Objective To observe the effects of tetrandrine on the proliferation,migration,and invasion of melanoma cell B16,and to explore its effects on epithelial mesenchymal transition(EMT)and potential regulatory mechanisms.Methods(1)The proliferation of B16 cells was detected by CCK-8 assay after 0,2,4,6,8 and 10 μmol·L-1 of tetrandrine intervention for 24 and 48 hours.The colony formation ability of B16 cells was detected by plate clone formation assay after 1,2 and 4 μmol·L-1 of tetrandrine intervention;the migration and invasion ability of B16 cells was detected by cell scratch assay and Transwell invasion assay;the expressions of N-cadherin,Vimentin and E-cadherin related to EMT in B16 cells were detected by Western Blot assay.The mouse melanoma lung metastasis model was replicated by tail vein injection of B16 cells to observe the effects of tetrandrine(50 and 100 mg·kg-1)administered by gavage on the number of metastatic tumor nodules in the lungs of mice.(2)The CTD,SwissTargetPrediction and Similarity Ensemble Approach databases were used to predict the targets of tetrandrine;the GeneCards database was used to search for targets related to melanoma disease;the intersection of these two databases was taken as the potential target of tetrandrine for melanoma treatment.The intersected targets were imported into STRING database to construct protein-protein interaction(PPI)network and screen the core targets;the intersected targets were imported into DAVID database for GO function and KEGG pathway enrichment analysis;and molecular docking between tetrandrine and the core targets was verified by Autodock software.(3)In vivo experimental validation:after intervention of 1,2 and 4 μmol·L-1 tetrandrine,Western Blot method was used to detect the expression of the key pathway AKT/NF-κB/CREB pathway-related proteins;and AKT agonist SC79 was used to validate the replication experiments.Results(1)The IC50 of B16 cells intervened by tetrandrine was 4.273 and 4.085 μmol·L-1 at 24 and 48 hours.Compared with the control group,the colony forming ability,scratch healing rate and invasion rate of cells in the 1,2 and 4 μmol·L-1 tetrandrine group were all significantly reduced(P＜0.05,P＜0.01,P＜0.001);the expressions of cellular Vimentin and N-cadherin protein expressions were significantly down-regulated(P＜0.01,P＜0.001),and E-cadherin protein expression was significantly up-regulated(P＜0.01,P＜0.001).Compared with the model control group,the number of melanoma lung metastatic nodules was significantly reduced in the mice in the high-dose group of tetrandrine(P＜0.05).(2)A total of 60 potential targets were obtained for the treatment of melanoma with tetrandrine;core targets such as AKT1,TNF,CCND1,RELA,CASP9,CHUK,and CREBBP were further screened,among which AKT1 was the most strongly interacting target;the signaling pathways such as apoptosis,FoxO,TNF,PI3K-AKT,and NF-κB were mainly involved.The molecular docking showed that tetrandrine had strong binding activity with AKT1,TNF,RELA and other core targets.Compared with the control group,protein expressions of p-AKT/AKT,p-NF-κB p65/NF-κ B p65,and p-CREB/CREB were significantly down-regulated in the cells of the tetrandrine 1,2,and 4 μmol·L-1 groups(P＜0.05,P＜0.01);protein expressions of p-AKT and p-NF-κB p65 were significantly up-regulated in the cells of the SC79 group(P＜0.001).Compared with the SC79 group,protein expressions of p-AKT,p-NF-κB p65,and p-CREB were significantly down-regulated in the cells of the 2 μmol·L-1 tetrandrine+ SC79 group(P＜0.001).Conclusion Tetrandrine may inhibit the proliferation,migration,invasion and EMT of mouse melanoma by regulating the AKT/NF-κB/CREB pathway,and thus inhibit the lung metastasis of mouse melanoma.