Human papillomavirus does not actively promote cutaneous SCC growth
MedWire News: Although β-human papillomavirus has been found in some cutaneous squamous cell carcinomas (SCCs), there is no evidence that it acts to promote carcinogenesis in such patients, show study findings.
Around 12% of all human cancers are known to be caused by viruses, but the presence of viral DNA in a cancer biopsy does not necessarily indicate causality.
β-human papillomavirus DNA has been found in some cutaneous SCCs. To assess whether the virus actively promotes carcinogenesis in these patients, Joseph DeRisi (University of California, San Francisco, USA) and colleagues carried out ultra-high-throughput sequencing of the cancer transcriptome of 67 cutaneous SCC samples to assess whether papillomavirus transcripts were also present.
Of the samples examined, 30% were positive for β-human papillomavirus DNA. People with β-human papillomavirus-positive tumors tended to be older and were more likely to be immunosuppressed than those with β-human papillomavirus-negative tumors.
However, no difference in viral load was observed between tumor and normal tissue in these individuals. In addition, transcriptome sequencing was unable to identify papillomavirus expression in any of the skin tumors, suggesting that the virus does not play an active carcinogenic role.
In contrast, mRNA transcripts of human papillomavirus 16 and 17 were identified in a significant number of primary cervical and periungual cancers, which were tested for comparison purposes.
"These data demonstrate that papillomavirus mRNA expression is not a factor in the maintenance of cutaneous SCCs," say DeRisi and team.
"The most straightforward interpretation of our data is that the sporadic and low-level presence of β-human papillomavirus genomic DNA in these tumors, unaccompanied by evidence of active viral gene expression, most likely represents colonization rather than an etiologic association," conclude the authors in the Journal of Investigative Dermatology.
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By Helen Albert