Human papillomaviruses (HPVs) are small double-stranded DNA viruses that are highly species specific and possess a strict tropism for squamous epithelium. Over 150 HPV types are capable of infecting mucosal and cutaneous epithelium, the majority of these types cause only benign lesions such as warts. HPVs are designated as oncogenic based on the ability of a specific viral genotype to cause transformation in the host cell. Of the oncogenic types, HPV-16 and HPV-18 together cause over 60% of cervical cancers and HPV-16 is associated with 72% of HPV[+] oropharyngeal squamous cell carcinomas (OSCCs). Although prophylactic vaccines are very effective in preventing infection by HPV-16 and HPV-18, the uptake of the vaccines is poor in the US and many millions of people are already HPV infected. Further, HPV[+] OSCC incidence is rising. The current heavy burden of HPV-related infections and diseases, as well as the morbidity and/or underachievement of current therapies, underscores the need for development of efficacious therapeutic strategies. Early proteins E5, E6, And E7 from oncogenic HPV types are known to regulate epidermal growth factor receptor (EGFR) gene transcription and recycling in infected cells. Based on previous studies indicating AP-1 transcription factors regulate HPV gene expression, we hypothesize that HPV infection establishes an intracellular feed-forward loop with the EGFR signaling pathway that does not require high levels of EGFR expression. We posit that HPV-mediated gene expression results in increased EGFR signal transduction leading to enhanced viral transcription through modulation of cell survival and proliferation signals.
Specific Aims are designed to determine if initiating a break in EGFR-pathway signaling will result in down regulation of HPV activities in infected cells, leading to recovered p53 and pRb activity, which could render cells more susceptible to chemotherapy and radiation. We expect to determine how AP-1 transcription factors regulate HPV replication in infected cells that maintain episomal or integrated viral genomes. We will use genetic and biochemical assays coupled with quantitative measures of viral replication and cell proliferation and viability. These are cutting-edge approaches and will evaluate the ability of EGFR-pathway inhibitors to decrease viral activities in human keratinocytes containing episomal or integrated high-risk HPVs. Our scientific expertise in HPV biology and cancer research makes us uniquely suited to carry out this work. Understanding the mechanism of the inhibitors effect on viral transcription and genome maintenance may lead to the development of more efficacious therapeutic strategies. Additionally, we will have learned critical aspects of the interplay between host and virus that may underlie progression to cancer and/or prognosis of HPV[+] lesions.
Human papillomavirus (HPV) infections cause a variety of tumors and malignancies of the skin and mucous membranes and change the infected cell's dependence on signals from growth factors. This study will investigate how inhibitors of the epidermal growth factor signaling pathway are able to affect viral activities in infected cells. No only will this work help clarify the relationship between virus and host cell response to growth signals, but may provide a basis to design better treatments for HPV infections and related cancers.
