azaserine and purine

Topics: Animals; Anti-Bacterial Agents; Antineoplastic Agents; Azaguanine; Azaserine; Carcinoma, Ehrlich Tumor; DNA; DNA, Neoplasm; Floxuridine; Fluorouracil; Folic Acid; Glutamine; Leukemia L1210; Mercaptopurine; Methotrexate; Mitomycin; Neoplasms; Neoplasms, Experimental; Pharmacology; Purines; Puromycin; Pyrimidines; Research; RNA; RNA, Neoplasm; Thioguanine; Thiouracil

Topics: Alkylating Agents; Antineoplastic Agents; Azaserine; Dactinomycin; DNA; Drug Resistance; Drug Resistance, Microbial; Drug Tolerance; Folic Acid; Humans; Leucine; Metabolism; Mitomycin; Mitomycins; Neoplasms; Neoplasms, Experimental; Pharmacology; Purines; Pyrimidines; RNA; Steroids; Tissue Culture Techniques

Topics: Alkylating Agents; Antimetabolites; Antineoplastic Agents; Azaserine; Colchicine; Drug Resistance; Drug Resistance, Microbial; Folic Acid Antagonists; Guanidines; Humans; Leucine; Metabolism; Neoplasms; Neoplasms, Experimental; Pharmacology; Purines; Pyrimidines; Steroids; Tissue Culture Techniques

The production of toxins A and B by Clostridium difficile was greatly enhanced under biotin-limited conditions, in which a 140-kDa protein was expressed strongly. Gene cloning revealed that this protein was a homologue of formylglycinamidine ribonucleotide synthetase (FGAM synthetase, EC 6.3.5.3), which is known as PurL in Escherichia coli and catalyses the fourth step of the de novo purine biosynthesis pathway. This enzyme consisted of a single polypeptide, although FGAM synthetases of gram-positive bacteria usually consist of two subunits. Inhibition of the enzymic activity of C. difficile PurL by O-diazoacetyl-L-serine (azaserine) resulted in enhanced toxin B production even in biotin-sufficient conditions. In contrast, blockade of the preceding step of the PurL catalysing step by sulfamethoxazole inhibited toxin B production almost completely. These results suggest that accumulation of formylglycinamide ribonucleotide (FGAR), a substrate of FGAM synthetase, enhances toxin production by C difficile and depletion of FGAR reduces toxin production.

Topics: Amino Acid Sequence; Anti-Bacterial Agents; Azaserine; Bacterial Proteins; Bacterial Toxins; Biotin; Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; Clostridioides difficile; Cytotoxins; Enterotoxins; Escherichia coli Proteins; Glycine; Humans; Ligases; Molecular Sequence Data; Polymerase Chain Reaction; Purines; Ribonucleotides; Sequence Homology; Sulfamethoxazole

This study was carried out to test the hypothesis that purine nucleotide-generating pathways are required for ligand-stimulated oocyte maturation in meiotically arrested cumulus cell-enclosed oocytes. Oocytes from hormonally primed, immature mice were cultured overnight in Eagle's minimum essential medium containing dibutyryl cyclic AMP (dbcAMP) (to maintain meiotic arrest), plus either mycophenolic acid or alanosine (inhibitors of guanyl and adenyl nucleotide production, respectively). Follicle-stimulating hormone (FSH) was added either at the outset of culture or after a 3-hr preincubation period. Under either of these conditions, the inhibitors suppressed FSH induction of germinal vesicle breakdown (GVB). In addition, the potency of FSH as an inducer of GVB was reduced following the 3-hr preincubation period, but this could be prevented if nucleotide precursors such as hypoxanthine, guanosine, or adenosine were included during the first 3 hr. Furthermore, preincubation had little effect on FSH induction of GVB when hypoxanthine was used to maintain meiotic arrest for the entire culture period. The phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine, could not mimic this protective effect of hypoxanthine. Azaserine and aminopterin, inhibitors of purine de novo synthesis, blocked hormone-triggered maturation in dbcAMP-arrested oocytes, but had little effect on hypoxanthine-arrested oocytes. The effect of azaserine on dbcAMP-treated oocytes could be reversed by the inclusion of AICA riboside, a compound that can be taken up by cells and phosphorylated to form AICAR, which can enter the purine de novo pathway at a point distal to the sites of azaserine inhibition. FSH was stimulatory to purine de novo synthesis, while azaserine, aminopterin, hypoxanthine, and AICA riboside all suppressed de novo synthesis in the presence or absence of FSH, with dbcAMP having no effect. HPLC analysis of 14C-hypoxanthine metabolism in oocyte-cumulus cell complexes revealed that changes in the pattern of purine metabolism did not mediate the meiosis-inducing effect of FSH. These data support the conclusion that purine nucleotide-generating pathways are vital participants in the mechanism(s) regulating hormone-induced meiotic maturation, and that either the de novo or salvage pathway can fulfill this nucleotide requirement.

Topics: Aminoimidazole Carboxamide; Animals; Azaserine; Chromatography, High Pressure Liquid; Cyclic AMP; Follicle Stimulating Hormone; Hypoxanthine; Meiosis; Mice; Mice, Inbred C57BL; Oocytes; Oogenesis; Purines; Ribonucleosides; Signal Transduction

5'-Deoxy-5'-methylthioadenosine phosphorylase (MTAP) is involved in the salvage of adenine and methylthio moieties of 5'-deoxy-5'-methylthioadenosine, a byproduct of polyamine synthesis, to adenine nucleotides and methionine, respectively. The gene encoding MTAP, MTAP, is frequently codeleted along with the tumor suppressor gene p16 in malignant cells bearing homozygous deletions in the chromosome 9p21 region. p16-, MTAP- malignant cells have been shown to be more susceptible to the purine de novo inhibitory actions of antifolates such as methotrexate than are p16+, MTAP+ cells. To understand the underlying mechanism, we reintroduced MTAP activity into two p16-, MTAP- cell model systems, the MiaPaCa-2 and PANC-1 human pancreatic carcinoma cell lines, by transfection with MTAP cDNA. It was found that transfection with MTAP cDNA (i) restored both the MTAP-dependent adenine and methionine salvage pathways, (ii) decreased the rates of purine de novo synthesis (18-47% lower than the wild-type or sham-transfected counterparts), and (iii) decreased cellular sensitivity to the antipurine-related growth-inhibitory actions of methotrexate and azaserine. These data support the hypothesis that operation of the MTAP-dependent adenine salvage pathway renders MTAP+ cells less dependent on de novo purine synthesis and hence less susceptible than MTAP- malignant cells to the growth-inhibitory actions of agents (e.g. antifolates) whose mechanism of action in part involves the de novo purine pathway. These findings provide a theoretical basis for the relatively selective action certain antifolates may have against MTAP-deficient malignancies.

Topics: Adenosine; Antimalarials; Antimetabolites, Antineoplastic; Azaserine; Biomarkers, Tumor; Cell Count; Deoxyadenosines; DNA, Complementary; Dose-Response Relationship, Drug; Humans; Methionine; Methotrexate; Pancreatic Neoplasms; Purine-Nucleoside Phosphorylase; Purines; RNA, Messenger; Thionucleosides; Tumor Cells, Cultured

Methotrexate pretreatment of L1210 cells had been shown previously by us to cause an enhancement of the intracellular accumulation of 5-fluorouracil and of the formation of 5-fluorouracil nucleotides which was correlated with synergistic cytotoxicity. This effect of methotrexate was associated with increases in 5-phosphoribosyl-1-pyrophosphate, the cofactor required for the conversion of 5-fluorouracil to 5-fluorouridine-5'-monophosphate (FUMP). Because these influences on 5-fluorouracil metabolism were most likely mediated by the activity of methotrexate as an inhibitor of purine synthesis, the effects of other agents that inhibit purine synthesis were examined. An inhibitor of amidophosphoribosyltransferase, 6-methylmercaptopurine ribonucleoside, the glutamine antagonists, azaserine and 6-diazo-5-oxo-L-norleucine (DON), and the L-aspartate analogue inhibitor of adenylsuccinate synthetase, L-alanosine, all reduced the incorporation of [1-14C]glycine into adenine and guanine bases isolated from nucleic acids. Each drug also resulted in intracellular elevations of 5-phosphoribosyl-1-pyrophosphate that were 15- to 25-fold greater than control levels. These alterations in de novo purine nucleotide synthesis were associated with enhanced intracellular 5-fluorouracil accumulation and synergistic cytotoxicity.

Topics: Alanine; Animals; Azaserine; Cell Line, Tumor; Cell Survival; Diazooxonorleucine; Dose-Response Relationship, Drug; Fluorouracil; Methotrexate; Nucleic Acid Synthesis Inhibitors; Purines; Thioinosine; Thionucleotides; Uracil Nucleotides

Topics: Adenine; Amino Acids; Azaserine; Cytosine; Cytosine Nucleotides; DNA; Glutamine; Guanine; Hypoxanthines; Leucine; Metabolism; Nucleic Acids; Orotic Acid; Pharmacology; Purines; Pyrimidines; Research; RNA; Thymine; Trypanosoma; Tryptophan; Tyrosine; Uracil; Uracil Nucleotides

Topics: Adenine; Animals; Antimetabolites; Antineoplastic Agents; Azaserine; Carcinoma, Squamous Cell; Glycine; Hypoxanthines; Imidazoles; Leukemia L1210; Mercaptopurine; Nucleotides; Pharmacology; Purines; Research; Ribonucleotides; Thioguanine; Tissue Culture Techniques; Xanthines

Topics: Adenine; Azaserine; Carbon Isotopes; Glycine; Guanine; Hypoxanthines; Imidazoles; Leukemia; Metabolism; Nucleic Acids; Pharmacology; Purines; Tissue Culture Techniques

Topics: Alkylating Agents; Animals; Antibody Formation; Antineoplastic Agents; Azaserine; Imidazoles; Mercaptopurine; Mice; Pharmacology; Purines; Rats; Research; Sarcoma 180; Tetanus Toxoid; Thioguanine; Toxicology

Topics: Amebicides; Anti-Bacterial Agents; Antineoplastic Agents; Azaserine; Carboxylic Acids; Cyclopentanes; Dactinomycin; Glycine; Mitomycin; Mitomycins; Pharmacology; Purines; Puromycin

Topics: Azaserine; Azo Compounds; Cell Cycle; Cell Division; Glutamine; Metabolism; Pharmacology; Phenylalanine; Purines; Research; Tetrahymena

Topics: Allografts; Animals; Azaserine; Azathioprine; Dogs; Immunosuppression Therapy; Kidney Transplantation; Pharmacology; Purines; Research; Skin Transplantation; Transplantation Immunology; Transplantation, Homologous

Topics: Animals; Azaserine; Blood Chemical Analysis; Dactinomycin; Dogs; Hematocrit; Immunosuppressive Agents; Kidney; Kidney Transplantation; Leukocyte Count; Pathology; Pharmacology; Purines; Research; Skin Transplantation; Transplantation Immunology; Transplantation, Homologous; Urine

Topics: Azaserine; Blood; Drug Therapy; Enzyme Inhibitors; Gout; Leucine; Metabolism; Orotic Acid; Oxidoreductases; Purines; Pyrimidines; Uric Acid; Xanthines

Topics: Adenine; Amino Acids; Animals; Antimetabolites; Antineoplastic Agents; Azaserine; Carbon Isotopes; Glycine; Guanine; Mercaptopurine; Metabolism; Mice; Neoplasm Transplantation; Nucleotides; Pharmacology; Purines; Research; Sarcoma 180

Topics: Adenine; Adenine Nucleotides; Azaserine; Metabolism; Nucleosides; Pharmacology; Purine Nucleosides; Purines; Research; Tissue Culture Techniques; Toxicology

Topics: Azaserine; Oncogenic Viruses; Purines

Topics: Allergy and Immunology; Allografts; Animals; Azaserine; Dactinomycin; Dogs; Immunosuppressive Agents; Kidney Transplantation; Leukopenia; Methotrexate; Purines; Pyrazoles; Pyrimidines; Research; Skin Transplantation; Thrombocytopenia; Urea

Topics: Animals; Antineoplastic Agents; Azaserine; Mice; Neoplasms; Pharmacology; Purines; Research; Sarcoma 180

Topics: Alkylating Agents; Animals; Antineoplastic Agents; Azaguanine; Azaserine; Carcinoma, Ehrlich Tumor; Carcinoma, Hepatocellular; DNA; DNA, Neoplasm; Fluorouracil; Idoxuridine; Liver Neoplasms; Lymphoma; Lymphoma, Non-Hodgkin; Mercaptopurine; Mice; Neoplasms, Experimental; Nitrogen Mustard Compounds; Nucleosides; Nucleotides; Purines; Research; RNA; RNA, Neoplasm; Sarcoma 180; Thioguanine; Uracil Mustard

Topics: Adenine; Adenine Nucleotides; Animals; Antineoplastic Agents; Azaserine; Carcinoma, Ehrlich Tumor; DNA; DNA, Neoplasm; Glycine; Metabolism; Mice; Nucleic Acids; Proteins; Purines; Research; RNA; RNA, Neoplasm; Thioguanine

Topics: Anti-Bacterial Agents; Antineoplastic Agents; Autoradiography; Azaserine; Azo Compounds; Carbon Isotopes; Formates; Metabolism; Mice; Neoplasms; Neoplasms, Experimental; Neoplasms, Plasma Cell; Nucleic Acids; Nucleotides; Pharmacology; Purines; Research

Topics: Anti-Bacterial Agents; Azaserine; Bacteria; Chemical Phenomena; Chemistry; Chloramphenicol; DNA; DNA, Bacterial; Erythromycin; Mitomycin; Mitomycins; Pharmacology; Purines; Puromycin; RNA; RNA, Bacterial

Topics: Acridines; Antineoplastic Agents; Arsenicals; Azaguanine; Azaserine; Busulfan; Cell Division; Chloramines; Colchicine; Humans; Mercaptopurine; Pharmacology; Purines; Thiotepa; Triethylenemelamine

Topics: Antineoplastic Agents; Azaserine; Purines

Topics: Antineoplastic Agents; Ascites; Azaserine; Neoplasms; Purines

Topics: Animals; Antineoplastic Agents; Azaserine; Carcinoma, Hepatocellular; Liver Neoplasms; Neoplasms; Purines; Sarcoma; Sarcoma 180

Topics: Antineoplastic Agents; Azaserine; Humans; Purines

Topics: Animals; Antineoplastic Agents; Azaserine; Glyceraldehyde; Humans; Purines; Sarcoma 180; Thioguanine

Topics: Antineoplastic Agents; Azaserine; Escherichia coli; Histidine; Leadership; Purines

Topics: Antineoplastic Agents; Azaserine; Escherichia coli; Histidine; Leadership; Purines

Topics: Animals; Anti-Bacterial Agents; Ascites; Azaserine; Carcinoma, Ehrlich Tumor; Mercaptopurine; Neoplasms; Purines

Topics: Antineoplastic Agents; Azaserine; Bacteria; Escherichia coli; Metabolic Networks and Pathways; Purines; Serine