Growth, Differentiation, Survival and Apoptosis in Human Neuroblastoma Cells

我们之前报道了神经营养因子在人神经母细胞瘤细胞中TRK-A和TRK-B受体的信号转导（Jpn J Cancer Res 1994,Acta pedlir Jpn， Med pediatrics Oncol 2000和Jpn J Cancer Res 2001）。本研究探讨了芬维啶对细胞凋亡的作用机制。芬维啶介导神经母细胞瘤细胞凋亡，被认为是一种新的神经母细胞瘤治疗药物。然而，芬瑞啶的细胞毒性机制尚未完全阐明。JNK和p38 MAPK信号的持续激活最近被证明在应激诱导的细胞凋亡中起关键作用。芬维甲酸是否激活神经母细胞瘤细胞的信号尚不清楚。在本研究中，芬维啶诱导神经母细胞瘤细胞中JNK和p38 MAPK的持续激活。抗氧化剂l -抗坏血酸预处理几乎完全抑制了芬维甲酸诱导的细胞内活性氧（ROS）的积累、JNK和p38 MAPK的激活以及细胞凋亡。另一方面，在耐药的神经母细胞瘤细胞中，芬维胺不改变细胞内ROS的产生和应激信号的激活。我们的研究表明，在神经母细胞瘤细胞中，芬维甲酸以ros依赖的方式诱导JNK和p38 MAPK的持续激活，表明JNK和p38 MAPK信号通路可能介导芬维甲酸诱导的细胞凋亡。我们的研究结果还表明，抑制芬维甲酸诱导的ROS生成系统以及下游JNK和p38 MAPK信号通路会导致神经母细胞瘤细胞对芬维甲酸产生抗性。

We have previously reported the signal transduction of TRK-A and TRK-B receptors by neurotrophic factors in human neuroblastoma cells (Jpn J Cancer Res 1994,Acta Pedliatr Jpn, Med Pediatr Oncol 2000 and Jpn J Cancer Res 2001). In this study the mechanisms of apoptosis by fenretinide was investigated.Fenretinide, which mediates apoptosis in neuroblastoma cells, is being considered as a novel therapeutic for neuroblastoma. However, the cytotoxic mechanisms of fenretinide have not been fully elucidated. Sustained-activation of JNK and p38 MAPK signaling has recently been shown to have a pivotal role in stress-induced apoptosis. Whether fenretinide activates the signaling in neuroblastoma cells is not known.In the present study, fenretinide induced sustained-activation of both JNK and p38 MAPK in neuroblastoma cells. Pretreatment with the antioxidant L-ascorbic acid almost completely inhibited the accumulation of fenretinide-induced intracellular reactive oxygen species (ROS), activation of JNK and p38 MAPK, and apoptosis. On the other hand, intracellular ROS production and activation of stress signaling was not altered by fenretinide in resistant neuroblastoma cells. Our study demonstrates that in neuroblastoma cells, fenretinide induces sustained-activation of JNK and p38 MAPK in an ROS-dependent manner, and indicates that JNK and p38 MAPK signaling might mediate fenretinide-induced apoptosis.Our results also indicate that suppression of the fenretinide-induced ROS productive system and the downstream JNK and p38 MAPK signaling pathways causes neuroblastoma cells to become resistant to fenretinide.