title: Cytosine deaminase gene as a positive selection marker.
abstract: Cytosine deaminase (EC 3.5.4.1), a non-mammalian enzyme, catalyzes the deamination of cytosine and 5-fluorocytosine to form uracil and 5-fluorouracil, respectively. Eukaryotic cells have been genetically modified with a bacterial cytosine deaminase gene to express a functional enzyme. When the genetically modified cells are combined with 5-fluorocytosine, it creates a potent negative selection system, which may have important applications in cancer gene therapy. In this paper, we introduce a novel positive selection method based upon the expression of the cytosine deaminase gene. This method utilizes inhibitors in the pyrimidine de novo synthesis pathway to create a condition in which cells are dependent on the conversion of pyrimidine supplements to uracil by cytosine deaminase. Thus, only cells expressing the cytosine deaminase gene can be rescued in a positive selection medium.
authors.affiliation: Department of Cell Biology, Wellcome Research Laboratories, Research Triangle Park, North Carolina 27709, USA.
authors.forename: K
authors.initials: K
authors.lastname: Wei
authors.forename: B E
authors.initials: BE
authors.lastname: Huber
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity*; D017209:Apoptosis; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000633:toxicity; D002453:Cell Cycle; D002455:Cell Division; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000187:drug effects*; D003470:Culture Media; D003596:Cytosine / Q000494:pharmacology*; D043525:Cytosine Deaminase; D005437:Flucytosine / Q000633:toxicity*; D015870:Gene Expression; D005798:Genes, Bacterial; D005819:Genetic Markers; D007288:Inosine / Q000494:pharmacology*; D051379:Mice; D009700:Nucleoside Deaminases / Q000096:biosynthesis* / Q000235:genetics; D010746:Phosphonoacetic Acid / Q000031:analogs & derivatives* / Q000633:toxicity; D051381:Rats; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D003470:Culture Media; D005819:Genetic Markers; D001224:Aspartic Acid; D007288:Inosine; C013195:sparfosic acid; D003596:Cytosine; D005437:Flucytosine; D009700:Nucleoside Deaminases; D043525:Cytosine Deaminase; D010746:Phosphonoacetic Acid