title: Tenascin-C aptamers are generated using tumor cells and purified protein.
abstract: Tenascin-C (TN-C) is an extracellular matrix protein that is overexpressed during tissue remodeling processes, including tumor growth. To identify an aptamer for testing as a tumor-selective ligand, SELEX (systematic evolution of ligands by exponential enrichment) procedures were performed using both TN-C and TN-C-expressing U251 glioblastoma cells. The different selection techniques yielded TN-C aptamers that are related in sequence. In addition, a crossover procedure that switched from tumor cell to purified protein selections was effective in isolating two high-affinity TN-C aptamers. When targeting tumor cells in vitro, the observed propensity of naive oligonucleotide pools to evolve TN-C aptamers may be due to the abundance of this protein. In vivo, TN-C abundance may also be well suited for aptamer accumulation in the tumor milieu. A size-minimized and nuclease-stabilized aptamer, TTA1, binds to the fibrinogen-like domain of TN-C with an equilibrium dissociation constant (K(d)) of 5 x 10(-9) m. At 13 kDa, this aptamer is intermediate in size between peptides and single chain antibody fragments, both of which are superior to antibodies for tumor targeting because of their smaller size. TTA1 defines a new class of ligands that are intended for targeted delivery of radioisotopes or chemical agents to diseased tissues.
authors.affiliation: SomaLogic, Boulder, Colorado 80301, USA. bhicke@somalogic.com
authors.forename: B J
authors.initials: BJ
authors.lastname: Hicke
authors.forename: C
authors.initials: C
authors.lastname: Marion
authors.forename: Y F
authors.initials: YF
authors.lastname: Chang
authors.forename: T
authors.initials: T
authors.lastname: Gould
authors.forename: C K
authors.initials: CK
authors.lastname: Lynott
authors.forename: D
authors.initials: D
authors.lastname: Parma
authors.forename: P G
authors.initials: PG
authors.lastname: Schmidt
authors.forename: S
authors.initials: S
authors.lastname: Warren
mesh_terms: D000818:Animals; D005109:Extracellular Matrix / Q000737:chemistry; D005909:Glioblastoma / Q000378:metabolism; D006801:Humans; D008024:Ligands; D051379:Mice; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D020349:Surface Plasmon Resonance; D019063:Tenascin / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D008024:Ligands; D009841:Oligonucleotides; D010446:Peptide Fragments; D019063:Tenascin