103. High-Capacity Adenoviral Vectors (HCAdV) Armed with a High Risk Human Papillomavirus (HPV) Oncogene Specific CRISPR/Cas9 Machinery Specifically Kill Cervical Cancer Cells

Abstract

Persistent high risk human Papillomavirus (HPV) infections are the main cause of cervical cancer and partially also head and neck cancer. Recent studies showed that plasmid transfection of HPV oncogene specific designer nucleases effectively induced in/del mutations in the early promotors or oncogenes of HPV genomes integrated into the genome of cervical cancer cells by double-strand DNA break mediated non homologous end joining (NHEJ). Destruction or suppression of HPV oncogenes lead to decreased suppression of HPV oncogenes mediated by tumor suppressor protein p53 and retinoblastoma protein pRB inducing recovery from HPV oncogene mediated inhibition of apoptosis induction and cell cycle control. However, only few attempts have been made to improve delivery of respective designer nucleases by means of viral delivery allowing for translating these promising findings towards in vivo applications. Here we aimed at arming gene deleted high-capacity adenoviral vectors (HCAdVs) with HPV-specific CRISPR/cas9 machineries. By using a new toolbox that facilitates customization, cloning and production of CRISPR-HCAdVs we assembled HCAdV genomes containing the Streptococcus pyogenes Cas9 (spCas9) gene including either one gRNA expression unit specific for HPV18-E6 or two gRNA expression units specific for HPV18 and HPV16-E6 that have been shown efficiency to destroy respective genes. HPV specific CRISPR-HCAdVs were amplified in medium scale using a shortened protocol yielding high virus titers. Hela and Caski cervical cancer cells containing HPV18 or HPV16 genomes integrated into their cellular genome, as well as HPV negative A549 cells were infected with HPV specific CRISPR-HCAdVs. Adenoviral delivery of HPV specific CRISPR/Cas9 resulted in strong cell death in HPV positive cervical cancer cell lines whereas HPV negative A549 cells were unaffected. Moreover, HPV-specific CRISPR-HCAdVs infected Hela and Caski cells showed decreased proliferation compared to untreated cells and HPV negative control cells and cytotoxicity assays revealed strongly decreased cell viability of cervical cancer cells. In sharp contrast to control groups, increased apoptosis in HPV specific CRISPR-HCAdV treated cervical cancer cells was measured after performing apoptosis detection assays. Our results suggest that also HCAdVs can serve as oncolytic agents when armed with target specific designer nucleases such as CRISPR/Cas9. We believe that our approach will pave the way towards in vivo applications of CRISPR/Cas9 mediated oncolysis of HPV induced cervical cancer. As our CRISPR/Cas9-HCAdV production pipeline is adaptable to incorporate other or even more gRNA expression units specific for further HPV types, it provides a valuable platform to develop personalized antiviral or oncolytic vectors for any specific HPV target.