The Role of Ape1 in Neurotoxicity of Cancer Treatments

描述(申请人提供)：癌症治疗的许多神经毒性副作用包括认知功能障碍，通常称为化疗和周围神经病。这些副作用的机制和保护神经元的方法仍有待阐明。DNA碱基切除修复(BER)途径包括基本内切核酸酶1/氧化还原因子(APE1/Ref-1或APE1)，是化疗和电离辐射(IR)引起的氧化和烷化剂损伤的主要DNA修复途径。此外，APE1还与许多转录因子相互作用，特别是与核因子：B、AP1和P53相互作用，通过氧化还原信号调节它们的功能。在神经元中，这些转录因子介导了一些与神经元存活有关的蛋白质的表达，并改变了对损伤和炎症的兴奋性。因此，APE1可能通过其DNA修复和/或氧化还原功能在维持神经元组织的动态平衡中发挥关键作用。这项工作的总体假设是，APE1通过减少对DNA的烷基化和氧化损伤以及通过调节AP1、NFkB和P53的活性来增强化疗或IR损伤后神经元的存活和功能，并帮助维持正常的神经元功能。我们将利用原代大鼠中枢神经系统(海马区)和感觉神经细胞(背根节或DRG)来确定APE1是否参与了化疗和IR相关的神经毒性和神经功能。我们将在正常情况下和添加癌症化疗药物和IR后减少或增强这些神经元中APE1的表达，并确定其对神经元功能和存活的各个方面的影响。我们还将使用仅具有氧化还原或修复功能的APE1突变蛋白或仅抑制修复或氧化还原活性的药物来确定APE1的哪些功能对神经保护/功能至关重要。最后，我们将确定APE1的氧化还原活性是否改变了化疗和IR后神经元培养中下游应激反应因子如AP1、NFkB和P53的活性。这一应用的实验将为研究化疗和IR患者经历的神经认知(化学训练)和周围神经病变的机制研究奠定基础。了解癌症治疗中神经保护的机制将是为患者提供神经保护的关键，这有助于减轻这些严重的副作用。

DESCRIPTION (provided by applicant): Numerous neurotoxic side effects of cancer treatments include cognitive dysfunction, commonly called chemobrain and peripheral neuropathy. The mechanisms for these side-effects and ways to protect neurons remain to be elucidated. The DNA base excision repair (BER) pathway including the abasic- endonuclease1/redox factor (Ape1/Ref-1 or Ape1) has been shown to be the major DNA repair pathway for oxidative and alkylating agent damage that occurs with chemotherapy and ionizing radiation (IR). Additionally, Ape1 interacts with a number of transcription factors, especially NF:B, AP1 and p53 to regulate their function through redox signaling. In neurons, these transcription factors mediate the expression of a number of proteins involved in neuronal survival and altered excitability in response to injury and inflammation. Thus, Ape1 could play a critical role in maintaining homeostasis in neuronal tissue through its DNA repair and/or its redox function. The overall hypothesis of the proposed work is that Ape1 acts to enhance neuronal survival and function after injury by chemotherapy or IR and helps to maintain normal neuronal function by minimizing alkylation and oxidative damage to DNA as well as by regulating the activity of AP1, NFkB and p53. We will determine if Ape1 is involved in the neurotoxicity and neuronal function associated with chemotherapy and IR using primary rat central nervous system (hippocampal) and sensory neuronal cells (dorsal root ganglia or DRG). We will reduce or augment Ape1 expression in these neurons under normal and following the addition of cancer chemotherapeutic agents and IR and ascertain the effects on various aspects of neuronal function and survival. We also will use Ape1 mutant proteins that only have either the redox or repair functions or drugs that inhibit only the repair or redox activity to ascertain which functions of Ape1 are critical for neuroprotection/function. Finally, we will determine whether the redox activity of Ape1 alters the activity of downstream stress response factors such as AP1, NFkB and p53 in neuronal cultures following chemotherapy and IR.Experiments in this application will form the basis for mechanistic studies into neurocognitive ("chemobrain") and peripheral neuropathy experienced by patients following chemotherapy and IR. Understanding the mechanism for neuroprotection during cancer therapy will be critical in providing patients with neuroprotection that can help alleviate these serious side effects.