ABSTRACT
<p><b>OBJECTIVE</b>To investigate DNA-dependent protein kinase catalytic subunit (DNA-PKcs) content and activity in lung adenocarcinoma cell lines and its correlation with radiosensitivity.</p><p><b>METHODS</b>The content and activity of DNA-PKcs were analyzed in two lung adenocarcinoma cell lines A549 and H1299 by Western blotting and the Signa TECT DNA-PK assay kit. The dose-survival relationship for two cell lines was analyzed using clonogenic formation assay.</p><p><b>RESULTS</b>A549 was more radiosensitive than H1299. The survival fractions at 2 Gy (SF2) were 0.7412 in A549 cell line and 0.2473 in H1299 cell line. The content of DNA-PKcs was significantly higher in A549 cells than in H1299 cells (t=10.37, P<0.001). The integrated optical densities were 3.29-/+0.44 in A549 cells and 0.50-/+0.17 in H1299 cells. DNA-PKcs activities in A549 and H1299 cells were 8.29-/+1.37 and 2.47-/+1.09, respectively, showing a significant difference between them (t=5.76, P=0.005).</p><p><b>CONCLUSION</b>DNA-PKcs is an important factor to affect the radiosensitivity of lung adenocarcinoma cell lines.</p>