title: Identification of new accessible tumor antigens in human colon cancer by ex vivo protein biotinylation and comparative mass spectrometry analysis.
abstract: One of the most promising new strategies for the development of efficacious cancer therapies relies on the targeted delivery of biopharmaceutical to the tumor environment by the use of selective and specific antibodies. The identification of accessible perivascular proteins selectively overexpressed in cancer tissue may facilitate the development of antibody-based biopharmaceutical administration. This approach is potentially highly selective and specific, combining the presence of tumor biomarkers readily accessible from the blood vessels and the high rate of angiogenesis characteristic of cancer tissues. We performed ex vivo perfusions of surgically resected human colon cancer using a reactive ester derivative of biotin, thus achieving a selective covalent modification of accessible proteins in vascular structures and stroma. After extraction and purification, biotinylated proteins were digested and the resulting peptides submitted to a comparative mass spectrometry-based proteomic analysis, revealing quantitative differences between normal and cancer colon. Sixty-seven of the total 367 proteins identified were found to be preferentially expressed at the tumor site. We generated human monoclonal antibodies against 2 potential tumor targets, NGAL and GW112, and we proved their selective expression in cancer colon and not or barely in healthy tissues. This article presents the first proteomic analysis of human colorectal cancer structures readily accessible from the tumor vasculature, revealing the overexpression of novel tumor antigens which may serve as selective targets for antibody-based imaging and therapeutic biomolecular strategies.
authors.affiliation: Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.
authors.forename: Paolo
authors.initials: P
authors.lastname: Conrotto
authors.forename: Christoph
authors.initials: C
authors.lastname: Roesli
authors.forename: Jascha
authors.initials: J
authors.lastname: Rybak
authors.forename: Philippe
authors.initials: P
authors.lastname: Kischel
authors.forename: David
authors.initials: D
authors.lastname: Waltregny
authors.forename: Dario
authors.initials: D
authors.lastname: Neri
authors.forename: Vincent
authors.initials: V
authors.lastname: Castronovo
mesh_terms: D000209:Acute-Phase Proteins / Q000037:antagonists & inhibitors* / Q000276:immunology; D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D000951:Antigens, Neoplasm / Q000302:isolation & purification*; D000970:Antineoplastic Agents / Q000494:pharmacology; D019921:Biotinylation / Q000379:methods; D001943:Breast Neoplasms / Q000276:immunology; D002851:Chromatography, High Pressure Liquid; D003110:Colonic Neoplasms / Q000175:diagnosis / Q000276:immunology* / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D016179:Granulocyte Colony-Stimulating Factor / Q000037:antagonists & inhibitors* / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D000071068:Lipocalin-2; D054834:Lipocalins / Q000037:antagonists & inhibitors* / Q000276:immunology; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D040901:Proteomics; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000276:immunology; D015203:Reproducibility of Results; D015854:Up-Regulation
chemical_list: D000209:Acute-Phase Proteins; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; C454127:OLFM4 protein, human; D011518:Proto-Oncogene Proteins; D016179:Granulocyte Colony-Stimulating Factor