CORRELATION OF EPIDERMAL GROWTH-FACTOR RECEPTOR AND RADIOSENSITIVITY IN HUMAN MAXILLARY CARCINOMA CELL-LINES

To determine the relationship between epidermal growth factor receptor (EGFR) and radiosensitivity, we immunostained cells from three maxill ary carcinoma cell lines with an anti-EGFR antibody. The intensity of staining reactivity, determined by means of an image analysis system, was expressed as grey value GO-black to 255-white). The mean grey valu es for cell lines IMC-2, IMC-3, and IMC-4 were 181, 210, and 222, resp ectively, and differed significantly (p < 0.001). This indicates that IMC-2 had the highest number of EGFR, followed by IMC-3 and IMC-4. The cells were then irradiated at 1, 2, 4, or 6 Gy, and cell survival was assessed by means of a standard colony-forming assay. IMC-2 had the h ighest survival rates at 1, 2 and 4 Gy. followed by IMC-3 and IMC-4. T herefore? the survival rates for IMC-2, IMC-3, and IMC-4 after irradia tion increased in proportion to the amount of EGFR in each cell line. The results support the findings of previous clinical studies which sh owed that increased expression of EGFR was associated with higher recu rrence rates of glottic and maxillary sinus carcinoma ill patients tre ated with radiation therapy. The amount of EGFR in cells may therefore be associated with their radiosensitivity.