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)

IL-12 is a heterodimeric cytokine that is known to induce tumor regression and long-term antitumor immunity. Recombinant adeno-associated virus (rAAV) vectors are advantageous for gene therapy in that they lack pathogenicity in humans, infect dividing as well as nondividing cells, and show a broad range of infectivity. We constructed an rAAV vector expressing interleukin-12 (IL-12) for cancer immunotherapy studies in a mouse model by inserting murine IL-12 (mIL-12) p35 and p40 cDNAs into the plasmid pRep4 and inserting the encephalomyocarditis virus internal ribosomal entry site between the p35 and p40 cDNAs. The mIL-12 expression cassette containing the Rous sarcoma virus promoter and a simian virus 40 polyadenylation signal was subcloned into the AAV plasmid p008Sub/NeoR, which contains two AAV inverted terminal repeat sequences and the NeoR gene driven by the thymidine kinase promoter. rAAV virions (10(4) infectious particles/ml) were generated by cotransfection of rAAV-mIL-12 and a helper plasmid (pAAV/Ad) into 293 cells previously infected with adenovirus 5. After infection of D6 fibroblasts with rAAV-mIL-12, G418-resistant clones were isolated. Each of the 1D D6 clones isolated produced up to 5.2 ng/10(6) cells/48 hours of mIL-12 as determined by enzyme-linked immunosorbent assay. Induction of interferon-gamma, enhanced lymphocyte proliferation, and cytotoxicity assays confirmed biologically functional IL-12 production by the vector. This is the first report indicating that an rAAV vector expresses mIL-12, which can be used to model the effects of mIL-12 alone and/or in combination with other antitumor agents.
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PMID:Construction of a recombinant adeno-associated virus (rAAV) vector expressing murine interleukin-12 (IL-12). 1077 Jun 41

Between December 1996 and September 1998, 13 patients with advanced recurrent malignant brain tumors (9 with glioblastoma multiforme, 1 with gliosarcoma, and 3 with anaplastic astrocytoma) were treated with a single intratumoral injection of 2 x 10(9), 2 x 10(10), 2 x 10(11), or 2 x 10(12) vector particles (VP) of a replication-defective adenoviral vector bearing the herpes simplex virus thymidine kinase gene driven by the Rous sarcoma virus promoter (Adv.RSVtk), followed by ganciclovir (GCV) treatment. The VP to infectious unit ratio was 20:1. Our primary objective was to determine the safety of this treatment. Injection of Adv.RSVtk in doses <==2 x 10(11) VP, followed by GCV, was safely tolerated. Patients treated with the highest dose, 2 x 10(12) VP, exhibited central nervous system toxicity with confusion, hyponatremia, and seizures. One patient is living and stable 29.2 months after treatment. Two patients survived >25 months before succumbing to tumor progression. Ten patients died within 10 months of treatment, 9 from tumor progression and 1 with sepsis and endocarditis. Neuropathologic examination of postmortem tissue demonstrated cavitation at the injection site, intratumoral foci of coagulative necrosis, and variable infiltration of the residual tumor with macrophages and lymphocytes.
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PMID:Phase I study of adenoviral delivery of the HSV-tk gene and ganciclovir administration in patients with current malignant brain tumors. 1093 31

These studies were undertaken to determine the feasibility, safety, and efficacy of suicide gene therapy using adenoviral-mediated herpes simplex virus thymidine kinase (ADV/RSV-tk) and the prodrug ganciclovir (GCV) in an orthotopic murine bladder cancer model. We utilized a replication-defective adenoviral construct containing the beta-galactosidase gene as a control and the herpes simplex virus thymidine kinase gene as the therapeutic vector under the transcription control of the Rous sarcoma virus long terminal repeat promoter. Intravesically created, orthotopic bladder tumors were established in syngeneic C3H/He female mice. India ink injection and beta-galactosidase studies were performed to determine if transurethral administration, direct tumor injection, or the combination was the most efficient route of virus administration. Optimal dosing of ADV/RSV-tk was determined by direct tumor injection with increasing viral doses and treatment with GCV. Treatment efficacy, long-term survival, and toxicity were determined in separate but similar controlled experiments. Growth curve studies demonstrated reliable tumor formation by 14 days. Direct transvesical tumor injection resulted in the best distribution and intratumor gene expression as measured by X-gal staining. Dose-ranging experiments demonstrated an optimal viral dose of 5 x 10(8) plaque-forming units and a greater than twofold reduction in tumor growth for the animals treated with ADV/RSV-tk compared to controls. Efficacy studies demonstrated a greater than threefold reduction in tumor growth. No clinical or gross pathologic toxicity was detected. Long-term survival results suggested a survival benefit for the treatment animals compared to controls. We conclude that ADV/RSV-tk in combination with GCV provides effective therapy for orthotopic murine bladder cancer by significantly inhibiting tumor growth with limited toxicity to the host. These data provide further support for testing this suicide gene therapy strategy in human Phase I trials.
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PMID:In vivo adenovirus-mediated suicide gene therapy of orthotopic bladder cancer. 1098 51

This study evaluated the synergistic effect of Allium sativum (AS) with suicide gene therapy for transitional cell carcinoma (TCC) of the bladder. Subcutaneous TCCs were established in syngeneic C3H/He mice with 1 x 10(5) MBT-2 cells. AS liquid extract was injected at the site of tumor transplantation on Day 1 for three weeks (Experiment I) and into the established tumors weekly for five weeks (Experiment II) in combination with or without gene therapy using a replication-defective adenoviral vector containing a herpes simplex virus thymidine kinase (HSV-TK) gene under the transcriptional control of Rous sarcoma virus (RSV) promoter (Ad-RSV-TK, 5 x 10(8) plaque-forming units) plus ganciclovir (20 mg/kg/day i.p.). AS demonstrated a statistically significant reduction in incidence of TCC (cumulative dose 25 mg of AS). Combination AS-suicide gene therapy significantly inhibited the tumor growth compared with the controls, which was evidenced by apoptosis on histomorphological and immunohistochemical studies. These results suggest that AS had a definite antitumor effect in inhibiting tumorigenesis and growth of TCC in a murine model. AS treatment combined with suicide gene therapy had significant additive antitumor effects on TCC and may provide a novel and effective treatment modality for TCC of the bladder.
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PMID:Allium sativum potentiates suicide gene therapy for murine transitional cell carcinoma. 1134 Oct 51

The most serious problem in current gene therapy is discrepancies between experimental data and actual clinical outcomes, which may be due to insufficient analyses and/or inappropriate animal models. We have explored suicide gene therapy by using various clinically relevant animal models and doubt the clinical use of maximal suicide gene expression, which has been generally recommended. To explore this subject further, we studied what expression level of suicide gene and what promoter led to the maximal clinical benefit in the case of hepatic metastatic cancer in mice. Therapeutic and adverse side effects of 4 adenoviral vectors that express herpes simplex virus thymidine kinase (HSV-tk) under different promoters were scrupulously investigated in 2 mouse models of hepatic metastasis of gastric cancer that possess clinical characteristics. Surprisingly, increases in HSV-tk expression beyond a certain point, achieved by the Rous sarcoma virus long terminal repeat promoter, not only enhanced the adverse side effects of lethal hepatotoxicity and ganciclovir-independent cytotoxicity but also failed to further increase therapeutic potential. Moreover, the carcinoembryonic antigen (CEA) tumor-specific promoter, the therapeutic potential of which had been underestimated, was much more useful-even in the case of low CEA-producing cancer-than had been previously reported. In conclusion, the optimal therapeutic expression level of a suicide gene is a novel concept and a crucial factor for successful cancer gene therapy. The present results, which contradict those of previous studies, alert researchers about possible problems with ongoing and future clinical trials that lack this concept.
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PMID:An optimal therapeutic expression level is crucial for suicide gene therapy for hepatic metastatic cancer in mice. 1250 Feb

Gene therapy requires the presence of a robust and yet small promoter to drive high-level expression of desired proteins. In comparative analysis, we investigated the promoter strength of the CTP:phosphocholine cytidylyltransferase promoter (CCT alpha) with other commonly used promoters, which were all cloned into a similar background vector (PGL3 basic). Transient promoter-reporter assays in murine lung epithelial (MLE-12) cells revealed that the core CCT alpha promoter (240 bp) was observed to exhibit a 40-fold, 8-fold, and 3-fold higher level of activity compared with the simian virus 40, human cytomegalovirus, and Rous sarcoma virus promoters, respectively. The CCT alpha promoter was significantly more active than the Clara cell 10, thymidine kinase, and phosphoglycerate kinase promoters. This pattern of high-level expression for CCT alpha was detected primarily in cell lines of distal lung epithelial origin (MLE-12, RLE, H441) and was reduced in other cell lines (A549, CHO, HepG 2). CCT alpha promoter-reporter activity, CCT alpha transcript levels, and immunoreactive protein levels increased significantly in the presence of all-trans retinoic acid. The CCT alpha promoter, in a retinoic acid-inducible manner, efficiently directed expression of murine erythropoietin in MLE-12 cells. Collectively, these observations suggest that the CCT alpha construct might be useful to drive high-level, regulatable expression of heterologous proteins in alveolar epithelia.
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PMID:The CCT promoter directs high-level transgene expression in distal lung epithelial cell lines. 1282 50

Adenovirus (ADV)-mediated gene therapy with the thymidine kinase (TK) gene under control of the Rous sarcoma virus (RSV) promotor followed by the administration of acyclovir has been established in vitro for the treatment of ovarian cancer cells and has been used as the basis for intraperitoneal phase I clinical trials. It is unclear how long a significant degree of transgene translation can be expected after adenovirus-mediated TK transduction, where the transcriptional complex is localized in the nucleus in an episomal fashion and thus without stable integration. The possible interaction of acyclovir pretreatment with subsequent ADV-RSV-TK transduction also remains to be elucidated. Transgene expression and cell killing efficacy were analysed based on multiplicity of infection (MOI) and MTT assay. Anti-TK-antibody 1397 was used for immunocytochemistry and Western blot analysis of TK expression. After transduction with ADV-RSV-TK at an MOI of 66, TK translation increased strongly in MDH 2774 and OVCAR-3 cell lines during the initial 48 hours. Virtually constant expression of the TK transgene was observed by Western blot during eight days. Cell killing efficacy was increased by repeated daily administrations of acyclovir. Pretreatment with acyclovir did not result in significantly increased cell killing efficacy. No negative effect of acyclovir on ADV-RSV-TK transduction was observed. The at least week-long expression of the TK transgene with persistently increasing efficacy of cell killing after ADV-mediated tumor cell transduction provide a realistic basis for the development of multicycle ADV-mediated TK gene therapy approaches in the treatment of ovarian cancer. Continuous i.v. acyclovir treatment or daily oral acyclovir-prodrug therapy might simplify the substrate regimen for the TK gene.
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PMID:Persistent adenovirus-mediated thymidine kinase gene expression in ovarian cancer cells increases cell killing efficacy over time. 1903 80

Coxsackie adenovirus receptor (CAR) expression is the main mechanism of adenovirus entry into target cells. It is unclear whether CAR expression itself is influenced by transduction with the adenovirus-Rous sarcoma virus-thymidine kinase (ADV-RSV-TK) gene therapy construct or by the subsequent intracellular accumulation of the TK gene product. Antibody generation and characterization, immunocytochemistry, Western blotting and 3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide (MTT) assay were performed to investigate the relationship of gene transfer and CAR expression as well as differences in therapeutic susceptibility of MDAH-2774 and OVCAR-3 cell lines to ADV-RSV-TK gene therapy. CAR expression was observed on the membranes but intracellular translocation of CAR also took place dependent on cellular growth patterns. TK gene expression was dependent on multiplicity of infection (MOI) and thus on vector dose in a linear fashion. Neither TK expression nor ADV transduction influenced CAR expression, or ADV-RSV-TK transduction. Differential susceptibility of different cell lines to TK-induced cell killing by acyclovir metabolites was observed. CAR expression appears not to be influenced by adenoviral transduction or by the accumulation of the TK gene product. Differences in therapeutic sensitivity are most likely mediated by intracellular mechanisms and not by modulation of CAR expression.
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PMID:Adenovirus-mediated thymidine kinase gene therapy and coxsackie adenovirus receptor expression in ovarian cancer cells. 1928 72

Adenoviral (ADV) gene therapy with the thymidine kinase gene (TK) under control of the Rous sarcoma virus (RSV) promotor followed by the administration of acyclovir leads to replication errors in transcription and to cell death. This concept of ADV-RSV-TK has been established for the treatment of ovarian cancer cells. The purpose of this investigation was to clarify whether cell death after ADV-RSV-TK gene therapy and acyclovir administration is indeed due to apoptosis induction, whether the synergistic effect of ADV-RSV-TK gene therapy with chemotherapy was limited to the primary mechanism of action or whether the vector transduction itself exerted any pro-apoptotic effect was examined using the epithelial cell lines OVCAR-3 and MDAH-2774, established from human poorly differentiated serous ovarian cancer. Fluorimetric assay of caspase-3 activity was performed, as well as ELISA of the CK 18 split product M30. PARP cleavage was analysed by Western blotting. Apoptosis induction was established in this investigation as the mechanism of the ADV-RSV-TK gene therapy effect of acyclovir administration by caspase activity and subsequent CK 18 cleavage. Neither acyclovir nor vector administration alone showed any apoptotic activity. The synergistic effect of TK gene therapy and chemotherapeutic agents was shown to be TK induced. Significant anti-PARP 1 activity was found to be an ADV-RSV-TK treatment effect after acyclovir addition.
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PMID:Adenovirus-mediated thymidine kinase gene therapy induces apoptosis in human epithelial ovarian cancer cells and damages PARP-1. 1936 28


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