Objective:To discuss the effect of zanubrutinib(BGB-3111)combined with bortezomib(Btz)on the apoptosis of the human multiple myeloma(MM)cells,and to clarify its possible mechanism.Methods:The human MM cell lines U266,PS-R,RPMI8226,KMS28-PE,KMS28-BM,and H929 were cultured in vitro.Western blotting method was used to detect the expression level of Bruton's tyrosine kinase(BTK)protein in various cells;cell counting kit-8(CCK-8)method was used to detect the survival rates of the RPMI8226,U266,and KMS28-BM cells after treated with 0,10,20,30,40,and 50 μmol·L?1 BGB-3111.The RPMI8226,U266,and KMS28-BM cells at the logarithmic growth phase were selected and divided into control group,BGB-3111 group,Btz group,and BGB-3111+Btz group.Flow cytometry was used to detect the apoptotic rates of the cells in various groups;Western blotting method was used to detect the expression levels of myeloid cell leukemia 1(MCL-1),B-cell lymphoma-2(Bcl-2),Bcl-2-interacting mediator of cell death(Bim),phosphorylated Bim(p-Bim),P65,phosphorylated P65(p-P65),tumor necrosis factor receptor-associated factor(TRAF)2,and tumor necrosis factor alpha-induced protein 3(A20)in different kinds of cells.The U266 cells were divided into A20 overexpression group(A20-OE group)and empty vector control group(EV group).Each group was further divided into control group,BGB-3111 group,Btz group,and BGB-3111+Btz group.The corresponding plasmids were transfected;Western blotting method was used to detect the transfection efficiency of the cells in various groups;flow cytometry was used to detect the apoptotic rates of the cells in various groups after over-expression of A20.Results:The Western blotting results showed that compared with KMS28-BM cells,the expression levels of BTK protein in the U266,RPMI8226,and H929 cells were significantly increased(P<0.05 or P<0.01).The CCK-8 results showed that compared with 0 μmol·L?1 BGB-3111 group,the survival rates of the RPMI8226 and U266 cells in 10,20,30,40,and 50 μmol·L?1 BGB-3111 groups were significantly decreased(P<0.05 or P<0.01),and the survival rates of the KMS28-BM cells in 20,30,40,and 50 μmol·L?1 BGB-3111 groups were significantly decreased(P<0.05).Compared with RPMI8226 and U266 cells,the survival rates of the KMS28-BM cells in 20,30,and 40 μmol·L?1 BGB-3111 groups were significantly increased(P<0.05).Therefore,10 μmol·L?1 BGB-3111 was selected for subsequent experiments.The flow cytometry results showed that compared with control group,the apoptotic rates of the RPMI8226 and U266 cells in BGB-3111 group,Btz group,and BGB-3111+Btz group were significantly increased(P<0.05 or P<0.01);compared with BGB-3111 group and Btz group,the apoptotic rates of the RPMI8226 and U266 cells in BGB-3111+Btz group were significantly increased(P<0.01);compared with control group,the apoptotic rates of the KMS28-BM cells in Btz group and BGB-3111+Btz group were significantly increased(P<0.01);compared with BGB-3111 group,the apoptotic rate of the KMS28-BM cells in BGB-3111+Btz group was significantly increased(P<0.01);compared with EV group,the apoptotic rates of the cells in A20-OE group in Btz group and BGB-3111+Btz group were significantly increased(P<0.05).The Western blotting results showed that compared with control group,the expression levels of Bim protein in the RPMI8226 and U266 cells in BGB-3111 group,Btz group,and BGB-3111+Btz group were significantly increased(P<0.05),while the expression levels of MCL-1,p-Bim,and Bcl-2 proteins in the RPMI8226 and U266 cells in Btz group and BGB-3111+Btz group were significantly decreased(P<0.05);compared with BGB-3111 group and Btz group,the expression levels of Bim protein in the RPMI8226 and U266 cells in BGB-3111+Btz group were significantly increased(P<0.05),while the expression levels of MCL-1,p-Bim,and Bcl-2 proteins were significantly decreased(P<0.05).Compared with control group,the expression levels of p-P65 protein in the RPMI8226 and U266 cells in Btz group and BGB-3111+Btz group were significantly increased(P<0.05),while the expression levels of TRAF2 and A20 proteins were significantly decreased(P<0.05);compared with BGB-3111 group and Btz group,the expression levels of p-P65 protein in the RPMI8226 and U266 cells in BGB-3111+Btz group were significantly increased(P<0.05),while the expression levels of TRAF2 and A20 proteins were significantly decreased(P<0.05).The flow cytometry results showed that compared with EV group,the expression level of A20 protein in A20-OE group cells was significantly increased(P<0.01).Conclusion:BGB-3111 induces apoptosis in the MM cells by inhibiting BTK activity and enhances the pro-apoptotic effect of Btz.Over-expression of A20 increases the sensitivity of the MM cells to the combined treatment.The antitumor effect may be related to the inhibition of the nuclear factor kappa B(NF-κB)signaling pathway.