Ruggeri Pierdomenico, Farina Antonietta R, Di Ianni Natalia, Cappabianca Lucia, Ragone Marzia, Ianni Giulia, Gulino Alberto, Mackay Andrew R
Department of Applied Clinical and Biotechnological Sciences, University of L'Aquila, L'Aquila, Italy.
Department of Applied Clinical and Biotechnological Sciences, University of L'Aquila, L'Aquila, Italy; Department of Medical-Surgical Science and Biotechnology, University of Rome "La Sapienza", Latina, Italy.
PLoS One. 2014 Apr 15;9(4):e94568. doi: 10.1371/journal.pone.0094568. eCollection 2014.
The developmental and stress-regulated alternative TrkAIII splice variant of the NGF receptor TrkA is expressed by advanced stage human neuroblastomas (NBs), correlates with worse outcome in high TrkA expressing unfavourable tumours and exhibits oncogenic activity in NB models. In the present study, we report that constitutive TrkAIII expression in human SH-SY5Y NB cells inhibits Rotenone, Paraquat and LY83583-induced mitochondrial free radical reactive oxygen species (ROS)-mediated death by stimulating SOD2 expression, increasing mitochondrial SOD2 activity and attenuating mitochondrial free radical ROS production, in association with increased mitochondrial capacity to produce H2O2, within the context of a more tumour stem cell-like phenotype. This effect can be reversed by the specific TrkA tyrosine kinase inhibitor GW441756, by the multi-kinase TrkA inhibitors K252a, CEP-701 and Gö6976, which inhibit SOD2 expression, and by siRNA knockdown of SOD2 expression, which restores the sensitivity of TrkAIII expressing SH-SY5Y cells to Rotenone, Paraquat and LY83583-induced mitochondrial free radical ROS production and ROS-mediated death. The data implicate the novel TrkAIII/SOD2 axis in promoting NB resistance to mitochondrial free radical-mediated death and staminality, and suggest that the combined use of TrkAIII and/or SOD2 inhibitors together with agents that induce mitochondrial free radical ROS-mediated death could provide a therapeutic advantage that may also target the stem cell niche in high TrkA expressing unfavourable NB.
神经营养因子（NGF）受体TrkA的发育和应激调节性可变剪接变体TrkAIII在晚期人类神经母细胞瘤（NB）中表达，与高表达TrkA的不良肿瘤的较差预后相关，并且在NB模型中表现出致癌活性。在本研究中，我们报告，在人SH-SY5Y NB细胞中组成性表达TrkAIII可通过刺激超氧化物歧化酶2（SOD2）表达、增加线粒体SOD2活性和减弱线粒体自由基活性氧（ROS）产生，来抑制鱼藤酮、百草枯和LY83583诱导的线粒体自由基ROS介导的死亡，这与在更具肿瘤干细胞样表型的背景下线粒体产生过氧化氢（H2O2）的能力增加有关。这种效应可被特异性TrkA酪氨酸激酶抑制剂GW441756、抑制SOD2表达的多激酶TrkA抑制剂K252a、CEP-701和Gö6976以及通过小干扰RNA（siRNA）敲低SOD2表达所逆转，siRNA敲低SOD2表达可恢复表达TrkAIII的SH-SY5Y细胞对鱼藤酮、百草枯和LY83583诱导的线粒体自由基ROS产生和ROS介导的死亡的敏感性。这些数据表明，新型的TrkAIII/SOD2轴在促进NB对线粒体自由基介导的死亡和干性的抗性中起作用，并提示TrkAIII和/或SOD2抑制剂与诱导线粒体自由基ROS介导的死亡的药物联合使用，可能提供一种治疗优势，这也可能靶向高表达TrkA的不良NB中的干细胞生态位。
