Abstract: Abstract: Objective To develop HER2 DNA aptamers that may potentially serve as tumor-binding ligand in novel HER2-targeted therapeutic strategies. Methods A single-stranded 86nt DNA library containing 40 random oligonucleotides was synthesized in vitro. A new aptamer HA5 were developed by SELEX technique with HER2 epitope peptide as target. Flow cytometry were performed to monitor the enrichment of aptamer pool and to evaluate the binding characterization of HA5. The structure of HA5 was performed by Mfold. Results The selected HA5 bound to the HER2 structure and had minimal cross reactivity to trypsin. In addition, the aptamer was found to preferentially bind to HER2-positive but not HER2-negative cells. Conclusion The results suggest that HA5 may have application potentials in targeted therapy against HER2-positive malignancies.

Key words: aptamer, SELEX, HER2, breast cancer