Targeting PP2A with lomitapide suppresses colorectal tumorigenesis through the activation of AMPK/Beclin1-mediated autophagy
Abstract Background Colorectal cancer (CRC) is one of the most malignant cancer worldwide, and the limited efficacy of existing treatments is the leading cause of death in patients with CRC. Thus, novel drugs for CRC treatment are urgently needed. Methods We screened an FDA-approved small-molecule library upon HCT116 cells, and identified lomitapide as a novel CRC anticancer compound. Then we confirmed the activities of lomitapide on CRC cells by WST-1 assay, colony formation, and flow cytometry. RNA sequencing and GO analysis were used to investigate the mechanisms underlying the anticancer effects of lomitapide. LiP-SMap was introduced to search for the potential targets of lomitapide. The in vivo experiment was conducted to confirm the therapeutic efficiency and safety of lomitapide as an anticancer agent. Results Lomitapide exhibited remarkable antitumor properties in vitro and in vivo, while activated autophagy is characterized by GO analysis as a key biological process in lomitapide-induced CRC repression. Moreover, lomitapide stimulated mitochondrial dysfunction-mediated AMPK activation, resulting in increased AMPK phosphorylation and enhanced Beclin1/Atg14/Vps34 interactions, provoking autophagy induction. LiP-SMap analysis showed that PP2A was the direct target of lomitapide, and the bioactivity of lomitapide was attenuated in PP2A-deficient cells, suggesting that the anticancer effect of lomitapide occurs in a PP2A-dependent manner. Conclusions Our results indicate that lomitapide activates AMPK-regulated autophagy to inhibit the proliferation and tumorigenesis of CRC cells by directly targeting PP2A, and can be a novel therapeutic agent for the treatment of CRC patients.