Human papillomavirus infection in oral verrucous carcinoma: genotyping analysis and inverse correlation with p53 expression.

OBJECTIVE: Verrucous carcinoma (VC) is a rare subtype of squamous cell carcinoma, occurring mostly in oral mucosa. To clarify the role of human papillomavirus (HPV) in VC tumorigenesis, we investigated localization and genotypes of HPV and p53 expression in oral VC. METHODS: We studied paraffin-embedded specimens of 23 VCs and 10 control non-neoplastic lesions in oral mucosa. To investigate HPV infection, HPV genotypes and p53 expression, we respectively employed in situ hybridization (ISH), sequence analysis following short PCR fragment-PCR assay and immunohistochemistry. RESULTS: Of the 23 VC specimens, 11 (48%) had HPV-DNA (detectable by PCR), and 6 (26%) had intranuclear HPV in the upper portion of the squamous epithelium (detectable by ISH). Nine of the 11 PCR-positive specimens showed multiple infections with low- and high-risk HPVs. No HPV-16 infection was detected. Although HPV-6 and HPV-18 were frequently detected by PCR, no HPV could be found in control specimens by ISH. p53 expression was inversely correlated with HPV infection. CONCLUSION: Thus, multiple infections with low- and high-risk HPVs and their rapid replication during hyperkeratinization may participate in the histogenesis of oral VC. Oral VC tumorigenesis may involve the inactivation of p53, which is associated with HPV infection