Abstract 3286: Overexpression of cornulin in histologically normal adjacent tissue predicts occult nodal metastases in head and neck cancer patients

As with many epithelial cancers, presence of nodal metastases in patients with Head and Neck Squamous Cell Carcinoma (HNSCC) predicts early recurrence and poor survival. Determination of occult metastases in the clinically N-zero (cN0) patient remains problematic and therefore prophylactic neck dissections are routinely performed for high risk cN0 patients. A cohort of 7 cN0 HNSCC patients who subsequently underwent planned neck dissection as part of their treatment was selected. Snap frozen tissue was enriched for tumor and adjacent normal tissue by laser capture microdissection. Total protein was extracted and separated by saturation-labeling 2D difference in-gel electrophoresis (2D-DIGE). Significance analysis of Microarray (SAM) method was used to evaluate for differential protein expression between patients with (n=3) and without (n=4) occult nodal metastases on neck dissection pathologic evaluation. Spot maps were generated for 14 gels (7 HNSCC, 7 normal) and relative abundance values calculated for each of 662 protein spots common to >90% of gels. A 5% false discovery rate and 2-fold change were used as criteria for significance in the defintion of candidate biomarkers. Protein spots meeting these criteria were then extracted, digested and analyzed by liquid chromatography and tandem mass spectrometry to obtain protein identifications. For tumor tissue, there was no significant difference between groups. There were considerable differences in protein expression for normal adjacent tissue between patients with and without occult metastases, with 60 spots meeting criteria for significance (FDR