Human papillomavirus (HPV) affects up to 75% of adults and is categorized as high risk (HR) or low risk (LR) based on its association with cancer. Although there are two preventive vaccines against two (HR HPV 16, 18) or four (HR HPV 16, 18 and LR HPV 6, 11) HPV genotypes, immunizations in the USA have had poor uptake and completion. This leaves many women and men at continued risk of HPV-associated cancers, some of which are increasing in incidence. The HR HPV oncogenes E6 and E7 drive cellular immortalization;HR E6 specifically partners with several endogenous proteins to dysregulate epithelial cells. In our own studies, we found that 16E6 interacts with the NFX1-123. Together, these proteins act post-transcriptionally to increase the expression of hTERT, the catalytic subunit of telomerase. Telomerase activation is critical for cellular immortalization, is a key step in cancer development, and is universally detected in HPV-associated cancers. We are now prepared to study other genes and cellular pathways regulated by the concerted actions of 16E6 and NFX1-123. In whole-genome expression microarray and validation studies, we identified several differentiation genes and a master differentiation regulator, Notch1, as upregulated by NFX1-123 and 16E6. Interestingly, this increase in differentiation pathway genes did not lead to cellular growth arrest. These data put us in a strong position to study the combined roles of 16E6 and NFX1-123 in the viral life cycle, the cell, cancer development and progression.
Our specific aims are to: (1) Determine the mechanism of gene regulation by 16E6 and NFX1-123. We have identified post-transcriptional gene regulation of hTERT as a new and critical role for 16E6 and NFX1-123. We hypothesize that NFX1-123 and 16E6 function together to dysregulate other genes, with hTERT regulation as our working model. (2) Determine how HPV and NFX1-123 affect the balance of differentiation and continued cellular proliferation in epithelium. We found NFX1-123 with 16E6 increased expression of differentiation genes and Notch1, and these same cells continued to proliferate in culture. We will define how NFX1-123, 16E6, and Notch1 modulate epithelial architecture, and hypothesize the differentiation and growth arrest pathways are uncoupled to allow cellular growth and support a productive and long-lived HPV infection that leads to malignant changes over time. (3) Determine how NFX1-123 expression changes and drives HPV-associated cancer development and progression. We found increased NFX1-123 in cervical cancer cell lines and in 30% of patient tumor samples. Therefore, we hypothesize that increased NFX1-123, and its downstream gene targets, favors oncogenic progression. Using cervical dysplasia models and patient samples, we will quantify changes in NFX1-123 and identify critical points where increased NFX1-123 is needed in HPV-associated cancers. These studies will expand our understanding of HPV-driven oncogenesis and help to identify biomarkers and therapeutic targets for HPV-associated cancers
High risk human papillomavirus (HPV) infection can drive cancer development. Despite two commercially available HPV vaccines, poor uptake in the USA and worldwide will leave decades of men and women at risk for HPV-associated cancers. This project will study how HPV dysregulates normal cell growth and longevity to engender viral productivity, will demonstrate how HPV can serve as a model for universal pathways in cancer development, and will help define critical steps in oncogenesis that might be targets for screening and treatment of HPV-associated cancers.
|Vliet-Gregg, Portia A; Hamilton, Jennifer R; Katzenellenbogen, Rachel A (2015) Human papillomavirus 16E6 and NFX1-123 potentiate Notch signaling and differentiation without activating cellular arrest. Virology 478:50-60|