Blockade of CXCR4 in oral squamous cell carcinoma inhibits lymph node metastases.

We have previously demonstrated that a stromal cell-derived factor-1 (SDF-1; CXCL12)/CXCR4 system is involved in the establishment of lymph node metastasis in oral squamous cell carcinoma (OSCC). In this study, we investigated whether the blockade of CXCR4 inhibits lymph node metastasis in B88 OSCC cells. These cells harbour a functional CXCR4 and have the potential to metastasise to the lymph node in vivo. Following introduction of a vector that expresses short hairpin small interfering RNA (shRNA) against CXCR4, we isolated three clones (shCXCR4-16, -17 and -21) that showed decreased expression of CXCR4 mRNA. These clones also had reduced CXCR4 protein levels and showed impairments in calcium flux and cell migration in response to SDF-1. These cells were orthotopically inoculated into the masseter muscle of nude mice. Lymph node metastases, loss in body weight and tumour volumes were significantly inhibited in mice inoculated with shCXCR4-17 cells compared to mice inoculated with control cells. SDF-1-induced migration of B88 cells was significantly inhibited in vitro by the treatment with 1,1'-[1,4-phenylenebis(methylene)]bis-1,4,8,11-tetraazacyclotetradecane octahydrochloride (AMD3100), a CXCR4 antagonist. Subcutaneous administration of AMD3100 significantly inhibited the lymph node metastases of B88 cells when they were orthotopically inoculated into the masseter muscle of nude mice. Moreover, the enhanced production of interleukin (IL)-6 and IL-8 in response to SDF-1 was inhibited by shRNA against CXCR4 or by treatment with AMD3100. These results suggest that blockade of CXCR4 may be a potent anti-metastatic therapy against lymph node metastases in cases of CXCR4-related OSCC.