Human papillomaviruses and skin cancer.

Human papillomavirus (HPV)-induced skin warts are classically benign lesions. However an association between specific HPV types and skin cancer becomes obvious in epidermodysplasia verruciformis (EV). The analysis of this disease suggests that lesions infected with HPV types 5 and 8 carry a high risk of developing squamous cell carcinomas. The oncogenes of EV-viruses appear to be E6 and E2, rather than E7. The 'high risk' EV-viruses, HPV 5, 8, and 47, differ from related HPV types in the transforming activity of the E6 gene and in the density of positive transcription control elements in the non-coding region (NCR) of the genome. The extrachromosomal viral DNA in cancers may show deletions affecting regulatory sequences. EV-specific lesions occasionally occur in immunosuppressed patients and HPV 5 or 8 persist in some of the skin cancers to which these patients are prone. DNAs of HPV 2, 16, 34, or 41 were identified in few premalignant and malignant skin tumors of the general population.