Objective:Cancer cell radioresistance is a stumbling block in radiation therapy.The activity in the nuclear factor kappa B(NFκB)pathway correlates with anti-apoptotic mechanisms and increased radioresistance.The IKK ...Objective:Cancer cell radioresistance is a stumbling block in radiation therapy.The activity in the nuclear factor kappa B(NFκB)pathway correlates with anti-apoptotic mechanisms and increased radioresistance.The IKK complex plays a major role in NFκB activation upon numerous signals.In this study,we examined the interaction between ionizing radiation(IR)and different members of the IKK-NFκB pathway,as well as upstream activators,RAF1,ERK,and AKT1.Methods:The effect of 4 Gy of IR on the expression of the RAF1-ERK-IKK-NFκB pathway was examined in A549 and H1299 lung cancer cell lines using Western blot analysis and confocal microscopy.We examined changes in radiation sensitivity using gene silencing or pharmacological inhibitors of ERK and IKKβ.Results:IKKα,IKKγ,and IκBαincreased upon exposure to IR,thereby affecting nuclear levels of NFκB(phospho-p65).ERK inhibition or si RNA-mediated down-regulation of RAF1 suppressed the post-irradiation survival of the examined lung cancer cell lines.A similar effect was detected on survival upon silencing IKKα/IKKγor inhibiting IKKβ.Conclusions:Exposure of lung cancer cells to IR results in NFκB activation via IKK.The genetic or pharmacological blockage of the RAF1-ERK-IKK-NFκB pathway sensitizes cells to therapeutic doses of radiation.Therefore,the IKK pathway is a promising target for therapeutic intervention in combination with radiotherapy.展开更多
文摘IKK／NF-κB信号通路是目前研究发现最重要的炎症通路之一。炎症反应广泛参与神经系统疾病的病理生理过程，脑缺血再灌注损伤是炎症反应的急性表现，慢性炎症反应也是神经系统退行性疾病发生发展的重要原因。 IKK／NF-κB信号通路是迄今研究的最为重要的炎症反应通路之一，生理条件下，核转录因子-κB（ nuclear factor-κB，NF-κB）与NF-κB抑制蛋白（ inhibitor of NF-κB，IκB）蛋白结合以无活性的形式存在于细胞质中，当机体受到外界刺激时，激活IκB活激酶复合物（inhibitor of IκB kinases，IKK）使其发生磷酸化和泛素化，致使NF-κB与IκB发生解离并进入细胞核，与靶基因中NF-κB的结合位点相结合，启动靶基因转录，从而增加下游炎性因子的表达［1］。
文摘Objective:Cancer cell radioresistance is a stumbling block in radiation therapy.The activity in the nuclear factor kappa B(NFκB)pathway correlates with anti-apoptotic mechanisms and increased radioresistance.The IKK complex plays a major role in NFκB activation upon numerous signals.In this study,we examined the interaction between ionizing radiation(IR)and different members of the IKK-NFκB pathway,as well as upstream activators,RAF1,ERK,and AKT1.Methods:The effect of 4 Gy of IR on the expression of the RAF1-ERK-IKK-NFκB pathway was examined in A549 and H1299 lung cancer cell lines using Western blot analysis and confocal microscopy.We examined changes in radiation sensitivity using gene silencing or pharmacological inhibitors of ERK and IKKβ.Results:IKKα,IKKγ,and IκBαincreased upon exposure to IR,thereby affecting nuclear levels of NFκB(phospho-p65).ERK inhibition or si RNA-mediated down-regulation of RAF1 suppressed the post-irradiation survival of the examined lung cancer cell lines.A similar effect was detected on survival upon silencing IKKα/IKKγor inhibiting IKKβ.Conclusions:Exposure of lung cancer cells to IR results in NFκB activation via IKK.The genetic or pharmacological blockage of the RAF1-ERK-IKK-NFκB pathway sensitizes cells to therapeutic doses of radiation.Therefore,the IKK pathway is a promising target for therapeutic intervention in combination with radiotherapy.
