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)

We have a developed a retroviral mediated molecular ablation method to specifically eliminate HIV Tat-expressing cells. This approach utilizes the Tat-inducible HIV-2 promoter and a conditional toxin gene. The Herpes Simplex Virus thymidine kinase gene product is toxic to mammalian cells only after treatment with Ganciclovir (GCV) or other nucleoside analogues. We demonstrate here that certain promoter modifications can decrease basal expression while retaining the ability to be transactivated. Furthermore, we show that a HIV-2 promoter thymidine kinase gene cassette transduced via retroviral vectors into tissue culture cells can specifically promote the ablation of HIV-Tat expressing cells in the presence GCV. We also show that there is a large differential in HIV-thymidine kinase gene transcription and lethal drug dose between Tat-expressing cells and Tat-negative cells.
Leukemia 1993 Aug
PMID:Studies of HIV-2 promoter activity and cell specific ablation. 836 Dec 35

The effect of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) on the intracellular metabolism of cytosine arabinoside (Ara-C) was comparatively analyzed in normal bone marrow mononuclear cells (NBMMC) from eight healthy volunteers and in leukemic blasts from 50 patients with acute myeloid leukemia (AML). Pretreatment with GM-CSF (100 U/ml) for 48 h resulted in a significant enhancement of DNA synthesis in both cell types: 21 of 35 AML specimens were found to be responsive to GM-CSF as defined by an increase of 3H-TdR incorporation into the DNA > 1.5-fold while NBMMC from normal donors were responsive in all cases. In GM-CSF responsive AML blasts, overall DNA polymerase and DNA polymerase alpha activity increased from a median of 84.4 to 96.1 and from 3.45 to 5.2 pmol/min x mg as compared to a median of 96.7 to 189.9 and 1.2 to 2.2 pmol/min x mg in NBMMC (P < 0.05). Median Ara-C-mediated inhibition of DNA synthesis was significantly more effective in AML blasts as compared to NBMMC (76.5 vs 55.0% at 0.05 microM and 99.0 vs 96.0% at 5.0 microM Ara-C, P < 0.01) but was not influenced by GM-CSF pretreatment. Similarly, intracellular Ara-CTP levels were higher in AML blasts as compared to NBMMC (median of 46.9 vs 18.7 at 1 microM, 167.8 vs 48.0 at 10 microM and 337.5 vs 59.5 ng/10(7) cells at 100 microM extracellular Ara-C, P < 0.01) but showed no enhancement in the presence of GM-CSF. Median deoxycytidine (DCK) and thymidine kinase (TK) activity were only slightly increased in AML blasts after GM-CSF priming. In contrast, NBMMC revealed a significant increase in TK activity after GM-CSF pretreatment (from a median of 1.9 to 3.6 pmol/min x mg, P = 0.039). At low; intermediate and high extracellular Ara-C concentrations GM-CSF pretreatment resulted in a significant enhancement of the 3H-Ara-C incorporation into the DNA in both GM-CSF responsive AML blasts and NBMMC (median of 1.3 to 2.1- and 1.4 to 1.6-fold, P < 0.05). GM-CSF non-responsive AML blasts showed no change in 3H-Ara-C incorporation into the DNA in response to GM-CSF at low Ara-C concentrations but significant increases at intermediate and high extracellular Ara-C concentrations (median increases of 1.63-fold at 1.06 microM with P = 0.01 and 1.37-fold at 10 microM extracellular Ara-C with P = 0.0+005). NBMMC revealed significantly lower GM-CSF-induced increases of the 3H-Ara-C incorporation into the DNA as compared to the effect of GM-CSF priming on DNA synthesis (median increases of 1.4 to 1.7-fold vs 2.6-fold, P < 0.05). These data reveal a different effect of GM-CSF priming on the metabolism of Ara-C in normal vs leukemic cells which may cause a preferential increase in the antileukemic cytotoxicity of Ara-C in the presence of GM-CSF.
Leukemia 1997 Apr
PMID:Differential effect of GM-CSF pretreatment on intracellular Ara-C metabolism in normal bone marrow mononuclear cells vs acute myeloid leukemia (AML) blasts. 909 97

DNA motifs that encode for specific transcriptional regulatory sequences (TRS) when engineered adjacent to the structural protein coding domain of a suicide enzyme can provide cell-lineage specific protein expression. The disparate up-regulation of several genes in adult T-cell leukemia (ATL) versus HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), seropositive carriers (SPC) and uninfected normals may reflect events at the molecular level related to leukemogenesis or to processes maintaining the heme-oncologic phenotype. Further, the genetic transduction of cytokine and receptor genes uniquely associated with ATL may provide targets for the development of leukemia-specific gene therapies aimed at exploiting differences in the production of certain growth factors and growth factor receptors. Comparisons of the transcriptional and translational levels of interleukin-2 receptor alpha chain (IL-2R alpha), transforming growth factor-beta 1 (TGF-beta 1) and intracellular adhesion molecule-1 (ICAM-1) in ATL, HAM/TSP, and SPC and in several control populations revealed selectively up-regulated expression in ATL. We evaluated the feasibility of using lymphoid-specific TRS to activate herpes simplex virus thymidine kinase (HSVtk) to achieve selective cytotoxicity in leukemias expressing terminal deoxynucleotidyl transferase (TdT). Selective and efficient leukemic cell killing was produced and suggests that similar chimeric gene constructs containing TRS elements for IL-2R alpha, TGF-beta 1, or ICAM-1 may prove useful in designing gene therapies to treat ATL.
Leukemia 1997 Apr
PMID:Pleiotropic expression of heterologous cytokine/receptor genes in HTLV-1 associated diseases: candidate TRS for chimeric gene therapy. 920 5

Two-gene vectors with positive or positive-negative drug-selectable markers enable the expansion or elimination of gentetically modified cells in vivo. We have established a bicistronic retroviral vector system which utilizes an internal ribosome entry site (IRES) to co-express two independent genes with high efficiency. As a positive-negative (suicide) marker, Herpes simplex virus thymidine kinase was co-expressed with the human multidrug resistance gene, MDR1. Using this vector, almost all the MDR1-transduced cells showed hypersensitivity to a nucleoside analog, ganciclovir. As a dominant selectable marker, the MDR1 gene was co-expressed with alpha-galactosidase A for the model of gene therapy of Fabry disease. Vincristine selection efficiently enhanced the population of transduced cells expressing the second non-selectable genes. These drug-selectable retroviral vectors could be applicable to the therapy of many diseases.
Leukemia 1997 Apr
PMID:In vivo drug-selectable markers in gene therapy. 920 54

A novel approach to the intracellular delivery of nucleotides using phosphoramidate-based prodrugs is described. Specifically, we have developed phosphoramidate prodrugs of the anticancer nucleotide 5-fluoro-2'-deoxyuridine-5'monophosphate (FdUMP). These phosphoramidate prodrugs contain an ester group that undergoes intracellular activation liberating phosphoramidate anion, which undergoes spontaneous cyclization and P-N bond cleavage to yield the nucleoside monophosphate quantitatively. In vitro evaluation of 5-fluoro-2'-deoxyuridine phosphoramidate prodrugs 2a and 3b against L1210 mouse leukemia cells show potent inhibition of cell growth (IC(50) 0.5-3 nM). Cell-based thymidylate synthase inhibition studies show that, in contrast to FUdR, the nitrofuran compound 2a is of comparable potency in wild type vs thymidine kinase deficient LM cells. This result indicates that the activation of this novel prodrug occurs via the proposed mechanism of intracellular delivery. However, naphthoquinone 3b has an IC(50) value for thymidylate synthase inhibition that is comparable to FUdR in thymidine kinase deficient cells. Further studies revealed that 3b rapidly decomposes to the nucleotide in cell culture medium, suggesting that the naphthoquinone analogue is not sufficiently stable to function as a nucleotide prodrug.
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PMID:Synthesis and biological studies of novel nucleoside phosphoramidate prodrugs. 1172 93

Recently, dimethyl sulfoxide (DMSO) has been used as a convenient cryoprotectant for stem cells in stem cell transplantation using allogenic peripheral blood or umbilical cord blood. As the stem cells have a multipotency, clarification of the extent of cell proliferation after transplantation is difficult. In the present study, DMSO gradually induced G(0)/G(1) arrest in mouse leukemia L(1210) cells with good cell viability. After removal of DMSO, the cells proliferated appropriately, resulting in expression of the DNA-synthesizing enzymes thymidylate synthase and thymidine kinase within 6h, and the cells entering into S phase within 12h. The sequence was followed by the marked activation of both enzymes within 24h and the increase of bromodeoxyuridine (BrdU) immunoreactive (S phase) cells with rapid cell proliferation within 36 h. In conclusion, mouse leukemia L(1210) cells, which were treated with 1.5% DMSO for 96 h, tolerated the treatment and reversed the cell cycle arrest within 36 h.
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PMID:Early progression from dimethyl sulfoxide-induced G(0)/G(1) arrest in L(1210) cells. 1184 51

The herpes simplex virus thymidine kinase (HSV-tk) gene conferring ganciclovir (GCV)-specific sensitivity to transduced cells might control Graft-versus-Leukemia (GvL)/Graft-versus-Host Disease (GvHD). Human T lymphocytes were engineered with an LSN-tk retroviral vector encoding tk and neomycin resistance (NeoR) genes. A total of 80 x 10(6) tk(+) lymphocytes were injected intraperitoneally in NOD-SCID mice. Engraftment was evaluated by human CD45(+)/CD3(+) cytofluorimetric analysis and NeoR-based polymerase chain reaction (PCR) on peripheral blood, bone marrow, liver, thymus, and spleen on day +5. After 14 days, GCV (10 mg/kg daily) cytofluorimetric analysis and PCR were repeated (day +19). Immunohistological studies with anti-CD3 monoclonal antibody followed by alkaline phosphatase and monoclonal anti-alkaline phosphatase staining were performed on spleen and liver at the same time points. Human CD45(+)/CD3(+) cells were engrafted in all tissues on day +5 according to cytofluorimetry, immunohistology, and PCR. Lymphocytes "homed" to the white pulp T-cell area and to the red pulp; liver localization is prevalently at the periportal area. After GCV (day +19), cytofluorimetry and immunohistology showed very few CD3(+) cells. PCR identified the transgene in 22% tissue samples (positive only in thymus and spleen). GvHD did not occur in any animal. These data demonstrate elevated doses of human-transduced CD3(+) cells engraft in NOD/SCID mice; after GCV, very few CD3(+) cells can be detected and those that escape treatment can be found in the thymus and in the spleen on day +19. Lack of full response to GCV may account for cases of GvHD in patients receiving tk-transduced T lymphocytes.
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PMID:Homing and survival of thymidine kinase-transduced human T cells in NOD/SCID mice. 1218 25

In B-CLL IgV(H) genes mutational status is a major prognostic factor. Since sequencing of IgV(H) genes is not available in most laboratories, an easily performed surrogate assay is desirable. To identify the best surrogate assay, and to better discriminate prognostic subgroups we analyzed clinical and biological data from 58 typical CLL cases. A higher serum thymidine kinase level (>15 U/l) proved to be a strong predictor of mutational status, and the only independent one among the studied parameters. To further identify prognostic subgroups, cluster analysis was employed on 38 cases on which all data were available, which segregated two groups including 25 and 13 patients, respectively. These two clusters differed by their proliferative potential and appeared to discriminate patients with very different clinical course and outcome. s-TK was strikingly different among these two clusters, suggesting that s-TK level could be used routinely to identify patients at risk of progression.
Leukemia 2003 Jan
PMID:Predictive value of serum thymidine kinase level for Ig-V mutational status in B-CLL. 1252 70

B-cell chronic lymphocytic leukemia (B-CLL) is a heterogenous disease with a highly variable clinical course. Recent studies have shown that expression of the protein tyrosine kinase ZAP-70 may serve as a prognostic marker in B-CLL. Employing a semiquantitative RT-PCR assay, we examined purified leukemia B cells of 39 CLL patients for the expression of ZAP-70 mRNA transcripts. Significant ZAP-70 mRNA levels exceeding those found in control samples with 5% T cells were detected in 36% of the CLL cases. Patients in the ZAP-70 positive cohort were characterized by an unfavorable clinical course with a significantly shorter progression-free survival as compared to the ZAP-70-negative patients (64%). These results were confirmed by flow-cytometric analysis of the ZAP-70 protein, and expanded to a larger patient cohort (n=67). A combined statistical analysis of 79 patients showed that the two patient subgroups also differed with regard to overall survival and a panel of known clinical prognostic factors including LDH, thymidine kinase serum levels and expression of the CD38 surface antigen by the leukemic cell clone. The level of ZAP-70 expression did not change over time in the majority of patients where sequential samples were available for analysis.
Leukemia 2003 Dec
PMID:ZAP-70 expression is a prognostic factor in chronic lymphocytic leukemia. 1452 69

Cancer cells are characterized by uncontrolled replication involving loss of control of cyclin dependent kinases (CDKs) and cyclins, and by abolished differentiation. In this study we introduce KGI, which is a nanoparticle with a Quillaja saponin as an active molecule. By the use of RNA array analysis and confirmation at the protein level, we show that KGI affects myeloid leukemia cells (in particular, the U937 monoblast cancer cell) by the following mechanisms: (A) ceasing cell replication via proteasome degradation, (B) down-regulation of key molecules at check points between G1/S and G2/M phases, (C) reduction of thymidine kinase activity, followed by (D) exit to differentiation and production of interleukin-8 (IL-8), eventually leading to apoptosis. Leukemia cell lines (U937 and HL-60 cells) were exposed to KGI for 8 h, after which the drug was removed. The cancer cells did not revert to replication over the following 10 days. Thus our findings suggest that the nanoparticle KGI inhibits proliferation and promotes differentiation in leukemic cells by interfering with the cell cycle process.
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PMID:The nanoparticulate Quillaja saponin KGI exerts anti-proliferative effects by down-regulation of cell cycle molecules in U937 and HL-60 human leukemia cells. 2413 32


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