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)

The transforming activity of DNA from a newly established undifferentiated human colon carcinoma cell line (MIP-101) was tested in the NIH-3T3 transfection assay. Southern blot analysis of the transfectant DNA revealed the presence of a human N-ras oncogene. Treatment of MIP-101 cells with the maturational agent sodium butyrate induced a more normal phenotype, including diminished growth rate, elimination of anchorage independent growth, and decreased tumorigenicity (R. Niles, S. Wilhelm, P. Thomas, and N. Zamcheck (1988) J. Cancer Invest. 6, 39). Here we report that there is a significant reduction in the transforming efficiency of the DNA from butyrate-treated MIP-101 cells. A nonspecific reduction in total DNA uptake as an explanation for these findings was eliminated by showing that there was similar uptake and expression of the thymidine kinase gene from the DNA of butyrate-treated and control MIP cells. Butyrate treatment had no detectable effect on the overall structure, methylation, and level of expression of the human N-ras gene from MIP-101 cells. An NIH-3T3 transformant ability after treatment with sodium butyrate. Although butyrate suppressed several transformed properties similar to MIP-101 cells, DNA from control and treated cultures had an identical level of transforming activity. The results suggest that the environment of the MIP cells may contain additional elements not present in the NIH-3T3 transformants which are required to observe the effect of butyrate on reduction of transforming activity.
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PMID:Sodium butyrate suppresses the transforming activity of an activated N-ras oncogene in human colon carcinoma cells. 267 72

Butyric acid increases fetal hemoglobin synthesis in adult animals and in erythroid cells in culture and induces the gamma-globin gene promoter in transient expression experiments in K562 cells (McDonagh KT, Nienhuis AW, Blood 78:255a, 1992 [abstr, suppl 1]). We compared the effect of butyrate and other short-chain carboxylic acids in transient expression studies with K562 cells using an expression plasmid bearing a luciferase reporter gene driven by the normal human A gamma-globin gene promoter. Butyrate (4 carbons) increased the activity of the human A gamma-globin gene promoter up to 123 times. Marked augmentation of the normal gamma-promoter activity was also noted with 5-carbon valeric acid (up to 394 times) and 3-carbon propionic acid (up to 129 times). The branched isobutyric acid as well as phenylacetate showed less ability to increase promoter activity. Addition of the tandemly repeated AP-1/NF-E2 (AP) enhancer sequences from hypersensitive site 2 (HS2) of the locus control region (LCR) increased gamma-promoter activity up to 24 times. Addition of a nearby 16-bp conserved motif (CM) in HS2 (Safaya S, Rieder RF, Blood 78:146a, 1992 [abstr, suppl 1]) to the AP-containing plasmid construct further increased gamma-promoter activity. In the presence of butyrate, the plasmid bearing both the AP and CM sequences showed gene expression up to 477 times greater than that of the basal gamma-promoter-driven luciferase plasmid in the absence of inducer. A plasmid bearing the herpes simplex thymidine kinase promoter was also tested and gene expression was markedly increased by the same organic acids. MEL cells responded to butyrate, valerate, and propionate with induction of hemoglobin synthesis. Responses to isobutyrate and 6-carbon caproate required higher concentrations of the compounds. Thus, other short-chain organic acids as well as butyrate increase gamma-promoter activity in the transient expression system, and this activity can be further augmented by incorporating LCR elements into the expression vector. Nonglobin promoters also respond to the same carboxylic acids.
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PMID:Augmentation of gamma-globin gene promoter activity by carboxylic acids and components of the human beta-globin locus control region. 794 49

Thyroid hormone (T3) and retinoic acid (RA) receptors regulate transcription of the rat growth hormone (GH) gene through binding to a common hormone response element (HRE) in the promoter. We have investigated the effect of histone acetylation on hormone-dependent expression of the rat GH gene. We examined the effect of butyrate, which induces histone hyperacetylation, and trichostatin A (TSA), a highly specific inhibitor of histone deacetylases. GH-mRNA levels were significantly increased in pituitary GH4C1 cells incubated with T3 and RA, and this response was further stimulated in the presence of 1 mM butyrate. The effect of butyrate was mimicked by TSA. Butyrate and TSA also enhanced the activity of recombinant constructs containing the GH promoter directing chloramphenicol acetyl transferase (CAT) reporter gene expression. CAT activity increased by 4- to 8-fold after incubation with 1 nM T3 and 1 microM RA, and this response was stimulated 2- to 4-fold further in the presence of 0.25 mM butyrate. This concentration of butyrate did not influence basal expression of CAT. TSA produced a dose-dependent increase of CAT activity in the absence of ligands, and between 5 and 200 nM potentiated the effect of T3 and RA. These compounds also increased the hormonal response of constructs in which the HRE was linked to heterologous [mouse mammary tumor virus (MMTV) and thymidine kinase (TK)] promoters. With butyrate >1 mM, basal activity of the GH promoter increased by more than 10-fold and the effect of T3 and RA was no longer observed. Overexpression of T3 receptors was able to counteract the stimulation of basal CAT levels caused by butyrate. Thus, in the absence of ligand, the T3 receptor acts as a constitutive repressor of gene expression. Upon binding of the hormone, the T3 receptor is converted into an activator. Our findings suggest that histone acetylation, which alters chromatin structure, may play an important role in hormone-mediated transcriptional regulation.
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PMID:Histone acetylation influences thyroid hormone and retinoic acid-mediated gene expression. 915 Apr 29

Sodium phenylbutyrate (NaPB) represent a new non-toxic class of compounds with antiproliferative activities to different tumors and has been shown to modulate many gene expressions by inhibiting histone deacetylation and DNA methylation as the major mechanism. Butyrate and other protein kinase C (PKC) activators have been reported to be able to activate virus enzymes. The present work investigates whether NaPB has an antiproliferative effect or modulatory effects on EBV-associated nasopharyngeal carcinoma (NPC) and whether EBV thymidine kinase gene can be activated to make cells susceptible to ganciclovir (GCV) therapy. NaPB treatment displayed a dose- and time-dependent antiproliferative effect on the NPC cell line CNE2. Cell cycle analysis revealed an inhibitory effect of NaPB on G1-S-phase progression. Shortly after NaPB treatment, we found that PKC activity was activated rapidly but also decreased rapidly. Down-regulation of PKC-alpha and translocation of PKC-alpha from the cytosol to membrane were seen by Western blot. The decrease in PKC activity by NaPB corresponds to an enhanced response to radiation on CEN2 cells. Moreover, NaPB up-regulated EBV thymidine kinase activity to render EBV-associated Daudi cells susceptible to killing by GCV. Based on the observations of NaPB as a PKC modulator, the combination of NaPB, GCV, and radiation may provide a potential novel approach for treatment of EBV-associated NPC.
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PMID:A novel approach for nasopharyngeal carcinoma treatment uses phenylbutyrate as a protein kinase C modulator: implications for radiosensitization and EBV-targeted therapy. 1077 77

Based on the structure of our previously identified mitochondrial thymidine kinase (TK-2) inhibitors, three series of thymine-derived carboxamides have been synthesized and tested against TK-2 and related enzymes. The methodology employed has been a solution-phase parallel synthesis based on the coupling of three thymine-derived acids [4-(thymin-1-yl)butyric acid (I), [4-(thymin-1-yl)-butyrylamino]acetic acid (II) and 6-(thymin-1-yl)hexanoic acid (III)] with different commercially available primary amines that carry cyano and/or phenyl groups. The couplings were performed in good yields (from 60% to 90%), with the exception of those that incorporate the highly crowded triphenylmethylamine (e). From the new synthesized compounds, the N-trityl-6-(thymin-1-yl)hexanamide (IIIe) was the most active TK-2 inhibitor (IC(50)=19+/-2microM).
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PMID:Synthesis and evaluation of thymine-derived carboxamides against mitochondrial thymidine kinase (TK-2) and related enzymes. 1535 91

Antiviral drugs alone have been unsuccessful in the treatment of Epstein-Barr virus (EBV)-associated malignancies because the virus maintains a latent state of replication in these tumors. In recent years, novel therapeutic approaches are being investigated wherein lytic replication of the virus is induced prior to the use of cytotoxic antiviral drugs. The choice of suitable agents to induce lytic replication has been a critical step in this novel approach. We have previously demonstrated that butyrate derivatives induce a lytic pattern of EBV gene expression in patient-derived EBV-positive lymphoblastoid cell lines and, together with nucleoside analogue ganciclovir, effectively reduce or eliminate tumor growth in humans. Butyrate has drawbacks as a therapeutic agent, however, as constant intravenous infusion is required to achieve detectable plasma levels of this drug. In this study, we investigated whether discontinuous exposure to butyrate is capable of initiating lytic phase gene expression and thymidine kinase induction, and sensitizing EBV-positive lymphoma cells to ganciclovir-mediated cell growth arrest and apoptosis. We demonstrate that multiple daily 6-h exposures of the EBV-positive Burkitt's lymphoma cell line P3HR1 to butyrate induced sustained expression of the EBV lytic phase protein BMRF. Viral thymidine kinase was also induced by intermittent exposure, although to a lower level than with continuous exposure treatment. However, discontinuous exposure to butyrate in combination with ganciclovir induced a similar level of tumor cell growth inhibition as did continuous treatment, as measured by serial enumeration of viable cells, MTT cell proliferation assays and measurement of cellular DNA content. We further demonstrated that those cells which survived initial exposure to butyrate plus ganciclovir remained susceptible to further cycles of combination treatment. These findings suggests that continuous infusion of butyrate may not be necessary for maintaining viral thymidine kinase gene expression and sensitization to antiviral agents in EBV-associated tumors, and that therapeutic regimens which employ more convenient, discontinuous exposure to butyrate may also be effective clinically.
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PMID:Short, discontinuous exposure to butyrate effectively sensitizes latently EBV-infected lymphoma cells to nucleoside analogue antiviral agents. 1716 33