Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche, Sezione di Scienze Biochimiche, Università degli Studi di Palermo, Palermo, Italy.
J Cell Physiol. 2013 May;228(5):952-67. doi: 10.1002/jcp.24131.
The mechanism of the cytotoxic effect exerted by parthenolide on tumor cells is not clearly defined today. This article shows that parthenolide stimulates in human osteosarcoma MG63 and melanoma SK-MEL-28 cells a mechanism of cell death, which is not prevented by z-VAD-fmk and other caspase inhibitors. In particular treatment with parthenolide rapidly stimulated (1-2 h) reactive oxygen species (ROS) generation by inducing activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and NADPH oxidase. This event caused depletion of thiol groups and glutathione, NF-κB inhibition, c-Jun N-terminal kinase (JNK) activation, cell detachment from the matrix, and cellular shrinkage. The increase of ROS generation together with the mitochondrial accumulation of Ca(2+) also favored dissipation of Δψm, which seemed primarily determined by permeability transition pore opening, since Δψm loss was partially prevented by the inhibitor cyclosporin A. Staining with Hoechst 33342 revealed in most cells, at 3-5 h of treatment, chromatin condensation, and fragmentation, while only few cells were propidium iodide (PI)-positive. In addition, at this stage apoptosis inducing factor (AIF) translocated to the nucleus and co-localized with areas of condensed chromatin. Prolonging the treatment (5-15 h) ATP content declined while PI-positive cells strongly augmented, denouncing the increase of necrotic effects. All these effects were prevented by N-acetylcysteine, while caspase inhibitors were ineffective. We suggest that AIF exerts a crucial role in parthenolide action. In accordance, down-regulation of AIF markedly inhibited parthenolide effect on the production of cells with apoptotic or necrotic signs. Taken together our results demonstrate that parthenolide causes in the two cell lines a caspase-independent cell death, which is mediated by AIF.
尚不清楚小白菊内酯对肿瘤细胞的细胞毒性作用机制。本文表明，小白菊内酯刺激人骨肉瘤 MG63 和黑色素瘤 SK-MEL-28 细胞发生一种细胞死亡机制，该机制不能被 z-VAD-fmk 和其他半胱天冬酶抑制剂所阻止。特别是，小白菊内酯处理在 1-2 小时内迅速刺激活性氧（ROS）的产生，这是通过诱导细胞外信号调节激酶 1/2（ERK 1/2）和 NADPH 氧化酶的激活来实现的。这一事件导致巯基和谷胱甘肽耗竭，NF-κB 抑制，c-Jun N-末端激酶（JNK）激活，细胞从基质上脱落和细胞收缩。ROS 的产生增加以及线粒体中 Ca(2+)的积累也有利于Δψm 的耗散，这似乎主要是由通透性转换孔的开放决定的，因为环孢菌素 A 部分阻止了 Δψm 的丧失。用 Hoechst 33342 染色显示，在处理 3-5 小时后，大多数细胞中染色质发生浓缩和片段化，而只有少数细胞呈碘化丙啶（PI）阳性。此外，在这个阶段，凋亡诱导因子（AIF）易位到细胞核，并与浓缩染色质的区域共定位。延长处理时间（5-15 小时）会导致 ATP 含量下降，而 PI 阳性细胞明显增加，表明坏死效应增加。所有这些效应都可以被 N-乙酰半胱氨酸所阻止，而半胱天冬酶抑制剂则无效。我们认为 AIF 在小白菊内酯的作用中发挥了关键作用。相应地，下调 AIF 显著抑制了小白菊内酯对具有凋亡或坏死特征的细胞的作用。总之，我们的结果表明，小白菊内酯在两种细胞系中引起一种不依赖半胱天冬酶的细胞死亡，该死亡是由 AIF 介导的。
