Effect of combined TRAIL and oxaliplatin on the apoptosis of colorectal cancer cell line SW480

Objective To determine the effect and mechanism of tumor necrosis factor-related apoptosis-inducing ligand(TRAIL)combined with oxaliplatin on apoptosis of human colorectal cancer cell line SW480.Methods Proliferation inhibitory rate of TRAIL and oxaliplatin was examined by methyl!thiazolyl tetrazolium(MTT)assay.AnnexinⅤ-FITC and Propidium iodide(PI)were used to stain SW480 cells,and flow cytometry(FCM)was used to determine apoptosis after treatment of TRAIL and/or oxaliplatin.Results SW480 cells were not sensitive to TRAIL but relatively sensitive to oxaliplatin with dose-dependent cytotoxicity.Combination therapy of TRAIL and subtoxic level of oxaliplatin resulted in a synergistic cytotoxic effect.The proliferation inhibitory rate after 24-hour treatment of 100 ng/ml TRAIL,100 μg/ml oxaliplatin and TRAIL plus oxaliplatin was 8.62%,60.51% and 81.28% respectively while the apoptosis rate was 2.43%,11.76% and 18.37%.The synergistic cytotoxicity was high partly attributed to cell apoptosis,which was proved by simultaneous flow cytometry assay.Conclusion TRAIL combined with subtoxic level of oxaliplatin enhances the killing effect in SW480 cell,which is mainly attributed to cell apoptosis.