ABSTRACT
Objective To discuss the role of DNA-dependent protein kinase catalytic subunit (DNA-DPKCS) in human lung adenocarcinoma cell line (A549) by using small interfering RNA (siRNA) to specifically knockdown DNA-DPKCS expression and its effects on cell proliferation, cell cycle and radio-sensitivity. Methods The DNA-DPKCS-siRNA expression vector was constructed and transfected into A549 cell line. The transformed clones were randomly selected and isolated. The cell cycle distribution and apop-tesis were analyzed by flowcytometry analysis. Cell survival was detected by using clonogenic formation as-say. Results With specific inhibition of DNA-DPKCS expression, stable transfected cell line 549pRNA-DNA-DPKCS was constructed by RNA interference technique. The 549pRNA-C and 549pSUPER cell lines were the control cell lines tansfected with control and blank plasmids, respectively. Compared with A549 cells, the expression levels of DNA-DPKCS mRNA (0.110: 1. 000), protein (0. 870: 2.967) and activity of DNA-DPKCS (0.004: 0.266) in 549pRNA-DNA-DPKCS cells were significantly lower (F = 80.55 ,P < 0.01;F=63.96, P<0.01;F=51.62,P<0.01, respectively). The analysis of SF_2(0.25:0.76), D_0 (1.42:1.62) and D_q (0.06: 1. 00) showed significant difference between 549pRNA-DNA-DPKCS and A549 cells (F = 996.86, P < 0.01 ; F = 17.41, P < 0.05 ; F = 68.92, P < 0.01). The number of 549pRNA-DNA-DPKCS cells in S (24.5%: 35.5%) and G_2 (10.7%: 11.0%) phases was significantly decreased (F = 4.83, P<0.05 and F=32.04, P <0.01, respectively). Conclusions In A549 cells, inhibit of DNA-DPKCS gene expression can enhance the radiosensitivity and affect cell cycle distribution.