Synergistic Interactions Of TRAIL And Radiation On Apoptosis Of Lung Cancer Cell Line A549in Vitro

Objective：To investigate the effect of proliferative inhibition and apoptosis induced byTRAIL alone, TRAIL combined with ionizing radiation in lung cancer cell line A549,and the possible mechanism.Methods：1. MTT assay was used to detect the proliferative inhibition on the logarithmicphase A549cells, which was intervened by TRAIL and X-ray at differentconcentrations after24or48hours, providing the appropriate TRAIL interventionconcentration and X-ray irradiation dose for follow-up experiments.2. The apoptosis rate of the control, TRAIL, X-ray and combined group wereexamined48hours after intervened by flow cytometry.3. The expression of the death receptors DR4, DR5on the cell surface weremeasured48hours after handled by Western Blotting analysis.Results：1. MTT results showed that the proliferation of A549cells was restrained byTRAIL within the concentration range from3.9063to500ug/ml. And the effectdepended on the concentration and time, enhanced either the concentration increasedor time extended. The IC50of24h was208.93ug/ml, while IC50of48h was92.3ug/ml.Meanwhile, the A549cells presented inhibited while involved in the range of2-14Gyof X-ray. The inhibitory effect was right correlated with the dose and time.2. The apoptosis rate was obviously increased by TRAIL (20ug/ml) combinedwith X-ray (8Gy) group through flow cytometry. The average apoptosis rate of theearly phase in the combined group was (48.78±3.09)%, while the TRAIL group(12.33±1.99)%and the X-ray group (17.85±1.02)%. The difference wassignificant statistically(P﹤0.01).3. Western Blotting results showed that the expression of the death receptors DR4 and DR5in the cimbined group was noticeably increased(P﹤0.05), compared withthe TRAIL and X-ray group.Conclusions:1. TRAIL can inhibit the proliferation of lung caner cell line A549, and displays adependency relationship with the concentration and time.2. The capacity of TRAIL’s proliferation inhibition is maily carried out byapoptosis-inducing effect.3. The combined group can apparently promote A549cells apoptosis, themechanism may be associated with up regulation of the death receptors DR4and DR5.