Radiobiological characteristics and MRN complex expression of human nasopharyngeal carcinoma cell lines

Objective To study the radiobiological characteristic of human nasopharyngeal carcinoma cell lines CNE1 and CNE2 and the changes in expression MRN （Mrel 1-RadS0-Nbsl ） complex in the cell lines exposed to irradiation. Methods CNE1 and CNE2 were irradiated by a linear accelerator. Radiobiological characteristics were detected by colony assay and MT'F assay. MRN complex expression were examined by Western blot. Results Surviving fraction at 2 Gy （SF2）, quasi-threshold Dose （Dq）, and mean lethal dose （Do） of CNE1 were 0.56, 1.449 Gy and 1.480 Gy; SF2, Dq, and Do of CNE2 were 0.44, 0.776 Gy and 1.685 Gy, respectively. Survival fraction of CNE1 at the day 6 after 4 Gy irradiation was 0.59 and that of CNE2 was 0.79 when compared with control, with the up-regulated expressions of RadS0 in CNE1 and Mrell, RadS0 and Nbsl in CNE2 （P <0.05）. Conclusions CNE1 and CNE2 were sensitive to radiation, but there were radioresistance cells in CNE2. The expressions of some components of MRN complex were up-regulated to repair DNA lesions induced by radiation. Key words: Nasopharyngeal neoplasms; Cell line, tumor; Radiation effects; Radiation tolerance; DNA-binding proteins; DNA repair enzymes; Nuclear proteins; Cell cycle proteins