University Children's Hospital, Ulm, Germany.
J Cell Mol Med. 2009 Oct;13(10):4239-56. doi: 10.1111/j.1582-4934.2009.00888.x. Epub 2009 Sep 1.
NF-kappaB is activated by DNA-damaging anticancer drugs as part of the cellular stress response. However, the consequences of drug-induced NF-kappaB activation are still only partly understood. To investigate the impact of NF-kappaB on the cell's response to DNA damage, we engineered glioblastoma cells that stably express mutant IkappaBalpha superrepressor (IkappaBalpha-SR) to block NF-kappaB activation. Here, we identify a novel pro-apoptotic function of NF-kappaB in the DNA damage response in glioblastoma cells. Chemotherapeutic drugs that intercalate into DNA and inhibit topoisomerase II such as Doxorubicin, Daunorubicin and Mitoxantrone stimulate NF-kappaB DNA binding and transcriptional activity prior to induction of cell death. Importantly, specific inhibition of drug-induced NF-kappaB activation by IkappaBalpha-SR or RNA interference against p65 significantly reduces apoptosis upon treatment with Doxorubicin, Daunorubicin or Mitoxantrone. NF-kappaB exerts this pro-apoptotic function especially after pulse drug exposure as compared to continuous treatment indicating that the contribution of NF-kappaB becomes relevant during the recovery phase following the initial DNA damage. Mechanistic studies show that NF-kappaB inhibition does not alter Doxorubicin uptake and efflux or cell cycle alterations. Genetic silencing of p53 by RNA interference reveals that NF-kappaB promotes drug-induced apoptosis in a p53-independent manner. Intriguingly, drug-mediated NF-kappaB activation results in a significant increase in DNA damage prior to the induction of apoptosis. By demonstrating that NF-kappaB promotes DNA damage formation and apoptosis upon pulse treatment with DNA intercalators, our findings provide novel insights into the control of the DNA damage response by NF-kappaB in glioblastoma.
NF-κB 被 DNA 损伤的抗癌药物激活，作为细胞应激反应的一部分。然而，药物诱导的 NF-κB 激活的后果仍不完全清楚。为了研究 NF-κB 对细胞对 DNA 损伤的反应的影响，我们构建了稳定表达突变型 IkappaBalpha 超级抑制剂（IkappaBalpha-SR）以阻断 NF-κB 激活的神经胶质瘤细胞。在这里，我们在神经胶质瘤细胞的 DNA 损伤反应中鉴定了 NF-κB 的一种新的促凋亡功能。与拓扑异构酶 II 结合并抑制其活性的 DNA 嵌入化疗药物，如阿霉素、柔红霉素和米托蒽醌，在诱导细胞死亡之前刺激 NF-κB DNA 结合和转录活性。重要的是，通过 IkappaBalpha-SR 特异性抑制或针对 p65 的 RNA 干扰抑制药物诱导的 NF-κB 激活，在用阿霉素、柔红霉素或米托蒽醌处理时显著减少细胞凋亡。与持续治疗相比，NF-κB 在脉冲药物暴露后发挥这种促凋亡功能，这表明 NF-κB 的贡献在初始 DNA 损伤后的恢复阶段变得相关。机制研究表明，NF-κB 抑制不改变阿霉素的摄取和外排或细胞周期改变。通过 RNA 干扰沉默 p53 表明，NF-κB 以 p53 非依赖性方式促进药物诱导的细胞凋亡。有趣的是，药物介导的 NF-κB 激活导致在诱导细胞凋亡之前 DNA 损伤显著增加。通过证明 NF-κB 在脉冲处理 DNA 嵌入剂时促进 DNA 损伤形成和细胞凋亡，我们的研究结果为 NF-κB 在神经胶质瘤中控制 DNA 损伤反应提供了新的见解。
