Quantitative Real-Time Monitoring of Antibody-Induced Internalization of Epidermal Growth Factor Receptor on Single Living Mammalian Cells Using Scanning Electrochemical Microscopy

An antibody-induced internalization of epidermal growth factor receptor (EGFR) was quantitatively monitored using scanning electrochemical microscopy (SECM) at the single-cell level. The antibody Cetuximab is used for cancer treatment because of its capability to bind and internalize EGFR, which is one of the key membrane proteins associated with many cancers. To monitor antibody-induced EGFR internalization, Cetuximab was simply labelled with enzymes and the resulting enzymatic products were then electrochemically detected by using a microelectrode. By optimizing experimental parameters, such as immunostaining condition, enzyme type, and buffer solution, we were able to successfully monitor the EGFR internalization by using SECM, from which we found a decrease in current responses from a single living cell by 20 % in the first 60 min, suggesting different internalization pathways from inherent ligand-induced internalization.