Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Regenerating rat liver was used as a semisynchronous system in which to investigate the effects of 6-thioguanine on biochemical processes occurring in discrete phases of the cell cycle. 6-Thioguanine inhibited the first wave of DNA biosynthesis in regenerating rat liver. This effect appeared to be the result of a decrease, caused by 6-thioguanine, in the induction of several enzyme activities (i.e., thymidine kinase, deoxycytidylate deaminase, cytidine diphosphate reductase, and DNA polymerase) necessary for the initiation of DNA replication in regenerating liver. There was a fairly short period during which 6-thioguanine could be given to rats to accomplish the inhibition of the appearance of the induced activities of these enzymes; this period corresponded to the time just before enzyme induction. The inhibition of the induced synthesis of this group of enzymes occurred in the presence of an intact translational apparatus and intact polysomes and in the absence of interference with the incorporation of radioactive leucine and tyrosine into total protein of liver. Synthesis of polyadenylate-containing RNA was depressed in 6-thioguanine-treated rats, whereas the synthesis of polyadenylate-lacking RNA was unaffected. It is suggested that the inhibition of the synthesis of polyadenylate-containing RNA by 6-thioguanine is at least in part responsible for the observed decrease in induced enzyme activities and the resulting interference with DNA replication.
Cancer Res 1977 Jun
PMID:Effects of 6-thioguanine on macromolecular events in regenerating rat liver. 87 Jan 91

Thymidine kinase activity in the lymphoid organs of healthy and tumor-bearing chickens was studied after hydrocortisone or dexamethasone treatment. Glucocorticoid hormones (10 mg/100 g body wt) administered twice in 48 hours resulted in an 80% decrease in thymidine kinase activity in the thymuses of healthy chickens, whereas birds with transplantable MC 29 chicken hepatoma failed to respond to the hormones. In the bursae of Fabricius of healthy or tumor-bearing chickens, thymidine kinase activity did not change considerably after administration of hydrocortisone or dexamethasone. The steroid-binding capacity in cellfree systems prepared from thymuses of tumor-bearing birds was significantly decreased. Thus the difference in steroid-binding capacity between thymuses of healthy and tumor-bearing chickens correlated well with, and could account for, the failure of hydrocortisone and dexamethasone to reduce the thymidine kinase level in tumor-bearing birds.
J Natl Cancer Inst 1977 Oct
PMID:Analysis of thymidine kinase activity and glucocorticoid-binding capacity in the thymuses of healthy and tumor-bearing chickens. 90 99

The effects of 5-mercapto-2'-deoxyuridine (MUdr) on DNA synthesis in a primary murine spleen lymphocyte culture system stimulated by phytohemagglutinin (PHA) were studied. Inhibition of thymidine incorporation into acid insoluble nucleic acid material was 50% at 0.5 mM MUdR concentration, while inhibition of deoxyuridine incorporation into acid-insoluble nucleic acids was 50% at 0.01 mM MUdR. Time course studies, at 0.5 and 0.05 mM MUdR, showed that the magnitude of inhibition of incorporation for thymidine and deoxyuridine, respectively, increased from a time point after PHA stimulation when increased synthesis of thymidine kinase and thymidylate synthetase had leveled off. At 1 mM MUdR, total cellular DNA in cultures was decreased 43% at 42 hr after PHA stimulation. Neither the total number of cells nor the percentage of PHA-transformed cells was decreased in comparison to that of controls. MUdR therefore blocks the increase in DNA content of lymphocytes that is initiated during the S phase of the cell cycle. Millimolar levels of MUdR inhibited incorporation or uridine, adenosine, and cytidine into acid-insoluble material in pha-stimulated primary murine lymphocyte cultures. Total cellular RNA synthesis was inhibited at these levels of MUdR, with no differential effects on 4, 18, or 28 S RNA species observed. Uptake of these nucleosides into the total cellular acid-soluble material was not blocked. Uptake of different labeled nucleosides into cellular, acid-soluble pools occurs at different rates. Thus, choice of a suitable minimum pulse time to achieve saturation for different labeled nucleosides must relate to this consideration. Thymidine kinase from whole-cell sonic extracts of PHA-stimulated lymphocytes was inhibited 65% by 1 mM MUdR at 24 and 48 hr after stimulation. Uridine kinase extracted from the PHA-stimulated cells was also significantly inhibited by 1mM MUdR at 24 hr (56%). Exogenous guanosine incorporation into lympohcyte acid-insoluble material is increased by MUdR. This increased utilization of exogenous nuceloside is apparently the result of MUdR inhibition of conversion of adenosine to guanine nucleotides within the lymphocytes and a consequent diminution of the total intracellular guanine nucleotide pool size. The active inhibitory compound is the deoxyribonucleoside or deoxyribonucleotide. Comparison with the riboside analog 5-mercaptouridine showed that MUdR was a more efficient inhibitor of nucleoside incorporation.
Cancer Res 1976 Sep
PMID:Effects of 5-mercapto-2'-deoxyuridine on the incorporation of nucleosides into RNA and DNA in a primary lymphocyte culture system. 97 90

The immunological properties of thymidine kinase from a variety of human tumors suggest that the form of the tumor enzyme resembles that found in the placenta and in the nondividing colonic flat mucosa. To examine the placenta-like characteristics of tumor thymidine kinase, the jejunum and colon from rats ranging in age from fetal to old and from animals treated with dimethylhydrazine (DMH), an intestinal carcinogen, have been studied. In normal jejunum, thymidine kinase activity decreased rapidly with age. Both the activity and the response to phospholipase C and to mercaptans in DMH-induced tumors resembled that of fetal gut, while those in abnormal appearing DMH-treated jejunum were intermediate between normal control of the same age and tumor. Similar but less pronounced changes were seen in the colon. In the jejunum, the level of another enzyme normally associated with rapid cell division, ornithine decarboxylase, was found to be over 100 times that of the liver, colon, and stomach. Treatment of the animals with acetylaminofluorene and with DMH resulted in elevated levels of the enzyme in liver and in colon, respectively, but had little effect on this enzyme in other tissues. The data presented indicate that there were premalignant changes in the levels of both of these enzymes in target tissues of animals treated with carcinogens.
Cancer Res 1976 Sep
PMID:Biochemical changes in premalignant intestines. 97 9

Thymidine kinase was partially purified from human adrenocortical carcinoma, hyperplasia, and normal adrenal glands. For the purpose of clarifying the qualitative and quantitative difference of thymidine kinase between cancer and normal tissue, biochemical properties of partially purified thymidine kinase were compared. Adrenocortical carcinoma and hyperplasia contained greater concentration of thymidine kinase than normal adrenal gland. By the DEAE-cellulose chromatography, adrenocortical carcinoma gave two peaks (Peak I and Peak II) of thymidine kinase, while in hyperplasia and normal adrenal gland, the second peak (Peak II) was only slightly detected or hardly detected. Thymidine kinase in these three glands was identical with respect to pH optimum and inhibition by dTTP, but inhibition by dCTP was quite different. dCTP inhibited the activity of normal adrenal gland and Peak II of adrenocortical carcinoma by 55% and 40% at 0.1 mM, respectively, but the activity of adrenocortical hyperplasia and Peak I of adrenocortical carcinoma was hardly affected. Normal adrenal enzyme was more stable against heat inactivation than adrenocortical carcinoma and hyperplasia. The apparent Km with thymidine for Peak I and Peak II of adrenocortical carcinoma, hyperplasia, and normal adrenal gland was 5.0, 11.1, 5.1 and 25.0 x 10(-6)M, respectively.
 ...
PMID:Properties of thymidine kinase partially purified from human adrenal glands. 103 Jun 78

Human T-cells (CCRF-HSB2) did not incorporate tritiated thymidine ([3H]TDR)--1.0-5.0 muCi/ml--into the nuclei, where.as they readily incorporated tritiated deoxycytidine (E13H]CDR). When contamination with pleuropneumonia-like organisms was ruled out, these findings strongly suggested a deficiency of the enzyme thymidine kinase in the cells. Human B-cells (CCRF-SB) and normal T-lymphocytes (NTL) readily incorporated [3H]CDR, [3H]TDR, and tritiated 5-bromodeoxyuridine, and they clearly exhibited differential staining of the sister chromatids (SCD). When nonisotopic bromodeoxyuridine (BUDR), 10(-6)-10(-4) M, was used with the B-cells and NTL, SCD were clearly evident and sister chromatid exchange (SCE) was relatively infrequent; when the concentration was 10(-7) M, SCD staining was poor but the frequency of SCE was high. SCE frequencies in NTL, measured by autoradiography after incorporation of [3H]CDR, were the same as SCE frequencies measured by staining with BUDR at 10(-4) M. In the case of CCRF-HSB2, 10(-4) M BUDR produced relatively high frequencies of SCE as did 10(-7) M BUDR with the former two cells. However, [3H]CDR with CCRF-HSB2 gave relatively low frequencies of SCE, of the magnitude observed after 10(-4) M BUDR was used with NTL and the B-cells. Thus the high frequency of SCE in CCRF-HSB2 cells may have been due to the staining property of chromosomes that had incorporated low levels of BUDR.
J Natl Cancer Inst 1976 Dec
PMID:Dependency of sister chromatid exchange in T- and B-cells on the incorporation of deoxyribonucleosides into chromosomal DNA. 108 52

The effect of methotrexate (MTX) on thymidylate synthetase activity during liver regeneration was examined with parenchymal cells isolated 22 and 44 hr after partial hepatectomy and cultured as a monolayer. The synthetase activity in these cells decreased with a half-life of 18 to 24 hr, but if MTX (1.5 X 10(-6) to 1.5 x 10(-5) M) was present in the culture media, this decline could be delayed for at least 48 hr. In contrast, thymidine kinase activity decreased at a rate which we unaffected by MTX. Dihydrofolate reductase was inhibited at all concentrations of MTX used to block the decrease in synthetase activity. Folic acid at 10(-4) M, although less effective than MTX, also delayed the decrease in synthetase activity. The addition of cycloheximide, puromycin, or antinomycin D to the culture media did not alter the response of the synthetase to MTX. The latter studies, coupled with those indicating that the rapid loss of synthetase activity in crude extracts could be prevented by MTX or, more effectively, by MTX plus deoxyuridine 5'-monophosphate, suggest that the primary effect of MTX on thymidylate synthetase in vivo is that of enzyme stabilization. Similar stabilizing effects were obtained in liver cell extracts with 10(-5) M deoxyuridine 5'-monophosphate in combination with 10(-4) M folate or 10(-4) M dihydrofolate.
Cancer Res 1975 Aug
PMID:Effect of methotrexate on thymidylate synthetase in cultured parenchymal cells isolated from regenerating rat liver. 117 Sep 38

The thymidine kinases extracted from the spleen of mice infected with Friend virus and from Yoshida sarcoma in rats were separated into two active peaks by diethylaminoethyl cellulose column chromatography, while those of normal tissues have been found to consist of only the first peak (P-1). The second peak (P-II) was also found in the enzyme from the extract of the spleen when the animals were treated by i.p. injections of 1-acetyl 2-phenylhydrazine. The two P-II peaks from tumor tissue and from spleen enlarged by anemia-inducing agents were indistinguishable on the chromatographic profile. On the other hand, the thymidine kinase extracted with Triton X-100 from a mitochondrial fraction of normal liver was found to consist of only one peak in the same position as the above P-II's on the chromatogram, but its faculty for deoxythymidine triphosphate inhibition was not identical to that of tumor tissue. This treatment with the detergent might cause dissociation of a certain component from the enzyme complex to make the extra peak (P-IIb), but it eventually shifts to P-II on the chromatogram.
Cancer Res 1976 Jul
PMID:Two forms of thymidine kinase in normal and tumor tissues of animals. 127 27

Roswell Park Memorial Institute 4265 human lymphoblasts were grown with three dihydrofolate reductase inhibitors: a 2,4-diaminopteridine, methotrexate; a 2,4-diaminoquinazoline, chlorasquin; and, a 2,4-diaminotriazine, triazinate. In the absence of inhibitor, dihydrofolate reductase activity increased to a peak at mid-log growth and then declined during the later growth stages. When cells were grown with 10(-8) M antifolate, cell growth was not affected, but dihydrofolate reductase activity (assayed at pH 7.0) remained at approximately initial levels throughout the growth cycle. This represented 60 to 70% less activity at the mid-log stage of growth, as compared to control cells. Dihydrofolate reductase activity in cells grown with 10(-8) M methotrexate, when assayed at pH 8.5, reached levels twice those in control cells. Enzyme activity in cells grown with 10(-8) M chlorasquin, when assayed at pH 8.5, was also higher than at pH 7.0, but it was not as high as that observed in methotrexate-treated cells. Activity in cells grown with 10(-8) M triazinate was approximately the same when assayed at either pH 7.0 or 8.5. At 10(-8) M, the three antifolates had no effect on the activities of thymidylate synthetase, thymidine kinase, serine trans-hydroxymethylase, 5,10-methylenetetrahydrofolate dehydrogenase, 10-formyltetrahydrofolate synthetase, and thymidylate kinase. However, when concentrations were used which completely inhibited growth (10(-7) to 10(-5) M methotrexate or chlorasuin; 10(-6) to 10(-5) M triazinate), dihydrofolate reductase was progressively inhibited, and there was a two- and a threefold elevation of thymidylate synthetase and thymidine kinase activity, respectively. Quantitatively, the elevation of either enzyme was similar over the range of growth-inhibitory concentrations studied. The activities of the other enzymes were unaffected. Methotrexate and chlorasquin inhibited thymidylate synthetase in a noncompetitive manner (with respect to 5,10-methylenetetrahydrofolate) with approximate Ki values of 4.5 X 10(-5) M and 4.9 X 10(-6) M, respectively. Triazinate, at 10(-3) M, had no significant effect on thymidylate synthetase activity. At 10(-3) M, the antifolates produced a negligible inhibition of thymidine kinase. Deoxyuridine 5'-monophosphate (10(-5) M) effectively protected thymidylate synthetase from heat inactivation in vitro. Dihydrofolate or 5,10-methylenetetrahydrofolate, at 10(-3) M, only partially protected thymidylate synthetase. Concentrations of methotrexate (10(-7) to 10(-6) M), chlorasquin (10(-7) M), and triazinate (10(-6) to 10(-5) M), which produced thymidylate synthetase elevation in vivo, did not protect the enzyme from heat inactivation in vitro. Methotrexate at 10(-5) M and chlorasquin at 10(-6) M gave slight protection. Thymidine kinase was stabilized only by thymidine.
Cancer Res 1976 Jul
PMID:Elevation of dihydrofolate reductase, thymidylate synthetase, and thymidine kinase in cultured mammalian cells after exposure to folate antagonists. 127 51

Two enzymes were examined as potential indicators of early precancerous changes. Ornithine decarboxylase, an enzyme normally associated with rapid cell division, is low in the rapidly dividing, cancer-susceptible colon. The level of this enzyme was also very high in the nondividing cells of the small intestines. Administration of an intestinal carcinogen, dimethylhydrazine, led to a large increase in colonic ornithine decarboxylase but did not affect the enzyme in liver. A liver carcinogen, acetylaminofluorene, induced manyfold increases in ornithine decarboxylase of the liver but not of the colon. Studies of thymidine kinase of the gut showed that this enzyme changed quantitatively and qualitatively throughout the life of the animal, from fetal rat to newborn and adult. The tumor enzyme has many fetal-like properties. Long-term treatment with dimethylhydrazine led to changes in thymidine kinase reminiscent of the fetal enzyme. Short-term treatment caused sharp increases in the thymidine kinase of nondividing cells of the jejunum and the proximal end of the colon; similar changes in the distal end of the colon were slower in appearing and less pronounced.
Cancer Res 1976 Jul
PMID:Biochemical changes in preneoplastic rodent intestines. 127 75


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