Establishment and cell cycle distribution pattern of a radioresistant subline from human lung cancer D6 cell line

Objective To establish a radioresistant cell subline from a human D6 lung cancer cell line and investigate the mechanism of radioresistance. Methods D6 human NSCLC cells were exposed to X-rays generated by a linear accelerator(650 cGy per fraction).After a total exposure dose of 5 200 cGy,a monoclone was obtained.The radiosensitivity and cell cycle distribution of this clone,together with its parent D6 cells,were measured by clonogenic assay and flow cytometry. Results The new clone,namely D6-R subline,had a higher D 0(D 0=2.08 Gy) and a broader initial shoulder(Dq=1.64 Gy, N =2.20)than those of the parent D6 cell line (D 0= 1.84 Gy、Dq=0.34 Gy, N =1.20),being 1.65-fold increase in radioresistance as regards to the SF 2.The D6-R subline also showed higher percentage of cells in S phase(53.4% vs 37.8%),but lower percentages in G 1(44.1% vs 57.2%) and G 2/M(2.5% vs 5%)phases. Conclusion The new subline D6-R is more radioresistant as compare to its parent D6 cell line,and has a different cell cycle distribution.