Tumor necrosis factor-related apoptosis-inducing ligand induces glioma U87 cell apoptosis through the mitochondrial apoptotic pathway

Objective To study the mechanism of tumor necrosis factor-related apoptosis-inducing ligand(TRAIL)-induced apoptosis of glioma U87 cells.Methods Human glioma U87 cells were treated with human recombinant soluble TRAIL(rsTRAIL),and the cell apoptosis was detecmd with flow cytometry with AnnexinV-FITC/PI double staining.Flow cytometry with DiOC6 staining was used to assess the changes in mitochondrial transmembrane potential(△ψm).The relative activity of caspase-3,-8 and-9 Was measmed by colorimetric assay,and the concentration of cytoplasmic cytochrome C(cyt C) determined using enzyme-linked immunosorbem assay.The effects ofcaspase-8 inhibitor(Z-IETD-fmk)on rsTRAIL-induced apoptosis,△ψm,caspase-3,-8 and-9 activities and cyt C concentration were observed. Results RsTRAIL tinle-dependently induced apoptosis and progressive collapse of △ψm in glioma U87 cells,resulting also in caspase-3,-8 and-9activation and elevated cytC concentration.Caspase-8 inhibitor partially antagonized these biological effects induced by rsTRAIL in U87 cells.Conclusion TRAIL initiates a cascade of mitochondrial events by activating caspase-8 and induces apoptosis of glioma U87 cells. Key words: Tumor necrosis factor-related apoptosis-inducing ligand; Glioma; Apoptosis; Mitochondria