Expression of Ku80 correlates with sensitivities to radiation in cancer cell lines of the head and neck

The Ku protein is essential for the repair of a majority of DNA double-strand breaks in mammalian cells. The purpose of this study was to investigate the relationship between the expression of Ku70/80 and sensitivity to radiation in cancer cell tines of the head and neck. The sensitivity to radiation in various head and neck cancer cell tines (AMC-HN-1 to -9) was analyzed by colony forming assay. Of the nine cell tines examined, the most radiosensitive cell line (AMC-HN-3) and the most radioresistant cell line (AMC-HN-9) were selected for this experiments. The expression of Ku70/80 was examined after irradiation using real time PCR, Western blotting and immunofluorescence in two different cell lines. Cell cycle distribution after irradiation were analysed. A differential. radioresponse was demonstrated by expression of Ku70/80 in AMC-HN-3 and AMC-HN-9 cells. While the expression of Ku70 was slightly increased in the radioresistant AMC-HN-9 cell line, the expression of Ku80 was remarkably increased, suggesting a correlation between Ku80 expression and radiation resistance. Overexpression of Ku80 plays an important rote in the repair of DNA damage induced by radiation. Ku80 expression may provide an effective predictive assay of radiosensitivity in head and neck cancers. (c) 2005 Elsevier Ltd. All rights reserved.