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Updated: Jun 14, 2025
Phthalic Acid Ester-Binding DNA Aptamer Selection, Characterization, and Application to an Electrochemical Aptasensor
Published on: March 21, 2018
PD-L1 DNA aptamers isolated from agarose-bead SELEX
Muhammad Najmi Mohd Nazri1, Nur Amira Khairil Anwar1, Nur Fatihah Mohd Zaidi1
1Institute for Research in Molecular Medicine (INFORMM), USM Health Campus, 16150 Kota Bharu, Kelantan, Malaysia.
Abstract:
Increased expression and activity of the PD-L1/PD-1 pathway suppresses the activation of cytotoxic T cells, which is vital in anti-tumour defence, allowing tumours to rise, expand and progress. Current strategies using antibodies to target PD-1/PD-L1 have been very effective in cancer therapeutics and companion diagnostics. Aptamers are a new class of molecules that offer an alternative to antibodies. Herein, the systematic evolution of ligands by exponential enrichment (SELEX) using agarose slurry beads was conducted to isolate DNA aptamers specific to recombinant human PD-L1 (rhPD-L1). Isolated aptamers were sequenced and analysed using MEGA X and structural features were examined using mFold. Three aptamer candidates (P33, P32, and P12) were selected for evaluation of binding affinity (dissociation constant, Kd) using ELONA and specificity and competitive inhibition assessment using the potentiostat-electrochemical method. Among those three, P32 displayed the highest specificity (8 nM) against PD-L1. However, P32 competes for the same binding site with the control antibody, 28-8. This study warrants further assessment of P32 aptamer as a potential, cost-effective alternative tool for targeting PD-L1.
Insights
Researchers developed DNA aptamers to target programmed cell death-ligand 1 (PD-L1), a key protein in cancer progression. Aptamer P32 showed high specificity for PD-L1, offering a potential alternative to antibodies for cancer therapy.
Area of Science:
- Biochemistry
- Molecular Biology
- Immunology
Background:
- The PD-L1/PD-1 pathway is crucial in anti-tumour immunity, and its dysregulation promotes tumor growth.
- Antibody-based therapies targeting PD-1/PD-L1 are effective cancer treatments but have limitations.
- Aptamers represent a novel class of molecules with potential as alternatives to antibodies.
Purpose of the Study:
- To isolate and characterize DNA aptamers specific to recombinant human PD-L1 (rhPD-L1).
- To evaluate the binding affinity, specificity, and competitive inhibition of selected aptamers against PD-L1.
Main Methods:
- Systematic Evolution of Ligands by Exponential Enrichment (SELEX) was used to isolate DNA aptamers.
- Aptamer sequences were analyzed using MEGA X, and structural features were examined with mFold.
- Binding affinity (Kd) was assessed using ELONA, and specificity/inhibition was evaluated electrochemically.
Main Results:
- Three aptamer candidates (P33, P32, P12) were identified.
- Aptamer P32 demonstrated high specificity for PD-L1 with a dissociation constant (Kd) of 8 nM.
- P32 competes with the control antibody 28-8 for the same binding site on PD-L1.
Conclusions:
- DNA aptamer P32 exhibits high specificity for PD-L1.
- P32 warrants further investigation as a potential cost-effective alternative to antibodies for targeting PD-L1 in cancer therapy.
