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

---

Query: EC:3.5.4.1 (cytosine deaminase)
747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Combined treatment using adenoviral-directed enzyme/prodrug therapy and immunotherapy has the potential to become a powerful alternative method of cancer therapy. We have developed adenoviral vectors encoding the cytosine deaminase gene (Ad-CD) and cytosine deaminase:uracil phosphoribosyltransferase fusion gene (Ad-CD:UPRT). A monoclonal antibody, TRA-8, specifically binds to death receptor 5, one of two death receptors bound by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). The purpose of this study was to evaluate cytotoxicity in vitro and therapeutic efficacy in vivo of the combination of Ad-CD:UPRT and TRA-8 against human pancreatic cancer and glioma cell lines. The present study demonstrates that Ad-CD:UPRT infection resulted in increased 5-FC-mediated cell killing, compared with Ad-CD. Furthermore, a significant increase of cytotoxicity following Ad-CD:UPRT/5-FC and TRA-8 treatment of cancer cells in vitro was demonstrated. Animal studies showed significant inhibition of tumor growth of MIA PaCa-2 pancreatic and D54MG glioma xenografts by the combination of Ad-CD:UPRT/5-FC plus TRA-8 as compared with either agent alone or no treatment. The results suggest that the combination of Ad-CD:UPRT/5-FC with TRA-8 produces an additive cytotoxic effect in cancer cells in vitro and in vivo. These data indicate that combined treatment with enzyme/prodrug therapy and TRAIL immunotherapy provides a promising approach for cancer therapy.
...
PMID:Combination of cytosine deaminase suicide gene expression with DR5 antibody treatment increases cancer cell cytotoxicity. 1608 79

Poor treatment results in advanced hepatoblastoma (HB) made alternative treatment approaches desirable. Gene-directed tumor therapy is increasingly investigated in different malignancies. The aim of this study was to analyze possible alternatives of gene transfer into HB cells and to study therapeutic applications based on different strategies. Liposomal transfection of HB cells was assessed using liver-specific promoters, and adenovirus and Sendai virus transductions were performed in vitro. Transfer efficiencies were measured via flow cytometry determining expression of vector-encoded marker gene green fluorescent protein. Gene silencing of the anti-apoptotic bcl-2 gene in HUH6 cells was performed using lipofection of small interfering RNA (siRNA). Additionally, suicide gene therapy was carried out through a yeast-derived cytosine deaminase (YCD)-combined yeast uracil phosphoribosyltransferase (YUPRT)-based adenovirus-mediated gene transfer, leading to a potent intracellular prodrug transformation of 5-fluorocytosine into 5-fluorouracil. Treatment efficiencies were monitored via MTT viability assay. Highest gene transfer rates (86%) were observed using adenovirus transduction. We furthermore observed a significant therapeutic effect of adenovirus-mediated YCD::YUPRT suicide gene transfer. Liposomal-mediated anti-bcl-2 siRNA transfer led to a significant improvement of cisplatin treatment in HUH6 cells. Liver-specific promoters were found to be strongly active in HUH6 cells (mixed HB-derived), but less active in HepT1 cells (embryonal HB-derived). Liposomal transfection and viral transduction are effective approaches to genetically manipulate HB cells in vitro. For the first time, we demonstrate a positive effect of siRNA gene silencing in this malignancy. Additionally, we successfully investigated a model of adenovirus-based suicide gene therapy in HB cell cultures. Our data strongly encourage further studies assessing these alternative treatment approaches.
...
PMID:In vitro gene targeting in human hepatoblastoma. 1637 44

Inactivation of the FCY2 (cytosine permease), FCY1 (cytosine deaminase), and FUR1 (uracil phosphoribosyltransferase) genes in Candida lusitaniae produced two patterns of resistance to flucytosine. Mutant fur1 demonstrated resistance to 5-fluorouracil, whereas mutants fcy1 and fcy2 demonstrated fluconazole resistance in the presence of subinhibitory flucytosine concentrations.
...
PMID:Molecular mechanism of flucytosine resistance in Candida lusitaniae: contribution of the FCY2, FCY1, and FUR1 genes to 5-fluorouracil and fluconazole cross-resistance. 1706 May 21

Gene therapy is a promising approach for cancer treatment; however, efficacy of current vectors remains insufficient. To improve the success of suicide gene therapy, we constructed a replication-competent adenoviral vector that has its protease gene deleted and expresses bacterial cytosine deaminase fused with bacterial uracil phosphoribosyltransferase (CU). The prodrug, 5-fluorocytosine, is transformed into the highly toxic and tissue-diffusible 5-fluorouracil by CU in infected cells. This vector is incapable of producing infectious particles but is able to undergo a single round of replication, thereby increasing transgene copy number and expression. In the presence of 5-FC, compared with the first-generation vector (AdCU), the replication-competent vector, Ad(dPS)CU-IRES-E1A, was significantly more efficacious for in vitro tumor cell killing and in bystander assays, whereas 25-fold fewer viral particles were required in a three-dimensional spheroid model. For in vivo experiments, in which virus was injected into preestablished intracranial glioma xenografts, followed by 5-FC treatment, mice receiving Ad(dPS)CU-IRES-E1A had significantly smaller tumors at 35 days postinjection as well as significantly longer median survival than mice treated with the replication-deficient, protease-deleted vector [Ad(dPS)CU]. In an immunocompetent syngeneic model, Ad(dPS)CU + 5-FC-treated mice had a median survival of only 23 days, whereas Ad(dPS)CU-IRES-E1A + 5-FC-treated animals had a survival of 57.1% at 365 days. In conclusion, Ad(dPS)CU-IRES-E1A in the presence of 5-FC produces more potent tumoricidal effects than its replication-deficient counterparts.
...
PMID:Improvement of antitumor activity by gene amplification with a replicating but nondisseminating adenovirus. 1740 49

Human adipose tissue-derived mesenchymal stem cells (AT-MSC) are considered to be a promising source of autologous stem cells in personalized cell-based therapies. Tumor tracking properties of MSC provide an attractive opportunity for targeted transgene delivery into the sites of tumor formation. In the present study, we addressed whether the suicide gene introduction into human AT-MSC could produce a tumor-specific prodrug converting cellular vehicle for targeted chemotherapy. We prepared yeast fusion cytosine deaminase::uracil phosphoribosyltransferase gene-expressing cells [cytosine deaminase (CD)-expressing AT-MSC (CD-AT-MSC)] by retrovirus transduction. We explored their therapeutic potential on a model of human colon cancer in the presence of prodrug 5-fluorocytosine (5-FC). Gene manipulation of human AT-MSC did not sensitize CD-AT-MSC to 5-FC, thus overcoming the inherent disadvantage of suicide effect on cellular vehicle. CD-AT-MSC in combination with 5-FC augmented the bystander effect and selective cytotoxicity on target tumor cells HT-29 in direct coculture in vitro. We confirmed directed migration ability of AT-MSC and CD-AT-MSC toward tumor cells HT-29 in vitro. Moreover, we achieved significant inhibition of s.c. tumor xenograft growth by s.c. or i.v. administered CD-AT-MSC in immunocompromised mice treated with 5-FC. We confirmed the ability of CD-AT-MSC to deliver the CD transgene to the site of tumor formation and mediate strong antitumor effect in vivo. Taken together, these data characterize MSC derived from adipose tissue as suitable delivery vehicles for prodrug converting gene and show their utility for a personalized cell-based targeted cancer gene therapy.
...
PMID:Adipose tissue-derived human mesenchymal stem cells mediated prodrug cancer gene therapy. 1761 89

Modified vaccinia virus Ankara (MVA) has been used successfully to express various antigens for the development of vaccines. Here we show that MVA can also be used as an efficient vector for the transfer of suicide genes to cancer cells. We have generated a new and highly potent suicide gene, FCU1, which encodes a fusion protein derived from the yeast cytosine deaminase and uracil phosphoribosyltransferase genes. We now describe the therapeutic benefit of using MVA to deliver and express the FCU1 gene in cancer cells. MVA-mediated transfer of the FCU1 gene to various human tumor cells results in the production of a bifunctional intracellular enzyme, such that exposure to the prodrug 5-FC suppresses the growth of the tumor cells both in vitro and in vivo. Moreover, we report a more potent tumor growth delay at lower doses of 5-FC using MVA-FCU1 in comparison to adenovirus encoding FCU1. Prolonged therapeutic levels of cytotoxic 5-FU were detected in tumors in mice treated with both MVA-FCU1 and 5-FC while no detectable 5-FU was found in the circulation. This original combination between MVA and FCU1 represents a potentially safe and attractive therapeutic option to test in man.
...
PMID:Modified vaccinia virus Ankara as a vector for suicide gene therapy. 1799 3

Development of novel suicide gene therapy vector with potential application in cancer treatment has a great impact on human health. Investigation to understand molecular mechanism of cell death is necessary to evaluate the therapeutic application of suicide vectors. For example, the bifunctional E.coli cytosine deaminase & uracil phosphoribosyltransferase fusion (CD-UPRT) gene expression is known to sensitize a wide range of cells toward nontoxic prodrug 5-flurocytosine (5-FC) by converting it to toxic compounds, but the exact pathway of cell death is yet to be defined. Herein, we investigated the mechanism of cell death by 5-FC/CD-UPRT suicide system in both cancer and non-cancer cells and found that the optimum 5-FC concentration led to programmed cell death in vitro. The CD-UPRT expression of transfected cells was measured by the RT-PCR analysis. Biochemical assays, such as mitochondrial activity (MTS) and lactate dehydrogenase (LDH) measurements exhibited cell death. Microscopic experiments showed characteristic onset of apoptosis which was further supported by internucleosomal DNA cleavage of BrdU labeled cellular DNA, appearance of characteristic laddering of chromosomal DNA and involvement of caspase pathway. Furthermore, the 5-FC/CD-UPRT-mediated apoptosis was potentiated with addition of a known anticancer agent curcumin. Our in vitro studies confirmed synergistic induction of apoptotic pathway in the combination treatment. Therefore, combination of 5-FC/CD-UPRT with curcumin could be a potential chemosensitization strategy for cancer treatment.
...
PMID:Apoptotic induction with bifunctional E.coli cytosine deaminase-uracil phosphoribosyltransferase mediated suicide gene therapy is synergized by curcumin treatment in vitro. 1809 45

The successful translation of gene therapy for clinical application will require the assessment of transgene activity as a measure of the biological function of a therapeutic transgene. Although current imaging permits the noninvasive detection of transgene expression, the critical need for quantitative imaging of the action of the expressed transgene has not been met. In vivo magnetic resonance spectroscopic imaging (MRSI) was applied to quantitatively delineate both the concentration and activity of a cytosine deaminase-uracil phosphoribosyltransferase (CD-UPRT) fusion enzyme expressed from a transgene. MRSI enabled the generation of anatomically accurate maps of the intratumoral heterogeneity in fusion enzyme activity. We observed an excellent association between the CD-UPRT concentration and activity and the percentage of CD-UPRT(+) cells. Moreover, the regional levels of UPRT activity, as measured by imaging, correlated well with the biological affect of the enzyme. This study presents a translational imaging paradigm for precise, in vivo measurements of transgene activity with potential applications in both preclinical and clinical settings.
...
PMID:Imaging transgene activity in vivo. 1841 56

We have generated a thymidine kinase gene-deleted vaccinia virus (VV) (Copenhagen strain) that expressed the fusion suicide gene FCU1 derived from the yeast cytosine deaminase and uracil phosphoribosyltransferase genes. Intratumoral inoculation of this thymidine kinase gene-deleted VV encoding FCU1 (VV-FCU1) in the presence of systemically administered prodrug 5-fluorocytosine (5-FC) produced statistically significant reductions in the growth of subcutaneous human colon cancer in nude mice compared with thymidine kinase gene-deleted VV treatments or with control 5-fluorouracil alone. A limitation of prodrug therapies has often been the requirement for the direct injection of the virus into relatively large, accessible tumors. Here we demonstrate vector targeting of tumors growing subcutaneously following systemic administration of VV-FCU1. More importantly we also demonstrate that the systemic injection of VV-FCU1 in nude mice bearing orthotopic liver metastasis of a human colon cancer, with concomitant administration of 5-FC, leads to substantial tumor growth retardation. In conclusion, the insertion of the fusion FCU1 suicide gene potentiates the oncolytic efficiency of the thymidine kinase gene-deleted VV and represents a potentially efficient means for gene therapy of distant metastasis from colon and other cancers.
...
PMID:Targeted delivery of a suicide gene to human colorectal tumors by a conditionally replicating vaccinia virus. 1848 Aug 46

Gene-Directed Enzyme Prodrug Therapy (GDEPT), commonly known as suicide gene therapy, provides a selective approach to eradicate tumor cells that is currently considered as an alternate approach to conventional therapy for cancers due to its high efficacy. Herein, we have demonstrated functional activity of the cytosine deaminase (CD) and the hybrid cytosine deaminase-uracil phosphoribosyltransferase (CD-UPRT) suicide genes in transfected cell lines. We have monitored retention profiles of various metabolites that were formed during enzymatic conversion of the prodrug 5-flurocytosine (5-FC) using reverse phase HPLC method. Therapeutic effect of suicide genes was established by cell viability and toxicity assay, whereas apoptotic induction was confirmed by DNA fragmentation ELISA. Our results demonstrated that 5-FC/CD-UPRT-mediated apoptotic cell death was more than 5-FC/CD, which could be further potentiated with anticancer compound curcumin. Such results corroborated 5-FC/CD-UPRT in combination with curcumin as a better chemosensitization method.
...
PMID:Implication of functional activity for determining therapeutic efficacy of suicide genes in vitro. 1859 69


<< Previous 1 2 3 4 5 6 7 8 Next >>

---