Design and Synthesis of Near-Infrared Peptide for in Vivo Molecular Imaging of HER2

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• 作者：Bishnu P. Joshi ; Juan Zhou ; Asha Pant ; Xiyu Duan ; Quan Zhou ; Rork Kuick ; Scott R. Owens ; Henry Appelman ; Thomas D. Wang
• 刊名：Bioconjugate Chemistry
• 出版年：2016
• 出版时间：February 17, 2016
• 年：2016
• 卷：27
• 期：2
• 页码：481-494
• 全文大小：873K
• ISSN：1520-4812

文摘

We report the development, characterization, and validation of a peptide specific for the extracellular domain of HER2. This probe chemistry was developed for molecular imaging by using a structural model to select an optimal combination of amino acids that maximize the likelihood for unique hydrophobic and hydrophilic interactions with HER2 domain 3. The sequence KSPNPRF was identified and conjugated with either FITC or Cy5.5 via a GGGSK linker using Fmoc-mediated solid-phase synthesis to demonstrate flexibility for this chemical structure to be labeled with different fluorophores. A scrambled sequence was developed for control by altering the conformationally rigid spacer and moving both hydrophobic and hydrophilic amino acids on the C-terminus. We validated peptide specificity for HER2 in knockdown and competition experiments using human colorectal cancer cells in vitro, and measured a binding affinity of k_d = 21 nM and time constant of k = 0.14 min^–1 (7.14 min). We used this peptide with either topical or intravenous administration in a preclinical model of colorectal cancer to demonstrate specific uptake in spontaneous adenomas and to show feasibility for real time in vivo imaging with near-infrared fluorescence. We used this peptide in immunofluorescence studies of human proximal colon specimens to evaluate specificity for sessile serrated and sporadic adenomas. Improved visualization can be used endoscopically to guide tissue biopsy and detect premalignant lesions that would otherwise be missed. Our peptide design for specificity to HER2 is promising for clinical translation in molecular imaging methods for early cancer detection.