Screening and characterization of aptamers for recombinant human programmed death-1 and recombinant extracellular domain of human programmed death ligand-1

Z.-F. Li, C. Chen, J.-Y. Zeng, S. Wang, S.-Q. Han, Y.-Q. Zhang, D.-D. Qiu, H.-X. Guo

School of Medicine, Huaqiao University, Fujian, China. lizhaofa@hqu.edu.cn

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• Oncology

OBJECTIVE: Programmed death ligand-1 (PD-L1) is expressed on tumor cells and macrophages. The detection of PD-L1 expression in cancer and the treatment by targeting the PD-L1/programmed death-1 (PD-1) are of great clinical significance. This work aims to screen the aptamers with high affinity and specificity for recombinant human PD-1 (rhPD-1)/recombinant human PD-L1 extracellular domain (rhPD-L1).

MATERIALS AND METHODS: In this study, we have expressed, purified, prepared, and identified rhPD-1 and rhPD-L1. The rhPD-L1/rhPD-1 aptamers with high affinity and specificity were obtained by systematic evolution of ligands by exponential enrichment technique. Ten aptamers sequences to rhPD-L1 and 10 aptamers sequences to rhPD-1 were obtained by cloning and sequencing. The affinity and specificity of candidate aptamers were analyzed by gold nanoparticles-based colorimetric assay, dot blot assay, and electrophoretic mobility shift assay.

RESULTS: The aptamers named A6 were picked out as the optimal aptamers that recognize PD-1, specifically with the Kd value of 47.84 ± 24.78 nM. The aptamers named B10 were picked out as the optimal aptamers that recognize PD-L1, specifically with the Kd value of 59.72 ± 15.87 nM.

CONCLUSIONS: The study lays a foundation for the development of detection methods and therapeutic drugs targeting PD-L1/PD-1.

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