〔Abstract〕 Objective To explore the effects of sinomenine(SIN) on proliferation, apoptosis, invasion and migration ability of gastric cancer cell line SGC-7901 and its mechanism. Methods Normal human gastric mucosal epithelial cells GES-1 and human gastric cancer cells SGC-7901 were normally cultured, and they were enrolled as blank control group(Control). They were treated with 0.5, 1.0 and 2.5 mmol/L SIN for 48 h. The positive control(50 μmol/L celecoxib) was set up. Cell growth was detected by CCK-8 method. The apoptosis was detected by flow cytometry. Cell invasion was detected by Transwell chamber. Cell migration was detected by scratch test.Western blot was applied to detect the expression of Bax,Bcl-2,Cleaved caspase3,E-cadherin,N-cadherin and Vimentin. The targeted relationship between miR-33 a-5 p and lactate dehydrogenase A( LDHA) was analyzed by online prediction software,which was confirmed by double luciferase report. The miR-33 a-5 p mimics was transfected into SGC-7901 cells. The expression of miR-33 a-5 p and LDHA mRNA in cells was detected by RT-qPCR. The LDHA overexpression vector was recombined and constructed to transfected into SGC-7901 cells. The cells were treated with 0. 5,1. 0 and 2. 5 mmol/L SIN for 48 h. The cell proliferation,apoptosis,invasion and migration were detected. Results Compared with Control group,SIN could increase apoptosis rate of SGC-7901 cells,the expression of Bax,Cleaved caspase-3,E-cadherin and miR-33 a-5 p,while decreased survival rate,invasion number,migration rate,the expression of Bcl-2,N-cadherin,Vimentin and LDHA mRNA( P<0. 05). LDHA was the predicted target spot of miR-33 a-5 p. SIN could up-regulate the expression of miR-33 a-5 p,and down-regulate the expression of LDHA mRNA( P<0. 05). Compared with Control group,after LDHA overexpression,apoptosis rate of SGC-7901 decreased,while the expression of LDHA protein,survival rate,invasion number and migration rate increased( P<0. 05). After SIN treatment,apoptosis rate of SGC-7901 increased,while the expression of LDHA protein,survival rate,invasion number and migration rate decreased( P<0. 05). Compared with pcDNA-LDHA group,after SIN intervention,apoptosis rate of SGC-7901 increased,while survival rate,invasion number and migration rate decreased( P<0. 05). Conclusion SIN can down-regulate LDHA level by targeting miR-33 a-5 p,mediate cell proliferation,apoptosis,invasion and migration for inhibiting gastric cancer cell line SGC-7901.