1 Nanomedicine, Department of Pharmacy, Faculty of Health and Medical Sciences, Københavns Universitet2 National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran.3 National Cell Bank of Iran, Pasteur Institute of Iran4 Department of Pharmacy, Faculty of Pharmaceutical Sciences, Københavns Universitet5 Department of Medical Biotechnology, Pasteur Institute of Iran6 Department of Medical Biotechnology, Faculty of Medical Sciences, Tarbiat Modares University7 Nanomedicine, Department of Pharmacy, Faculty of Health and Medical Sciences, Københavns Universitet8 Department of Pharmacy, Faculty of Pharmaceutical Sciences, Københavns Universitet
The tumor-associated glycoprotein 72 (TAG-72) is a membrane mucin whose over-expression is correlated with advanced tumor stage and increased invasion and metastasis. In this study, we identified a panel of four nanobodies, single variable domains of dromedary heavy-chain antibodies that specifically recognize the TAG-72 antigen. All selected nanobodies were shown to selectively bind to this cancer-related molecule with low-nanomolar affinities and do not cross-react with other antigens, such as MUC1 or HER2. Furthermore, they can detect TAG-72 in concentrations as low as 5 U/ml which is valuable in sensitive detection of this molecule in cancerous patients. Cell ELISA experiments proved their ability for binding to the native target antigen on TAG-72 expressing cells while not showing any reactivity to HT-29 cells, a TAG-72-negative cell line. Using competition studies, we found that each nanobody recognizes a distinct epitope on the TAG-72 antigen that is different from the one recognized by the mouse anti-TAG-72 antibody, CC49. Considering their high specificity, reduced immunogenicity and multi-targeting behavior, these oligoclonal nanobodies represent a promising tool to target TAG-72 over-expressing tumor cells.
Applied Biochemistry and Biotechnology, 2013, Vol 54, Issue 2, p. 590-601