Abstract
Three cell lines, IMC-2, IMC-3 and IMC-4 established from a patient with maxillary squamous cell carcinoma were used to determine the relationship between epidermal growth factor receptor (EGFR) and radiosensitivity. Immunostaining was performed with an anti-EGFR antibody. The intensity of staining reactivity was determined using an image analysis system and expressed as grey value (0-black to 255-white). The mean grey values of IMC-2, IMC-3 and IMC-4 were 181, 210 and 222, respectively, and were significantly different from one another (p<0.001). Therefore, there was the highest number of EGFR in IMC-2, secondary in IMC-3 and the lowest in IMC-4. The cells were then irradiated at 1, 2, 4, or 6Gy. Cell survival was assessed by a standard colony-forming assay. The highest surviving rates were shown in IMC-2 at 1, 2 and 4Gy, secondary in IMC-3 and the lowest in IMC-4. These results were significantly different between IMC-2 and IMC-4, and IMC-3 and IMC-4, but not significantly different between IMC-2 and IMC-3. The surviving rates of IMC-2, IMC-3 and IMC-4 after irradiation increased in the order of amount of EGFR in each cell line. The results support the findings of previous clinical studies that showed that increased expression of EGFR was associated with higher recurrence rates of glottic and maxillary sinus carcinoma in patients treated with radiation therapy. The amount of EGFR in cells may therefore be associated with their radiosensitivity.
