Targeting chemokine receptor CXCR7 inhibits glioma cell proliferation and mobility.

BACKGROUND The functional contribution of chemokine receptor CXCR7 to malignant brain tumor biology remains controversial. MATERIALS AND METHODS Complementary methods were used to confirm CXCR7 expression in clinical glioblastoma multiforme (GBM) specimens and multiple GBM cell lines. Loss-of-function studies were performed using small interfering RNA (siRNA) technology. RESULTS Elevated CXCR7 levels correlated with reduced survival in glioma patients. CXCR7 was expressed by GBM cell lines and stem-like progenitor cells. Knockdown of CXCR7 by siRNA attenuated phosphorylation of the extracellular signal-regulated kinase (ERK1/2) signaling pathway in response to CXCL12 and resulted in significantly reduced cell proliferation, invasion and migration. Similarly, treatment of glioma cells with a small molecule antagonist of CXCR7, CCX771, significantly inhibited cell proliferation and invasion. CONCLUSION CXCR7 actively promotes the proliferation and invasive behavior of glioma tumor cells and stem-like progenitor cells and may be a potential target for glioma therapy.