title: Identification and characterization of high affinity antisense PNAs for the human unr (upstream of N-ras) mRNA which is uniquely overexpressed in MCF-7 breast cancer cells.
abstract: We have recently shown that an MCF-7 tumor can be imaged in a mouse by PET with 64Cu-labeled Peptide nucleic acids (PNAs) tethered to the permeation peptide Lys4 that recognize the uniquely overexpressed and very abundant upstream of N-ras or N-ras related gene (unr mRNA) expressed in these cells. Herein we describe how the high affinity antisense PNAs to the unr mRNA were identified and characterized. First, antisense binding sites on the unr mRNA were mapped by an reverse transcriptase random oligonucleotide library (RT-ROL) method that we have improved, and by a serial analysis of antisense binding sites (SAABS) method that we have developed which is similar to another recently described method. The relative binding affinities of oligodeoxynucleotides (ODNs) complementary to the antisense binding sites were then qualitatively ranked by a new Dynabead-based dot blot assay. Dissociation constants for a subset of the ODNs were determined by a new Dynabead-based solution assay and were found to be 300 pM for the best binders in 1 M salt. PNAs corresponding to the ODNs with the highest affinities were synthesized with an N-terminal CysTyr and C-terminal Lys4 sequence. Dissociation constants of these hybrid PNAs were determined by the Dynabead-based solution assay to be about 10 pM for the highest affinity binders.
authors.affiliation: Department of Chemistry, Washington University St Louis, MO 63130, USA.
authors.forename: Huafeng
authors.initials: H
authors.lastname: Fang
authors.forename: Xuan
authors.initials: X
authors.lastname: Yue
authors.forename: Xiaoxu
authors.initials: X
authors.lastname: Li
authors.forename: John-Stephen
authors.initials: JS
authors.lastname: Taylor
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry*; D001665:Binding Sites; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D005260:Female; D006801:Humans; D009693:Nucleic Acid Hybridization / Q000379:methods; D020319:Oligodeoxyribonucleotides, Antisense / Q000737:chemistry; D016376:Oligonucleotides, Antisense / Q000138:chemical synthesis / Q000737:chemistry*; D020135:Peptide Nucleic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C079950:CSDE1 protein, human; D004268:DNA-Binding Proteins; D020319:Oligodeoxyribonucleotides, Antisense; D016376:Oligonucleotides, Antisense; D020135:Peptide Nucleic Acids; D012333:RNA, Messenger; D016601:RNA-Binding Proteins