OBJECTIVETo study the effect of gamma-interferon (IFNgamma), tumor necrosis factor related apoptosis inducing ligand (TRAIL), and cisplatin or etoposide induced apoptosis in human neuroblastoma cell line SH-SY5Y and its possible molecular mechanisms.

METHODSThe expressions of Caspase 8 mRNA and protein were detected with RT-PCR and Western blot analysis. The effects of IFN-gamma, TRAIL, IFNgamma + TRAIL, IFN-gamma + Caspase 8 inhibitor + TRAIL, IFNgamma + cisplatin + TRAIL, and IFNgamma + etoposide + TRAIL on the growth and apoptosis of SH-SY5Y cells were detected with the methods of MTT and flow cytometry. The relative Caspase 8 activity was measured with colorimetric assay.

RESULTSCaspase 8 was undetectable in SH-SY5Y cells but an increased expression of Caspase 8 mRNA and protein was found after treatment with IFNgamma. SH-SY5Y cells themselves were not sensitive to TRAIL, but those expressing Caspase 8 after treatment with IFNgamma were. The killing effect of TRAIL on SH-SY5Y cells expressing Caspase 8 was depressed by Caspase 8 inhibitor. Cisplatin and etoposide could enhance the sensitivity of TRAIL on SH-SY5Y cells. The relative Caspase 8 activity of SH-SY5Y cells in IFN-gamma + TRAIL group was significantly higher than those of control group, IFN-gamma group, TRAIL group, and inhibitor group (P < 0.01). There was no significant difference among IFN-gamma + TRAIL group, IFNgamma + cisplatin + TRAIL group, and IFNgamma + etoposide + TRAIL group.

CONCLUSIONSIFNgamma could sensitize SH-SY5Y cells to TRAIL-induced apoptosis and this may be realized by the up-regulation of Caspase 8. Cisplatin and etoposide could enhance the killing effect of TRAIL on SH-SY5Y cells.