Nitidine chloride inhibits mTORC1 signaling through ATF4-mediated Sestrin2 induction and targets IGF2R for autophagic degradation

Nitidine chloride (NC), a natural phytochemical alkaloid derived from Zanthoxylum nitidum (Roxb.) DC, exhibits multiple bioactivities in cancer, infection disease, and other therapeutic areas. However, the primary targets of NC and the mechanism of action (MOA) have not been defined explicitly. Here, we report that NC inhibit mTORC1 activity by targeting amino acid sensing signaling through activating transcription factor 4 (ATF4)-mediated Sestrin2 induction, and it efficiently induces autophagy in cells and tumor xenograft. NC displays potent cytotoxicity against various cancer cells and inhibits xenograft tumor growth of B16 melanoma. Furthermore, we identified insulin-like growth factor 2 receptor (IGF2R) as a direct target of NC by drug affinity responsive target stability (DARTS) technique. NC may functional as a IGF2R antagonist to inhibit growth factor-mediated mTORC1 activation. This study suggested that NC targets mTORC1 signaling through nutrients sensing and growth factor receptor binding, providing mechanistic insights into the MOA of NC. Overall design: HEK-293T cells were treated with DMSO and 10µM nitidine chloride for 12 hours, with 3 replicates set for each treatment. RNA was extracted and subjected to high-throughput sequencing.