title: Coexpression of rat glutathione S-transferase A3 and human cytidine deaminase by a bicistronic retroviral vector confers in vitro resistance to nitrogen mustards and cytosine arabinoside in murine fibroblasts.
abstract: The transfer of drug resistance genes into hematopoietic cells is an experimental approach to protect patients from drug-induced myelosuppression. Because anti-cancer drugs are often administered in combination to increase their clinical efficacy, vectors that express two drug resistance genes are being developed to broaden the spectrum of chemoprotection. We have constructed a bicistronic vector, MFG/GST-IRES-CD (MFG/GIC) coexpressing rat glutathione S-transferase (GST) A3 isoform (rGST Yc1) and human cytidine deaminase (CD). Murine NIH 3T3 fibroblast cells transduced with this vector were evaluated for their resistance to nitrogen mustards and cytosine nucleoside analogs. GIC-transduced polyclonal cell populations (GIC cells) demonstrated marked increases in selenium-independent glutathione peroxidase (peroxidase) and CD activities, as well as increased resistance to melphalan (2.3-fold), chlorambucil (3.4-fold), and cytosine arabinoside (Ara-C) (8.1-fold). After selection with Ara-C, the peroxidase and CD activities of GIC cells were augmented 2.6- and 2.9-fold, respectively, in comparison with unselected cells, and the resistance to melphalan, chlorambucil, and Ara-C was further increased to 3.7-, 5.9-, and 53-fold, respectively. Melphalan selection of GIC cells likewise augmented their peroxidase (2.3-fold) and CD (1.9-fold) activities. GIC cells proliferated in the simultaneous presence of melphalan and Ara-C at drug concentrations that completely inhibited the growth of untransduced cells. The growth rate of unselected GIC cells exposed to the drug combination averaged 18% that of drug-free cultures. The growth rate of GIC cells exposed to the drug combination increased to 30% of controls after Ara-C selection and to 50% after melphalan selection. Our results suggest that retroviral transfer of MFG/GIC may be useful for chemoprotection against the toxicities of nitrogen mustards and cytosine nucleoside analogs.
authors.affiliation: Department of Medicine, Montréal General Hospital and Research Institute, McGill University, Québec, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Létourneau
authors.forename: J S
authors.initials: JS
authors.lastname: Palerme
authors.forename: J S
authors.initials: JS
authors.lastname: Delisle
authors.forename: C M
authors.initials: CM
authors.lastname: Beauséjour
authors.forename: R L
authors.initials: RL
authors.lastname: Momparler
authors.forename: D
authors.initials: D
authors.lastname: Cournoyer
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D015139:Blotting, Southern; D002455:Cell Division / Q000187:drug effects; D003561:Cytarabine / Q000494:pharmacology*; D003564:Cytidine Deaminase / Q000235:genetics* / Q000378:metabolism*; D018076:DNA, Complementary / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D005347:Fibroblasts / Q000187:drug effects*; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008466:Mechlorethamine / Q000494:pharmacology*; D008558:Melphalan / Q000494:pharmacology; D051379:Mice; D014176:Protein Biosynthesis; D051381:Rats; D012190:Retroviridae / Q000235:genetics*; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D014161:Transduction, Genetic
chemical_list: D000964:Antimetabolites, Antineoplastic; D018906:Antineoplastic Agents, Alkylating; D018076:DNA, Complementary; D013778:Tetrazolium Salts; D013844:Thiazoles; D003561:Cytarabine; D008466:Mechlorethamine; D005982:Glutathione Transferase; D003564:Cytidine Deaminase; C022616:thiazolyl blue; D008558:Melphalan