title: Transcriptional expression profiles of oral squamous cell carcinomas.
abstract: BACKGROUND
  Currently, the classification of oral squamous cell carcinoma (OSCC) depends heavily on the clinical and pathologic examination of tissue. This system can lead to the classification of potentially heterogeneous tumors into single groups when they may have different degrees of aggressiveness. No system to date has incorporated genetic changes as a factor by which to classify OSCC tumors.
  
  
  METHODS
  To test the hypothesis that OSCC has a genome-wide genetic expression profile that differs from normal oral tissue and that transcriptional expression profiling can be used to characterize the heterogeneity among tumors, the authors examined the genetic expression profiles of 26 invasive squamous cell carcinomas of the oral cavity and oropharynx, 2 premalignant lesions, and 18 normal oral tissue samples using oligonucleotide arrays that contained probes representing approximately 7000 full-length human genes.
  
  
  RESULTS
  Using hierarchical clustering analysis, the data show that oral carcinomas are distinguishable from normal oral tissue based on genome-wide transcriptional expression patterns. However, there is genetic expression profile heterogeneity among tumors of a particular histopathologic grade and stage. In addition, using a statistical approach that integrated normalization and regression analysis, the authors found 314 genes that were expressed differentially in the OSCC samples with statistical significance (P <or= 0.05). Of these, 239 genes were overexpressed in the OSCC samples, whereas 75 genes were down-regulated.
  
  
  CONCLUSIONS
  No statistically significant differences in gene expression were found between early-stage disease and late-stage disease or between metastatic tumors and nonmetastatic tumors. The implications of these findings for the prediction of clinical outcome and for the discovery of new OSCC tumor markers are discussed.
authors.affiliation: Department of Otolaryngology: Head and Neck Surgery, University of Washington, Seattle, Washington, USA.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Méndez
authors.forename: Chun
authors.initials: C
authors.lastname: Cheng
authors.forename: D Gregory
authors.initials: DG
authors.lastname: Farwell
authors.forename: Sherianne
authors.initials: S
authors.lastname: Ricks
authors.forename: S Nicholas
authors.initials: SN
authors.lastname: Agoff
authors.forename: Neal D
authors.initials: ND
authors.lastname: Futran
authors.forename: Ernest A
authors.initials: EA
authors.lastname: Weymuller
authors.forename: Nicole C
authors.initials: NC
authors.lastname: Maronian
authors.forename: Lue Ping
authors.initials: LP
authors.lastname: Zhao
authors.forename: Chu
authors.initials: C
authors.lastname: Chen
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000145:classification / Q000235:genetics* / Q000473:pathology; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009062:Mouth Neoplasms / Q000145:classification / Q000235:genetics* / Q000473:pathology; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D012044:Regression Analysis