Order of amino acids in C-terminal cysteine-containing peptide-based chelators influences cellular processing and biodistribution of (99m)Tc-labeled recombinant Affibody molecules
2012 (English)In: Amino Acids, ISSN 0939-4451, E-ISSN 1438-2199, Vol. 42, no 5, 1975-1985 p.Article in journal (Refereed) Published
Affibody molecules constitute a novel class of molecular display selected affinity proteins based on non-immunoglobulin scaffold. Preclinical investigations and pilot clinical data have demonstrated that Affibody molecules provide high contrast imaging of tumor-associated molecular targets shortly after injection. The use of cysteine-containing peptide-based chelators at the C-terminus of recombinant Affibody molecules enabled site-specific labeling with the radionuclide (99m)Tc. Earlier studies have demonstrated that position, composition and the order of amino acids in peptide-based chelators influence labeling stability, cellular processing and biodistribution of Affibody molecules. To investigate the influence of the amino acid order, a series of anti-HER2 Affibody molecules, containing GSGC, GEGC and GKGC chelators have been prepared and characterized. The affinity to HER2, cellular processing of (99m)Tc-labeled Affibody molecules and their biodistribution were investigated. These properties were compared with that of the previously studied (99m)Tc-labeled Affibody molecules containing GGSC, GGEC and GGKC chelators. All variants displayed picomolar affinities to HER2. The substitution of a single amino acid in the chelator had an appreciable influence on the cellular processing of (99m)Tc. The biodistribution of all (99m)Tc-labeled Affibody molecules was in general comparable, with the main difference in uptake and retention of radioactivity in excretory organs. The hepatic accumulation of radioactivity was higher for the lysine-containing chelators and the renal retention of (99m)Tc was significantly affected by the amino acid composition of chelators. The order of amino acids influenced renal uptake of some conjugates at 1 h after injection, but the difference decreased at later time points. Such information can be helpful for the development of other scaffold protein-based imaging and therapeutic radiolabeled conjugates.
Place, publisher, year, edition, pages
2012. Vol. 42, no 5, 1975-1985 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-164422DOI: 10.1007/s00726-011-0927-xISI: 000302812700042PubMedID: 21573874OAI: oai:DiVA.org:uu-164422DiVA: diva2:525016