Cell cycle block by p53 acrivation reduces SARS-COV-2 release in infected alveolar basal epithelial A549-hACE2 cells

The two last decades have shown great sanitary emergencies due to the pandemic diffusion of SARS-CoV-2 that has presented a new scientific challenge for the search of effective therapies against infection, replication and spreading. Among the intracellular targets of the virus, p53 is one of the targets that plays an important role both in the mechanisms of innate immunity as well as in the control of the cell cycle and other pathways that regulate cell replication, damage repair, apoptosis and metabolism. SARS-CoV viruses adopt several strategies to silence p53, including the stabilization of its inhibitor, MDM2 and the interference with its transcriptional activity, indicating that p53 has a central role in controlling its proliferation in the host. For these reasons, the aim of the project was to evaluate a new approach against the virus, by using MDM2 inhibitors to effectively raise p53 levels and activate p53-dependent pathways including cell cycle inhibition. Experiments setting was done in the alveolar basal epithelial cell line A549-hACE2 expressing TP53wild-type and the SARS-CoV2 receptor ACE2. Cells were treated with several concentration of Nutlin-3 or RG7112 at the time points of 24 and 72 hours post treatment for the instauration of a cell cycle block steady-state condition before and during SARS-CoV-2 infection, and for the evaluation of p53 activation and impact on virus release and related innate immune events.The results of the project suggest that Nutlin-3, as well as RG-7112, significantly reduced SARS-CoV-2 replication in A549-ACE2 cells and promoted a complete inhibition of IL-6 expression, associated with inhibition of NF-kB and interferon-lambda, important mediators of inflammation. These data indicate that p53 represents an efficient target for new therapies against the virus and that MDM2 inhibitors can be a realistic therapeutic option.