Guanylate-binding protein 2 (GBP2) is an interferon-inducible large GTPase which is crucial to the protective immunity against microorganisms. However, its biological function in cancer remains largely unknown. Glioblastoma multiforme (GBM) is the most common and deadly brain tumor in adults. Here we show that GBP2 expression is highly elevated in GBM tumor and cell lines, particularly in those of the mesenchymal subtype. High GBP2 expression is associated with poor prognosis. GBP2 overexpression significantly promotes GBM cell migration and invasion in vitro, and GBP2 silencing by RNA interference exhibits opposite effects. We further show that fibronectin (FN1) is dramatically induced by GBP2 expression at both mRNA and protein levels, and FN1 is essential for GBP2-promoted GBM invasiveness. Inhibition of Stat3 pathway prevents GBP2-promoted FN1 induction and cell invasion. Consistently, GBP2 dramatically promotes GBM tumor growth and invasion in mice and significantly reduces the survival time of the mice with tumor. Taken together, these findings establish the role of GBP2/Stat3/FN1 signaling cascade in GBM invasion and suggest GBP2 may serve as a potential therapeutic target for inhibiting GBM invasion.
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Acknowledgements This work was supported with a grant from the National Natural Sciences Foundation of China (81572480). We thank Drs. Frank Furnari and Benjamin Purow for the gift of cell lines.