GFP/HPV-16E6 fusion protein induces apoptosis in MCF-7 and 293T cells using a transient expression system

Since mucosal high-risk human papillomavirus (HPV) E6 can target and degrade the tumor suppressor p53, it is recognized as a major causative agent of cervical cancer. However, to date the distribution of high-risk HPV-E6 protein remains elusive. Thus, in the present study we used a mammalian green fluorescent protein (GFP) expression system to express a GFP/HPV-16E6 fusion protein (GFP-16E6) in wild-type (wt) p53 cells, such as MCF-7 and 293T cells to investigate the trafficking and localization of E6 and p53. Following transfection, we observed that the overexpressed GFP-16E6 was a nuclear protein, and that endogenous wt p53 localized to the nucleus together with GFP-16E6. Strikingly, p53 levels were not decreased but increased in 24 h transfected with pGFP-16E6. Furthermore, we observed significant apoptosis induced by GFP-16E6, which proved to be dependent on p53 expression.