Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.5.1.3 (dihydrofolate reductase)
5,819 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1-Acyl- and 1,2-diacyl-1,2,4-triazolidine-3,5-diones were found to be potent cytotoxic agents in murine and human cancer cell lines, e.g. L1210, P388, Tmolt3, colon adenocarcinoma, Hela cells and glioma. In vivo activity was demonstrated at 8 mg/kg/day against Ehrlich ascites carcinoma growth. In L1210 cells, 1-acetyl-4-phenyl-1,2,4-triazolidine-3,5-dione, 41, reduced DNA synthesis significantly with moderate reduction in RNA synthesis. Enzyme sites in L1210 cells which were markedly affected were m- and r-RNA polymerase, PRPP amidotransferase, IMP dehydrogenase, dihydrofolate reductase, thymidine, TMP and TDP kinases. Kinetic studies suggest the inhibition of rate limiting enzymes in the purine pathway by 41 was responsible for its cytotoxicity. Acute toxicity studies in mice indicated 41 was safe for therapeutic use at 20, 50, and 100 mg/ky/day.
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PMID:Antineoplastic activities and cytotoxicity of 1-acyl and 1,2-diacyl-1,2,4-triazolidine-3,5-diones in murine and human tissue culture cells. 144 91

2,3-Dihydrophthalazine-1,4-dione derivatives demonstrated potent cytotoxicity against the growth of murine leukemia cells and human single cell suspension, i.e. Tmolt3 leukemia and HeLa-S3, as well as colon adenocarcinoma and KB nasopharynx. However, only select compounds demonstrated activity against bronchogenic lung, osteosarcoma and glioma growth. 2,3-Dihydrophthalazine-1,4-dione was active in vivo against L1210 leukemia, Lewis lung and Ehrlich ascites carcinoma growth. In L1210 cells the agents inhibited both DNA and RNA synthesis, and a few of the compounds were capable of inhibiting protein synthesis at 3 times their ED50 values. When 2,3-dihydrophthalazine-1,4-dione and N-butyl-2,3-dihydrophthalazine-1,4-dione were examined for their mode of action in the L1210 lymphoid leukemia cells, the sites of inhibition by the agents appear to be the de novo purine pathway at the enzymes IMP dehydrogenase and PRPP amido transferase. IMP dehydrogenase activity was inhibited at least 45% by 45 min at 100 microM concentration of drugs whereas the remaining enzymes that were affected by the drugs were not inhibited as early. Secondary sites were dihydrofolate reductase and thymidylate synthetase. The d(NTP) levels were also reduced specifically dATP and dCTP levels.
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PMID:The anti-neoplastic activity of 2,3-dihydrophthalazine-1,4-dione and N-butyl-2,3-dihydrophthalazine-1,4-dione in human and murine tumor cells. 162 17

gamma-Glutamyl hydrolase (also known as conjugase) is a ubiquitous enzyme that has the capacity to cleave folyl- and antifolylpolyglutamates. This study has revealed that the enzyme is secreted by primary cultures of rat hepatocytes and by H35 hepatoma cells. H35 cells have lower cellular levels of gamma-glutamyl hydrolase than do hepatocytes but secrete a greater proportion of gamma-glutamyl hydrolase. More than 99% of the total enzyme from H35 cells accumulated in the medium after 48 h. The cells were shown to remain intact during the secretion period since lactate dehydrogenase, dihydrofolate reductase, and lysosomal hydrolases other than gamma-glutamyl hydrolase were retained within the cell. Using the substrate 4-amino-10-methyl-pteroyldiglutamate (4-NH2-10-CH3-Pte-Glu2), the intracellular and secreted enzyme form(s) from H35 cells were found to have the following properties (a) Km values of 24.3 +/- 3.7 microM and 34.8 +/- 8.6 microM, respectively, and (b) maximal activity at pH 5 to 7 and apparent molecular weights of 120,000 by gel filtration. Both the cellular and secreted enzymes convert 4-NH2-10-CH3-PteGlu4 and pteroylpentaglutamate acid, to the corresponding monoglutamates with little or no appearance of intermediate chain length polyglutamates. This suggests that both act primarily as endopeptidases. Thus far, the cellular and secreted enzymes cannot be differentiated although the current studies do not establish this point unequivocally. Alterations in the cellular and secreted H35 cell gamma-glutamyl hydrolase levels in response to changes in culture conditions revealed that glutamine enhances activity while insulin diminishes it. Other transformed cells found to secrete this protein are Hep-G2 human hepatoma, JAR human choriocarcinoma, HeLa, and rat glioma. gamma-Glutamyl hydrolase could not be detected in medium conditioned by human MCF-7 breast cancer cells, and relatively low activities were found in the medium from CCRF-CEM or K562 leukemia cells. These studies directly establish for the first time the secretion of gamma-glutamyl hydrolase in vitro.
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PMID:Secretion of gamma-glutamyl hydrolase in vitro. 171 22

Substituted oxoisoindolines are effective cytotoxic agents, causing cell death in a number of tissue culture lines, e.g. L1210, Tmolt-3, and HeLa-S3. In general these agents were not active against the solid cell growth, i.e. KB, skin, HCT-8 ileum, colon, bronchogenic lung, osteosarcoma and glioma. The mode of action of the derivatives involves inhibition of de novo purine synthesis of Tmolt-3 cells, which reduces DNA and RNA syntheses. Purine synthesis was reduced by compound 16 at both regulatory enzymes, i.e. PRPP amido transferase, IMP dehydrogenase and dihydrofolate reductase. The agent lowered d(GTP) and d(CTP) pool levels, further reducing DNA synthesis. DNA strand scission was evident after incubation with Compound 16 for 24 hr at 100 microM and some undefined interaction between the drug and the nucleoside bases appeared to occur, lowering DNA synthesis and causing cell death.
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PMID:The cytotoxicity of [(N-alkyl-1H,3H-1-oxoisoindoline-5-yl-oxyl alkanoates and related benzamides in murine and human tissue cultured cell lines. 765 21

Piritrexim is a lipid-soluble drug which is as effective an inhibitor of dihydrofolate reductase as methotrexate. Phase I and II studies have indicated activity in some tumour types. Because of its lipophilicity we have conducted a phase II study in recurrent high-grade malignant glioma (grades III and IV). Twenty-seven patients were treated with 25 mg p.o. three times daily for five consecutive days, repeated weekly, with provision for dose escalation or reduction according to toxicity. Five patients received less than 4 weeks' treatment because of disease progression or death. Twenty-two patients were evaluable for response. One complete and one partial response was seen (duration 262+ and 241+ weeks) and 13 patients had static disease for a median duration of 13 weeks (range 7-35). The major toxicity was myelosuppression. This response rate of 9% of evaluable patients is much lower than that seen for some conventionally used drugs and we conclude that piritrexim is unlikely to be of value in the management of high-grade gliomas.
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PMID:A phase II study of oral piritrexim in recurrent high-grade (III, IV) glioma. 766 91

The 1-acyl- and 1,2-diacyl-4,4-diethyl-3,5-pyrazolinediones proved to be cytotoxic against the growth of a number of cell lines, including murine and human leukemias. HeLa suspended carcinoma, colon adencarcinoma SW480, KB nasopharynx and glioma tumors. Selected compounds were also active in the human lung bronchogenic MB-9812, and osteosarcoma TE418 screens. These derivatives were active in vivo in the Ehrlich ascites carcinoma screen in CF-1 mice at 8 mg/kg/day I.P. The mode of action in Tmol3 leukemia cells showed that the compounds reduced de novo synthesis of purines and pyrimidines and inhibited dihydrofolate reductase and ribonucleoside reductase activities. The DNA molecule was not a target although limited DNA strand scission may be possible.
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PMID:The cytotoxic activity of 1-acyl- and 1,2-diacyl-4,4-diethyl-3,5-pyrazolidinediones. 773 34

Certain types of hypolipidemic agents have been observed to also function as cytotoxic agents. Previously reported hypolipidemic agents, 3-imino-1-oxoisoindolines, were evaluated for their anti-neoplastic activity. Selected agents were effective at inhibiting L1210, Tmolt3, HeLa-S3, KB nasopharynx, lung, osteosarcoma and glioma growth. 2-Propyl-3-imino-1-oxoisoindoline, (4), a representative compound of the class of agents, inhibited DNA and RNA syntheses of L1210 cells. The major site of inhibition was the purine pathway at IMP dehydrogenase. Other enzyme sites which were affected by (4) marginally were t-RNA and r-RNA polymerases, dihydrofolate reductase, aspartate transcarboxylase, and nucleoside kinases. d(NTP) pools of L1210 cells were reduced after 60 min. Incubation with (4).
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PMID:The cytotoxicity of 3-imino-1-oxoisoindolines in murine and human tissue culture cells. 804 4

(6R)-5,6,7,8-Tetrahydrobiopterin (BH4), which is synthesized intracellularly from GTP, caused a concentration-dependent increase in rat pheochromocytoma (PC12) cell proliferation when added exogenously. Incubation with sepiapterin, which is converted enzymatically to BH4 within cells, also increased PC12 cell proliferation and BH4 levels concomitantly. These sepiapterin effects were mediated by BH4 as inhibition of sepiapterin conversion to BH4 by a sepiapterin reductase inhibitor, N-acetyl-serotonin, blocked the increase in proliferation and the elevation of BH4 levels. 7,8-Dihydrobiopterin (BH2) also increased BH4 levels and PC12 cell proliferation, both of which were reversed by methotrexate, which blocks the conversion of BH2 to BH4 by dihydrofolate reductase. The BH4-induced increase in PC12 cell proliferation was not related to elevated catecholamine or nitric oxide synthesis as inhibitors of tyrosine hydroxylase or nitric oxide synthase did not reduce the BH4 effect. BH4 and its precursors did not alter intracellular cAMP levels, suggesting that this second messenger is not involved in the enhancement of PC12 cell proliferation by BH4. Sepiapterin and BH4 also enhanced the proliferation of SV40-transformed human fibroblasts and rat C6 glioma cells, indicating that the stimulatory effect of BH4 on cell proliferation is not restricted to PC12 cells.
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PMID:Mitogenic effects of tetrahydrobiopterin in PC12 cells. 856

The 3,5-isoxazolidinediones and 2-isoxazolin-5-ones demonstrated potent cytotoxicity against the growth of human Tmolt3 T cell leukemia, murine P388 and L1210 leukemias, as well as human HeLa-S3 uterine carcinoma and glioma tumor cell growth. The specificity of the 3,5-isoxazolidinedione and 2-isoxazoline-5-one derivatives as cytotoxic agents varied with the histological type of tumor cell. Selected compounds were active against solid HeLa uterine. KB nasopharynx, skin A431, SW-480 adenocarcinoma, osteosarcoma and glioma growth. Selected compounds demonstrated in vivo antineoplastic activity against Ehrlich ascites carcinoma growth. In L-1210 leukemia cells, the agents blocked DNA and protein synthesis at 25, 50 and 100 microM over 60 min. The agents were effective in reducing rate limiting enzymes in the de novo purine and pyrimidine pathways. In addition they suppressed dihydrofolate reductase and ribonucleoside reductase activities with moderate inhibition of DNA and RNA polymerase activities. DNA itself was not a target of the agents.
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PMID:Synthesis and cytotoxic action of 3,5-isoxazolidinediones and 2-isoxazolin-5-ones in murine and human tumors. 916 49

4-Carbethoxy-1-methyl-2-phenacyl-3-phenylpyrrole (9), 4-carbethoxy-2-(4-methoxybenzoyl)-3-(4-methoxyphenyl)pyrrole (10) and 2-(4-methoxybenzoyl)-3,4-bis-(4-methoxyphenyl)pyrrole (11) proved to be potent cytotoxic agents against the growth of murine and human leukemias and lymphomas. Selective toxicity was demonstrated against the growth of solid tumors, e.g., human adenocarcinoma of the colon SW480 and ileum HCT-8, glioma U-87-MG, and rat UMR-106 osteosarcoma. A mode of action study in Tmolt4 leukemia cells demonstrated that the agents inhibited de novo purine synthesis at the regulatory sites PRPP-amido transferase, IMP dehydrogenase as well as dihydrofolate reductase resulting in significant inhibition of DNA synthesis in 60 min. Other biochemical sites which were affected significantly were thymidylate synthetase, DNA polymerase alpha, RNA polymerases, nucleoside kinase and ribonucleoside reductase.
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PMID:The cytotoxicity and mode of action of 2,3,4-trisubstituted pyrroles and related derivatives in human Tmolt4 leukemia cells. 1052 73


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