倍半萜烯内酯对鼻咽癌细胞内核因子-кB活化的影响

背景与目的:探讨倍半萜烯内酯化合物对人鼻咽癌(nasopharyngeal carcinoma,NPC)细胞内核因子-κB(NF-κB)信号转导活化的影响。材料与方法:采用小白菊内酯(parthenolide,PN)作为受试物,以对PN诱导转归敏感的CNE1细胞给予TNF-α预诱导建立模型,PN处理后提取胞质和胞核蛋白,分别检测IκBα降解、NF-κB p65亚单位活化后核内迁移,电泳迁移率改变试验(EMSA)检测核内活化NF-κB的DNA结合活性。进行PN剂量和作用时间依赖关系分析。结果:阴性对照组IκBα蛋白存在于胞质中,PN处理组使TNF-α诱导的胞质IκBα蛋白降解被抑制、胞核内蛋白含量减少;相应地,阴性对照组p65亚单位在胞质中含量高于胞核内,PN处理组抑制TNF-α诱导的胞质p65核转位;同步进行的EMSA可见,PN处理组NF-κB核结合活性比TNF-α诱导组明显降低。随PN处理时间(0.5~4h)和剂量(5~25μmol/L)增加,胞质中IκBα蛋白降解的抑制作用增强(其蛋白含量增加),胞核内p65亚单位蛋白减少,EMSA结合活性降低,呈明显的剂量和时间依赖性(P均<0.05)。结论:PN可影响NPC细胞内NF-κB因子的活化,提示PN对TNF-α诱导NF-κB信号的抑制作用可能是PN诱导NPC细胞凋亡敏感性的分子机制之一。

Effects of Sesquiterpene Lactones on the Nuclear Factor.kappa B Activation in Human Nasopharyngeal Carcinoma Cell Line

BACKGROUND AND AIM:To elucidate the effect of sesquiterpene lactones on the nuclear factor-kappa B(NF-κB)signal transduction regulation in human nasopharyngeal carcinoma(NPC)cells.MATERIALS AND METHODS:Parthenolide(PN)was used for treatment.Human CNE1 cell line was used to establish the cellular model after induction by TNF-α.The cytoplasmic and nuclear proteins were extracted after treatment by PN.The degradation of IκBα,the activation of p65 subunit and its nuclear translocation,and the DNA binding activity of nuclear activated NF-κB in EMSA assay were evaluated.RESULTS:In negative control group IκBα protein was expressed in the cytoplasm but not in nucleus.In the PN-pretreated group,however,the IκBα protein was increased in cytoplasm and decreased in nuclear protein.Meanwhile in PN-pretreated followed by TNF-α treatment cells,NF-κB p65 subunit level was increased in cytoplasm but was decreased in nuclei,when compared to non-PN-pretreated but TNF-α induction cells.Further EMSA analysis showed that NF-κB binding activity in PN-treated group was significantly lower than that in TNF-α-induced group.The alterations of intracellular NF-κB signal correlated with PN-pretreatment time(0.5-4 h)and in a dose-dependent(5-25 μmol/L)manner.CONCLUSION:PN inhibited the TNF-α-activated NF-κB signal transduction pathway in NPC cells.Such inhibitory effect may be one of the molecular mechanisms associated with the sensitization of NPC to PN-inducible apoptosis.