Ammann Johannes U, Haag Christian, Kasperczyk Hubert, Debatin Klaus-Michael, Fulda Simone
University Children's Hospital, Ulm, Germany.
Int J Cancer. 2009 Mar 15;124(6):1301-11. doi: 10.1002/ijc.24068.
The transcription factor nuclear factor-kappaB (NF-kappaB) plays a central role in stress-induced transcriptional activation and has been implicated in chemoresistance of cancers. In the present study, we investigated the role of NF-kappaB in inducible chemoresistance of neuroblastoma. Doxorubicin, VP16 and the cytotoxic ligand TRAIL trigger NF-kappaB activation, whereas cisplatin and taxol have no impact on NF-kappaB activity. Specific inhibition of NF-kappaB activation by overexpression of dominant-negative mutant IkappaBalpha-super-repressor does not alter cell death upon doxorubicin or VP16 treatment, although it prevents doxorubicin- or VP16-mediated NF-kappaB activation. By comparison, inhibition of TRAIL-stimulated NF-kappaB activation by IkappaBalpha-superrepressor or the small molecule NF-kappaB inhibitor BMS-345541 significantly enhances TRAIL-induced apoptosis, pointing to an antiapoptotic function of NF-kappaB in TRAIL-mediated apoptosis. Analysis of signaling pathways reveals that NF-kappaB inhibition prevents TRAIL-triggered up-regulation of Mcl-1, promoting TRAIL-induced cytochrome c release and activation of caspases. Accordingly, knockdown of Mcl-1 by RNA interference significantly enhances TRAIL-induced apoptosis and also increases sensitivity of neuroblastoma cells to CD95- or chemotherapy-induced apoptosis. In conclusion, NF-kappaB regulates apoptosis in a stimulus-specific manner in neuroblastoma cells and confers protection against TRAIL-induced apoptosis. By demonstrating that NF-kappaB inhibition sensitizes neuroblastoma cells for TRAIL-induced apoptosis, our findings have important implications. Thus, NF-kappaB inhibitors may open new perspectives to potentiate the efficacy of TRAIL-based protocols in the treatment of neuroblastoma.
转录因子核因子-κB（NF-κB）在应激诱导的转录激活中起核心作用，并与癌症的化疗耐药性有关。在本研究中，我们调查了NF-κB在神经母细胞瘤诱导性化疗耐药中的作用。阿霉素、依托泊苷和细胞毒性配体TRAIL可触发NF-κB激活，而顺铂和紫杉醇对NF-κB活性无影响。通过过表达显性负性突变体IκBα-超级阻遏物特异性抑制NF-κB激活，虽可阻止阿霉素或依托泊苷介导的NF-κB激活，但并不改变阿霉素或依托泊苷处理后的细胞死亡情况。相比之下，IκBα-超级阻遏物或小分子NF-κB抑制剂BMS-345541抑制TRAIL刺激的NF-κB激活，可显著增强TRAIL诱导的细胞凋亡，表明NF-κB在TRAIL介导的细胞凋亡中具有抗凋亡功能。信号通路分析显示，NF-κB抑制可阻止TRAIL触发的Mcl-1上调，促进TRAIL诱导的细胞色素c释放和半胱天冬酶激活。因此，通过RNA干扰敲低Mcl-1可显著增强TRAIL诱导的细胞凋亡，并增加神经母细胞瘤细胞对CD95或化疗诱导的细胞凋亡的敏感性。总之，NF-κB以刺激特异性方式调节神经母细胞瘤细胞的凋亡，并赋予细胞对TRAIL诱导凋亡的保护作用。通过证明NF-κB抑制可使神经母细胞瘤细胞对TRAIL诱导的凋亡敏感，我们的研究结果具有重要意义。因此，NF-κB抑制剂可能为增强基于TRAIL的方案治疗神经母细胞瘤的疗效开辟新的前景。
