Backgound The aim of this study was to explore whether the inhibition of nuclear factor-κB (NF-κB) activation by mutant IκBα (S32,36→A) can enhance TNF-α-induced apoptosis of leukemia cells and to investigate t...Backgound The aim of this study was to explore whether the inhibition of nuclear factor-κB (NF-κB) activation by mutant IκBα (S32,36→A) can enhance TNF-α-induced apoptosis of leukemia cells and to investigate the possible mechanism.Methods The mutant IκBα gene was transfected into HL-60 cells by liposome-mediated techniques. G418 resistant clones stably expressing mutant IκBα were obtained by the limiting dilution method. TNF-α-induced NF-κB activation was measured by electrophoretic mobility shift assay (EMSA). The expression of bcl-x L was detected by RT-PCR and Western blot after 4 hours exposure of parental HL-60 and transfected HL-60 cells to a variety of concentrations of TNF-α. The percentage of apoptotic leukemia cells was evaluated by flow cytometry (FCM). Results Mutant IκBα protein was confirmed to exist by Western blot. The results of EMSA showed that NF-κB activation by TNF-α in HL-60 cells was induced in a dose-dependent manner, but was almost completely inhibited by mutant IκBα repressor in transfected cells. The levels of bcl-x L mRNA and protein in HL-60 cells increased after exposure to TNF-α, but changed very little in transfected HL-60 cells. The inhibition of NF-κB activation by mutant IκBα enhanced TNF-α-induced apoptosis. The cytotoxic effects of TNF-α were amplified in a time- and dose-dependent manner.Conclusions NF-κB activation plays an important role in the resistance to TNF-α-induced apoptosis. The inhibition of NF-κB by mutant IκBα could provide a new approach that may enhance the anti-leukemia effects of TNF-α or even of other cytotoxic agents.展开更多
文摘目的考察麦冬中主要皂苷元鲁斯可皂苷元(Rusco-gen in)抑制细胞黏附的作用,为深入研究其抗炎作用机制提供依据。方法采用MTT比色法检测Ruscogen in对人原髓性白血病细胞株HL-60细胞与正常或肿瘤坏死因子-α(TNF-α)活化的人脐静脉内皮细胞株ECV304细胞黏附的影响及其对ECV304与HL-60细胞增殖的影响。结果Ruscogen in 0.1,1.0μmol.L-1预处理ECV304细胞后,均抑制TNF-α诱导的ECV304细胞与HL-60细胞黏附的增加,Ruscogen in 0.001,0.01,0.1μmol.L-1预处理HL-60后,亦抑制TNF-α诱导的ECV304细胞与HL-60细胞黏附的增加;同时Ruscogen in在实验浓度范围内不影响ECV304细胞与HL-60细胞的增殖及二者之间的正常黏附。结论Ruscoge-n in可通过抑制HL-60细胞与活化的ECV304细胞之间的黏附作用,发挥抗炎活性。
文摘Backgound The aim of this study was to explore whether the inhibition of nuclear factor-κB (NF-κB) activation by mutant IκBα (S32,36→A) can enhance TNF-α-induced apoptosis of leukemia cells and to investigate the possible mechanism.Methods The mutant IκBα gene was transfected into HL-60 cells by liposome-mediated techniques. G418 resistant clones stably expressing mutant IκBα were obtained by the limiting dilution method. TNF-α-induced NF-κB activation was measured by electrophoretic mobility shift assay (EMSA). The expression of bcl-x L was detected by RT-PCR and Western blot after 4 hours exposure of parental HL-60 and transfected HL-60 cells to a variety of concentrations of TNF-α. The percentage of apoptotic leukemia cells was evaluated by flow cytometry (FCM). Results Mutant IκBα protein was confirmed to exist by Western blot. The results of EMSA showed that NF-κB activation by TNF-α in HL-60 cells was induced in a dose-dependent manner, but was almost completely inhibited by mutant IκBα repressor in transfected cells. The levels of bcl-x L mRNA and protein in HL-60 cells increased after exposure to TNF-α, but changed very little in transfected HL-60 cells. The inhibition of NF-κB activation by mutant IκBα enhanced TNF-α-induced apoptosis. The cytotoxic effects of TNF-α were amplified in a time- and dose-dependent manner.Conclusions NF-κB activation plays an important role in the resistance to TNF-α-induced apoptosis. The inhibition of NF-κB by mutant IκBα could provide a new approach that may enhance the anti-leukemia effects of TNF-α or even of other cytotoxic agents.
