1. Tenascin-C aptamers are generated using tumor cells and purified protein
- Author
-
Paul Schmidt, Ty A. Gould, Chris Marion, Ying-Fon Chang, Steve Warren, Brian Hicke, David Parma, and Cynthia K. Lynott
- Subjects
Aptamer ,Oligonucleotides ,Plasma protein binding ,Ligands ,Biochemistry ,Mice ,In vivo ,Tumor Cells, Cultured ,Animals ,Humans ,Molecular Biology ,biology ,Oligonucleotide ,Tenascin C ,Tenascin ,Cell Biology ,Surface Plasmon Resonance ,Molecular biology ,In vitro ,Peptide Fragments ,Extracellular Matrix ,Dissociation constant ,biology.protein ,Nucleic Acid Conformation ,Glioblastoma ,Systematic evolution of ligands by exponential enrichment ,Protein Binding - 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.
- Published
- 2001