title: Potential of ribozymes against deoxycytidine kinase to confer drug resistance to cytosine nucleoside analogs.
abstract: Hematopoietic toxicity is the dose-limiting side effect produced in cancer chemotherapy with deoxycytidine nucleoside analogs. Deletion of the deoxycytidine kinase (dCK), results in a drug resistance phenotype to these analogs. An interesting gene therapy strategy to confer drug resistance to cytosine nucleoside analogs would be to specifically inactivate the dCK in normal hematopoietic stem cell. In this study, we designed hammerhead ribozymes that can specifically cut and downregulate the murine dCK mRNA. Three different ribozymes were identified and shown to cleave in vitro the dCK RNA. After introduction of ribozyme cDNA into murine L1210 leukemic cells by retroviral transfer, two of the ribozymes showed some capacity in reducing dCK activity. However, analysis of transduced L1210 clones showed that the significant reduction in the dCK mRNA was not sufficient to confer drug resistance to cytosine arabinoside. Nevertheless, these results provide a new avenue of modulating the dCK enzyme activity and with improved modifications may have the potential for use in gene therapy to confer drug resistance to deoxycytidine analogs.
authors.affiliation: Centre de recherche de l'hôpital Ste-Justine, Université de Montréal, Montréal, Canada.
authors.forename: C M
authors.initials: CM
authors.lastname: Beauséjour
authors.forename: G
authors.initials: G
authors.lastname: Tremblay
authors.forename: R L
authors.initials: RL
authors.lastname: Momparler
mesh_terms: D000818:Animals; D001483:Base Sequence; D002999:Clone Cells; D003561:Cytarabine / Q000633:toxicity*; D017931:DNA Primers; D003842:Deoxycytidine Kinase / Q000235:genetics* / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D007939:Leukemia L1210; D051379:Mice; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D020319:Oligodeoxyribonucleotides, Antisense; D016337:RNA, Catalytic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D017931:DNA Primers; D020319:Oligodeoxyribonucleotides, Antisense; D016337:RNA, Catalytic; D012333:RNA, Messenger; D003561:Cytarabine; D003842:Deoxycytidine Kinase