title: Inhibition of transcription of the human c-myc protooncogene by intermolecular triplex.
abstract: Triplex-forming oligonucleotides (TFOs) have been shown to inhibit both transcription in vitro and the expression of target genes in cell culture by binding to polypurine/polypyrimidine sequences in several human gene promoters. The c-myc protooncogene is overexpressed in a variety of human cancers and appears to play an important role in the proliferation of these cells. In an attempt to assay the ability of triplex-forming oligonucleotides to inhibit expression of a target gene in vivo, we have developed a cellular system involving transfection of a c-myc promoter-driven luciferase reporter plasmid with triplex-forming oligonucleotides targeted to the human c-myc protooncogene. To increase the stability of the TFO, we have used modified phosphorothioate oligonucleotides. Triplex formation with a modified phosphorothioate oligonucleotide occurs with approximately equal binding affinity as that seen using a phosphodiester oligonucleotide. Phosphorothioate-modified TFOs targeted to c-myc inhibit transcription of the c-myc promoter in HeLa cells as demonstrated by a decrease in luciferase expression from a luciferase reporter gene construct. These results suggests that triplex formation may represent a gene-specific means of inhibiting specific protooncogene expression.
authors.affiliation: Department of Biochemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294-0001, USA.
authors.forename: H G
authors.initials: HG
authors.lastname: Kim
authors.forename: J F
authors.initials: JF
authors.lastname: Reddoch
authors.forename: C
authors.initials: C
authors.lastname: Mayfield
authors.forename: S
authors.initials: S
authors.lastname: Ebbinghaus
authors.forename: N
authors.initials: N
authors.lastname: Vigneswaran
authors.forename: S
authors.initials: S
authors.lastname: Thomas
authors.forename: D E
authors.initials: DE
authors.lastname: Jones
authors.forename: D M
authors.initials: DM
authors.lastname: Miller
mesh_terms: D001483:Base Sequence; D015870:Gene Expression / Q000187:drug effects; D017930:Genes, Reporter; D016259:Genes, myc / Q000187:drug effects*; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000235:genetics; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D009838:Oligodeoxyribonucleotides; D008156:Luciferases