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Updated: Nov 28, 2025
Validated Immunochemical Assay for Comprehensive Determination of the Human Epidermal Growth Factor Receptor 2 Released from and Bound to Cells
Published on: May 9, 2025
EGFR Expression in HER2-Driven Breast Cancer Cells
Florian Weinberg1, Diana B Peckys2, Niels de Jonge1,3
1INM-Leibniz Institute for New Materials, 66123 Saarbrücken, Germany.
Abstract:
The epidermal growth factor receptor HER2 is overexpressed in 20% of breast cancer cases. HER2 is an orphan receptor that is activated ligand-independently by homodimerization. In addition, HER2 is able to heterodimerize with EGFR, HER3, and HER4. Heterodimerization has been proposed as a mechanism of resistance to therapy for HER2 overexpressing breast cancer. Here, a method is presented for the simultaneous detection of individual EGFR and HER2 receptors in the plasma membrane of breast cancer cells via specific labeling with quantum dot nanoparticles (QDs). Correlative fluorescence microscopy and liquid phase electron microscopy were used to analyze the plasma membrane expression levels of both receptors in individual intact cells. Fluorescent single-cell analysis of SKBR3 breast cancer cells dual-labeled for EGFR and HER2 revealed a heterogeneous expression for receptors within both the cell population as well as within individual cells. Subsequent electron microscopy of individual cells allowed the determination of individual receptors label distributions. QD-labeled EGFR was observed with a surface density of (0.5-5) × 101 QDs/µm2, whereas labeled HER2 expression was higher ranging from (2-10) × 102 QDs/µm2. Although most SKBR3 cells expressed low levels of EGFR, an enrichment was observed at large plasma membrane protrusions, and amongst a newly discovered cellular subpopulation termed EGFR-enriched cells.
Insights
This study introduces a novel method using quantum dots to simultaneously detect epidermal growth factor receptor (EGFR) and HER2 in breast cancer cells. Findings reveal heterogeneous receptor expression, crucial for understanding therapy resistance.
Area of Science:
- Oncology
- Molecular Biology
- Nanotechnology
Background:
- Epidermal growth factor receptor (HER2) is overexpressed in 20% of breast cancers.
- HER2, an orphan receptor, activates ligand-independently via homodimerization and heterodimerization with EGFR, HER3, and HER4.
- Heterodimerization is implicated in therapeutic resistance in HER2-overexpressing breast cancer.
Purpose of the Study:
- To develop a method for simultaneous detection of individual EGFR and HER2 receptors on breast cancer cell plasma membranes.
- To analyze plasma membrane expression levels and distribution of EGFR and HER2 in individual cells.
Main Methods:
- Specific labeling of EGFR and HER2 with quantum dot nanoparticles (QDs).
- Correlative fluorescence microscopy and liquid phase electron microscopy for single-cell analysis.
- Quantification of QD-labeled receptor surface densities.
Main Results:
- Heterogeneous expression of EGFR and HER2 observed within the cell population and on individual SKBR3 breast cancer cells.
- QD-labeled EGFR surface density: (0.5-5) × 101 QDs/µm2.
- QD-labeled HER2 surface density: (2-10) × 102 QDs/µm2.
- EGFR enrichment observed at plasma membrane protrusions and in a subpopulation of EGFR-enriched cells.
Conclusions:
- A novel QD-based method enables simultaneous detection and quantification of EGFR and HER2.
- Demonstrated heterogeneous expression of EGFR and HER2, with distinct distribution patterns.
- Identified a novel EGFR-enriched cell subpopulation, potentially relevant for therapeutic resistance mechanisms.
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