HPV hijacking of the epidermal growth factor receptor via its oncogenic ion channel, the E5 viroporin: a new mechanism of virus-driven pathogenesis

Infection with human papillomavirus (HPV) is associated with a number of diseases including genital warts, cervical cancer in women and oral cancers in both sexes. Estimates predict that the cost associated with treating HPV infections and disease is $8 billion in the USA alone. Whilst vaccines are available that can prevent HPV infection, these do not work in those already infected with the virus and they are not routinely available in the developing world, where the largest disease burden exists. Urgent need exists to identify drugs capable of treating those already infected with the virus. Towards this a better understanding of how HPV re-wires an infected cell to cause disease is required. We have focused on a less well understood protein coded by the virus and shown it plays a critical role during infection. We now want to take our research further to understand how this protein interacts with components of the infected cell, and how changes brought about by the protein might lead to cancer development. For these studies we will use a model system allowing us to investigate HPV infection in cells. Our work should give us a clear picture of how this virus coded protein works and open up the possibility of developing drugs that prevent its action.

HPV infection causes ~6% of all human cancers. These include cervical cancer in women, which results in an estimated 266,000 deaths annually. Moreover, the past decade has witnessed a new epidemic of HPV-associated head and neck squamous cell carcinomas (HNSCC), primarily in white, middle-aged men. The majority of HPV cancer patients (~85%) reside in low-income countries, with limited health infrastructure and finance. HPV-related health care costs are extreme and are estimated to cost $8 billion per annum in the USA alone. Despite FDA-approved prophylactic vaccines, the burden of HPV disease will remain high for decades due to limited access to vaccines in low-income countries, and also poor coverage in those countries which have access to the vaccines, and the long latency period separating infection from carcinogenesis. Development of HPV-specific therapies to complement the vaccine strategy is clearly warranted.
To develop such interventions a detailed understanding of HPV biology is required. Our research has focused on E5, which is the least well understood virus oncoprotein. We previously showed that E5 functioned as a virus-coded ion channel or viroporin. Now we demonstrate a role for the viroporin activity of E5 in hijacking host epidermal growth factor receptor (EGFR) signalling. This serves to maintain keratinocyte proliferation and as a novel means of blocking p53 function, resulting in a delay of Notch-mediated differentiation. Critically, small molecule inhibitors targeting the viroporin activity of E5 prevent EGFR activation. Thus our data greatly expands the role of E5 in the HPV life cycle and provides a clear function for viroporin activity as an activator of EGFR. Using established primary cell cultures that model genital and oropharyngeal infection with oncogenic HPV we will test the hypothesis that E5 activates EGFR function to manipulate keratinocyte proliferation and suppress differentiation during productive infection.

Human papillomavirus hijacking of the epidermal growth factor receptor via its oncogenic ion channel, the E5 viroporin: a new mechanism of virus-driven pathogenesis. Longer term, the outputs of this research should benefit both the pharmaceutical industry and society as a whole. Shorter term, this work will be of value to fundamental and translationally focussed scientists in academia and industry as well as research clinicians. HPV infection causes ~6% of all human cancers, resulting in >266,000 deaths per annum predominantly in low-income countries. HPV is also the most common sexually transmited infection (STI), and is associated with a significant financial burden. Whilst vaccines are available that can prevent HPV infection, these do not work on those already infected with the virus and they are not routinely available in low-income countries, where the largest disease burden exists. There is a need to identify therapeutics capable of treating both cancer causing HPV viruses and low-risk HPV associated with benign but hugely costly infections. Fundamental studies of how HPV interacts with the host keratinocyte cell, like that proposed here, have the potential to unearth new mechanisms to target virus-coded proteins for therapeutic intervention and ideally will also demonstrate the significance of specific host pathways and processes as necessary for virus replication and transformation and as such indicate their potential as host coded therapeutic targets. We have data demonstrating a previously unrecognised role for the least well understood virus transforming proteins called E5 in dysregulating keratinocyte proliferation and differentiation pathways in the infected keratinocyte. Our data shows that E5 is a virus-coded ion channel that activates the critical growth promoting EGF receptor (EGFR) to drive keratinocyte proliferation. In addition, we show novel down-stream targets impacted by dysregulated EGFR including the transcription factors CREB and p53. The processes we identified as being subverted by E5 are key candidates for cancer therapeutics. Our proposed work offers a valuable opportunity to understand the molecular basis for E5 function and to discern the potential for these virus and host coded proteins as targets for therapeutic intervention. We are leaders in the field of HPV research and the strategy proposed in this application will ensure that this continues. We will disseminate the results of this project to the scientific community through publications and presentation at conferences and workshops. We will publish our data in Open Access journals when possible in order to increase their availability. The commercial potential of our work will be identified during regular self-assessments of progress and appropriate discoveries will be discussed with Commercialisation Services at UoL and partner company IP Group PLC. The purpose of IP Group PLC is to bring scientific results from Leeds-based scientists into public use for public benefit. This is an established route within the University, which currently boasts 37 spin-put companies. The potential for future translational links with industry or by expansion into clinical investigation will be explored through consultation with the UoL Pharmaceutical and BioPharmaceutical Hub and Medical Hub and specific meetings arranged with interested parties. We will work closely with the University of Leeds Media Relations Communications Team and the Faculty Marketing Team to maximise publicity and press coverage for the high-impact papers we expect to publish from this work to audiences outside academia, for example in print (e.g. Yorkshire Evening Post and New Scientist), online (e.g. BBC, Daily Telegraph) and Social Media (e.g. Twitter). We will ensure the wider public benefit from this work by becoming involved in initiatives to inspire school children to study science including workshops on cancer and infections through National Science and Engineering Week.