Effects of an EGFR-binding affibody molecule on intracellular signaling pathways.
Effects on intracellular signaling were studied in cells treated with the affibody molecule (ZEGFR:955)2 that targets the epithelial growth factor receptor (EGFR). EGFR is overexpressed in many types of cancers and plays a fundamental role in cell signaling and it is of interest to find targeting agents capable of blocking the receptor. The clinically approved antibody cetuximab (Erbitux) and the natural ligand EGF were included as reference molecules. Two EGFR-rich cell lines, A-431 and U-343, were exposed to the three targeting agents and lysed. The cell lysates were immunoprecipitated with the receptors, or directly separated by SDS-Page. Autophosphorylation of the receptors and phosphorylation of the downstream signaling proteins Erk and Akt, were evaluated by Western blotting. Although the three different agents compete for the same binding site on EGFR, they influenced the signaling differently. The affibody molecule did not induce autophosphorylation of EGFR or any other receptor in the EGFR-family but, in spite of this, induced phosphorylation of Erk in both cell lines and Akt in the A-431 cells. Thus, the results suggest that the signaling pattern induced by (ZEGFR:955)2 is only partly similar to that induced by cetuximab. This makes the affibody molecule a potentially interesting alternative to cetuximab for EGFR-targeted therapy since it might give different therapy-related effects on tumor cells and different side effects on normal tissues.
Nordberg
E
E
Biomedical Radiation Sciences, Department of Oncology, Radiology and Clinical Immunology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala, Sweden.
Ekerljung
L
L
Sahlberg
S H
SH
Carlsson
J
J
Lennartsson
J
J
Glimelius
B
B
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D045744:Cell Line, Tumor; D000068818:Cetuximab; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000187:drug effects* / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008024:Ligands; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D008024:Ligands; D011993:Recombinant Fusion Proteins; D004815:Epidermal Growth Factor; C512478:EGFR protein, human; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D000068818:Cetuximab