NF-κB participates in chemokine receptor 7-mediated cell survival in metastatic squamous cell carcinoma of the head and neck

Metastatic squamous cell carcinoma of the head and neck (SCCHN) has been shown to express chemokine receptor 7 (CCR7), which activates phosphoinositide-3 kinase/Akt/mammalian target of rapamycin (PI3K/Akt/ mTOR) signal pathway to promote the invasion and survival of SCCHN cells. Since nuclear factor-kappa B (NF-κB) is shown to be the downstream signal molecule of PI3K/Akt in many tumors, we investigated whether it also exists in the CCR7 pathway in SCCHN, and the relationship between NF-κB and PI3K/Akt/mTOR, and the role it plays in SCCHN. We assayed the phosphorylation of the inhibitor of NF-κB (IκBα), the NF-κB DNA-binding capacity and location. The results showed that the interaction between CCR7 and the ligand for CCR7, CCL19, induces phosphorylation of IκBα, causes NF-κB to translocate to the nucleus and raises the DNA-binding capacity of NF-κB. The phosphorylation and DNA-binding capacity were abolished by the inhibition of CCR7, PI3K, Akt and mTOR. Further research demonstrated that inhibitors of NF-κB and CCR7-PI3K attenuate the survival of CCR7-mediated cells, causing decreased viability, increased apoptosis and increased cell cycle arrest in SCCHN cells. In clinical samples from 78 patients, immunohistochemical assay also showed that CCR7 and NF-κB are not only highly expressed in SCCHN, but also correlated with each other, and related to lymph node metastasis and clinical stage. Together, our data indicate that NF-κB is activated by CCR7 via PI3K/Akt/mTOR, and this signal pathway plays an important role in regulating the cell survival and prognosis of SCCHN.