Department of Experimental Radiology and Health Physics, Faculty of Medical Science, University of Fukui, Fukui 910-1193, Japan.
Int J Mol Med. 2010 Jan;25(1):81-7.
We investigated the mechanisms of thermosensitization related to combination therapy with sesquiterpene lactone parthenolide (PTL), a nuclear factor-kappaB (NF-kappaB) inhibitor, and hyperthermia using human lung adenocarcinoma cells A549. The kinetics of apoptosis induction and cell cycle of cells treated with PTL, heating, and combined treatment were examined by flow cytometric analysis. The flow cytometric distribution was calculated and expressed as a percentage. The ratios of the sub-G1 division, used to determine the induction of apoptosis, increased significantly with the combination therapy. Furthermore, the ratios of G2/M division increased and the ratios of G0/G1 division decreased, indicating cell cycle arrest in G2/M. The cell phase response to PTL by A549 cells synchronized in the G1/S border with hydroxyurea was also analyzed. PTL showed remarkable cytotoxicity at the S phase of the cell cycle in A549 cells at all concentrations as well as with hyperthermia, thus PTL reduced the number of cells in the proliferation phase. Inhibition of intracellular transcription factor NF-kappaB activation in A549 cells with various incubation periods after treatments with PTL, heating and combined treatment was examined by Western blot analysis. Unexpectedly, PTL alone did not inhibit NF-kappaB activation in cells stimulated with TNF-alpha, while heating alone inhibited NF-kappaB early after treatment and that effect faded over time. In contrast, PTL combined with heating completely inhibited NF-kappaB activation. Our results demonstrated that PTL and heating in combination cause significant thermosensitization of A549 cells via induction of apoptosis or cell cycle arrest in G2/M by inhibiting NF-kappaB activation in a synergistic manner.
我们研究了与倍半萜内酯（PTL）联合热疗治疗相关的热致敏机制，PTL 是一种核因子-κB（NF-κB）抑制剂，采用人肺腺癌细胞 A549 进行研究。通过流式细胞术分析检测用 PTL、加热和联合治疗处理的细胞凋亡诱导和细胞周期的动力学。通过流式细胞术分布计算并表示为百分比。亚 G1 分裂的比例，用于确定细胞凋亡的诱导，随着联合治疗显著增加。此外，G2/M 分裂的比例增加，G0/G1 分裂的比例减少，表明细胞周期在 G2/M 期被阻断。还分析了 A549 细胞在 G1/S 边界用羟基脲同步化后对 PTL 的细胞相反应。PTL 在所有浓度下以及与热疗联合使用时在 A549 细胞的细胞周期 S 期表现出显著的细胞毒性，从而减少了增殖期的细胞数量。通过 Western blot 分析，在用 PTL、加热和联合处理后不同孵育期，检测 A549 细胞中细胞内转录因子 NF-κB 激活的抑制作用。出乎意料的是，PTL 单独处理不能抑制 TNF-α刺激的细胞中 NF-κB 的激活，而单独加热则在治疗后早期抑制 NF-κB，并且该效应随时间减弱。相比之下，PTL 与加热联合完全抑制 NF-κB 的激活。我们的结果表明，PTL 和加热联合通过协同抑制 NF-κB 激活，导致 A549 细胞显著的热致敏，通过诱导细胞凋亡或细胞周期在 G2/M 期停滞。
