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)

Tumor cells that express a fusion gene of Escherichia coli cytosine deaminase (CD) and herpes simplex virus type 1 thymidine kinase (TK) sequences activate and are subsequently killed by the nontoxic prodrugs 5-fluorocytosine and ganciclovir. We have previously developed a recombinant adenovirus containing the CD-TK fusion gene controlled by the human inducible heat shock protein 70 promoter so that heat at 41 degrees C for 1 hour induces therapeutic gene expression. This adenovirus effectively transduces heat-inducible expression of the CD-TK gene into human prostate carcinoma cells. However, because a limited number of cells in a tumor can actually be infected, we created a replicating adenoviral vector to increase CD-TK gene expression. This vector is a replication-competent, E1B-attenuated adenoviral vector containing the hsp70 promoter-driven CD-TK gene (Ad.E1A(+)HS-CDTK). When human prostate adenocarcinoma DU-145 cells (mutant p53) were infected with the virus at a multiplicity of infection (MOI) of 1 or 10, the viral replication was detected within 2 days at both MOIs. Similar results were observed in human colorectal carcinoma CX-1 cells. When DU-145 cells were infected with the virus at an MOI of 10, incubated for 24 hours, heated at 41 degrees C for 4 hours, and then harvested 20 hours later, Western blot analysis demonstrated that this virus successfully produced viral E1A proteins and heat shock stimulated the CD-TK gene expression by 12.3-fold. In addition, Ad.E1A(+)HS-CDTK effectively suppressed cell proliferation by viral cytopathic effect). Unlike with a replication-incompetent virus (Ad.HS-CDTK), the cytopathic effect of the virus and cytotoxicity in the presence of the prodrugs were still observed even at low MOI (MOI=1.0).
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PMID:Replicating adenoviral vector-mediated transfer of a heat-inducible double suicide gene for gene therapy. 1149 59

Two tandem cassettes, one containing the telomerase reverse transcriptase gene (hTERT) promoter upstream of a constitutively activated form of heat shock transcription factor 1 (cHSF1) and followed by the other containing the heat shock protein 70B (hsp70B) promoter (HSE) upstream of the cytosine deaminase (CD) gene, could greatly enhance the efficiency of CD gene therapy while retaining tumor specificity in vitro and in vivo. This hTERT-cHSF1/HSE promoter could restrict gene expression in tumor cells and was about 1.5-3-fold more potent than the cytomegalovirus (CMV) promoter. hTERT-cHSF1/HSE-CD transfection led to tumor cells more sensitive to 5-fluorocytosine compared with hTERT-CD and its toxicity was comparable to that of CMV-CD. Besides enhancement of promoter activity, cHSF1 overexpression itself could enhance the bystander effect of CD gene therapy that could be reversed by anti-Fas antibody. This system also led to activation of stress-related genes such as hsp70 in tumor cells, which in the presence of cell killing by the cytotoxic gene is a highly immunostimulatory event. Furthermore, a more potent anti-tumor effect of hTERT-cHSF1/HSE-CD was observed in nude mice inoculated with Bcap37 cells. No obvious activity of the hTERT-cHSF1/HSE promoter was observed in normal tissues after intravenous administration. These results indicate that the hTERT-cHSF1/HSE promoter is highly tumor-specific and strong with potential application in targeted gene therapy, and therefore may be useful for construction of vectors for systemic therapy.
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PMID:Enhanced suicide gene therapy by chimeric tumor-specific promoter based on HSF1 transcriptional regulation. 1283 60