RECK regulated endoplasmic reticulum stress response and enhanced cisplatin-induced cell death in neuroblastoma cells

Background. Reversion:inducing-cysteine-rich protein with Kazal motifs (RECK) is critical for the invasiveness and metastasis of tumor cells; however, its role in regulating the endoplasmic reticulum (ER) stress response remains unclear In this study we investigated the protein that interacts with RECK and the effects of RECK overexpression on the ER stress response and on cisplatin-induced cell death in neuroblastoma cells. Methods. Full-length RECK (FL-RECK) or a C-terminus-deleted mutant of RECK (del-C-RECK) was transfected into neuroblastoma cells. An immunoprecipitation (IF) assay and liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis were used to identify the RECK-interacting proteins. The interaction between RECK and these proteins was confirmed using co-IP and an immunofluorescence assay. Phosphorylation of double-stranded, RNA-activated protein kinase-like, ER-localized eukaryotic initiation factor-2 alpha (eIF-2 alpha) kinase (PERK) and eIF-2 alpha, and expression of ER stress-related apoptotic factors were studied by Western blot analysis. Results. Glucose-legulated protein 78 (GRP78) was identified as the RECK-interacting protein in neuroblastoma cells, and the C-terminus region of the RECK protein was shown to interact with GRP78. Overexpression of FL-RECK, but not of del-C-RECK, increased the phosphorylation of PERK and eIF-2 alpha in neuroblastoma cells. With cisplatin treatment, the expression of phosphorylated PERK and eIF-2 alpha, CCAAT/enhancer-binding protein-homologous protein, Bax, and caspase-4 and -7 was higher and the cell viability was lower (P < .01) in FL-RECK-overexpressing cells than in del-C-RECK-overexpressing or vector control cells. Conclusion. RECK regulated the cellular ER stress response through interaction with GRP78 and enhanced cisplatin-induced cell death in neuroblastoma cells.