CXCL12-induced upregulation of FOXM1 expression promotes human glioblastoma cell invasion

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor; it is highly aggressive and is associated with a poor prognosis. Binding of the chemokine CXCL12 to its receptors (CXCR4 and CXCR7) contributes to the activation of many downstream signaling pathways and promotes the invasion of various malignant tumor cells, including GBM cells. FOXM1, a transcription factor involved in cell cycle regulation, is overexpressed in GBM and is involved in GBM progression. However, the molecular mechanisms by which CXCL12 promotes the invasion of human GBM cells remain unclear. In this study, we demonstrate that CXCL12 increases the production of FOXM1 by binding to CXCR4 in GBM cell lines. Furthermore, pretreatment with an inhibitor of the PI3K/AKT pathway abrogated the CXCL12-induced expression of FOXM1. In addition, there was a positive correlation between CXCL12/CXCR4 expression and FOXM1 expression in human malignant glioma tissues. Finally, a functional assay revealed that CXCL12 does not stimulate GBM cell invasion when FOXM1 expression is silenced using a small interfering RNA (siRNA). Collectively, these findings suggest that CXCL12 promotes GBM cell invasion in part by increasing the expression of FOXM1, which is mediated in part by a PI3K/AKT-dependent mechanism in vitro.