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

Gene therapy describes the transfer of genetic material into a cell for therapeutic purposes. This opens new therapeutic perspectives for cardiovascular medicine. It includes the inhibition of restenosis following angioplasty, e.g., by transfer of suicide genes such as CMV-thymidine kinase or by inhibition of the cell cycle of cells within the vessel wall. On the other hand, there is promising data concerning the induction of therapeutic angiogenesis using the transfer of angiogenic genes such as the one for vascular endothelial growth factor VEGF. During the past three years significant progress was made by a number of preclinical studies. On the other hand, the therapeutic success of gene therapy in humans is still missing, and this is true for all different strategies tested so far. Important and basic issues of gene transfer and the resulting cellular response need to be solved before a therapeutic use might become a routine procedure. In the meanwhile, an important focus of the experimental work lies in the identification and characterization of molecular targets for therapeutic interventions, another in the improvement of gene transfer systems. Such work will provide new information about the biology of cellular and viral structures including their functional interrelation; in addition a better insight into the pathogenesis of the various disease processes should be obtained.
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PMID:[Prospects of gene therapy in treatment of coronary heart disease]. 982 74

Increased reactive oxygen species (ROS) production has been reported as a distinctive feature of different pathologies including cancer. Therefore, we assessed whether increased ROS production in the cancer microenvironment could be selectively exploited to develop a selective anticancer therapy. For this purpose, we constructed a novel chimeric promoter, based on a ROS-response motif located in the VEGF gene promoter placed, in turn, downstream of a second ROS-response motif obtained from the early growth response 1 (Egr-1) gene promoter. The activity of the chimeric promoter was largely dependent on variations in intracellular ROS levels and showed a high inducible response to exogenous H(2)O(2). Transient expression of the thymidine kinase (TK) gene driven by the chimeric promoter, followed by gancyclovir (GCV) administration, inhibited human colorectal cancer and melanoma cell growth in vitro and in vivo. Moreover, electrotransfer of the TK gene followed by GCV administration exerted a potent therapeutic effect on established tumors. This response was improved when combined with chemotherapeutic drugs. Thus, we show for the first time that a distinctive pro-oxidant state can be used to develop new selective gene therapeutics for cancer.
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PMID:Suppression of cancer growth by nonviral gene therapy based on a novel reactive oxygen species-responsive promoter. 1943 70

Adenovirus vector-mediated herpes simplex virus-thymidine kinase/ganciclovir (ADV.tk/GCV) system is a promising approach for cancer gene therapy. This study aimed to investigate the anti-tumor efficacy and the underlying mechanisms of ADV.tk/GCV system in orthotopic hepatocellular carcinoma (HCC) model. A total of 132 female nude mice orthotopic HCC models were established and tumors were directly injected with ADV.tk (5.0 x 10(6) vector particles/kg) or saline solution, 24 h later the animals were intraperitoneally administrated by ganciclovir (30 mg/kg) or saline solution for 7 consecutive days. We observed that ADV.tk/GCV resulted in a significant regression of tumor growth and a significant prolongation of survival of the mice. At each given time point, the percentages of cleaved caspae-3, caspase-9 and TUNEL positive cells were significantly higher in the ADV.tk + GCV group than saline group (P < 0.005), while CD31 and VEGF staining were significantly less in ADV.tk + GCV group than in saline group (P < 0.005). In summary, ADV.tk/GCV system exhibits dramatic anti-tumor effects in orthotopic hepatocellular carcinoma model by promoting apoptosis and inhibiting angiogenesis, and is a promising treatment strategy for hepatic carcinoma.
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PMID:Adenovirus vector-mediated herpes simplex virus-thymidine kinase gene/ganciclovir system exhibits anti-tumor effects in an orthotopic hepatocellular carcinoma model. 2507 2

The aim of the present study was to investigate the selective killing effect on hepatocellular carcinoma (HCC) cells of an adenovirus (Ad)-mediated cytosine deaminase (CD) in combination with thymidine kinase (TK) suicide gene system, driven by the vascular endothelial growth factor promoter (VEGFp), in vitro and in vivo. A double suicide gene system with VEGFp, named Ad-VEGFp-CDglyTK, was constructed and transfected into human HCC cells (BEL-7402 or HepG2; the latter cell type is deficient in VEGF) and human umbilical vein vascular endothelial cells (HUVEC). Green fluorescent protein expression was detected by fluoroscopy to verify transfection efficiency, and CDglyTK gene expression was detected by reverse transcription-polymerase chain reaction (PCR). The selective killing effect of Ad-VEGFp-CDglyTK was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry (FCM) in vitro and by xenograft studies in vivo. PCR revealed that the transgenic CDglyTK gene was expressed in BEL-7402 cells and HUVEC, but not in HepG2 cells. The cell survival rate significantly decreased in line with increasing concentrations of the prodrugs, ganciclovir (GCV) alone, 5-fluorocytosine (5-FC) alone or a combination of the two, in HUVEC and BEL-7402 cells with the transfected CDglyTK gene, but not in untransfected HUVEC or BEL-7402 cells, or in transfected or untransfected HepG2 cells. This result was additionally confirmed by FCM. GCV and 5-FC inhibited the HUVEC and BEL-7402 cells containing the transfected CDglyTK gene and also inhibited adjacent unmodified cells via the 'bystander effect'. No similar results were observed in HepG2 cells. Compared with the control group, tumors with the transfected CDglyTK gene were smaller and the microvessel density of the tumor tissue was significantly decreased. It was concluded that a combination TK/GCV and CD/5-FC suicide gene system driven by VEGFp may provide a promising treatment strategy for HCC.
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PMID:A double suicide gene system driven by vascular endothelial growth factor promoter selectively kills human hepatocellular carcinoma cells. 2712 81