Role of caspase 8 as a determinant in trail sensitivity of neuroblastoma cell lines.

Objective: Resistance of neuroblastoma (NB) cells to tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-mediated apoptosis is thought to be caused by loss of caspase 8 expression. The aim of this study is to investigate if induction of caspase 8 by gamma-interferon (IFN gamma) renders NB cells sensitive to TRAIL. Methods: Caspase 8 expression was monitored by RT-PCR and Western blot analysis. The effects of IFN gamma, TRAIL, IFN gamma + TRAIL, and caspase 8 inhibitor + TRAIL on the growth and apoptosis of NB cells were detected with the methods of reduction rate of Alamar blue assay and flow cytometry. The relative caspase 8 activity was measured with colorimetric assay. Results: An increased expression of caspase 8 mRNA and protein was found after treatment with IFN gamma. IFN gamma in combination with TRAIL decreased proliferation of NB cell line SH-SY5Y cells. The killing effect of TRAIL on NB cells expressing caspase 8 was depressed by caspase 8 inhibitor. The relative caspase 8 activity of NB cells expressing caspase 8 increased with the prolongation of TRAIL action time. Conclusions: TRAIL induced apoptosis in NB cells expressing caspase 8.