1. ^*Institute of Virology, University of Cologne, Koeln, Germany;
2. ^†Department of Dermatology, Charité, University of Berlin, Berlin, Germany;
3. ^‡Cancer Research UK Skin Tumour Laboratory, Centre for Cutaneous Research, London, UK;
4. ^§Department of Virology, Barts and the London School of Medicine and Dentistry, London, UK;
5. ^¶Department of Dermatology and Venereology, Warsaw School of Medicine, Warsaw, Poland

Correspondence: S. J. Weissenborn, PhD, Institute of Virology, University of Cologne, Fuerst-Pueckler-Str. 56, 50935 Koeln, Germany. Email: Soenke.Weissenborn@medizin.uni-koeln.de or ulrike.wieland@uni-koeln.de

Received 7 October 2004; Revised 15 January 2005; Accepted 30 January 2005.

Abstract

Recent studies suggest a role of cutaneous human papillomaviruses (HPV) in non-melanoma skin cancer (NMSC) development. In this study viral DNA loads of six frequent HPV types were determined by quantitative, type-specific real-time-PCR (Q-PCR) in actinic keratoses (AK, n=26), NMSC (n=31), perilesional tissue (n=22), and metastases of squamous cell carcinomas (SCC) (n=8) which were previously shown to be positive for HPV5, 8, 15, 20, 24, or 36. HPV-DNA loads in AK, (partially microdissected) NMSC, and perilesional skin ranged between one HPV-DNA copy per 0.02 and 14,200 cell equivalents (median: 1 HPV-DNA copy per 344 cell equivalents; n=48). In 32 of the 79 HPV-positive skin biopsies and in seven of the eight metastases viral loads were even below the detection limit of Q-PCR. Low viral loads in NMSC were confirmed by in situ-hybridization showing only a few HPV-DNA-positive nuclei per section. Viral loads in SCC, basal cell carcinomas, and perilesional tissue were similar. But, viral loads found in AK were significantly higher than in SCC (p=0.035). Our data suggest that persistence of HPV is not necessary for the maintenance of the malignant phenotype of individual NMSC cells. Although a passenger state cannot be excluded, the data are compatible with a carcinogenic role of HPV in early steps of tumor development.