Condello Salvatore, Caccamo Daniela, Currò Monica, Ferlazzo Nadia, Parisi Giulia, Ientile Riccardo
Department of Biochemical, Physiological and Nutritional Sciences, University of Messina, Policlinico Universitario, Via Consolare Valeria, 98125 Messina, Italy.
Brain Res. 2008 May 1;1207:1-8. doi: 10.1016/j.brainres.2008.02.044. Epub 2008 Feb 29.
NGF treatment of neuroblastoma cells stimulates outgrowth of neurite processes associated with the expression of TrkA receptor and several differentiation markers. In this study, a 6 DIV exposure to NGF (50 ng/ml) increased immunostaining for alpha-tubulin, and expression of both alpha-tubulin and protein kinase C in the neuroblastoma cell line Neuro2a. Further, up-regulation of transglutaminase 1 and transglutaminase 2 expression, and reduction of transglutaminase 3 levels, were also observed in NGF-treated cells in comparison to untreated cells. Moreover, when Neuro2a cells were treated with the specific NF-kappaB inhibitor SN-50, the strong reduction of NF-kappaB activation was concomitant with a significant decrease of transglutaminase 2 expression, suggesting that NGF-evoked transglutaminase 2 induction could be related to NF-kappaB activation. To characterize the possible transglutaminase 2/NF-kappaB interplay, NGF treatment was carried out in Neuro2a cells which already over-expressed transglutaminase 2 after retinoic acid treatment. An additive effect of NGF was observed on the retinoic acid-induced transglutaminase 2 expression and enzyme activity, and NF-kappaB activation. However, a cystamine-mediated significant inhibition of transglutaminase activity (70%) was accompanied by a drastically reduced NF-kappaB activation only in cells exposed to NGF following retinoic acid treatment. We hypothesize that NF-kappaB activation was dependent on the transamidating activity related to high levels of TG2, and NGF enhanced NF-kappaB activation by a different, synergistically acting, pathway. These data suggest that the combined use of NGF and retinoic acid, or mimicking drugs, may provide the basics for the development of novel strategies in the therapeutic management of neuroblastomas.
神经生长因子（NGF）对神经母细胞瘤细胞的治疗可刺激与TrkA受体表达及多种分化标志物相关的神经突生长。在本研究中，将神经母细胞瘤细胞系Neuro2a暴露于NGF（50 ng/ml）6天可增加α-微管蛋白的免疫染色，以及α-微管蛋白和蛋白激酶C的表达。此外，与未处理的细胞相比，在NGF处理的细胞中还观察到转谷氨酰胺酶1和转谷氨酰胺酶2表达上调，以及转谷氨酰胺酶3水平降低。此外，当用特异性NF-κB抑制剂SN-50处理Neuro2a细胞时，NF-κB激活的强烈降低与转谷氨酰胺酶2表达的显著下降同时发生，这表明NGF诱导的转谷氨酰胺酶2诱导可能与NF-κB激活有关。为了表征转谷氨酰胺酶2/NF-κB可能的相互作用，在经视黄酸处理后已过表达转谷氨酰胺酶2的Neuro2a细胞中进行了NGF处理。观察到NGF对视黄酸诱导的转谷氨酰胺酶2表达、酶活性及NF-κB激活具有叠加效应。然而，胱胺介导的转谷氨酰胺酶活性显著抑制（70%）仅在视黄酸处理后暴露于NGF的细胞中伴随着NF-κB激活的急剧降低。我们推测NF-κB激活依赖于与高水平TG2相关的转酰胺活性，并且NGF通过不同的、协同作用的途径增强NF-κB激活。这些数据表明，NGF和视黄酸或模拟药物的联合使用可能为神经母细胞瘤治疗管理新策略的开发提供基础。
