Gene expression profiling in squamous cell carcinoma of the oral cavity shows abnormalities in several signaling pathways

Objectives/Hypothesis: To examine gene expression profiles in squamous cell carcinoma of the oral cavity (oral SCC) compared with histologically matched normal tissue. Study Design: Fresh-frozen tissue was prospectively obtained from individuals undergoing surgical resections for oral SCC. Methods: RNA was extracted from seven sets of oral SCC and matched normal tissue. Gene expression profiles were obtained by interrogation of Affymetrix Gene Chip Arrays with cRNA prepared from the tissue. Expression values were subjected to a paired t test. Genes that were judged to differ between oral SCC and normal tissue were annotated according to their name in the Affymetrix Netaffx database and according to their function as indicated by their Gene Ontology Consortium number. Results: Of the 10,509 probe sets that were analyzed, 523 genes were abnormally expressed in SCC of the head and neck (P ≤ .01), and 417 of these genes were abnormally expressed. in all seven tumors in the same manner. Hierarchical clustering of the 121 genes that were abnormally expressed in cancerous relative to normal tissue (P ≤ .001) showed that the tissue segregated into two groups consisting of normal and transformed tissue, as expected. The abnormal expression of two genes that were up regulated in oral SCC (ADAM 12 and PTHLH) and two genes that were down-regulated in SCCHN (EMP-1 and P11) were confirmed by real-time polymerase chain reaction and immunohistochemistry (ADAM 12) using additional sets of tissue. Conclusions: The data showed that oral SCC aberrantly express genes in cellular pathways related to proliferation, apoptosis, extracellular matrix degradation, adhesion, transforming growth factor-β signaling, and transcription. Further work is needed to determine the role of these genes in the development and progression of oral SCC.