Objective:To discuss the role of M2 macrophages in epithelial-mesenchymal transition(EMT)and cisplatin(DDP)resistance in the non-small cell lung cancer(NSCLC),and to clarify the regulatory mechanism of nuclear factor κB(NF-κB)signaling pathway.Methods:The human monocytic leukemia THP-1 cells were selected and differentiated into M0 macrophages by phorbol myristate acetate(PMA)induction,followed by M2 macrophage polarization through interleukin(IL)-4 and IL-13 stimulation.Western blotting and immunofluorescence methods were used to detect the protein expression levels of CD163,CD86,and arginase-1(Arg-1)in M0 and M2 macrophages.The human NSCLC A549 cells were co-cultured non-contactly with M0 or M2 macrophages in Transwell chambers,and the cells were divided into A549+M0 group(A549 cells co-cultured with M0 macrophages),A549+M2 group(A549 cells co-cultured with M2 macrophages),and A549+M2+BAY11-7082 group(A549 cells co-cultured with M2 macrophages and treated with 10 mmol·L-1 NF-κB inhibitor BAY11-7082).Wound healing assay was used to detect the wound healing rate of the A549 cells in various groups;Transwell assay was used to detect the number of invasion A549 cells in various groups;cell counting kit-8(CCK-8)assay was used to detect the inhibitory rate of proliferation and half maximal inhibitory concentration(IC50)value of the A549 cells after treated with DDP in the co-culture system;Western blotting method was used to detect the expression levels of vimentin,E-cadherin,N-cadherin,transcription factor Snail,phosphorylated P65(p-P65),P-glycoprotein(P-gp),and programmed death-ligand 1(PD-L1)proteins in the A549 cells in various groups.Results:The Western blotting results showed that compared with M0 group,the expression levels of CD163 and Arg-1 proteins in the macrophages in M2 group were significantly increased(P<0.05),while the expression level of CD86 protein was significantly decreased(P<0.05).The immunofluorescence results showed that compared with M0 group,the expression of CD163 protein in the macrophages in M2 group was enhanced and the expression of CD86 protein was weakened.The wound healing assay results showed that at 24 and 48 h of culture,compared with A549+M0 group,the wound healing rate of the A549 cells in A549+M2 group was significantly increased(P<0.05);in the co-culture system,compared with A549+M0 group,the wound healing rate of the A549 cells in A549+M2 group was significantly increased(P<0.05);compared with A549+M2 group,the wound healing rate of the A549 cells in A549+M2+BAY11-7082 group was significantly decreased(P<0.05).The Transwell assay results showed that compared with A549+M0 group,the number of invasion A549 cells in A549+M2 group was significantly increased(P<0.05);compared with A549+M2 group,the number of invasion A549 cells in A549+M2+BAY11-7082 group was significantly decreased(P<0.05);in the co-culture system,compared with A549+M0 group,the number of invasion A549 cells in A549+M2 group was significantly increased(P<0.05).The CCK-8 assay results showed that after treated with 2.50,5.00,10.00,20.00,and 40.00 mg·L-1 DDP,compared with A549+M0 group,the inhibitory rate of proliferation of the A549 cells in A549+M2 group was significantly decreased(P<0.05 or P<0.01),and the IC50 value was significantly increased(P<0.01);in the co-culture system,compared with A549+M0 group,the inhibitory rate of proliferation of the A549 cells in A549+M2 group was significantly decreased(P<0.05 or P<0.01),and the IC50 value was significantly increased(P<0.01);compared with A549+M2 group,the inhibitory rate of proliferation of the A549 cells in A549+M2+BAY11-7082 group was significantly increased(P<0.05),and the IC50 value was significantly decreased(P<0.05).The Western blotting results showed that compared with A549+M0 group,the expression level of E-cadherin proteins in the A549 cells in A549+M2 group was significantly decreased(P<0.05),while the expression levels of N-cadherin,vimentin,and Snail proteins were significantly increased(P<0.05);in the co-culture system,compared with A549+M0 group,the expression levels of vimentin,Snail,N-cadherin,and p-P65 proteins in the A549 cells in A549+M2 group were significantly increased(P<0.05),while the expression level of E-cadherin proteins was significantly decreased(P<0.05);compared with A549+M2 group,the expression levels of vimentin,N-cadherin,and p-P65 proteins in the A549 cells in A549+M2+BAY11-7082 group were significantly decreased(P<0.05),while the expression level of E-cadherin proteins was significantly increased(P<0.05);compared with A549+M0 group,the expression levels of P-gp and PD-L1 proteins in the A549 cells in A549+M2 group were significantly increased(P<0.05);in the co-culture system,compared with A549+M0 group,the expression levels of P-gp and PD-L1 proteins in the A549 cells in A549+M2 group were significantly increased(P<0.05);compared with A549+M2 group,the expression levels of P-gp and PD-L1 proteins in the A549 cells in A549+M2+BAY11-7082 group were significantly decreased(P<0.05).Conclusion:The M2 macrophages can regulate EMT in the NSCLC cells to promote the invasion and metastasis of tumor,and modulate the expressions of P-gp and PD-L1 to enhance DDP resistance,which is associated with the NF-κB signaling pathway.