Induction of radioresistant nasopharyngeal carcinoma cell line CNE-2R by repeated high-dose X-ray irradiation

Background: all to enhance the curative effect of radiotherapy, we established a radio-resistant cell line, cne-2r from cne-2, a radio-sensitive type of cne, through repeated irradiation. the developed cell line provides a basis for further studies on the radio-resistance of cne and the molecular mechanism of radiotherapy sensitization drugs. materials and methods: the cne-2 cell line was selected and exposed repeatedly to high-dose x-ray intermittent irradiation (6 gy/fraction for seven fractions and 20 gy/fraction for three fractions). after the entire irradiation process, 20 gy/time was administered to cne irregularly. the cell growth curves of cne-2 and cne-2r were constructed based on mtt assays. dose-survival curves were obtained through colony-forming tests and subjected to linear quadratic formulation matching. sf2 and correlation parameters of radiation biology were calculated. changes in the cell cycle of cne-2 and cne-2r were also assessed by serum starvation. results: the doubling time of cne-2 was 2.4 days, which is 0.4 days shorter than that of cne-2r, indicating the faster growth rate of cne- 2. in the dose-survival equation of the survival clone test, the sensitization ratio of cne-2r was enhanced relative to that of cne-2. after synchronization and desynchronization for 24 h, g1 was arrested in cne-2r. in the s phase, which is insensitive to radiation, the ratio of g1 increased, hence altering the cell cycle. conclusion: we have established a radio-resistant nasopharyngeal carcinoma cell line by repeated exposure to radiation which is relevant to changes in the cell cycle.