Characterization of a radioresistant lung cancer cell subline D6-R

Objective: To investigate the radioresistant mechanism of the newly established D6-R subline with respects to cell growth kinetics, radiation-induced apoptosis, DNA damage and repair. Methods: D6-R and the parent D6 cells were engaged in this study. Cell growth kinetics was determined using MTT assay, apoptosis was analyzed by flow cytometry and fluorescence microscopy, and DNA damage and repair were detected using alkaline comet assay. Results: D6-R and D6 cells showed the same growth kinetics pattern, and no evident apoptosis could be found pre- and post-irradiation in both cell lines. There were significant differences in radiation-induced initial DNA single strand breaks (SSB) and repair capacity between D6-R and D6 cells,i.e., D6-R showed less initial DNA SSB and better repair capacity. Conclusion: The milder initial DNA damage and stronger repair capacity exhibited in D6-R cells might be the cause of their radioresistance. (authors)