OBJECTIVES: To compare quantitatively the expression of CXCR4 mRNA in established OSCC cell lines with normal oral keratinocytes and to determine CXCR4 protein production.
METHODS: Normal oral keratinocytes and four OSCC cell lines (SCC4, SCC25, H357 and TR146) were grown under optimum conditions. RNA was extracted and amplified using standard techniques. Microarray hybridisations were run in duplicate and quantitative RT-PCR in quadruplicate. Immunocytochemistry with an anti-CXCR4 monoclonal antibody was performed using standard protocols.
RESULTS: Microarray data showed that CXCR4 was the only chemokine receptor that significantly increased in expression (8-10 fold, p<0.05) and this occurred in two of four (SCC4 and SCC25) OSCC cell lines. This finding was replicated by qRT-PCR (500-1000 fold, p<0.001). In two OSCC lines (H357 and TR146) expression did not differ from normal oral keratinocytes. Immunocytochemistry showed that CXCR4 protein expression mirrors mRNA expression.
CONCLUSIONS: Significantly increased CXCR4 expression occurs in two out of four OSCC lines tested and this raises the possibility that CXCR4 is important in the metastatic spread of OSCC to cervical nodes. Further work is required to determine its exact role in vivo.
FUNDING: British Association of Oral & Maxillofacial Surgeons Research Grant, British Association of Oral & Maxillofacial Pathologists Research Grant (no numbers).