Type-specific interaction between human papillomavirus type 58 E2 protein and E7 protein inhibits E7-mediated oncogenicity

Human Papillomavirus (HPV)-associated Oral Cancers and Treatment Strategies

Human papillomavirus (HPV) is known to be associated with several types of human cancer, including cervical, vulvar, vaginal, penile, anal, and head-and-neck cancers. Among these cancers, HPV-associated head-and-neck cancers, inclusive of oropharyngeal squamous cell carcinoma (OSCC) and oral cavity squamous cell carcinomas (OCSCC), have recently risen dramatically in men under 50 years old. Within 20 years, the percentage of HPV-positive OSCC in total OSCC went from less than 20% to more than 70% in the United States and some European countries. This article reviews the incidence trend and pathogenesis of HPV-associated head-and-neck cancers as well as current treatment modalities for the disease.

The papillomavirus E7 proteins

E7 is an accessory protein that is not encoded by all papillomaviruses. The E7 amino terminus contains two regions of similarity to conserved regions 1 and 2 of the adenovirus E1A protein, which are also conserved in the simian vacuolating virus 40 large tumor antigen. The E7 carboxyl terminus consists of a zinc-binding motif, which is related to similar motifs in E6 proteins. E7 proteins play a central role in the human papillomavirus life cycle, reprogramming the cellular environment to be conducive to viral replication. E7 proteins encoded by the cancer-associated alpha human papillomaviruses have potent transforming activities, which together with E6, are necessary but not sufficient to render their host squamous epithelial cell tumorigenic. This article strives to provide a comprehensive summary of the published research studies on human papillomavirus E7 proteins.