Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.7 (adenine phosphoribosyltransferase)
 692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cis-diammine dichloroplatinum (cisplatin) is an effective anti-cancer drug which forms adducts with DNA, in both bacterial and mammalian cells. It is suspected of producing tumors as well. To determine the molecular nature of genetic alterations induced by cisplatin, we cloned and sequenced cisplatin-induced mutants in the adenine phosphoribosyltransferase (aprt) gene of Chinese hamster ovary (CHO) cells. Mutation by cisplatin appears to be targeted as the sites of mutation are consistent with the known binding specificity of cisplatin. Many mutations occur at or proximal to the sequence 5'-AGG-3' and 5'-GAG-3' and include transversions, transitions, frameshifts and short deletions and duplications. Several double changes were also observed. No major rearrangements were recovered in our collection. At several locations, a number of mutants were found to be clustered within a small target region, but unlike traditional hotspots, these represent diverse changes occurring in a localized region of a few base pairs.
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PMID:Sequence specificity of mutation induced by the anti-tumor drug cisplatin in the CHO aprt gene. 275 12

Ehrlich carcinoma and P388 leukemia cells were rendered resistant to 4-carbamoylimidazolium 5-olate (SM-108), and assessments were made of biochemical and pharmacological determinants for the sensitivity to SM-108 using both sensitive and resistant sublines. We observed that the treatment of cells with SM-108 in vitro caused a remarkable decrease in the intracellular guanosine 5'-triphosphate pool level in sensitive but not in resistant sublines. There was no difference in the ability to take up SM-108 between sensitive and resistant sublines, but the cellular conversion of SM-108 to its nucleotide, which is the putative active anabolite of SM-108, proceeded only in sensitive sublines. Enzymological studies revealed that the activity of adenine phosphoribosyltransferase (EC 2.4.2.7), which is believed to conjugate SM-108 with 5-phospho-alpha-D-ribose 1-diphosphate, was very low in the resistant sublines. These results strongly support our previous hypothesis that SM-108 is activated by adenine phosphoribosyltransferase to SM-108-nucleotide which then inhibits hypoxanthine-5'-monophosphate dehydrogenase (EC 1.2.1.14), a key enzyme for the de novo synthesis of guanosine 5'-monophosphate.
Cancer Res 1986 Jan
PMID:Selective reduction of intracellular guanosine 5'-triphosphate pool by 4-carbamoylimidazolium 5-olate in murine tumor cells. 286 32

The purpose of this study was to elucidate the purine enzymic programs of human primary colorectal carcinomas. Marked alteration in the enzymology of the human colon neoplasm clearly distinguished it from that of the normal colon mucosa. In the human colon mucosa, the activities of ribonucleotide reductase, inosine phosphate dehydrogenase, formylglycinamidine ribonucleotide synthetase, guanosine phosphate synthetase, and amidophosphoribosyltransferase were 0.042, 5.2, 5.6, 8.2 and 36.0 nmol/h/mg protein, respectively, and in the colon carcinomas the activities increased to 755, 575, 295, 280, and 294% of the normal values. The activities of the salvage enzymes, adenine and hypoxanthine-guanine phosphoribosyltransferases, were 310, 249, and 602 nmol/h/mg protein, respectively, whereas in the tumors, only the activity of adenine phosphoribosyltransferase was increased (2-fold). The markedly higher absolute enzymic capacity for salvage in the tumors accounts, in part at least, for the lack of chemotherapeutic success of inhibitors of enzymes of de novo synthesis that have been used in the clinical treatment of colorectal carcinomas. Combinations of inhibitors of de novo biosynthesis and blockers of the salvage enzymes or of salvage transport (e.g., dipyridamole) should improve the chemotherapy of colon neoplasms. Since in the colon carcinoma the activities of glutamine-utilizing enzymes (guanosine phosphate and formylglycinamidine ribonucleotide synthetase and amidophosphoribosyltransferase) were markedly increased, and the glutamine concentration was decreased (50%), treatment with an antiglutamine agent (e.g., acivicin) should be of relevance. Since the activity of ribonucleotide reductase, the rate-limiting enzyme of nucleic acid biosynthesis, was markedly increased in the colon neoplasms, combination chemotherapy might include drugs against this enzyme.
Cancer Res 1985 Jun
PMID:Purine enzymology of human colon carcinomas. 398 94

The mechanism of action of 5-carbamoyl-1H-imidazol-4-yl piperonylate (SL-1250), which has a broad antitumor spectrum, was examined by in vitro cell culture and enzymatic studies. In the serum-containing culture medium, SL-1250 was rapidly deacylated to 4-carbamoylimidazolium 5-olate (SM-108). Thus, SL-1250 might be acting on the cells in the form of SM-108. The growth of L5178Y cells was completely inhibited by 10(-5) M SL-1250. It should be noted that this growth inhibition was significantly reversed in the presence of equimolar concentrations of guanine, guanosine, or guanosine 5'-monophosphate to those of SL-1250. However, hypoxanthine and xanthine were not effective. These effects of purine addition were observed to be quite similar in growth inhibition by SM-108. It was found that inosine 5'-monophosphate dehydrogenase (EC 1.2.1.14; IMP dehydrogenase), a key enzyme of de novo purine synthesis, from Ehrlich carcinoma cells was inhibited by SM-108 only when 5-phospho-alpha-D-ribose 1-diphosphate (PRPP) and MgCl2 coexisted with SM-108. In contrast, a chemically synthetic ribonucleotide of SM-108 inhibited IMP dehydrogenase without PRPP and MgCl2, and the mode of inhibition was competitive with the Ki value of 2 x 10(-8) M. On the other hand, the inhibition of either growth of L5178Y cells or IMP dehydrogenase in the presence of PRPP and MgCl2 by these compounds was reversed by adenine. A nucleotide of SM-108 was chromatographically identified when [14C]SM-108 was incubated in the enzyme solution with PRPP and MgCl2. This conversion by enzyme was also inhibited by adenine. Viewed together, these results strongly suggest that SL-1250 is, after being converted to SM-108, activated to its nucleotide form by adenine phosphoribosyltransferase (EC 2.4.2.7) and that this SM-108 nucleotide blocks de novo synthesis of guanosine 5'-monophosphate by inhibiting IMP dehydrogenase.
Cancer Res 1982 Mar
PMID:New antitumor imidazole derivative, 5-carbamoyl-1H-imidazol-4-yl piperonylate, as an inhibitor of purine synthesis and its activation by adenine phosphoribosyltransferase. 612 Jul 58

The mechanism of action of acivicin and tiazofurin was compared in hepatoma 3924A. The results were evaluated by assessing the impact of these drugs on primary targets, the activities of key enzymes, and on secondary and tertiary targets, the concentrations of pools of ribonucleotides and deoxyribonucleotides. The action of acivicin entails inhibition and inactivation of the key enzymes of glutamine utilization in the biosynthesis of purines and pyrimidines. As a result, the GTP and CTP pools were markedly depleted, whereas those of ATP and UTP were unaffected. Acivicin also markedly decreased the concentrations of all 4 deoxynucleoside triphosphates. The nucleotide pools returned to normal or near normal range within 2 to 3 days after a single acivicin injection. The pharmacologic targets of acivicin in anticancer chemotherapy include prominently the activities of glutamine-utilizing enzymes and the pools of GTP and CTP and all 4 dNTP's. These biochemical targets also serve as indicators of acivicin action in cancer cells. The action of tiazofurin in hepatoma cells entails the primary target, IMP dehydrogenase. The subsequent effects include marked enlargement of IMP and PRPP pools and depletion of the pools of GDP and GTP. The increased IMP concentration selectively inhibited the activities of hypoxanthine-guanine phosphoribosyltransferase, but did not affect that of adenine phosphoribosyltransferase. The markedly decreased GTP pool de-inhibited the activity of AMP deaminase which permitted the channeling of AMP to IMP. An important indicator of tiazofurin action is the prolonged depletion of dGTP pools and similar but less pronounced declines in the pools of dCTP and dATP. In contrast, dTTP pools were increased. The crucial biochemical targets and indicators of tiazofurin action in sensitive cancer cells include inhibition of IMP dehydrogenase, a decrease in the concentrations of GDP, GTP, dGTP, dCTP, dATP and marked rise in the pools of IMP, PRPP and dTTP. Measurements of the molecular targets and indicators of drug action should be helpful in identifying cancer cells and tissues sensitive or resistant to the action of acivicin or tiazofurin. Identification of the targets and indicators should also be helpful in the design of frequency of administration of the drugs in combatting animal and human neoplasia.
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PMID:Control of enzymic programs and nucleotide pattern in cancer cells by acivicin and tiazofurin. 620 92

Two new purine antagonists, 5-carbamoyl-1H-imidazol-4-yl piperonylate (SL-1250) and 4-carbamoylimidazolium 5-olate (SM-108), were investigated for their antitumor activities against 6-mercaptopurine (6-MP)-resistant sublines of P388 and L1210 leukemia. It was found that both resistant sublines exhibited collateral sensitivity instead of cross-resistance to these new antipurine drugs. Since more potent cytotoxic activities of these drugs against 6-MP-resistant cells were observed even in vivo cell culture systems, this collateral sensitivity was proved on a cellular basis. Biochemical studies revealed that 6-MP-resistant sublines of both P388 and L1210 leukemia are deficient in hypoxanthine-guanine phosphoribosyltransferase activity. In these cells, not only the activation of 6-MP to its nucleotide but also the synthesis of guanosine 5'-monophosphate via the salvage pathway seems to be severely restricted. However, SL-1250 and SM-108 can be activated to their nucleotide even in these 6-MP-resistant cells because the activation of these compounds is proceeded by adenine phosphoribosyltransferase. In conclusion, suppression of de novo purine synthesis with SL-1250 and SM-108 seems to be a very efficient means of killing these 6-MP-resistant cells, which lack a salvage pathway for guanosine 5'-monophosphate.
Cancer Res 1982 Mar
PMID:Collateral sensitivity of 6-mercaptopurine-resistant sublines of P388 and L1210 leukemia to the new purine antagonists, 5-carbamoyl-1H-imidazol-4-yl piperonylate and 4-carbamoylimidazolium 5-olate. 627 74

The enzymic capacities of the de novo and the salvage pathways for purine nucleotide synthesis were compared in rat in normal, differentiating, and regenerating liver, and in three hepatomas of widely different growth rates. The activities of the key de novo and salvage enzymes were also determined in mouse lung and Lewis lung carcinoma, in human kidney and liver, and in renal cell carcinoma and hepatocellular carcinomas. A precise and reproducible assay was worked out for measuring the activities of adenine phosphoribosyltransferase (EC 2.4.2.7) and hypoxanthine-guanine phosphoribosyltransferase (HGPRT; EC 2.4.2.8) in crude liver and hepatoma systems. Kinetic studies on the salvage enzymes were carried out in the crude 100,000 X g supernatant fluid from normal liver and rapidly growing hepatoma 3924A. In both tissue extracts, Michaelis-Menten kinetics was observed for adenine phosphoribosyltransferase and HGPRT. The reciprocal plots for 5-phosphoribosyl-1-pyrophosphate (PRPP) of liver and hepatoma enzymes gave apparent KmS of 2 microM for adenine phosphoribosyltransferase and 4 microM for HGPRT, showing two orders of magnitude higher affinities for PRPP than that of the rate-limiting enzyme of de novo purine synthesis, amidophosphoribosyltransferase (EC 2.4.2.14) (Km = 400 to 900 microM). The apparent Km values for adenine of liver and hepatoma adenine phosphoribosyltransferase were 0.6 to 0.9 microM, respectively. For both liver and hepatoma HGPRT, the reciprocal plots for hypoxanthine and guanine yielded the same Km of 3 microM. The specific activities of purine phosphoribosyltransferases were markedly higher than that of amidophosphoribosyltransferase in rat thymus, spleen, testis, bone marrow, colon, liver, kidney cortex, lung, heart, brain, and skeletal muscle, but were lower in the small intestine. In hepatomas and regenerating and differentiating liver, the activities of the salvage enzymes were 2.1- to 32-fold higher than that of amidophosphoribosyltransferase. The purine phosphoribosyltransferase activities were also higher than that of amidophosphoribosyltransferase in Lewis lung carcinoma (8.2- to 32-fold), human renal cell carcinoma (3.5- to 22-fold), and hepatocellular carcinoma (3.4- to 30-fold). The high activities and the high affinity to PRPP of the purine phosphoribosyltransferases might explain the lack of linkage of the behavior of these enzymic activities with proliferation in normal, regenerating, differentiating, or neoplastic tissues. In contrast, the specific activity of the amidophosphoribosyltransferase, which is lower than that of the salvage enzymes, is linked with transformation as it is increased in all examined tumors.4
Cancer Res 1984 Jun
PMID:Enzymic capacities of purine de Novo and salvage pathways for nucleotide synthesis in normal and neoplastic tissues. 632 16

The potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) was tested for its ability (a) to induce sister chromatid exchange, (b) to increase the rate of transition at the adenine phosphoribosyltransferase (apt) locus from the presumptive heterozygous state ((+/- to the homozygous state (-/ - or -), and (c) to enhance the frequency of mutations expressed after ultraviolet radiation mutagenesis. We have found no significant effect of TPA in any of these experiments. Sister chromatid exchange frequencies in both V79 and Chinese hamster ovary cells remained unchanged by TPA treatment under various conditions, a result inconsistent with the hypothesis that an important effect of TPA might be to increase the rate of chromosomal mitotic recombination (and hence segregation of recessive mutations) in a manner akin to increased chromatid recombination. We have also been unable to obtain evidence for mitotic recombination affecting the aprt locus in Chinese hamster ovary cells for which the rate of change to a high level of resistance to azaadenine was measured. The rate of 8.6 X 10(-7) mutation (and/or segregations) per cell generation assessed by fluctuation analysis was not increased by the continuous presence of TPA, 4 microgram/ml, in the medium. In the third set of experiments, mutant frequencies in Chinese hamster ovary cells after ultraviolet mutagenesis were measured for the markers ouabain resistance, thioguanine resistance, and azaadenine resistance, under conditions with and without pretreatment with TPA before mutant selection. No convincing enhancement in mutation expression was observed. In summary, these results argue that promotion by TPA does not proceed by a mechanism involving genetic recombination or the altered expression of newly mutated alleles.
Cancer Res 1980 Sep
PMID:Failure of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate to enhance sister chromatid exchange, mitotic segregation, or expression of mutations in Chinese hamster cells. 693 1

4-Carbamoylimidazolium 5-olate (CIO), the aglycone of the nucleoside antibiotic, bredinin (4-carbamoyl-1-beta-D-ribofuranosylimidazolium 5-olate), exhibited potent cytotoxic effects of subclonal line F28-7 of C3H mouse mammary carcinoma FM3A cells in culture. We isolated 11 cell lines resistant to CIO from wild-type F28-7 cells mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine. These resistant (cio') lines were 160- to 400-fold less sensitive to CIO than were the wild-type cells and inherited the resistant phenotypes during subculture for more than 3 months in the drug-free medium. They were cross-resistant to an adenine analog, 2,6-diaminopurine, while 2,6-diaminopurine-resistant (dap') lines, isolated independently, were cross-resistant to CIO. Neither of the cio' lines tested were able to form colonies in agar medium containing azaserine and adenine, nor were they able to incorporate tritiated adenine into the macromolecular fraction, indicating that they could not utilize exogenous adenine for growth. Enzyme assays using cell-free extracts revealed that all the cio' lines had undetectable levels of adenine phosphoribosyltransferase (EC 2.4.2.7) activity, but they, except one, had normal levels of hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) and adenosine kinase (EC 2.7.1.20) activities. These results demonstrate that the CIO resistance in these lines is attributed to deficient adenine phosphoribosyltransferase activity and therefore that CIO is activated by adenine phosphoribosyltransferase to form a cytotoxic nucleotide within the drug-sensitive cells.
Cancer Res 1982 Oct
PMID:Adenine phosphoribosyltransferase deficiency in cultured mouse mammary tumor FM3A cells resistant to 4-carbamoylimidazolium 5-olate. 710 14

Chromosomal aberrations in human gliomas are principally numerical. In tumours of low malignancy, karyotypes are frequently normal, but occasionally an excess of chromosome 7 and a loss of sex chromosome are observed. In highly malignant tumours, the most frequent aberrations are gain of chromosome 7, loss of chromosome 10 and less frequently losses or deletions of chromosomes 9, 22, 6, 13 and 14 or gains of chromosomes 19 and 20. To understand the meaning of these chromosome imbalances, the relationships between chromosome abnormalities and metabolic disturbances were studied. The losses or deletions observed affected principally chromosomes carrying genes encoding enzymes involved in purine metabolism. The activities of ten enzymes were measured: adenosine kinase, adenine phosphoribosyltransferase, adenylate kinase, methylthioadenosine phosphorylase, hypoxanthine phosphoribosyltransferase, adenylosuccinate lyase, inosine monophosphate dehydrogenase, adenosine deaminase, nucleoside phosphorylase and adenosine monophosphate deaminase. In parallel, two enzymes involved in pyrimidine metabolism, thymidine kinase and thymidylate synthase (TS), were studied. The activities of all these enzymes were measured on samples from 30 human primary glial tumours with low or high malignancy, six xenografted tumours at different passages, four portions of normal brain tissue and four non-glial brain neoplasms. As suggested by cytogenetic data, the enzymatic results showed a relatively low activity of purine metabolism in glial tumours when compared with normal brain and non-glial brain neoplasms. Considering the two enzymes involved in pyrimidine metabolism, only TS had higher activity in glial tumours of high malignancy than in normal brain. In comparison with normal brain, the balance between salvage and de novo pathways changes in gliomas, and even more in grafted tumours, in favour of de novo synthesis. The relation between chromosomes and metabolic imbalances does not correspond to a simple gene dosage effect in these tumours. These data suggest that the decrease of adenosine metabolism occurs before chromosomal aberrations appear, since it is observed in tumours of low malignancy when most karyotypes are still normal, and that the de novo pathway increases with tumour progression.
Br J Cancer 1994 Aug
PMID:Purine and pyrimidine metabolism in human gliomas: relation to chromosomal aberrations. 805 68


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