Department of Internal Medicine, Division of Hematology/Oncology, University of California, Davis and Sacramento, CA 95817, USA.
Department of Biomedical Engineering, University of California, Davis, CA 95616, USA.
Molecules. 2019 Jan 16;24(2):309. doi: 10.3390/molecules24020309.
The current translation of peptides identified through the one-bead one-compound (OBOC) technology into positron emission tomography (PET) imaging agents is a slow process, with a major delay between ligand identification and subsequent lead optimization. This work aims to streamline the development process of F-peptide based PET imaging agents to target the integrin αβ₆. By directly identify αβ₆⁻targeting peptides from a 9-mer 4-fluorobenzoyl peptide library using the on-bead two-color (OBTC) cell-screening assay, a total of 185 peptide beads were identified and 5 beads sequenced for further evaluation. The lead peptide (VGDLTYLKK(FB), IC = 0.45 ± 0.06 μM, 25% stable in serum at 1 h) was further modified at the N-, C-, and bi-termini. C-terminal PEGylation increased the metabolic stability (>95% stable), but decreased binding affinity (IC = 3.7 ± 1 μM) was noted. C-terminal extension (, VGDLTYLKK(FB)KVART) significantly increased binding affinity for integrin αβ₆ (IC = 0.021 ± 0.002 μM), binding selectivity for αβ₆-expressing cells (3.1 ± 0.8:1), and the serum stability (>99% stable). Our results demonstrate the challenges in optimizing OBOC-derived peptides, indicate both termini of are sensitive to modifications, and show that further modification of is necessary to demonstrate utility as an F-peptide imaging agent.
当前，通过单珠单化合物（OBOC）技术鉴定的肽类物转化为正电子发射断层扫描（PET）成像剂的过程较为缓慢，配体鉴定与随后的先导优化之间存在重大延迟。本研究旨在为靶向整合素 αβ₆的 F 肽基 PET 成像剂的开发提供助力。通过采用基于珠上双色（OBTC）的细胞筛选测定法，直接从 9 肽 4-氟苯甲酰基肽文库中鉴定出针对 αβ₆的肽类物，共鉴定出 185 个肽珠，并对其中 5 个珠序列进行了进一步评估。先导肽（VGDLTYLKK（FB），IC = 0.45 ± 0.06 μM，在 1 小时内 25%稳定存在于血清中）在 N-、C-和双末端进一步修饰。C 末端聚乙二醇化增加了代谢稳定性（>95%稳定），但结合亲和力降低（IC = 3.7 ± 1 μM）。C 末端延伸（，VGDLTYLKK（FB）KVART）显著提高了对整合素 αβ₆的结合亲和力（IC = 0.021 ± 0.002 μM）、对表达 αβ₆的细胞的结合选择性（3.1 ± 0.8:1）以及血清稳定性（>99%稳定）。我们的研究结果表明，对 OBOC 衍生肽进行优化具有挑战性，表明肽的两端均对修饰敏感，并表明进一步修饰 是有必要的，以证明其作为 F 肽成像剂的实用性。
