Objective:To discuss the inhibitory effect of Schisandrin B on the proliferation of pancreatic cancer Pan02 cells,and to clarify the mechanism.Methods:CCK-8 method was used to detect the proliferation rates of the Pan02 cells after treated with different concentrations(0,0.78,1.56,3.12,6.25,12.50,and 25.00 mg·L-1)of Schisandrin B to select the optimal concentration and treatment time of Schisandrin B.The mouse pancreatic cancer Pan02 cells were divided into control group(0 mg·L-1 Schisandrin B),2.5 mg·L-1 Schisandrin B group,5.0 mg·L-1 Schisandrin B group,and 10.0 mg·L-1 Schisandrin B group.The morpholoy of Pan02 cells invarious groups was observed with light microscope;5-ethynyl-2'-deoxyuridine(EdU)staining assay was used to detect the positive expression rates of the Pan02 cells in various groups;flow cytometry was used to detect the percentages of the Pan02 cells at different cell cycles and the apoptotic rates of the cells in various groups;Western blotting method was used to detect the expression levels of cell cycle and apoptosis-related proteins in the cells in various groups.Results:The CCK-8 method results showed that after treated with Schisandrin B for 48 and 72 h,compared with 0 mg·L-1 Schisandrin B,the proliferation rates of the Pan02 cells after treated with different concentrations of Schisandrin B were decreased(P<0.01),especially at 72 h.0.25,5.0,and 10.0 mg·L-1 Schisandrin B were selected to treat the Pan02 cells,and 72 h was the treatment time.In control group,the Pan02 cells had a spindle shape,with good condition,and grew closely adhered to the wall with normal organelles and cytoplasm,in 2.5 and 5.0 mg·L-1 Schisandrin B groups,the cell volume was decreased,the intercellular adhesion was disappeared,and the cell membrane was intact but more permeable;the cytoplasm shrank and vacuolar structures appeared inside the cells,with some fragmented and floating on the surface of the solution;in 10.0 mg·L-1 Schisandrin B group,the Pan02 cells exhibited notable apoptotic bodies,indicating an apoptotic state.The EdU staining results showed that compared with control group,the rates of EdU positive cells in 2.5,5.0,and 10.0 mg·L-1 Schisandrin B groups were significantly decreased(P<0.01).The flow cytometry results showed that compared with control group,the percentages of the cells at S phase in 2.5,5.0,and 10.0 mg·L-1 Schisandrin B groups were significantly increased(P<0.01),while the percentages of the cells at G2/M phase were significantly decreased(P<0.01),and the percentages of the cells at G0/G1 phase in 5.0 amd 1.0 mg·L-1 Schisandrin groups were decreased(P<0.01);compared with control group,the apoptotic rates of the cells in 2.5,5.0,and 10.0 mg·L-1 Schisandrin B groups were significantly increased(P<0.01).The Western blotting results showed that compared with control group,the expression levels of p27,B-cell lymphoma 2(Bcl-2)associated X protein(Bax),cleaved cysteine aspartic acid protease-3(cleaved Caspase-3),and cleaved poly adenosine diphosphate(ADP)ribose polymerase(cleaved PARP)proteins in the cells in 2.5 mg·L-1 Schisandrin B group were significantly increased(P<0.05 or P<0.01),the expression levels of cyclin A2,cyclin E2,and Bcl-2 proteins in the cells in 5.0 and 10.0 mg·L-1 Schisandrin B groups were significantly decreased(P<0.05 or P<0.01),while the expression levels of p27,Bax,cleaved Caspase-3,and cleaved PARP proteins in the cells in 5.0 and 10.0 mg·L-1 Schisandrin B groups were significantly increased(P<0.01).Conclusion:Schisandrin B has an inhibitory effect on proliferation of the pancreatic cancer Pan02 cells,and its mechanism may be related to the activation of the cysteine aspartic acid protease-3(Caspase-3)pathway to induce the apoptosis and activating p27 protein to induce the arrest of cell cycle at S phase.