title: Adenoviral-mediated imaging of gene transfer using a somatostatin receptor-cytosine deaminase fusion protein.
abstract: Suicide gene therapy is a process by which cells are administered a gene that encodes a protein capable of converting a nontoxic prodrug into an active toxin. Cytosine deaminase (CD) has been widely investigated as a means of suicide gene therapy owing to the enzyme's ability to convert the prodrug 5-fluorocytosine (5-FC) into the toxic compound 5-fluorouracil (5-FU). However, the extent of gene transfer is a limiting factor in predicting therapeutic outcome. The ability to monitor gene transfer, non-invasively, would strengthen the efficiency of therapy. In this regard, we have constructed and evaluated a replication-deficient adenovirus (Ad) containing the human somatostatin receptor subtype 2 (SSTR2) fused with a C-terminal yeast CD gene for the non-invasive monitoring of gene transfer and therapy. The resulting Ad (AdSSTR2-yCD) was evaluated in vitro in breast cancer cells to determine the function of the fusion protein. These studies demonstrated that both the SSTR2 and yCD were functional in binding assays, conversion assays and cytotoxicity assays. In vivo studies similarly demonstrated the functionality using conversion assays, biodistribution studies and small animal positron-emission tomography (PET) imaging studies. In conclusion, the fusion protein has been validated as useful for the non-invasive imaging of yCD expression and will be evaluated in the future for monitoring yCD-based therapy.
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Lears
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Parry
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: R
authors.initials: R
authors.lastname: Andrews
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: K
authors.initials: K
authors.lastname: Nguyen
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Wadas
authors.affiliation: 1] Department of Radiation Oncology, Washington University School of Medicine, St Louis, MO, USA [2] Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Rogers
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D001667:Binding, Competitive; D043525:Cytosine Deaminase / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D005437:Flucytosine / Q000493:pharmacokinetics / Q000627:therapeutic use; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics; D017930:Genes, Reporter; D015316:Genetic Therapy; D006801:Humans; D061986:MCF-7 Cells; D016513:Mice, SCID; D009928:Organ Specificity; D011355:Prodrugs / Q000493:pharmacokinetics / Q000627:therapeutic use; D017481:Receptors, Somatostatin / Q000096:biosynthesis / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D014161:Transduction, Genetic; D023041:Xenograft Model Antitumor Assays
chemical_list: D005656:Fungal Proteins; D011355:Prodrugs; D017481:Receptors, Somatostatin; D011993:Recombinant Fusion Proteins; C574734:SSTR2 protein, human; D005437:Flucytosine; D043525:Cytosine Deaminase
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