Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.1 (cytosine deaminase)
 747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gene therapy is a novel therapeutic approach that might soon improve the prognosis of some cancers. We investigated the feasibility of cytosine deaminase (CD) suicide gene therapy in a model of peritoneal carcinomatosis. DHD/K12 colorectal adenocarcinoma cells transfected in vitro with the CD gene were highly sensitive to 5-fluorocytosine (5-FC), and a bystander effect could also be observed. Treating CD+ cells with 5-FC resulted in apoptosis as detected by terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick-end labeling. In vitro, several human cell lines derived from ovarian or colorectal carcinomas, as well as the rat glioblastoma 9 L cell line, responded to CD/5-FC and showed a very strong bystander effect. 5-FC treatment of peritoneal carcinomatosis generated in syngeneic BDIX rats by CD-expressing DHD/K12 cells led to a complete and prolonged response and to prolonged survival. Our study thus demonstrated the efficacy of CD suicide gene therapy for the treatment of peritoneal carcinomatosis.
Cancer Gene Ther 2000 Jan
PMID:Cytosine deaminase suicide gene therapy for peritoneal carcinomatosis. 1067 52

We evaluated the therapeutic efficacy and neurotoxicity of adenovirus-mediated transduction of the cytosine deaminase (CD) gene and 5-fluorocytosine (5-FC) for experimental malignant brain tumors. The 5-FC sensitivity in 9 L cells infected by an adenovirus vector expressing CD (AdexCACD) was increased 1700-fold compared with control cells. Rats bearing 9 L brain tumors were treated with an intratumoral injection of AdexCACD followed by intraperitoneal administration of 5-FC. The rats demonstrated remarkable inhibition of tumor growth by magnetic resonance imaging, and 7 of 10 rats survived for >90 days. To evaluate the potential side-effects of the 5-FC/CD gene therapy, rats were treated with an intracerebral injection of AdexCACD into the right basal ganglia and with 5-FC. The magnetic resonance imaging showed a highly enhanced area on the gadollinium-enhanced T1-weighted image at 18 days postinjection. Pathologically, this corresponded to an area of necrosis with surrounding apoptotic cells. In addition, there was demyelination and gliosis with enlargement of the lateral ventricles. These results suggest that the 5-FC/CD gene therapy may provide an anticancer effect for malignant brain tumors in humans, but also show that there are neurotoxic effects on normal brain tissue.
Cancer Gene Ther 2000 Jan
PMID:In vivo efficacy and toxicity of 5-fluorocytosine/cytosine deaminase gene therapy for malignant gliomas mediated by adenovirus. 1067 59

Epstein-Barr virus (EBV)-based gene delivery vectors that preferentially express toxic genes in EBV-infected cells could be used to target EBV-positive tumors for destruction. We have shown previously that the cytosine deaminase (CD) enzyme, which converts the prodrug 5-fluorocytosine (5-FC) into the toxic compound 5-fluorouracil efficiently kills EBV-positive cells in the presence of 5-FC, with a substantial bystander killing effect in vitro and in vivo. To identify the optimal enzyme/prodrug combination for treating EBV-positive lymphomas, we have compared the effectiveness of the CD/5-FC combination with the nitroreductase (NTR)/CB1954 combination for killing EBV-positive B-cell lines. NTR metabolizes CB1954 into an alkylating agent that cross-links DNA. When the CD gene or the NTR gene were transfected into two different EBV-positive B-cell lines in vitro, approximately 90% of cells were killed in a prodrug-dependent manner, although the transfection efficiency was <5%. However, severe combined immunodeficient mouse tumors containing either 30% or 100% of NTR-expressing Burkitt lymphoma (Jijoye) cells were growth inhibited, but not cured, by treatment with intraperitoneal CB1954 (20 mg/kg/day) for 10 days. These results suggest that the NTR/CB1954 combination induces efficient bystander killing of EBV-positive B-cell lines in vitro but may not be as effective as the CD/5-FC combination for treating B-cell lymphomas in vivo.
Cancer Gene Ther 2000 Jan
PMID:The nitroreductase/CB1954 combination in Epstein-Barr virus-positive B-cell lines: induction of bystander killing in vitro and in vivo. 1067 62

A versatile expression vector is described for the rapid construction and evaluation of bispecific scFvs and scFv-based fusion proteins. An important feature of this vector is the presence of two multiple cloning sites (MCS) separated by an in frame linker sequence. The first MCS was specifically designed to contain unique SfiI and NotI restriction enzyme sites that can be used for directional and in frame insertion of scFvs (or potentially any molecule) selected from established phage-display systems. Using this new vector, a functional bs-(scFv)(2) (2C11-MOC31) was constructed for retargeted T-cell cytotoxicity towards EGP2 positive tumor cells. The vector was also used for grafting of a number of promising biological effector principles onto scFv MOC31, including the prodrug converting enzyme cytosine deaminase, the anti-angiogenic factor angiostatin, and the thrombogenic molecule tissue factor. We aimed at producing biologically active fusion proteins by directing them through the endoplasmic reticulum-based protein folding machinery of eukaryotic cells (COS-7) using a kappa light chain leader, thereby taking advantage of the associated quality control mechanisms that allow only fully folded and processed fusion proteins to be secreted into the medium. Supernatants derived from fusion protein transfected COS-7 cells, which were transiently transfected at low transfection rates, were directly assayed for the biological and/or targeting activity of the excreted fusion proteins without any prior purification steps. This procedure might help to identify those fusion proteins that have favourable characteristics like stability and biological activity in the presence of serum and at low protein concentrations. Targeted delivery of all effector principles was subsequently assessed in an in vitro model system. The method we devised is both rapid and versatile and can be useful to construct and identify series of new chimeric proteins with enhanced therapeutic potential in human cancer therapy.
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PMID:A rapid and versatile method for harnessing scFv antibody fragments with various biological effector functions. 1072 58

We report here the use of viral fusogenic membrane glycoproteins (FMGs) as a new class of therapeutic genes for the control of tumor growth. FMGs kill cells by fusing them into large multinucleated syncytia, which die by sequestration of cell nuclei and subsequent nuclear fusion by a mechanism that is nonapoptotic, as assessed by multiple criteria. Direct and bystander killing of three different FMGs were at least one log more potent than that of herpes simplex virus thymidine kinase or cytosine deaminase suicide genes. Transduction of human tumor xenografts with plasmid DNA prevented tumor outgrowth in vivo, and cytotoxicity could be regulated through transcriptional targeting. Syncytial formation is accompanied by the induction of immunostimulatory heat shock proteins, and tumor-associated FMG expression in immunocompetent animals generated specific antitumor immunity.
Cancer Res 2000 Mar 15
PMID:Fusogenic membrane glycoproteins as a novel class of genes for the local and immune-mediated control of tumor growth. 1074 10

Suicide gene therapy has been studied intensively for the treatment of cancer. A limited antitumoral effect was obtained by intratumoral injection of adenovirus harboring Escherichia coli cytosine deaminase gene (AdCD) in tumor-bearing mice followed by continuous administration of 5-fluorocytosine (5FC). To address the drawbacks of the limited potential for the induction of antitumoral immunity by CD suicide gene therapy, we hypothesized that antigen-presenting cells (APCs) might contribute to the efficient induction of an antitumoral immune response in tumor-bearing mice undergoing suicide gene therapy. We preinjected the mice with murine stem cell factor (SCF)-encoding adenovirus (AdSCF) and murine granulocyte-macrophage colony-stimulating factor (GM-CSF)-encoding adenovirus (AdGM-CSF); after 7 days, the mice were inoculated with CT26 colon adenocarcinoma. AdCD was injected intratumorally into tumor-bearing mice followed by 5FC administration. The results showed that AdSCF/AdGM-CSF treatment could increase the number, surface molecule expression, and function of APCs efficiently. A more significant growth inhibition of established tumors and a prolongation of the survival period were observed in tumor-bearing mice after AdSCF/AdGM-CSF pretreatment in combination with AdCD/5FC therapy when compared with mice treated with AdSCF or AdGM-CSF in combination with AdCD/5FC, or AdCD/5FC alone (P < .01). Cytotoxic T-lymphocyte activity was induced efficiently after the combined therapy, and mRNA of tumor necrosis factor-alpha, interleukin-4, interferon-gamma, and interleukin-2 was present in the tumor mass after combined therapy, suggesting that a more potent antitumoral response was induced by enhanced APCs. Our results demonstrated that AdSCF/AdGM-CSF pretreatment could activate APCs, and that these APCs could present the tumor antigens released from AdCD/5FC-killed tumor cells and activate the antitumoral response of the host, thus increasing the therapeutic efficiency of suicide gene therapy.
Cancer Gene Ther 2000 Feb
PMID:Enhanced antitumoral effect of adenovirus-mediated cytosine deaminase gene therapy by induction of antigen-presenting cells through stem cell factor/granulocyte-macrophage colony-stimulating factor gene transfer. 1077 Jun 25

The success of chemotherapeutic intervention is limited because the necessary high local drug doses cannot be achieved without systemic toxicity. Application of suicide genes (SGs) and direct conversion of prodrugs (PDs) to toxic metabolites in situ by SGs may enhance the efficacy of chemotherapy. To evaluate this strategy in two murine breast cancer models, TS/A and GR, we injected cellulose sulfate capsules harboring cat kidney cells expressing the SGs cytosine deaminase and cytochrome P450 2B1 (CYP2B1) intratumorally. The PDs 5-fluorocytosine and ifosfamide were administered in 3-day intervals. The effect of in situ chemotherapy with each PD alone and the combination was analyzed over a period of 100 days. The results reveal that for TS/A tumors, the antitumoral effect mediated by CYP2B1 is more efficient than that of cytosine deaminase, whereas for GR tumors, both systems worked equally well. Furthermore, we find additive toxicity using both SG/PD systems for both TS/A and GR tumors.
Cancer Gene Ther 2000 Apr
PMID:Combined chemotherapy of murine mammary tumors by local activation of the prodrugs ifosfamide and 5-fluorocytosine. 1081 82

Escherichia coli cytosine deaminase (CD), which is a prokaryotic enzyme, converts nontoxic prodrug 5-fluorocytosine (5-FC) into the toxic chemotherapeutic agent 5-fluorouracil (5-FU). To investigate an enzyme/prodrug gene therapy for colorectal cancer, using adenoviral gene transfer of the E. coli CD gene associated with administration of 5-FC, we constructed replication-defective adenovirus vectors expressing the E. coli CD gene or lacZ gene driven by a CAG promoter (composed of a cytomegalovirus immediate early enhancer and a chicken beta-actin promotor). The present study demonstrated that an adenoviral gene transfer system using a CAG promoter induced sufficient gene expression of CD to confer the cytotoxicity of 5-FC to HT29 human colon cancer cells by converting it into 5-FU even at an moi of one. Furthermore, experimental gene therapy using intratumoral injection of the CD-expressing adenovirus with systemical administration of 5'-FC successfully suppressed the growth of established HT29 subcutaneous tumors in nude mice. These results suggest that enzyme/prodrug gene therapy using the adenoviral gene transfer of the E. coli CD gene with concomitant administration of 5-FC may be an effective strategy in the local control of colorectal cancer.
J Exp Clin Cancer Res 2000 Mar
PMID:Enzyme/prodrug gene therapy for human colon cancer cells using adenovirus-mediated transfer of the Escherichia coli cytosine deaminase gene driven by a CAG promoter associated with 5-fluorocytosine administration. 1084 Sep 40

L6 is an IgG2a murine monoclonal antibody which we have demonstrated binds well to HT29 human colon carcinoma cells by flow cytometry, whole cell ELISA, and mixed hemadsorption. In vitro cytotoxicity studies revealed that the monoclonal antibody L6-cytosine deaminase (L6-CD) immunoconjugate plus the nontoxic prodrug, 5-fluorocytosine (5-FC), is equivalent to 5-fluorouracil (5-FU) in its ability to kill HT29 cells. Human alpha-interferon (A/D) was able to enhance this cytotoxic effect. The I.C.50's revealed that very small amounts of L6-CD are needed for this cytotoxic effect (approximately, 5 pg/ml resulted in 50% viability). The limiting factor was the amount of 5-FC employed with L6-CD (3 microM yielded 50% cell viability). alpha-Interferon (A/D) lowered the requirement of 5-FC to 1 microM to achieve 50% cell lethality. In vivo biodistribution experiments indicated that 1 microgram of L6-CD is nonspecifically taken up by the liver and spleen and cleared rapidly from the blood. Significant localization of L6-CD to HT29 tumors occurred only when 99 micrograms of unlabeled L6-CD was added to 1 microgram of 125I-labeled immunoconjugate injected intravenously. Further augmentation of tumor/blood ratios without reduction in percent injected dose per gram of tumor was possible with the intravenous injection of 100 micrograms of anti-idiotypic monoclonal antibody 13B, 24 hours after L6-CD, which bound unreacted L6-CD and cleared it from the blood. The addition of 100,000 U of alpha-interferon (A/D) given intraperitoneally every day increased the clearance of L6-CD by the liver and spleen, but impaired tumor localization (percent injected dose per gram). These studies demonstrated that in vivo localization of the L6-CD conjugate to HT29 tumors could be optimized by injecting excess L6-CD followed by an equal amount of L6 anti-idiotype mAb 13B, 24 hours after L6-CD.
Cancer Biother Radiopharm 1998 Feb
PMID:Effects of a hybrid recombinant human alpha interferon (A/D) on in vitro cytotoxicity and in vivo localization of monoclonal antibody L6-cytosine deaminase conjugate in a colon cancer model. 1085 Mar 40

Detection of a therapeutic response early in the course of cancer treatment, before tumor growth delay or regression, is not currently possible in experimental models or clinical medicine. New interim measures of therapeutic response would be particularly useful in the development of cancer chemosensitization gene therapy by facilitating optimization of gene transfer protocols and prodrug dosing schedules. Diffusion MRI is a sensitive technique producing quantitative and noninvasive images of the apparent mobility of water within a tissue. We investigated the utility of diffusion MRI for detecting early changes associated with a refined cytosine deaminase (CD)/5-fluorocytosine (5FC) chemosensitization gene therapy paradigm in orthotopic 9L gliomas stably expressing the recently cloned S. cerevisiae CD gene. Mean tumor diffusion increased 31% within 8 days of initiating 5-FC treatment, preceding tumor growth arrest and regression. Complete regression of the intracranial tumor was observed in four of five treated animals, and recurrent tumor in the remaining animal exhibited water diffusion behavior similar to primary, untreated tumors. These results demonstrate the efficacy of the yCD/5FC strategy for glioma and suggest that increased tumor water diffusion is an indicator of active therapeutic intervention.
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PMID:Diffusion MRI detects early events in the response of a glioma model to the yeast cytosine deaminase gene therapy strategy. 1087 48


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