No association between HPV positive breast cancer and expression of human papilloma viral transcripts

Infectious agents are thought to be responsible for approximately 16% of cancers worldwide, however there are mixed reports in the literature as to the prevalence and potential pathogenicity of viruses in breast cancer. Furthermore, most studies to date have focused primarily on viral DNA rather than the expression of viral transcripts. We screened a large cohort of fresh frozen breast cancer and normal breast tissue specimens collected from patients in Australia for the presence of human papilloma virus (HPV) DNA, with an overall prevalence of HPV of 16% and 10% in malignant and non-malignant tissue respectively. Samples that were positive for HPV DNA by nested PCR were screened by RNA-sequencing for the presence of transcripts of viral origin, using three different bioinformatic pipelines. We did not find any evidence for HPV or other viral transcripts in HPV DNA positive samples. In addition, we also screened publicly available breast RNA-seq data sets for the presence of viral transcripts and did not find any evidence for the expression of viral transcripts (HPV or otherwise) in other data sets. This data suggests that transcription of viral genomes is unlikely to be a significant factor in breast cancer pathogenesis.