48. Relationship between Cellular Radiosensitivity and DNA Damage Measured by Come Assay

Miyako Goto, Yoshimi Ohtsuka, Mayumi Iwakawa, Kumiko Saegusa, Kaori Yasuda, Ryonfa Lee, Atsuko Ishikawa, Yoshinobu Harada and Takashi Imai

Keywords: comet assay, radiosensitivity, microarray

The purpose of this investigation was to determine whether comet assay and expression analysis of genes would predict the radiosensitivity of human cancer cell lines which showed differences in D10 or Dq values. Two human cancer cell lines were investigated. For comet assay, cells were irradiated with X-rays ato dose of 4 or 8Gy and DNA damage was assessed under alkali conditions. For expression analysis of genes, cells of each cell lines were exposed to X-rays at a dose of 2 Gy. The gene expression profiles of the two cell lines after irradiation using cDNA microarray analysis of 14,000 genes were clustered. The survival curve after X-ray irradiation for each cell lines introduced each D10 value. Comet assay was used as an index of induced DNA damage after irradiation. The value of the mean tail moment in each cell line was observed. A correlation between the D10 value of each cell line and the mean tail moment by the comet assay in each cell line was obtained. Cell lines could be separated as two groups a radiosensitive group and a radioresisitant group, depending on the comet assay and D10 values. Expression analysis of the microarray reveled several genes were induced in the radiosensitive cell line and suppressed in the radioresistant cell lines. These results suggest that the comet assay and gene expression analysis would promising for predicting the radiosensitivity of tumor tissue.