate analogues were equally inhibitory toward mouse liver folylpolyglutamate synthetase (Ki = 190 microM), but in the AMT series the gamma-phosphonate (Ki = 8.4 microM) was more potent than the gamma-sulfonate (Ki = 45 microM). The AMT analogues were consistently more inhibitory than the MTX analogues against cultured L1210 murine leukemia cells, but neither the gamma-phosphonates nor the gamma-sulfonates were as potent as their respective parent drugs. The gamma-phosphonate analogue of MTX was three times more potent than MTX against the MTX-resistant mutant line L1210/R81, but the AMT gamma-phosphonate was less potent than AMT; however, these differences were small in comparison with the level of resistance to all these compounds in the L1210/R81 line. The results suggest that N10-methyl and N10-unsubstituted compounds altered at the gamma-position do not necessarily follow identical structure-activity patterns in every test system.
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PMID:Methotrexate analogues-27. Dual inhibition of dihydrofolate reductase and folylpolyglutamate synthetase by methotrexate and aminopterin analogues with a gamma-phosphonate group in the side chain. 376 24

Four folate analogues, methotrexate, aminopterin, 10-deazaminopterin, and 10-ethyl-10-deazaaminopterin were assessed for their ability to be metabolized to poly-gamma-glutamyl derivatives in three tumor lines which vary in their sensitivity to these agents. Cytotoxicity of the four analogues against the murine L1210 leukemia and the human Manca B cell leukemia, as determined by a 3-h clonogenic assay, showed aminopterin and the two 10-deazaaminopterin compounds to be approximately equivalent for each cell type and were 3- to 10- (L1210) and 7- to 14-fold (Manca) more potent than methotrexate. In murine Sarcoma 180 cells, 10-ethyl-10-deazaaminopterin and aminopterin were similarly potent but were 5- to 10-fold more potent than 10-deazaaminopterin and 40- to 80-fold more potent than methotrexate. These results could be explained in part by the differences in transport properties and substrate activities for polyglutamylation for each analogue in these cell types. Initial rates of polyglutamate accumulation of the four analogues, which were determined under conditions of comparable rates of drug entry into the three tumor cell lines, were 7- to 18-fold less than drug entry rates. In L1210 and Sarcoma 180 cells, the relative rates of polyglutamylation were in the order aminopterin greater than 10-ethyl-10-deazaaminopterin greater than methotrexate greater than 10-deazaaminopterin. In contrast, the relative rates of polyglutamylation in Manca cells were in the order 10-ethyl-10-deazaaminopterin approximately equal to aminopterin greater than 10-deazaaminopterin greater than methotrexate, suggesting that folylpolyglutamyl synthetase may have varying substrate preferences in different cell types. The maximum relative extents of total polyglutamate accumulation in L1210 cells were 85 to 95% of the total drug at 24 h. In Manca cells, the maximum polyglutamate accumulation was also 85 to 95%, but this was obtained by 6 h. However, in Sarcoma 180 cells, only aminopterin polyglutamates reached a similar maximum percentage of accumulation, while lower relative polyglutamate levels were achieved with the other analogues. Accumulation of individual polyglutamates in each cell line was similar for all analogues except aminopterin. For methotrexate and the two 10-deazaaminopterins, accumulation occurred mainly as the tetraglutamate or as higher polyglutamates. Aminopterin was accumulated mainly as the diglutamate, particularly in Manca cells where 70% of total drug was in the diglutamate form within the first 3 h and remained the predominant form for 24 h.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Similar differential for total polyglutamylation and cytotoxicity among various folate analogues in human and murine tumor cells in vitro. 397 16

Chain-extended analogues of methotrexate were synthesized by condensation of 4-amino-4-deoxy-N10-methylpteroic acid with esters of L-alpha-aminoadipic, L-alpha-aminopimelic, and L-alpha-aminosuberic acids, followed by ester hydrolysis with acid or base. Coupling was accomplished in up to 85% yield by the use of the peptide bond forming reagent diethyl phosphorocyanidate at room temperature. The products were found to bind bacterial (Lactobacillus casei) and mammalian (L1210 mouse leukemia) dihydrofolate reductase with an affinity comparable to methotrexate and were also equitoxic to L1210 cells in culture. Cytotoxicity increased up to 3-fold as the number of CH2 groups in the amino acid side chain was extended from two to five. The alpha-aminoadipate and alpha-aminopimelate analogues were poor substrates for carboxypeptidase G1, confirming that this enzyme has a strict requirement for a C-terminal L-glutamic acid residue. The in vivo antitumor activity of the chain-extended analogues against L1210 leukemia in mice was comparable to that of the parent drug on the qd X 9 schedule, but higher doses were required to achieve the same increase in survival. The results were consistent with findings, reported separately, that these compounds are poor substrates for folate polyglutamate synthetase and therefore would not be expected to form gamma-polyglutamates once they enter a cell. This distinctive property has potential therapeutic implications for the treatment of certain MTX-resistant tumors whose resistance may be associated with a lower than normal capacity to form gamma-polyglutamates in comparison with proliferative tissues such as intestinal mucosa or marrow.
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PMID:Methotrexate analogues. 20. Replacement of glutamate by longer-chain amino diacids: effects on dihydrofolate reductase inhibition, cytotoxicity, and in vivo antitumor activity. 613 80

7-Hydroxymethotrexate, an important metabolite of methotrexate, is a substrate for folylpolyglutamate synthetase (FPGS) isolated from rat liver and several human leukemia cell lines. The substrate activity it displays over a wide range of concentrations (0-200 microM) is nearly equivalent to that of methotrexate. The 7-hydroxy derivative of dichloromethotrexate is also a substrate for FPGS. The pattern of polyglutamate products synthesized by rat liver FPGS was nearly identical with both 7-hydroxymethotrexate and methotrexate. In addition, conversion of MTX polyglutamates to the corresponding 7-hydroxy compounds was demonstrated using partially purified rabbit liver aldehyde oxidase. The rate of conversion was concentration dependent, and the relative rate decreased as the MTX polyglutamate chain length increased. We propose that 7-hydroxymethotrexate polyglutamates may be formed by initial hydroxylation of methotrexate and subsequent polyglutamate formation or by direct hydroxylation of methotrexate polyglutamates. It was further shown that the relative substrate activity of folate analogs for folylpolyglutamate synthetase is dependent on the source of the enzyme.
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PMID:Enzymatic synthesis of polyglutamate derivatives of 7-hydroxymethotrexate. 620 Nov 78

Variation of the bridge linking the heterocyclic ring and p-aminobenzoyl-L-glutamate portions of our previously described classical 2,4-diaminofuro[2,3-d]pyrimidines 1 and 2 are reported as inhibitors of dihydrofolate reductase (DHFR) and thymidylate synthase (TS) and as antitumor agents. Specifically -CH2CH2- and -CH2NHCH2- bridged analogues, N-[4-[2-(2,4-diaminofuro[2,3-d]pyrimidin-5-yl) ethyl]benzoyl]-L-glutamic acid (3) and N-[4-[[N-[(2,4-diaminofuro[2,3-d]pyrimidin-5-yl) methyl]amino]methyl]benzoyl]-L-glutamic acid (4), respectively, were synthesized. Compound 3 was obtained via a Wittig reaction of the tributylphosphonium salt of 2,4-diamino-5-(chloromethyl)furo[2,3-d]pyrimidine (5) and methyl 4-formylbenzoate (6) followed by reduction and coupling with the diethyl ester of L-glutamic acid. Compound 4 was synthesized by the nucleophilic displacement of 5 with diethyl N-[4-(aminomethyl)benzoyl]-L-glutamate (15) and saponification. Both analogues were evaluated in vitro as inhibitors of DHFRs from (recombinant) human, human CCRF-CEM cells, and Lactobacillus casei. Compound 3 showed moderate activity (IC50 10(-6)-10(-7) M). Compound 4 was essentially inactive (IC50 10(-5) M, CCRF-CEM). The compounds were also evaluated against TS from (recombinant) human and L. casei and were of low activity (IC50 10(-5) M). The three-atom-bridged analogue 4 was somewhat more inhibitory to human TS than methotrexate (MTX). Compound 3 inhibited the growth of tumor cells in culture (IC50 10(-7) M) while 4 showed a low level of growth inhibitory activity. The inhibition of the growth of leukemia CCRF-CEM cells by both compounds parallels their inhibition of CCRF-CEM DHFR. Analogue 3 was a good substrate for human folylpolyglutamate synthetase (FPGS) derived from CCRF-CEM cells (Km 8.5 microM). Further evaluation of the growth inhibitory activity of 3 against the MTX-resistant subline of CCRF-CEM cells (R30dm) with decreased FPGS indicated that poly-gamma-glutamylation was important for its action. Protection studies with 3 in the FaDu squamous cell carcinoma cell line indicated that inhibition was completely reversed by leucovorin [(6R,S-5-formyltetrahydrofolate] or by a combination of thymidine and hypoxanthine, suggesting an antifolate effect directed at DHFR.
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PMID:Effect of bridge region variation on antifolate and antitumor activity of classical 5-substituted 2,4-diaminofuro[2,3-d]pyrimidines. 756 10


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