Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 effect of alpha-interferon (alpha-IFN) on spontaneous or induced proliferation of isolated peripheral blood mononuclear cells from 5 hairy cell leukemia patients was studied. alpha-IFN inhibited the low spontaneous proliferation of B-ly7 positive hairy cells (HCs) and also the proliferation induced by tumour necrosis factor (TNF). Interleukin-2 did not affect HCs, but induced CD4 positive T cells to proliferate, an effect which alpha-IFN antagonized. The stimulatory effect of TNF on the growth of HCs proved to be reversible and was partially blocked with either anti-TNF receptor or anti-lymphotoxin antibodies. Cellular or secreted thymidine kinase levels reflected the proliferative state of HCs in response to different in vitro treatments, as confirmed by thymidine incorporation and cell cycle studies.
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PMID:alpha-Interferon inhibits spontaneous and induced DNA synthesis in hairy cell leukemia. 147 34

The neuroendocrine hormone PRL acts as a progression factor during interleukin-2 (IL2) stimulated lymphocyte proliferation. Since the sequential expression of cell cycle regulated genes occurs during this process, we examined the contribution of IL2 and PRL to specific RNA accumulation. Stimulation of the cloned T cell line L2 with IL2 and PRL induced the sequential expression of interferon regulatory factor-1, c-myc, proliferating cell nuclear antigen, thymidine kinase, cyclin B, and histone H3. Stimulation of L2 cells with PRL alone, however, induced only the expression of interferon regulatory factor-1. Depletion of PRL, through the use of an anti-PRL antiserum, inhibited IL2 driven proliferation and the expression of cyclin B and histone H3. These results demonstrate that PRL may regulate T cell proliferation by enhancing the expression of some genes necessary for entry into S-phase.
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PMID:Requirement for prolactin during cell cycle regulated gene expression in cloned T-lymphocytes. 153 39

Recombinant vaccinia viruses have been proposed as live vaccines against a variety of infectious diseases, including AIDS (acquired immune deficiency syndrome). Objections have been concerned primarily with side effects of the vaccinia virus vector itself. Recently it has been shown that inactivation of the vaccinia virus thymidine kinase gene or deletion of certain other non-essential genes is associated with a marked reduction in pathogenicity. Nevertheless, the ability of vaccinia virus to produce a progressive infection in immunodeficient individuals remains a most serious problem. Indeed, an incident of this type in a vaccinated man seropositive for human immunodeficiency virus was recently reported. We have used immunodeficient athymic nude mice to establish a model of disseminated vaccinia virus infection, and to demonstrate a novel approach to virus attenuation which involves insertion of a gene encoding human interleukin-2 into the genome of vaccinia virus vectors.
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PMID:Prevention of vaccinia virus infection in immunodeficient mice by vector-directed IL-2 expression. 311 19

The human 4F2 cell surface antigen is a 120-kilodalton (kDa) disulfide-linked heterodimer which is composed of an 80- to 90-kDa glycosylated heavy chain (4F2HC) and a 35- to 40-kDa nonglycosylated light chain (4F2LC). 4F2 belongs to a family of inducible cell surface molecules which are involved in T-lymphocyte activation and growth. To better understand the molecular mechanism(s) that controls 4F2HC gene expression in both resting and activated T cells, a 4F2HC human genomic clone was isolated and structurally characterized. The 4F2HC gene spans 8 kilobases of chromosome 11 and is composed of nine exons. The 5' upstream region of the gene displays several properties which are characteristic of housekeeping genes. It is G+C rich and hypomethylated in peripheral blood lymphocyte DNA and contains multiple binding sites for the Sp1 transcription factor while lacking TATA or CCAAT sequences. This region of the gene also displays sequence homologies with several other inducible T-cell genes, including the interleukin-2, interleukin-2 receptor alpha chain, dihydrofolate reductase, thymidine kinase, and transferrin receptor genes. A 255-base-pair fragment of the 4F2HC gene which contains 154 base pairs of the 5' flanking sequence was able to efficiently promote expression of the bacterial chloramphenicol acetyltransferase gene in human Jurkat T cells, indicating that it contains promoter or enhancer (or both) sequences. Analyses of chromatin structure in resting and lectin-activated T cells revealed the presence of stable DNase I-hypersensitive sites within both the 5' flanking and intron 1 regions of the 4F2HC gene. Although the 4F2HC gene displayed many of the structural features characteristic of a constitutively expressed gene, lectin-mediated activation of resting peripheral blood T lymphocytes resulted in a dramatic increase in steady-state levels of 4F2HC mRNA.
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PMID:Isolation and structural characterization of the human 4F2 heavy-chain gene, an inducible gene involved in T-lymphocyte activation. 326 70

We compared the efficacy of gene therapy mediated by interleukin-2 (IL-2) gene-modified tumor cells to gene therapy mediated by IL-2 transduced fibroblasts in the CT-26 model of murine colorectal carcinoma. We transduced CT-26 tumor cells and BALB/c 3T3 fibroblasts with three different retroviral vectors using three different promoters for the human IL-2 gene: DC/TKIL-2 (thymidine kinase promoter), LXSN-iIL2 (long terminal repeat promoter), and LNCX-iIL2 (cytomegalovirus promoter). These transductions resulted in CT-26 and 3T3 subclones that secreted different amounts of IL-2. Immunization of animals with either CT-26/IL-2 cells or with fibroblast/IL-2 cells mixed with CT-26 induced similar levels of immunity that protected 62-82% of animals against a subsequent tumor challenge with parental CT-26. However, mice developed tumors at the site of inoculation in 46% of the animals immunized with CT-26/IL-2 cells. In a separate experiment, CT-26/IL-2 cells were exposed to 6,000 cGy of gamma irradiation to prevent tumor growth at the site of inoculation. Although the CT-26/IL-2 cells continued to secrete IL-2 after irradiation, they were no longer effective at inducing antitumor immunity. In contrast, both irradiated and nonirradiated fibroblast/IL-2 cells, mixed with irradiated CT-26, were equally effective at inducing antitumor immunity. These data suggest that in the CT-26 model, fibroblast-mediated IL-2 gene therapy has advantages for the induction of antitumor immunity and abrogation of tumorigenic potential at the site of inoculation compared with tumor cell-mediated IL-2 gene therapy.
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PMID:Comparison of gene therapy with interleukin-2 gene modified fibroblasts and tumor cells in the murine CT-26 model of colorectal carcinoma. 758 56

To target therapeutic genes specifically to melanoma cells, we have constructed recombinant retroviruses where transcriptional control of the murine interleukin-2 (mIL-2) or herpes simplex virus thymidine kinase (HSVtk) genes is provided by the 5' promoter region of the murine tyrosinase gene. Tissue-specific expression of these genes is observed both at the mRNA and protein levels in the B16 melanoma line compared with NIH3T3 fibroblasts. Thus, B16 cells infected with one such retrovirus containing the HSVtk gene exhibited a > 90% reduction in colony-forming efficiency after exposure to 1 microgram/ml ganciclovir, relative to controls, whereas similarly infected NIH3T3 cells showed < 10% reduction in colony-forming efficiency under comparable conditions. The degree of preservation of tissue-specific expression from the internal tyrosinase promoter depended upon the exact molecular design of the vector, possibly as a consequence of the interference between closely juxtaposed promoters within the provirus. Our results show that retroviral vectors can be prepared with the capacity to regulate expression of inserted genes specifically in a particular cell type and may be useful for developing efficient, targeted vectors for the in vivo delivery of genetic therapies for malignant melanoma.
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PMID:A comparison of the properties of different retroviral vectors containing the murine tyrosinase promoter to achieve transcriptionally targeted expression of the HSVtk or IL-2 genes. 758 96

Allogeneic bone marrow transplantation (BMT) is associated with a severe complication--graft-versus-host disease (GVHD). Although effectively preventing GVHD, ex vivo T-lymphocyte marrow depletion unfortunately increases graft rejection and reduces the graft-versus-leukemia (GVL) effect. The ex vivo transfer of the herpes simplex thymidine kinase (HS-tk) suicide gene into T cells before their infusion with hematopoietic stem cells could allow for selective in vivo depletion of these T cells with ganciclovir (GCV) if subsequent GVHD was to occur. Thus, one could preserve the beneficial effects of the T cells on engraftment and tumor control in patients not experiencing severe GVHD. To obtain T cells specifically depleted by GCV, we transduced primary T cells with a retroviral vector containing the HS-tk and neomycin resistance (NeoR) genes. Gene transfer was performed by coculturing PHA +/- CD3- or alloantigen-stimulated purified T cells on an irradiated retroviral vector producer cell line or by incubating the T cells in supernatant from the producer. Subsequent culture in G418 for 1 week allowed for the selection of transduced cells. GCV treatment of interleukin-2-responding transduced and selected cells resulted in greater than 80% growth inhibition, whereas GCV treatment of control cells had no effect. Similarly, the allogeneic reactivity of HS-tk-transduced cells was specifically inhibited by GCV. Combining transduced and nontransduced T cells did not show a bystander effect, thus implying that all of the cells inhibited by GCV were indeed transduced. Lastly, studies involving the transduction of the HUT-78 (T-lymphoma) cell line suggest that stable expression of HS-tk can be maintained over 3 months in vitro in the absence of G418. In summary, we have established the feasibility of generating HS-tk-transduced T cells for subsequent in vivo transfer with hematopoietic stem cells and, if GVHD occurs, specific in vivo GCV-induced T-cell depletion in allogeneic BMT recipients.
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PMID:Ganciclovir treatment of herpes simplex thymidine kinase-transduced primary T lymphocytes: an approach for specific in vivo donor T-cell depletion after bone marrow transplantation? 804 49

The authors have recently shown the feasibility of eradicating brain tumors using in vivo retroviral-mediated transduction of tumors with the herpes simplex thymidine kinase (HStk) gene and ganciclovir therapy. However, thymidine kinase-transduced subcutaneous tumors in immunocompromised (athymic) mice were less responsive to this therapy than in immunocompetent animals, suggesting a role of the immune system in the process of tumor eradication. Broad suppression of humoral and cell-mediated immunity is found in patients with malignant gliomas. Interleukin-2 (IL-2) production and IL-2 receptor expression are decreased in gliomas patients. These findings and the proposed association between lymphocytic infiltration of brain tumors and survival suggest that immune response modifiers may be useful in treating glioma patients. To evaluate the role of local cytokine expression by tumor cells, alone or combined with HStk gene transfer and ganciclovir therapy, the authors investigated the efficacy of tumor (9L gliosarcoma) eradication in Fischer rats by in vitro and in vivo tumor transduction with the IL-2 gene alone or with a combined vector carrying both the HStk and IL-2 genes. Tumors injected with HStk vector-producer cells alone, with or without ganciclovir, and rats inoculated in the brain and subcutaneously with 9L cells that had previously been transduced in vitro served as controls. Murine vector-producer cells (3 x 10(6)/50 microliters) were injected into the brain tumors 7 days after tumor inoculation. Ganciclovir (15 mg/kg) was administered intraperitoneally twice daily for 10 days to animals that received HStk with or without IL-2 vector-producer cells, starting 5 days after producer-cell injection. The experiment was repeated with continuous daily treatment of all rats with oral dexamethasone (0.5 mg/kg). Rats were sacrificed 21 days after tumor inoculation, and the brains were removed for histological and immunohistochemical analysis for IL-2. Within each experimental group, tumors were found in a similar proportion in the dexamethasone-treated and untreated rats. Large brain tumors developed in all 10 rats that had been inoculated with 9L cells which had been pretransduced in vitro with the IL-2 gene, whereas only three of eight rats receiving subcutaneous inoculation of similar cells developed palpable tumors. No enhancement of tumor eradication was observed by adding the IL-2 gene in the HStk vector construct compared to the use of the vector with HStk alone. Lymphocytic infiltration was absent in all dexamethasone-treated rats but was observed in all treatment groups not receiving steroids.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:In vivo transfer of the human interleukin-2 gene: negative tumoricidal results in experimental brain tumors. 811 67

Melanin biosynthesis is restricted to melanocytes partly as a consequence of transcriptional regulation of the mRNA coding for those enzymes involved in this biochemical pathway. Promoter sequences of these genes may be used to regulate expression of complementary DNA coding for therapeutic genes so as to provide transcriptional targeting. As a model system we have used the 5'-flanking sequences of the murine tyrosinase or tyrosinase-related protein 1 (TRP-1) genes to show that such transcriptional targeting can be accomplished both in vitro and in vivo. Using interleukin-2 (IL-2) as an example of an immunostimulatory gene and herpes simplex virus thymidine kinase (HSVTK), as an example of a prodrug-activating gene we have shown, in murine model systems, that marked antitumour effects can be achieved by targeted gene therapy approaches. Because other tumor types produce particular proteins as a consequence of specific transcription it is possible that this approach may provide a way of targeting therapeutic genes to various cancers.
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PMID:Tissue specific promoters in targeting systemically delivered gene therapy. 860 25

Transfer of a herpes simplex virus-derived thymidine kinase (HSV-tk) gene into brain tumor cells and subsequent ganciclovir (GCV) treatment has been shown by others to be an effective treatment in rats with intracerebrally inoculated 9L gliosarcomas. Mechanism of action and reproducibility are, however, still a matter of debate. We have used the same model to test the therapeutic effects of both retrovirus- and adenovirus-mediated transfer of the HSV-tk gene followed by GCV treatment. Survival time of rats with intracerebral 9L tumors was significantly prolonged after a single administration of adenovirus carrying a HSV-tk gene as compared to controls. Retrovirus-mediated gene transfer also resulted in significantly prolonged survival time when recombinant retrovirus-producing cells were transplanted. Direct injection of the recombinant retrovirus, HSV-tk-expressing cells, virus-producing cells without GCV administration and recombinant retrovirus-lacZ or interleukin-2 (IL-2)-producing cells did not result in tumor cell kill. In the present study, no significant difference in survival of 9L brain tumor carrying rats was found after treatment with adenovirus as compared to retrovirus-mediated HSV-tk-mediated gene transfer and subsequent GCV treatment.
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PMID:Herpes simplex virus thymidine kinase gene therapy for rat malignant brain tumors. 878 70


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