Tumor-specific genetic expression profile of metastatic oral squamous cell carcinoma

Background. Metastasis is the most important predictor of survival in patients with oral squamous cell carcinoma (OSCC). We tested the hypothesis that there is a genetic expression profile associated with OSCC metastasis. Methods. We obtained samples from 6 OSCC node-positive primary tumors and their matched metastatic lymph nodes, and 5 OSCC node-negative primary tumors. Using laser capture microdissection, we isolated OSCC cells from metastatic lymph nodes and compared them with those from matched primary tumors and unmatched node-negative primary tumors using Affymetrix Human Genome Focus arrays. Results. Comparison of tumor cells from the lymph nodes with those from the unmatched, node-negative primary tumors revealed differential expression of 160 genes. Hierarchical clustering and principal component analysis using this 160-gene set showed that the node-negative samples were distinguishable from both, node-positive primary tumors and tumors in the lymph nodes. Many of the expression changes found in the metastatic cells from the lymph nodes were also found in the node-positive primary tumors. Immunohistochemical analysis for transglutaminase-3 and keratin 16 confirmed the differential genetic expression for these genes. Conclusion. These preliminary results suggest that there may be a metastatic gene expression profile present in nodepositive primary OSCC.