Detection of colonic neoplasia in vivo using near-infrared-labeled peptide targeting cMet

Xiaoli Wu,Henry D Appelman,Tse-Shao Chang,Fa Wang,Thomas D Wang,Rork Kuick,Xiaoqing Meng,Xue Li,Miki Lee,Juan Zhou,Gaoming Li,Jing Chen

doi:10.1038/s41598-019-54385-7

Xiaoli Wu, Henry D Appelman + Show 10 more

Open Access

https://doi.org/10.1038/s41598-019-54385-7

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Journal: Scientific Reports	Publication Date: Nov 29, 2019
Citations: 10	License type: open-access

Affiliation: University of Michigan–Ann Arbor

Abstract

White light colonoscopy is widely used to detect colorectal polyps, but flat and depressed lesions are often missed. Here, we report a molecular imaging strategy to potentially improve diagnostic performance by developing a fluorescently-labeled peptide specific for cMet. This 7mer is conjugated to Cy5.5, a near-infrared (NIR) cyanine dye. Specific binding to cMet was confirmed by cell staining, knockdown, and competition assays. The probe showed high binding affinity (kd = 57 nM) and fast onset (k = 1.6 min) to support topical administration in vivo. A mouse model (CPC;Apc) that develops spontaneous adenomas that overexpress cMet was used to demonstrate feasibility for real time in vivo imaging. This targeting ligand showed significantly higher target-to-background (T/B) ratio for polypoid and non-polypoid lesions by comparison with a scrambled control peptide. Immunofluorescence staining on human colon specimens show significantly greater binding to tubular and sessile serrated adenomas versus hyperplastic polyps and normal mucosa. These results demonstrate a peptide specific for cMet that is promising for endoscopic detection of pre-malignant lesions and guiding of tissue biopsy.

Highlights

White light colonoscopy is widely used to detect colorectal polyps, but flat and depressed lesions are often missed
The peptides were synthesized with >95% purity by HPLC, and an experimental mass-to-charge ratio (m/z) of 1827.10 was measured using mass spectrometry, which agrees with expected values, Fig. S1A,B
A linear, 7mer peptide specific for cMet was identified using methods of phage display by biopanning against the extracellular domain (ECD) of the purified protein

Summary

Introduction

White light colonoscopy is widely used to detect colorectal polyps, but flat and depressed lesions are often missed. A mouse model (CPC;Apc) that develops spontaneous adenomas that overexpress cMet was used to demonstrate feasibility for real time in vivo imaging This targeting ligand showed significantly higher target-to-background (T/B) ratio for polypoid and non-polypoid lesions by comparison with a scrambled control peptide. Immunofluorescence staining on human colon specimens show significantly greater binding to tubular and sessile serrated adenomas versus hyperplastic polyps and normal mucosa These results demonstrate a peptide specific for cMet that is promising for endoscopic detection of pre-malignant lesions and guiding of tissue biopsy. Chromoendoscopy uses topically-administered intravital dyes and narrow band imaging (NBI) uses filtered light in different spectral bands to highlight mucosal changes suspicious for disease[16,17] In these approaches, contrast is generated from non-specific mechanisms that are unrelated to the biological processes that drive CRC progression, and have shown limited effectiveness in clinical studies.

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