Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

5-(2-Acylethynyl)-2,4-dimethoxypyrimidines (3-6) were synthesized in excellent yields from 2,4-dimethoxy-5-[2-(trimethylsilyl)ethynyl]pyrimidine (2) by treatment with acid chlorides in the presence of anhydrous aluminum chloride. Compounds 3-6 were deblocked with chlorotrimethylsilane and sodium iodide in acetonitrile to the corresponding 5-[(2-acyl-1-iodo)vinyl]uracils (7-10), which on treatment with potassium hydroxide in dioxane yielded the corresponding 5-(2-acylethynyl)uracils (11-14). The 5-(2-acylethynyl)uracils were found to be active against Ehrlich ascites carcinoma (EAC) cells in vivo, the most active compounds being 5-(2-benzoylethynyl)uracil (11) and 5-(2-p-toluoylethynyl)uracil (12). The T/C values of 281 and 300 were obtained for compounds 11 and 12, respectively, in the case of mice bearing EAC cells. The 5-(2-acylethynyl)uracils have also shown in vitro activity against CCRF-CEM and L1210/0 tumor cell lines. The lead compound 5-(2-p-toluoylethynyl)uracil effectively inhibited thymidylate synthetase.
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PMID:Synthesis and biological activities of novel 5-(2-acylethynyl)uracils. 236 78

A new pyrimidine antimetabolite, 2',2'-difluorodeoxycytidine, Gemcitabine (LY188011, dFdCyd) has been synthesized and evaluated in experimental tumor models. dFdCyd is a very potent and specific deoxycytidine analogue. The concentration required for 50% inhibition of growth is 1 ng/ml in the CCRF-CEM human leukemia cell culture assay. Concurrent addition of deoxycytidine to the cell culture system provides about a 1000-fold decrease in biological activity. The inhibition of growth of human leukemia cells in culture led to the in vivo evaluation of this compound as a potential oncolytic agent. Maximal activity in vivo was seen with dFdCyd when administered on an every third day schedule. 1-beta-D-Arabinofuranosylcytosine, administered on a daily for 10-day schedule, was directly compared to dFdCyd in this evaluation. dFdCyd demonstrated good to excellent antitumor activity in eight of the eight murine tumor models evaluated. 1-beta-D-Arabinofuranosylcytosine was substantially less active or had no activity in these same tumor models. This in vivo activity against murine solid tumors supports the conclusion that dFdCyd is an excellent candidate for clinical trials in the treatment of cancer.
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PMID:Evaluation of the antitumor activity of gemcitabine (2',2'-difluoro-2'-deoxycytidine). 236 94

Brequinar sodium is a quinoline carboxylic acid derivative that has shown antitumor activity in a number of in vivo murine and human tumor xenograft models. Its mechanism of action is blockade of de novo pyrimidine biosynthesis by inhibition of dihydroorotic acid dehydrogenase. In vitro and in vivo studies demonstrate the superiority of prolonged drug exposure in achieving tumor growth inhibition. This phase I study evaluated the administration of brequinar sodium by short, daily i.v. infusion for 5 days repeated every 4 weeks. Fifty-four subjects were enrolled in the study and received drug in doses ranging from 36-300 mg/m2. The dose-limiting toxicities were mucositis and diffuse skin rash. Other toxicities included myelosuppression, nausea, vomiting, malaise, and burning at the infusion site. The maximum tolerated dose on the "daily times 5" schedule was 300 mg/m2. The recommended phase II dose is 250 mg/m2. Pharmacokinetic analysis of the day 1 drug clearance curves in 51 subjects showed slight nonlinearity in the relationship between dose and area under the clearance curve (AUC). The dose versus AUC relationship was well described using a Michaelis-Menten model of brequinar elimination kinetics with Vmax = 45 (micrograms/ml)/h and Km = 123 micrograms. Analysis of the day 5 drug clearance curves revealed a diminution in Vmax to 30 (micrograms/ml)/h. As a consequence of the reduction in Vmax brequinar plasma concentrations on day 5 were higher than predicted from day 1 drug kinetics. Pharmacodynamic analysis of the day 1 kinetic parameters and the toxicities occurring during the first cycle of drug therapy revealed significant correlations between mucositis and dose, AUC, and peak brequinar concentration; between leukopenia and AUC and peak drug concentration; and between thrombocytopenia and beta elimination rate.
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PMID:Phase I and pharmacokinetic study of brequinar sodium (NSC 368390). 236 34

The influence of the duration of exposure to the halogenated pyrimidines iododeoxyuridine (IdUrd) and bromodeoxyuridine (BrdUrd) on incorporation into DNA and the resulting radiosensitization was studied in cultured human colon cancer cells. Cells were incubated with either 10 microM BrdUrd or IdUrd for periods up to 7 days. They were also assessed for up to 4 days after removal of drug from the medium. Replacement of thymidine by fraudulent bases was measured using a sensitive gas chromatographic, mass spectrometric (GC/MS) assay. Incorporation of BrdUrd and IdUrd plateaued at 35% and 30%, respectively, after 4 days of exposure. Prolonging the time of exposure to 7 days increased cytotoxicity without affecting either incorporation or radiosensitization. Incorporation remained constant for 1-2 days after removal of drug from the medium. Radiosensitization was linearly related to incorporation throughout the range of conditions assessed. These data suggest that it may be possible to develop a predictive assay for radiosensitization based on measurements of halogenated pyrimidine incorporation in a tumor biopsy specimen. They also suggest that a clinical approach based on repeated short exposures to halogenated pyrimidines may present certain advantages over the current practice of prolonged continuous exposure. A Phase I/II trial using IdUrd and external beam irradiation for the treatment of patients with poor prognosis soft tissue sarcomas has been initiated based on this concept.
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PMID:The dependence of halogenated pyrimidine incorporation and radiosensitization on the duration of drug exposure. 204 13

7 beta-Hydroxycholesterol, which has been shown to be selectively cytotoxic toward tumor cells cultured in vitro, was converted into the corresponding water-soluble phosphoric acid ester and linked to a pyrimidine nucleoside such as 5-fluoro-2'-deoxyuridine or 2'-deoxyuridine. 2-Chlorophenyl phosphorodichloridate (3), without activation, was used directly to phosphorylate the protected oxygenated sterol. The intermediate phosphorylated the 5'-OH group of nucleoside selectively, leading to compounds 1a and 1b after deprotection. These compounds were screened for their antiproliferative activity toward EL-4 murine leukemia cells in vitro and for their antitumor activity against the mice bearing Krebs II ascitic carcinoma in vivo.
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PMID:Monophosphoric acid diesters of 7 beta-hydroxycholesterol and of pyrimidine nucleosides as potential antitumor agents: synthesis and preliminary evaluation of antitumor activity. 237 52

The halogenated pyrimidine, iododeoxyuridine (IUdR), enhances cytotoxicity of ionizing irradiation experimentally. Continuous intraarterial infusion of IUdR was combined with irradiation to maximize drug concentration in tumor and reduce potential systemic toxicity. Percutaneous tumor-specific artery catheterization was utilized in five patients, with delivery of IUdR (20 mg/kg/day) by continuous infusion 5 days prior to irradiation treatments and continued for 10-14 days. Infusion vessels included the internal mammary, the internal iliac, the renal, the common femoral, and the bronchial arteries. Conventional radiotherapy fields, fractionation, and total doses were utilized, and therapy was well tolerated. Low-grade leukopenia and thrombocytopenia was observed several weeks following infusion. A clinically nonsignificant skin reaction was observed within the irradiation fields 2-3 weeks after initiation of irradiation in several patients. No alopecia or stomatitis was observed. This study minimizes initial hepatic dehalogenation of IUdR when given by intraarterial administration. Two patients have been free of disease for over 20 years, with no long-term toxicity from IUdR therapy.
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PMID:Intraarterial iododeoxyuridine infusion combined with irradiation. A pilot study. 237 11

The pattern of purine and pyrimidine derivatives was studied in the erythrocytes of C3HA and ICR mice during Hepatoma 22 and Ehrlich ascites tumor cell growth. Concentrations of purine nucleotides, nucleosides and nucleobases of host erythrocytes were changed after the implantation of the tumors. The host erythrocytes markedly concentrated adenine and guanine nucleotides both during logarithmic and plateau phase of tumor growth (5th and 11-12th days after inoculation of the tumor). The contents of nucleosides and nucleobases in the red blood cells were decreased during the logarithmic growth phase but restored within the plateau phase.
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PMID:Metabolism of purine and pyrimidine compounds in erythrocytes of tumor-bearing mice. 238 97

To better understand the mechanism underlying halogenated pyrimidine-mediated cytotoxicity and radiosensitization in human tumor cells, a study was undertaken to determine the influence of unifilar (one DNA strand) versus bifilar (both DNA strands) substitution of thymidine by the halogenated bases 5-iodo-2'-deoxyuridine (IdUrd) and 5-bromo-2'-deoxyuridine (BrdUrd) in HT29 human colon cancer cells. Unifilar labeling was obtained by incubating cells with IdUrd or BrdUrd for one doubling time. Cells were incubated for at least three doublings to approximate bifilar substitution. Only IdUrd caused significant cytotoxicity, which correlated with incorporation into DNA. Both BrdUrd and IdUrd were potent radiosensitizers. Radiosensitization was linearly correlated with incorporation of both bases regardless of the number of strands in which thymidine was substituted. In contrast, the relationship between radiosensitization and DNA double-strand breakage was critically dependent in the case of IdUrd, but not for BrdUrd, on whether substitution was unifilar or bifilar. These findings suggest that incorporation is the best predictor of radiation sensitivity, and that the induction of DNA double-strand breaks alone does not account for radiosensitization mediated by halogenated pyrimidines in these human tumor cells.
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PMID:The effect of single versus double-strand substitution on halogenated pyrimidine-induced radiosensitization and DNA strand breakage in human tumor cells. 238 5

Bolus doses of 5-chlorodeoxycytidine (CldC) administered with modulators of pyrimidine metabolism, followed by X-irradiation, resulted in a 2-fold dose increase effect against RIF-1 tumors in C3H mice. Pool size studies of the fate of [14C]-CldC in BDF1 mice bearing Sarcoma-180 tumors, which demonstrated the rapid formation of 5-chlorodeoxycytidylate (CldCMP), and incorporation of CldC as such in RIF-1 tumor DNA, indicate that CldC is a substrate for deoxycytidine kinase, as our past Km studies have shown. Our data indicate that 5-chlorodeoxyuridine triphosphate (CldUTP) accumulates from both the cytidine deaminase-thymidine kinase pathway, as well as from the deoxycytidine kinase-dCMP deaminase pathway, in tumor tissue. As shown in a previous study, tetrahydrouridine (H4U), a potent inhibitor of cytidine deaminase, can effectively inhibit the enzyme in the normal tissues of BDF1 mice. When H4U was administered with the modulators N-(phosphonacetyl)-L-aspartic acid (PALA) and 5-fluorodeoxycytidine (FdC), the levels of CldC-derived RNA and DNA directed metabolites increased in tumor and decreased in normal tissues compared to when CldC was administered alone. These modulators inhibit the de novo pathway of thymidine biosynthesis, lowering thymidine triphosphate (TTP) levels, which compete with CldUTP for incorporation into DNA. 5-Benzylacyclouridine (BAU), an inhibitor of uridine phosphorylase, was also utilized. DNA incorporation studies using C3H mice bearing RIF-1 tumors showed that the extent of incorporation of 5-chlorodeoxyuridine (CldU) into DNA correlates with the levels of cytidine and dCMP deaminases; this is encouraging in view of their high activity in many human malignancies and the low activities in normal tissues, including those undergoing active replication. Up to 3.9% replacement of thymidine by CldU took place in RIF-1 tumors, whereas incorporation into bone marrow was below our limit of detection. CldC did not result in photosensitization under conditions in cell culture in which radiosensitization to X rays was obtained. Thus, the combination of CldC with modulators of its metabolism has potential as a modality of selective radiosensitization for ultimate clinical use in a wider range of tumors than those of the brain.
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PMID:Radiation, pool size and incorporation studies in mice with 5-chloro-2'-deoxycytidine. 239 14

In TA3 mammary carcinoma cells in suspension culture, D-glucosamine X HCl (GlcN) induced a diversion of uridylate from UTP into UDP-N-acetylhexosamines, reducing the intracellular pool of UTP and eliciting an increased rate of de novo uridylate synthesis. This rise in de novo synthesis was completely suppressed by addition of 6-azauridine (6-AzaUrd) to the cell suspension in vitro or in the solid TA3 mammary tumor in NMRI mice in vivo. A synergistic depletion of UTP pools to less than 6% of the UTP in controls was observed in TA3 cell suspensions exposed to GlcN and 6-AzaUrd. In solid TA3 tumors in vivo, UTP was reduced by this combination to 19% of the control value. A high sensitivity of the solid tumor to inhibition of pyrimidine synthesis de novo was indicated by the reduction of the UTP content after administration of 6-AzaUrd alone. UTP deficiency in TA3 tumor cells was accompanied by CTP deficiency. In addition, 6-AzaUrd caused a lowering of GTP in the neoplastic tissue. Host liver was resistant to 6-AzaUrd but responded to treatment with GlcN with a decrease in UTP to 67%. Uridine-cytidine kinase was less inhibited in the presence of lowered UTP and CTP, which are potent feedback inhibitors of the enzyme, and enabled an enhanced formation of phosphorylated derivatives of 5-fluorouridine (FUrd). Aside from the formation of 5-fluoro-UTP, we have identified 5-fluoro-UDP-N-acetylhexosamines (FUDPHexNAc), which accumulated when FUrd and GlcN were sequentially administered. Treatment of TA3 cells with FUrd after a pretreatment with 6-AzaUrd and GlcN resulted in a 2.5-fold increase in [14C]FUrd uptake and a duplication of 5-fluorouridylate incorporation into the RNA. The proportion of FUDPHexNAc increased to 58% of the phosphorylated FUrd metabolites, as compared to 6% in TA3 cells exposed exclusively to FUrd. In vivo chemotherapy of mice bearing TA3 ascites tumors was most effective with respect to tumor growth inhibition and animal survival when GlcN and FUrd were combined.
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PMID:Effects of D-glucosamine and 6-azauridine on nucleotide contents, 5-fluorouridine uptake, and cytotoxicity in TA3 mammary tumor cells. 241 23


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