Functional Charaterization Of GBP2 In Glioblastoma

Objective: To investigate the biological functions and molecular mechanisms of Guanine nuclectide binding protein 2(GBP2)in glioblastoma multiforme(GBM).Methods: We fisrt examined the expression profile of GBP2 in GBM with the Cancer Genome Atlas(TCGA)dataset and a collection of GBM patient samples and cell lines by RT-q PCR and Western blot.We then investigated the biological function of GBP2 in a cell culture system using the gain-/loss-of-function strategies.The cell migration was determined by Wound Healing assay;cell proliferation was analyzed by the WST-1 assay;cell invasion ability was assessed by the Matrigel Invasion Assay.The q RT-PCR was used to screen cell movement/invasion-related target genes which were induced by GBP2 desregulation in GBM cells.Western blot method was done to validate the expression level of the screened genes and to examine the potential signal pathway regulating the downstream target genes induction.The effect of GBP2 on tumor growth and invasion in vivo was studied by subcutaneous and intracranial tumor models of nude mice.H&E and immunohistochemistry staining of tissue sections were performed to study the effect of GBP2 expression in particular gene expression.Kaplan-Meier survival studies were performed on tumor bearing mice.Results: We found that GBP2 is highly elevated in GBM patient samples and cell lines,and its expression is inversely correlated with the survival time of GBM patiens.Wound Healing assay showed that overexpression of GBP2 significantly promotes the cell migration of GBM cells,and the silencing of GBP2 expression inhibits cell migration.WST-1 assay showed that GBP2 has no obvious effect on the cell growth of GBM cell in vitro.Matrigel Invasion Assay showed that GBP2 can significantly increase the invasion ability of glioma cells.The q RT-RCR results and Western blot showed that Fibronectin(FN1)is dramatically induced by GBP2 exression at both m RNA and protein levels.We further showed that STAT3-FN1 pathway is essential for GBP2-promotedd cell invasion.Our subcutaneous nude mice model showed that GBP2 significantly increases the growth rate of glioma in vivo;the orthotopic model showed that GBP2 is able to promote both glioma growth and invasion of gloma in vivo,and the survival experiments show that GBP2 can significantly reduce the survival time of the nude mice bearing tumor(P < 0.05).Conclusions:1.GBP2 is significantly overexpressed in GBM tissues and cell lines,and its high expression pattern is related to poor outcomes of GBM patients.2.GBP2 expression has minor effect on GBM cell proliferation in vitro.3.Over-expression of GBP2 enhances GBM cell migration and invasion in vitro.4.STAT3-FN1 pathway is required for GBP2-driven GBM cell invasion.5.GBP2 promotes giloblastoma growth and invasion in mice,and its expression shortens the survival time of tumor bearing mice.