MnSODm对化疗损伤的保护作用及分子机制研究

Many studies have shown that oxidative stress plays an important role in side effects of chemotherapy.The oxidative stress following the free radical generation and alteration in redox status are the main mechanisms of tissue damages of chemotherapy. Manganese superoxide dismutase analog compounds (MnSODm) is a new synthetic drug by Lanzhou University. Our previous study has demonstrated that treatment with MnSODm exhibited the potential to prevent significant liver toxicity,and the protective effect of MnSODm against CCl4-induced hepatic injury may rely on its ability to reduce oxidative stress and suppress inflammatory responses. Based on the preliminary study，we put forward the following hypothesis: MnSODm may provides significant protection against chemotherapeutic agents-induced cardiotoxicity, hepatotoxicity, nephrotoxicity, and hematotoxicity, and might be helpful in abrogation of tissue damages of chemotherapy.Meanwhile, MnSODm may induce cytoprotective genes through the Nrf2/ARE pathway, an important mechanism for the induction of cytoprotective genes in response to oxidative stress. To examine this hypothesis, in the present study, we will explicate the protective activity of MnSODm against organ damages associated with oxidative stress in vivo and in vitro and its possible mechanism. Rats (mice) and cell lines will be employed to construct damage models in vivo and in vitro. Some biochemistry parameters in certain organs and blood will be evaluated. Oxidant/antioxidant biochemical parameters, such as GST, GSH-PX, SOD, CAT and MDA, will be detected. The tissues will be examined with light microscopy and Electron microscope. To evaluate the protective mechanism and antioxidant defense potential of MnSODm in organ oxidative damage, proinflammatory mediators such as iNOS,COX-2, TNFα,IL1β and IL-2,as well as NF-κB will be investigated in this study. In addition ,Nrf2 translocation in tissue will be detected by Western blotting,and real-time PCR will be used to measure the expression levels of GCLC, NQO1 and HO-1 mRNA. Futhermore ，Nrf2 siRNA and gene chips will be used to investigate its molecular mechanisms.The research will provide theoretical rationale and experimental evidences for its potential clinical application .

化疗副作用的产生与氧化应激损伤有关。申请人前期研究发现兰州大学合成的锰超氧化物歧化酶模拟化合物（MnS0Dm)对小鼠四氯化碳致肝损伤有显著保护作用，且抗氧化应激损伤、抑制炎症反应是重要作用机制之一。我们假设：MnSODm可能对化疗药物致心、肝、肾等重要脏器的损伤产生保护作用，分子机制为通过激活抗氧化应激重要分子Nrf2/ARE信号通路诱导靶基因表达而产生保护效应。本项目通过体内外实验研究MnSODm 对化疗损伤的保护作用及其分子机制。首先分别建立化疗药物损伤细胞学模型和动物模型（大鼠及小鼠），对生化、氧化/抗氧化指标、炎症因子进行检测；应用光镜及电镜观察组织学损害；应用real-time PCR检测GCLC、NQO1 和HO-1 mRNA表达，Western blotting检测Nrf2核内水平；siRNA和基因芯片技术探讨分子机制。研究将为MnSODm的临床应用奠定理论和实验基础。

本项目通过体内外实验研究MnSODm 对化疗损伤的保护作用及其分子机制。首先分别建立化疗药物致肝脏、心脏、肾脏损害动物模型，研究MnSODm 对化疗药物致肝脏、心脏、肾脏损害的保护作用，并探讨其分子机制。项目组经过大量动物实验研究发现，MnSODm保肝作用确切，MnSODm及其衍生物VALD-1在一定剂量范围内分别对阿霉素引起的心脏损害、顺铂引起的肾脏损害有一定保护作用，联合应用可能减轻上述化疗药物的心肝肾骨髓毒副作用，其机制可能与通过激活Nrf2/ARE 通路产生抗氧化应激损伤作用有关。提示MnSODm及VALD-1可能通过抗氧化应激损伤而产生化疗保护作用。鉴于该类药物为自主开发的抗肿瘤化合物，具有潜在的临床应用价值，未来需要进一步研究其抗肿瘤和脏器保护作用机制，对其剂量、作用时间等进行深入研究研究，为开发具有高效低毒的、具有独立知识产权的抗肿瘤新药继续努力。