ABSTRACT
Objective: To observe the apoptosis-inducing effect of recombinant mutant human tumor necrosis factor-related apoptosis-inducing ligand (rmhTRAIL): on human lung cancer cell line A549 and to identify the different protein expression profiles related to apoptosis. Methods: After the A549 cells were treated with rmhTRAIL, the proliferation viability was assessed by MTT assay, and the cell cycle and apoptosis were analyzed by flow cytometry. Then the liquid chromatograph-tandem mass spectrometer (LC-MS/MS): was used to detect the different expression profiles related to apoptosis. Finally, real-time fluorescence quantitative PCR (RFQ-PCR): and Western blotting were performed to identify the expression levels of apoptosis-related genes. Results: After A549 cells were treated with different concentrations of rmhTRAIL for 24 h, the inhibitory rates of proliferation were significantly increased in a concentration-dependent manner (all P < 0.05). The half maximal inhibitory concentration was (9.5±3.9): ×105 ng/mL. The early apoptosis rate was significantly increased after 5×105 ng/mL rmhTRAIL treatment for 24 h (P < 0.01). However, rmhTRAIL had no effect on cell cycle. After treatment with rmhTRAIL, the expressions of tumor necrosis factor receptor superfamily (TNFRSF): members 1 OB and 1 OD were down-regulated by 21.3% and 31.8%, respectively; and the expression of cellular FLICE-inhibitory protein (c-FLIP): was up-regulated by 2.867 times. Both RFQ-PCR and Western blotting analysis indicated that the expression of death receptor 5 (DR5), one of TNFRSF members, was down-regulated in both mRNA and protein levels (both P < 0.05). Relatively, the expression of c-FLIP was up-regulated in both mRNA and protein levels (both P < 0.05). Conclusion: rmhTRAIL can induce apoptosis of human lung cancer A549 cells, and this mechanism is associated with the down-regulation of DR5 expression and up-regulation of c-FLIP expression.