Small-molecule MX-C2/3 suppresses non-small cell lung cancer progression via p53 activation

p53 inactivation is a common feature in non-small cell lung cancer (NSCLC) resulting in NSCLC malignant transformation. Targeting serine 392 phosphorylation to restore p53 anticancer activity has proven to be an effective therapeutic strategy against NSCLC. A synthetic p53 activator, NA-17, has been developed that shows promise in preclinical models of NSCLC. However, NA-17 exhibits limited therapeutic efficacy in oncogene-driven tumors as well as relatively high toxicity to normal cells. It is possible that high efficiency and low toxicity p53 activators can be obtained by optimizing the leading molecule. Here, we performed high-throughput screening of compounds optimized based on NA-17 to identify new p53 activators. Two promising candidates named MX-C2 and MX-C3 were identified, both exhibited considerable therapeutic efficacy in oncogene-driven tumor models. Similar to NA-17, MX-C2/3 induced p53 activation via phosphorylating serine-392 without DNA damage. Both compounds showed broad antitumor activity in NSCLC cells and limited toxicity in normal cell lines. Moreover, MX-C2/3 suppressed tumor progression by arresting the cell cycle at G2/M phase, exhibiting a different mechanism of cell cycle arrest than NA-17. In addition, MX-C2/3 promoted the enrichment of p-p53 (s392) in mitochondria, leading to the conformational activation of Bak for cell apoptosis, which is consistent with NA-17. Finally, we demonstrated that MX-C2 significantly inhibited tumor growth without obvious systemic toxicity in oncogene-driven HCC-827 xenograft models. Collectively, we report two p53 activators with high-efficiency and low-toxicity that target p53 serine 392 phosphorylation for anticancer translational investigation.