Expression profiles of viral responsive genes in oral and oropharyngeal cancers

The association between Human Papillomavirus (HPV) DNA and oropharyngeal squamous cell carcinoma (SCC) has been supported by numerous studies strongly implicating HPV infection as a factor in the development of this cancer. In contrast, squamous cell carcinoma of the oral cavity has not been associated with HPV DNA, suggesting alternate aetiologic factors. The possibility that viral agents other than HPV could contribute to the development of oral cavity SCC should be given consideration, especially given the association of Epstein-Barr virus (EBV) with nasopharyngeal cancer. We used quantitative polymerase chain reaction (qPCR) studies to compare the expression levels of genes that may act as indicators of persistent stimulation by viral antigen in both oral cavity and oropharyngeal squamous cell cancers. Our results demonstrate that HPV-positive oropharyngeal tumours displayed gene expression patterns indicative of a viral signature and that HPV-negative oropharyngeal tumours do not display similar expression patterns. In contrast, we saw no evidence of either a viral or bacterial signature in the oral tumours examined. This would suggest that either an as of yet unidentified virus present in the oral tumour samples is not eliciting a typical immune response, or that there are no novel viral sequences or viruses present in the oral tumours examined.