Epidermal Growth Factor Receptor protein detection in head and neck cancer patients: a many faceted picture
Menée sur des échantillons tumoraux prélevés sur 79 patients atteints d'un carcinome épidermoïde de la tête et du cou, cette étude compare trois méthodes de mesure de l'expression du récepteur du facteur de croissance épidermique
Purpose: Epidermal growth factor receptor (EGFR) overexpression is associated with poor prognosis in head and neck squamous cell carcinoma (HNSCC). Despite intensive biomarker studies, a consensual method for quantification of EGFR protein expression is still lacking. Here we set out to compare three EGFR detection methods in tumor specimens from HNSCC patients. Experimental Design: Tumors were prospectively excised from a series of 79 high-risk HNSCC patients enrolled in a GORTEC-promoted clinical trial. EGFR expression was determined using ligand-binding assay on membranes, Western blotting (WB) on membranes and total homogenates, and immunohistochemistry (IHC) on tissue microarrays. In addition, phosphorylated EGFR (pEGFR) was measured by WB on membranes. Results: Distributions and ranges of tumor EGFR expression were method-dependent. Moderate positive correlations (Spearman coefficient r ≈ 0.50) were observed between EGFR expression measured by the binding assay and by WB or IHC. pEGFR level positively and significantly correlated with total EGFR expression measured by WB on membrane (highest correlation: r = 0.85), WB on homogenates, or binding assay. However, IHC did not correlate with pEGFR. Interestingly, the fraction of phosphorylated receptor (pEGFR/EGFR both measured by WB on membranes) significantly declined with increasing tumor EGFR expression, whatever the method used for total EGFR measurement (including IHC). Conclusion: This study shows significant correlations between EGFR detection methods. The observed relationships between EGFR and pEGFR indicate that high throughput pEGFR/EGFR analyses merit further investigations and consideration for routine use in patient samples.
Clinical Cancer Research , résumé, 2012