title: Epidermal growth factor receptor downregulation by small heterodimeric binding proteins.
abstract: No single engineered protein has been shown previously to robustly downregulate epidermal growth factor receptor (EGFR), a validated cancer target. A panel of fibronectin-based domains was engineered to bind with picomolar to nanomolar affinity to multiple epitopes of EGFR. Monovalent and homo- and hetero-bivalent dimers of these domains were tested for EGFR downregulation. Selected orientations of non-competitive heterodimers decrease EGFR levels by up to 80% in multiple cell types, without activating receptor signaling. These heterodimers inhibit autophosphorylation, proliferation and migration, and are synergistic with the monoclonal antibody cetuximab in these activities. These small (25 kDa) heterodimers represent a novel modality for modulating surface receptor levels.
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Hackel
authors.forename: Jason R
authors.initials: JR
authors.lastname: Neil
authors.forename: Forest M
authors.initials: FM
authors.lastname: White
authors.forename: K Dane
authors.initials: KD
authors.lastname: Wittrup
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D015536:Down-Regulation / Q000187:drug effects; D000939:Epitopes; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D019151:Peptide Library; D010455:Peptides / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D015202:Protein Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D012441:Saccharomyces cerevisiae
chemical_list: D000939:Epitopes; D005353:Fibronectins; D019151:Peptide Library; D010455:Peptides; D011994:Recombinant Proteins; D066246:ErbB Receptors