ABSTRACT
Objective To observe the radiosensitization effect of Aidi injection on human lung adenocarcinoma A549 cells, and to analyze its possible mechanism.Methods ① A549 cells were treated with different concentrations of Aidi injection (1.875, 3.75, 7.5, 15, 30, 60 mg/mL) for 24 hours, and in the mean time, a blank control group was set up; the effect of Aidi injection on lung adenocarcinoma A549 cells proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay, and the 10% cell growth inhibitor concentration (IC10) was calculated. ② The experiments were divided into blank control, Aidi control, radiation and Aidi pretreatment groups. The Aidi control group was incubated for 24 hours by Aidi injection IC10; the radiotherapy group was given X-ray irradiation of 4 Gy followed by incubation for 24 hours; the Aidi pretreatment group was incubated for 24 hours by Aidi injection IC10 and then given X-ray irradiation of 4 Gy; the blank control group received equal volume of normal saline and was incubated for 24 hours. The survival fraction (SF) value was detected by cell colony formation assay; the protein levels of the serine phosphorylation at 139 locus of histone (γ-H2AX protein), the key protein in homologous recombination repair pathway (Rad51 protein) and the cell autophage characteristic protein (LC3 protein) were detected by Western Blot; the formation of autophagosome was observed by transmission electron microscope.Results Aidi injection possessed the suppression of the growth of human lung adenocarcinoma A549 cells, the proliferation of the cells in various Aidi groups was lower than that in the blank control group, with the increase in drug concentration, the A549 cell growth inhibition ratio (IR) was gradually increased, representing a dose dependent manner, and the IC10 was 3.09 mg/mL. Compared with the blank control group, the SF value in Aidi control group was not significantly different [(94.7±3.85)% vs. (100.0±0.00)%,P > 0.05], the SF value in radiation group was decreased [(71.8±5.9)% vs. (100.0±0.0)%,P < 0.05], and in Aidi pretreatment group, the value was further decreased compared with that in radiation group [(51.9±4.7)% vs. (71.8±5.9)%,P < 0.05]. Compared with the blank control group, the expression of γ-H2AX protein in the three treatment groups was significantly increased, the degree of increase in Aidi pretreatment group was the most obvious, and it was significantly higher than that in radiation group (gray value: 1.44±0.11 vs. 0.93±0.09,P < 0.05). But the expression of Rad51 protein was the highest in radiation group, and it was higher than that in Aidi pretreatment group (gray value: 1.37±0.07 vs. 0.78±0.04, P < 0.05). Compared with the blank control group, the LC3Ⅱ/LC3Ⅰ value in Aidi control group, radiation group and Aidi pretreatment group were increased, and the degree of increase in Aidi pretreatment group was the most significant (0.35±0.06, 0.37±0.07, 0.49±0.06 vs. 0.05±0.04, allP < 0.05). Under transmission electron microscope, compared with the blank control group, the autophagosome in all treatment groups was increased to some extent, and the degree of increase in Aidi pretreatment group was the most remarkable.Conclusion Aidi injection has the enhancing effect of radiosensitization on human lung adenocarcinoma A549 cells, and its mechanism is possibly related to the up-regulation of A549 cell autophagy level.