Effects of IGFBP-2 on proliferation,phosphorylation and nuclear translocation of ERK1/2 in U251 human glioblastoma cells

Objective To investigate the effects of exogenous insulin-like growth factor binding protein-2(IGFBP-2) on U251 human glioblastoma cells proliferation and activation of extracellular signal regulated kinases(ERK1/2) signaling pathway.Methods MTT assay was used to examine the influence of IGFBP-2 on U251cells proliferation;the phosphorylation level and intracellular localization of ERK1/2 in cells treated with IGFBP-2 were tested by Western blotting analysis and immunofluorescence staining respectively.Results IGFBP-2(125,250,500 ng/ml) stimulated U251 cells growth(P0.01).When U251 cells treated by 500 ng/ml IGFBP-2 for 5 min,phosphorylated ERK1/2 increased by nearly one-fold(P0.05);and treated by 500 ng/ml IGFBP-2 for 30 min,phosphorylated ERK1/2 increased by nearly three-fold(P0.05).Stimulation of U251 cells with 500 ng/ml IGFBP-2 for 30 min resulted in nuclear translocation of phosphorylated ERK1/2(P0.01).Conclusion IGFBP-2 induced U251 cell proliferation may be mediated by activation of the ERK1/2 pathway.