Effect of repeated irradiation on biological characteristics of lung adenocarcinoma cell line Anip973 in vitro

Objective: To study the effect of repeated irradiation on biological characteristics of human lung adenocarcinoma cell line Anip973 in vitro. Methods: Anip973 cells were treated with high energy X-ray to a total dose of 60 Gy at 4 Gy fractions. The radiosensitivity of Anip973R and its parental cell were measured by clonogenic assay. The biological parameters were fitted to the single hit multitarget formula. Furthermore, the population double time(PDT) and cell cycle distribution were measured by cell growth curve and flow cytometry, respectively. Results: Comparing with its parental cell, Anip973 R acquired radioresistance showing increased D0, Dq and SF2 and a broader shoulder. PDT of Anip973R extended 3 h more than that of Anip973. The Anip973R also showed higher and lower percentage of cells in G1 and S phase (P<0.05), respectively, but similar G2/M distribution (P>0.05). Conclusions: A radioresistant lung adenocarcinoma cell line Anip973R is established by repeatedly irradiation. Its radioresistance displays obviously in lower dose area. However, its characteristic of cell cycle is not completely coincident with the classical radiobiological theory. (authors)