Peptide Reagents for Detection of Colonic Dysplasia

University Of Michigan At Ann Arbor, Ann Arbor MI

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Abstract

[unreadable] DESCRIPTION (provided by applicant): [unreadable] Cancer originating from the epithelium of hollow organs, such as colon, esophagus, stomach, lung, cervix, and bladder, result in over 90% of all deaths by cancer in the U.S. The morbidity and mortality associated with this disease may be prevented by early detection of pre-malignant (dysplastic) mucosa. Confocal microendoscopy is an emerging technique of optical sectioning that can perform real time in vivo histopathology when adequately developed. The dual axes confocal architecture is a novel approach that provides sub-cellular resolution with long working distance, deep tissue penetration, high dynamic range, and scalability to millimeter dimensions with use of post-objective scanning and MEMS micro-mirrors. The long term objectives of this application are to identify peptide reagents that bind preferentially to dysplastic mucosa and to evaluate the clinical utility of confocal microendoscopy to perform in vivo detection, monitoring, and risk stratification of dysplasia present on epithelial surfaces with use of these peptide-dye reagents. This integrated optical methodology will first be demonstrated in colon using the adenoma as a model for dysplasia, and can then be applied to the early detection of other cancers with epithelial origin. The specific aims of this proposal include 1) to identify high affinity peptides that preferentially bind colonic dysplasia with high target-to-background ratio, screen candidate peptides for optimal mucosal binding affinity, and conjugate peptides to FITC; 2) to collect confocal fluorescence images ex vivo from biopsy specimens of colonic mucosa with topically administered peptide-FITC conjugates with the tabletop dual axes prototype, and 3) with the miniature, endoscope compatible dual axes prototype, including characterizing image signal-to-noise ratio, contrast ratio, and resolution. The preferential binding peptides will be identified using a M13 phage display library that expresses linear 7 amino acid peptides with a complexity of 109. Non-specific binding peptides will be removed from the library by panning against non-dysplastic columnar cells in culture and excised specimens of normal colonic mucosa. Dysplasia specific binding peptides will then be identified by panning with freshly resected adenomas. Candidate peptide-FITC reagents will then be administered topically to additional freshly resected adenomas, and then imaged first with the tabletop dual axes confocal microscope, and then with the miniature prototype. [unreadable] [unreadable] [unreadable]