Abstract:

Objective: To detect the inhibitory effect of gallic acid on the proliferation of human non-small cell lung cancer A549 cells,and to investigate the molecular mechanisms of its drug toxicity.Methods: The human non-small cell lung cancer A549 cells were cultured in vitro.The cells were divided into control group,low,middle,and high dosages of gallic acid groups (0,300,500 and 750 μmol·L^-1).The survival rates of cells were tested by MTT method; the morphology of A549 cells were tested by Switzerland and Giemsa staining; the apoptotic rates of A549 cells and the levels of reactive oxygen species (ROS) in A549 cells were analyzed by FCM; the expression levels of Fas and FasL in the A549 cells in various groups were detected by Western blotting method; the activities of catalase(CAT),superoxide dismutase (SOD)and glutathione peroxidase(GSH-Px) in the A549 cells in various groups were analyzed by spectrophotometry.Results: Compared with gallic acid treatment for 6 h,the survival rates of A549 cells treated for 12 and 24 h in different dosages of gallic acid groups were significantly decreased(P<0.05),and the cell survival rates were gradually decreased with the prolongation of treatment time.Compared with control group,the survival rates of A549 cells in different dosages of gallic acid groups were significantly decreased after treatment for 24 h (P<0.05).The morphology of A549 cells in different dosages of gallic acid groups showed the typical apoptosis which were observed by Switzerland and Giemsa staining,such as the cytoplasmic shrinkage, small and round cell volume and so on.The results of and so on apoptotic examination showed that the apoptotic rates were increased with the increasing of dosage of gallic acid.The expression levels of Fas and FasL in A549 cells were increased with the increasing of gallic acid dosages.The expression levels of Fas were positively correlated with the expression levels of FasL (r=0.92,P<0.05).Compared with control group,the levels of ROS in A549 cells in low,middle and high dosages of gallic acid groups were increased (P<0.05).Compared with control group,the activities of CAT in A549 cells in different dosages of gallic acid groups were also increased,but there were no significant differences (P>0.05); the activities of CAT in A549 cells in different dosages of gallic acid groups were reduced with the increasing of gallic acid dosage.The activity of SOD in low dosage of gallic acid group was higher than that in control group (P<0.05).The activities of SOD in middle and high dosage of gallic acid groups were higher than that in control group (P<0.05),but there were no significant differences between various groups (P>0.05).The activities of SOD were reduced with the increasing of gallic acid dosages.The activity of GSH-Px in A549 cells in low dosage of gallic acid group was higher than that in control group,but there was no significant difference between various groups (P>0.05).The activities of GSH-Px in middle and high dosages of gallic acid groups were lower than that in control group,but there were also no significant differences between various groups (P>0.05).The activities of GSH-Px were also reduced with the increasing of gallic acid dosage.There were no significant differences of the activities of CAT,SOD, and GSH-Px in A549 cells between low,middle, and high dosages of gallic acid groups(P>0.05).Conclusion: Gallic acid can inhibit the proliferation of lung cancer cells by oxidative damages,and the Fas/FasL signal pathway might be one of the mechanisms for apoptosis-induced by gallic acid.

Key words: cancer,non-small cell lung, reactive oxygen species, catalase, glutathione peroxidase, gallic acid