SDF-1alpha promotes invasion of head and neck squamous cell carcinoma by activating NF-kappaB

CXCL12/stromal cell-derived factor-1alpha (SDF-1alpha), a chemokine ligand for the G protein-coupled receptor CXCR4, plays an important role in the directed movement of cells. Many studies have documented the importance of CXCR4 in tumor progression and organ-specific metastasis. Recently, several studies have implicated a role for SDF-1alpha in head and neck squamous cell carcinoma (HNSCC) metastasis, but currently there is little information about how SDF-1alpha promotes HNSCC metastasis. In this report we show that the NF-kappaB signaling pathway is activated in response to SDF-1alpha in HNSCC while primary and immortalized keratinocytes show no SDF-1alpha-mediated NF-kappaB activity. We found that SDF-1alpha-mediated NF-kappaB signaling is independent of phosphoinositide 3-kinase/Akt and ERK/MAPK pathways. We observed that SDF-1alpha induces IkappaBalpha phosphorylation and degradation and the nuclear translocation of NF-kappaB in HNSCC cell lines, suggesting that SDF-1alpha activates the classical NF-kappaB signaling pathway. Contrary to previous reports, SDF-1alpha-induced NF-kappaB activation is not mediated by tumor necrosis factor alpha. Furthermore, blocking the NF-kappaB signaling pathway with an IKKbeta inhibitor significantly reduces SDF-1alpha-mediated HNSCC invasion. Taken together, our data suggest SDF-1alpha/CXCR4 may promote HNSCC invasion and metastasis by activating NF-kappaB and that targeting NF-kappaB may provide therapeutic opportunities in preventing HNSCC metastasis mediated by SDF-1alpha.