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.