EPIDERMAL GROWTH-FACTOR RECEPTOR EXPRESSION BY HUMAN SQUAMOUS-CELL CARCINOMAS OF THE HEAD AND NECK, CELL-LINES AND XENOGRAFTS

Epidermal growth factor receptor (EGFR) overexpression has been associ ated frequently with squamous cell carcinomas (SCC) and SCC cell lines . In most cases the level of EGFR on the tumours from which the cell l ines were derived has not been determined, nor have EGFR levels been d etermined for xenograft tumours from the cell lines. In this study we determined EGFR expression on a new series of head and neck SCC (SCCHN )-derived cell lines, which were obtained from tumours representing a spectrum of malignant progression, and two cell strains derived from e rythroplakia premalignant lesions. The level of EGFR on cell lines was determined by [I-125]EGF competitive binding assays. EGFR levels on s ome of the original tumours and xenografts of the cell lines were dete rmined on cryosections by a competitive binding assay based on [I-125] EGFR1, an EGFR-specific monoclonal antibody. EGFR expression on the tu mour cryosections was compared with expression on cryosections of skin and buccal mucosa. Eight of the ten tumour cell lines had elevated EG FR. Two of the tumour-derived cell lines and the two erythroplakia-der ived cell strains expressed EGFR at levels similar to that detected on normal keratinocytes in tissue culture. Only two of the tumours overe xpressed EGFR when compared with normal tissue. The other tumours had levels similar to that detected on the basal layers of skin or buccal mucosa. The xenografts expressed EGFR, as did the original tumours, ev en though they were derived from cell lines that displayed significant overexpression of EGFR. This study suggests that most tumours have a latent potential to overexpress EGFR which is realised in tissue cultu re.