Analysis of the impact of E6/E7 proteins of different HPV-16 molecular variants upon signal transduction pathways mediated by MAPK

Abstract

HPV-16 infection with is strongly associated with increased risk of developing cervical cancer. This is the most prevalent viral type in both cytologically normal and in cervical cancer samples worldwide. HPV-16 intra-type nucleotide variability has been extensively studied, resulting in important findings concerning the evolution and phylogeny of the virus and the natural history of infections. Asian American and E-350G HPV-16 variants have been associated with increased risk of persistent infection and cervical cancer when compared to the European prototype variant, although it still presents a high risk when compared to other HPV types. Some studies have demonstrated functional differences between E6/E7 proteins of different HPV-16 molecular variants, which could explain the observed differences in oncogenic potential observed. Recent data from our group pointed to the increased expression of MAP2K1 protein specifically in keratinocytes infected with the variant E-350G (or L83V). These data support other results which showed that the MAPK pathway is increased in cells expressing the E6 protein of the variant E-350G (or L83V). Therefore, it is necessary to examine the impact of E6/E7 proteins of HPV-16 different molecular variants upon signal transduction pathways mediated by MAPK. Thus, our aim is: (1) analyze the levels of activation of effector proteins of the MAPK pathway (NOTCH1, MEK1 / 2 and ERK1 / 2) in keratinocytes infected with E6/E7 of different HPV-16 molecular variants (AA, EP, E-350G), (2) analyze the effects of the interaction between E6/E7 of different HPV-16 molecular variants with NOTCH1 in the transforming potential measured indirectly by colony formation assays, (3) analyze the effects of the interaction between E6/E7 of different HPV-16 molecular variants with NOTCH1 upon angiogenesis induction; (4) analyze the effects of different E6/E7 HPV-16 molecular variants upon MAPK induced pathway concerning the induction of AP1, NFºB and other transcription factors. The results from this study will be of extreme importance to assess the impact of HPV-16 intra-typical variability upon the oncogenic potential observed. (AU)