Impact of TEAD4 on the transcriptional activity of HPV-16

• Grant number: 25/06774-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2025
• End date: May 31, 2026
• Field of knowledge: Health Sciences - Collective Health - Epidemiology
• Principal Investigator: Laura Cristina Sichero Vettorazzo
• Grantee: Patricia Massabki Lomonaco
• Host Institution: Instituto do Câncer do Estado de São Paulo Octavio Frias de Oliveira (ICESP). Coordenadoria de Serviços de Saúde (CSS). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
• Associated research grant: 24/13024-0 - Cellular transcription factors as prognostic biomarker and therapeutic target in tumors induced by human papillomavirus 16 (HPV-16)., AP.R

Abstract

The development of tumors associated with HPV infection results from persistent infections with high-risk oncogenic HPVs, with HPV-16 being the most prevalent worldwide in both pre-neoplastic lesions and cancers of different anatomical sites. The E6 and E7 oncoproteins of high-risk HPVs associate with and inactivate, respectively, the tumor suppressor proteins p53 and pRb, which results in the evasion of apoptosis, dysregulation of the cell cycle, among other alterations that together induce the transformation of infected cells. Different viral and cellular TFs that regulate the replication and transcription of HPVs bind to the viral LCR. There are still no targeted treatments aimed at containing the proliferation of HPV-infected cells, thus limiting clinical progression. Thus, the search for prognostic biomarkers and the pathways associated with these tumors that enable the development of treatments targeted at patients affected by HPV-induced tumors is justified.TEAD4 (TEA domain transcription factor 4), also known as TEF-3 (transcriptional enhancer factor-3), is an important member of the TEAD family of TFs. TEAD4 is a downstream transcriptional factor of the Hippo signaling pathway, and plays an important role in cell proliferation and survival, tissue regeneration, and stem cell maintenance. TEAD4 does not impact transcriptional activity in the absence of critical cofactors. For example, TEAD4 binds to the YAP/TAZ proteins through a domain in the carboxy-terminal region, both of which are important effector proteins of the Hippo signaling pathway. Some genes regulated by the TEAD-YAP/TAZ complex include survinin, vimentin, MYC, and MMP9.When phosphorylated, YAP and TAZ accumulate in the cytoplasm and are unable to bind to TEAD, which induces ubiquitin-mediated proteolysis of both and/or autophagy-induced degradation; when dephosphorylated, YAP and TAZ translocate to the nucleus, where they interact with TEADs to induce the transcription of several genes involved in proliferation, metastasis and apoptosis. High levels of TEAD4 are detected in several tumor tissues, suggesting that this protein may play an important role as a prognostic biomarker in different tumor types. Since TEAD4 overexpression is correlated with poor survival, it is important to develop antitumor therapies that target this protein. It has recently been demonstrated that the Hippo pathway is actively involved in the establishment, development and maintenance of HPV-related tumors. However, the role and mechanism of the YAP/TAZ-TEAD4 pathway in cervical cancer remain to be clarified.In our laboratory, in a screening, we observed that TEAD4 potentially induces the transcriptional activity of HPV-16. Furthermore, in silico analysis indicated putative binding sites to the HPV-16 LCR, indicating that this TF may play an important role in HPV-induced tumorigenesis by increasing the levels of the oncoproteins E6 and E7. However, additional assays are needed to evaluate the impact of TEAD4 upon viral transcription in the context of cells immortalized by HPV-16. Thus, the objectives of this project are: (1) To evaluate the impact of TEAD4 on the transcriptional activity of HPV-16 in cells transformed by this virus; (2) To evaluate the impact of TEAD4 on the transcriptional activity of HPV-16 in cells immortalized by this virus. For this purpose, TEAD4 will be overexpressed in different HPV-positive cells (SiHa and CasKi) using a plasmid in which HPV-16 LCR is upstream of the firefly luciferase gene. Luminescence measurements will be used as an indirect measure of viral transcriptional activity. The measured transcriptional activity will be compared to the basal activity, defined as a reference and assigned the value 1.