RESUMO
AIM:To investigate the synergistic effect of toosendanin on regulating the cytotoxicity of γδ T cells to colorectal cancer cells. METHODS:γδ T cells amplified in vitro were identified by flow cytometry. Lactate dehydro-genase (LDH) release was detected to evaluate the cytotoxicity of γδ T cells and toosendanin to SW480 cells. The role of toosendanin in regulating the protein expression of Bcl-xL,Bcl-2 and MCL-1 was determined by Western blot. The effect of toosendanin on regulating the secretion of TNF-related apoptosis-inducing ligand(TRAIL) and Fas ligand(FasL) by γδ T cells was evaluated by ELISA. The mitochondrial membrane potential and apoptosis in SW480 cells treated with γδ T cells and toosendanin were analyzed by flow cytometry. The activation of caspase-9 and caspase-3 were determined by Western blot. RESULTS:CD3 and γδ T-cell receptor(TCR) were highly expressed in the γδ T cells amplified in vitro. Combina-tion with toosendanin significantly enhanced the cytotoxicity of γδ T cells to SW480 cells. Toosendanin did not influence the secretion of TRAIL and FasL secreted by γδ T cells. Toosendanin did not regulate the expression of Bcl-xL and Bcl-2 but suppressed the expression of MCL-1 in SW480 cells. In addition, enforced expression of MCL-1 obviously suppressed the synergistic effect of toosendanin on γδ T cell-induced cell death in SW480 cells. Meanwhile,co-treatment with toosendanin was able to enhance the γδ T cell-induced apoptosis and decrease of mitochondrial membrane potential. γδ T cell-depend-ent activation of caspase-9 and caspase-3 was significantly enhanced by toosendanin co-treatment in SW480 cells. CON-CLUSION:Toosendanin exerts synergistic effect on γδ T cell-induced cytotoxicity to colorectal cancer by suppressing the expression of MCL-1.