Dictamnine, a Novel c-Met Inhibitor, Suppresses the Proliferation of Lung Cancer Cells by Downregulating the PI3K/Ak/mTOR and MAPK Signaling Pathways

Abstract Background: Dictamnine (Dic), a naturally occurring furoquinoline alkaloid isolated from the root bark of Dictamnus dasycarpus Turcz., is reported to display a wide range of potential pharmacological properties including anticancer activity against multiple cancer types. However, little is known about the direct target proteins and anticancer mechanisms of Dic.Methods: Anticancer effects of Dic and chemotherapy resistance of lung cancer were determined by CCK8, EdU and apoptosis assay. Boyden chamber migration and invasion, wound healing assay, plate colony formation and sphere formation assay were performed to explore the effects of Dic on metastasis and stemness of lung cancer cells. Protein docking analysis, cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DARTS) were used for prediction and confirmation of the interaction between Dic and c-Met. qRT-PCR, Western blotting and immunohistochemistry (IHC) were used in mechanism investigation. Tumor xenograft model was used to evaluate the anti-tumor effects of Dic in vivo.Results: Dic was found to suppress the proliferation of lung cancer cells and attenuate the activation of the PI3K/AKT/mTOR and mitogen-activated protein kinase (MAPK) signaling pathways by directly inhibiting the phosphorylation and activation of the receptor tyrosine kinase c-Met. Moreover, Dic treatment significantly inhibited the colony formation, migration, invasion, stemness, adhesive ability, epithelial-mesenchymal transition and in vivo xenograft tumor growth of A549 lung cancer cells. Notably, the combination of Dic and gefitinib synergistically inhibited the cell proliferation, induced apoptosis, and suppressed the PI3K/Akt/mTOR and MAPK signaling pathways in PC9 gefitinib resistant cells.Conclusions: In conclusion, Dic was identified as a novel c-Met inhibitor and our results suggest the potential use of Dic as a new therapeutic agent in the treatment of lung cancer or other cancers with overactive c-Met pathway.