Biological and biochemical properties of natural variants of HPV-18

• Grant number: 18/14697-7
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: October 16, 2018
• End date: July 15, 2019
• Field of knowledge: Biological Sciences - Biochemistry - Biochemistry of Microorganisms
• Principal Investigator: Laura Cristina Sichero Vettorazzo
• Grantee: Emily Montosa Nunes
• Supervisor: Lawrence Murren Banks
• 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
• Institution abroad: International Centre for Genetic Engineering and Biotechnology (ICGEB), Italy
• Associated to the scholarship: 15/26346-6 - Biological and biochemical properties of natural variants of HPV-18, BP.DR

Abstract

HPV-16 and HPV-18 are strongly associated with the risk of developing cervical cancer. Worldwide, HPV-16 is the most prevalent type in invasive squamous cell carcinomas of the cervix, followed by HPV-18, whereas HPV-18 is the most prevalent type in adenocarcinoma specimens. HPV-18 intratypic nucleotide variability has been studied resulting in important findings concerning the evolution and phylogeny of the virus and the natural history of infections. In an epidemiological study of the natural history of HPV infection in women conducted in our country, we found that HPV-18 E variants significantly associated with persistence of the viral infection. Furthermore, although studies about the clinical relevance of HPV-18 genetic variability are very limited, overall it is suggested that As+AI and E variants represent variants with a higher oncogenic potential compared to Af variants. Furthermore, it was observed that Af HPV-18 variants are exclusively detected in samples of invasive squamous cell carcinoma of the cervix, whereas As+AI and E variants are more prevalent in adenocarcinoma and adenosquamous cell carcinoma. Regarding biological differences between HPV-18 variants, it is crucial to emphasize that the few studies conducted so far explored only the variability of the viral E6 oncoprotein, and most importantly, none of the studies was performed in HPV-18 natural host cell models, which are primary human keratinocytes (PHKs). For these reasons, this project aims to comprehensively characterize the differential activity of E6/E7 of As+AI, E and Af HPV-18 variants in primary human keratinocytes transduced with these proteins. More specifically, our objective is to analyze biological differences among HPV-18 variants concerning (1) E6 induced p53 in vitro degradation; (2) interaction and degradation of different PDZ domain-containing cellular proteins by the E6 viral protein; (3) identify HPV-18 E6 cell partners by a proteomics approach; (4) E7 binding and degradation of pRb in vitro; and (5) the ability of E7 in immortalizing mouse kidney cells in cooperation with an activated RAS protein.