Repurposing MDM2 Inhibitor RG7388 For TP53-Mutant NSCLC: A p53-Independent Pyroptotic Mechanism via ROS/p-p38/NOXA/Caspase-3/GSDME Axis

Non-small cell lung cancer (NSCLC) is highly malignant with limited treatment options due to the inherent tumoral heterogeneity and acquired resistance towards chemotherapy and immunotherapy. RG7388 was previously reported to have anticancer activity against TP53WT NSCLC which was designed as MDM2 inhibitor triggering p53/PUMA axis-dependent apoptosis. However, RG7388 exhibited p53-independent anticancer effect against TP53mutant NSCLC in our current research, the underlying mechanisms of which were still uncertain. Here, we reported that RG7388 specifically induced NOXA/Caspase-3 axis dependent apoptosis and gasdermin E (GSDME)-mediated secondary pyroptosis in TP53mutant NSCLC using in silico and multiple biological methods. Mechanically, we identified accumulated reactive oxygen species (ROS) served as the pivotal factor in NOXA upregulation and p38 MAPK pathway activation in RG7388 treated TP53mutant NSCLC by using two ROS scavengers N-acetylcysteine (NAC) and Ferrostatin-1 (Fer-1) respectively. Furthermore, pharmacologic inhibition of p38 MAPK signaling by SB203580 rescued RG7388 induced ROS-dependent NOXA accumulation and subsequent apoptosis and pyroptosis, thus suggesting a leading role of ROS/phosphorylated p38 MAPK (p-p38)/NOXA/Caspase-3 axis in RG7388 induced TP53mutant NSCLC cell death. Taken together, our work unraveled a novel mechanism of selective targeting of mutant p53 derived cancers via ROS/p-p38-mediated NOXA accumulation that could have potential therapeutic implications given the relative lack of direct mutant p53 targeting strategies in cancer. Moreover, A strong positive correlation between p-p38 and NOXA expression was confirmed by using an NSCLC tissue microarray and immunohistochemical (IHC) staining. Clinical data analysis suggested that the p-p38/NOXA axis could serve as a potential indicator for predicting overall survival (OS) in NSCLC patients.