Visualization and quantitation of epidermal growth factor receptor homodimerization and activation with a proximity ligation assay.

Objectives: Activation of the epidermal growth factor receptor (EGFR) results from receptor homodimerization and autophosphorylation and confers sensitivity to tyrosine kinase inhibitors in some tumors. However, the visual detection and quantitation of activated EGFR in the clinical setting has not been established.

Materials And Methods: A proximity ligation assay (PLA) was applied to detect EGFR homodimers in non-small cell lung cancer (NSCLC) cell lines and tissue specimens.

Results: PLA signals corresponding to EGFR homodimers were higher in NSCLC cell lines and tissue specimens positive for activating mutations than in those wild type (WT) for . Stimulation with EGF in NSCLC cells WT for or forced overexpression of EGFR in Ba/F3 cells resulted in marked EGFR homodimerization. The extent of EGFR homodimerization appeared related to that of EGFR autophosphorylation in NSCLC cells WT for .

Conclusion: PLA may provide a new tool for detection and quantitation of EGFR homodimers in NSCLC and other tumors.