Elucidation and Structural Modeling of CD71 as a Molecular Target for Cell-Specific Aptamer Binding
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Xiaoqiu Wu1, Honglin Liu1,2, Dongmei Han1
1Molecular Science and Biomedicine Laboratory (MBL), State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Aptamer Engineering Center of Hunan Province , Hunan University , Changsha , Hunan 410082 , China.
Abstract:
Pancreatic cancer is a highly lethal malignancy associated with tissues of the pancreas. Early diagnosis and effective treatment are crucial to improving the survival rate of patients with pancreatic cancer. In a previous study, we employed the cell-SELEX strategy to obtain an ssDNA aptamer termed XQ-2d with high binding affinity for pancreatic cancer. Here, we first identify CD71 as the XQ-2d-binding target. We found that knockdown of CD71 abolished the binding of XQ-2d and that the binding affinity of XQ-2d is associated with membrane-bound CD71, rather than total CD71 levels. Competitive analysis revealed that XQ-2d shares the same binding site on CD71 with transferrin (Tf), but not anti-CD71 antibody. We then used a surface energy transfer (SET) nanoruler to measure the distance between the binding sites of XQ-2d and anti-CD71 antibody, and it was about 15 nm. Furthermore, we did molecular dynamics simulation to clarify that the spatial structure of XQ-2d and Tf competitively binding to CD71. We also engineered XQ-2d-mediated targeted therapy for pancreatic cancer, using an XQ-2d-based complex for loading doxorubicin (Dox). Because CD71 is overexpressed not only in pancreatic cancer but also in a variety of tumors, our work provides a systematic novel way of studying a potential biomarker and also promising tools for cancer diagnosis and therapy, opening new doors for effective cancer theranostics.
Insights
Researchers identified CD71 as the target for aptamer XQ-2d, crucial for pancreatic cancer diagnosis and therapy. This aptamer shows potential for targeted drug delivery, improving cancer treatment outcomes.
Area of Science:
- Biotechnology
- Molecular Biology
- Cancer Research
Background:
- Pancreatic cancer is a deadly disease requiring early diagnosis and effective treatments.
- An ssDNA aptamer, XQ-2d, was previously developed for pancreatic cancer targeting.
- Identifying the specific binding target of XQ-2d is essential for its therapeutic application.
Purpose of the Study:
- To identify the target of the ssDNA aptamer XQ-2d.
- To characterize the binding interaction between XQ-2d and its target.
- To develop XQ-2d-based targeted therapy for pancreatic cancer.
Main Methods:
- Cell-SELEX strategy to develop aptamer XQ-2d.
- CD71 knockdown experiments to confirm target binding.
- Competitive binding assays with transferrin and anti-CD71 antibody.
- Surface energy transfer nanoruler for binding site distance measurement.
- Molecular dynamics simulations for binding interaction analysis.
- Engineering of XQ-2d-doxorubicin complex for drug delivery.
Main Results:
- CD71 was identified as the specific binding target for aptamer XQ-2d.
- XQ-2d binds to membrane-bound CD71 and shares a binding site with transferrin.
- The distance between XQ-2d and anti-CD71 antibody binding sites is approximately 15 nm.
- Molecular dynamics simulations elucidated the competitive binding mechanism of XQ-2d and transferrin to CD71.
- An XQ-2d-based drug delivery system for doxorubicin was successfully engineered.
Conclusions:
- CD71 is a validated target for the aptamer XQ-2d in pancreatic cancer.
- XQ-2d demonstrates potential as a diagnostic biomarker and therapeutic agent.
- The developed XQ-2d-based theranostic tools offer a novel approach for cancer treatment.
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