Dihydroartemisinin inhibits NSCLC by targeting MDM2/c-Myc axis independent of p53.

The antimalarial agent Dihydroartemisinin (DHA) has significant potential for drug repurposing for cancer therapy including non-small cell lung cancer (NSCLC). However, its underlying anti-tumor mechanisms remain to be elucidated. In this study, we demonstrated that DHA suppressed the mouse double minute 2 (MDM2) in A549 and H1299 cells, whereas MDM2 overexpression effectively restored DHA's inhibition on both NSCLC cell lines. We showed that DHA acted via phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) and Janus kinase (JAK)/Signal Transducer and Activator of Transcription 3 (STAT3) signaling pathways to inhibit MDM2 expression. Being an established MDM2 target, p53 was significantly upregulated in p53 wild-type A549 cells upon DHA treatment both in vitro and in vivo; however, the mediating role of MDM2 in DHA's suppression on NSCLC is independent of p53 since DHA-treated si-p53 A549 cells had comparable colony formation capacity compared with that of si-Control. The anti-tumor effects of DHA bypass p53 was further implicated using H1299, a cell line which is MDM2-overexpressed but p53-null. Instead, c-Myc was observed to mediate the effects of DHA/MDM2 axis as co-immunoprecipitation (Co-IP) analysis showed the direct protein interaction between MDM2 and c-Myc, both were substantially reduced upon DHA treatment. Furthermore, c-Myc overexpression effectively restored DHA's suppression on proliferation, and DHA's induction on apoptosis of A549 and H1299 cells. Finally, immunohistochemistry (IHC) analysis showed that in vivo administration of DHA substantially reduced both MDM2 and c-Myc expression in xenograft murine models. Taken together, our results demonstrated that DHA inhibits NSCLC by targeting MDM2/c-Myc axis independent of p53.