Erythropoietin Protects Pancreatic beta-cell Line NIT-1 Cells Against Cytokine-Induced Apoptosis via Phosphatidylinositol 3-Kinase/Akt Signaling

Objective: Erythropoietin (EPO) is a cytokine that regulates the proliferation, differentiation, and survival of erythroid progenitor cells. EPO has recently been demonstrated to have a tissue-protective role by mediating anti-apoptotic signals through the erythropoietin receptor (EPOR) in various tissues, including brain, liver, and heart. We have previously examined pancreatic beta-cell line NIT-1 cells for the expression of EPOR by real-time PCR and determined that these cells were protected by EPO against cytokine-induced apoptosis. The precise underlying anti-apoptotic mechanisms in pancreatic beta-cells are poorly understood. The purpose of this study is to examine erythropoietin receptor expression in the NIT-1 pancreatic beta-cell line and the intracellular pathway related with its anti-apoptosis effect in NIT-1 cells. Methods: we examined the expression of EPOR by western blot. We investigate the role of erythropoietin in the survival of these cells, and whether the PI3K/AKT pathway is involved in this protective process. Results: NIT-1 cells expressed EPOR and, in the presence of certain cytokines, exposure of NIT-1 cells to recombinant human erythropoietin (rhEPO) significantly improved the impaired insulin secretion and inhibited cytokine-induced apoptosis. RhEPO caused a rapid activation of Akt and increased expression of Bcl-2. The protective anti-apoptotic effect of rhEPO was significantly abolished by a specific phosphatidylinositol 3-kiniase (PI3K) inhibitor, LY294002. Conclusions: Our findings indicate that EPOR is expressed in pancreatic beta-cell line NIT-1 cells and suggest that EPO may act as a survival factor requiring the PI3K/Akt pathway.