Cell cycle block by p53 activation reduces SARS-CoV-2 release in 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. One of the targets of the virus that plays an important role both in the mechanisms of innate immunity and in the control of the cell cycle and other pathways that regulate cell replication, damage repair, apoptosis and metabolism is the p53 protein. SARS-CoV, as observed for other viruses, have evolved specific molecular mechanisms to contrast p53, in order to avoid the host response to infection. For example 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. Following all these evidence and considerations, 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 RG-7112 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.