mPTP开放介导双氢青蒿素增敏TTField杀伤胶质瘤细胞的作用及机制研究

Tumor treating field (TTField) is an emerging therapy for glioma. Clinical trials have demonstrated comparable therapeutic effects of TTField with standard chemo and radiotherapy. However, the trials also demonstrated that response rate is relative low, which indicates that glioma cells are not quite sensitive to TTField. Hence, the phenomenon may limit the improvement of therapeutic effects of TTField. But there are few effective clinical intervention measures to fulfill this problem. Our data shown that TTField could induce glioma cells to release large amount of labile iron in glioma cells. It may provide new entry to enhance the sensitivity of glioma cells to TTField by utilizing and magnifying the labile iron. Preliminary results indicate that labile iron could entry mitochondria matrix through the opened mitochondrial permeability transition pore (mPTP). Our previous data also indicated that dihydroartemisinin may induce the opening of mPTP. We then speculate that dihydroartemisinin may improve the sensitivity of glioma cells to TTField. And the potential mechanism is that dihydroartemisinin induce the opening of mPTP and enhance labile iron in the cytosol to enter the mitochondria matrix, leading to mitochondria iron overload and cell apoptosis. The project will be performed based on previous work. To test the hypothesis, we will utilize inhouse gene knockout mice, biochemical and functional monitoring of mitochondria and other experimental strategies, to reveal the new role of dihydroartemisinin in glioma therapy. The aim of present study is to provide new intervention targets for improving glioma sensitivity to TTField.

肿瘤治疗电场（TTField）是一种新兴的胶质瘤治疗手段，临床研究结果显示其治疗效果与标准放化疗相当，但胶质瘤细胞对TTField敏感性低，限制了治疗效果的进一步提升，目前尚无有效干预手段。前期研究显示TTField能诱导胶质瘤细胞释放大量游离铁，如何利用并放大游离铁的杀伤效应可能成为TTField增敏的突破口。预实验发现，游离铁可经线粒体膜通透性转换孔（mPTP）进入线粒体，而mPTP可被双氢青蒿素诱导开放。因而我们推测双氢青蒿素具有TTField增敏作用，其机制为双氢青蒿素介导mPTP开放，促进胞质游离铁进入线粒体基质，导致线粒体铁超载，诱导细胞凋亡，发挥增敏效应。本项目将在前期工作基础上，利用已有的基因敲除小鼠，结合线粒体生化和功能监测等手段，通过在体和离体实验验证研究假设。该研究可为胶质瘤TTField增敏提供新的治疗策略与思路。

胶质瘤是颅内最常见的原发性恶性肿瘤，约占颅内肿瘤的80%，而其中胶质母细胞瘤患者的5年生存率仅为4.7%。肿瘤治疗电场（TTFields）可抑制肿瘤细胞的有丝分裂，成为继“手术+放疗+化疗三板斧”之后的新型GBM物理治疗手段。国际多中心随机对照临床显示TTFields能延长患者生存期，但效果有限。我们在本项目研究中发现，短时程TTFields能够有效杀伤胶质瘤细胞，双氢青蒿素能增敏TTFields的杀伤效应，其机制为线粒体游离铁超载，导致线粒体膜电位去极化，从而使线粒体ROS水平显著升高，继而导致细胞凋亡。为了模拟临床实践中患者长时程佩戴TTFields装置的实际情况，我们进行了TTFields的长时程加载。我们首次发现胶质瘤细胞在TTFields连续处理2周后出现治疗抵抗现象。蛋白质组学分析发现TTFields耐受的胶质瘤细胞高表达Kv1.3及细胞骨架运动相关通路。移植瘤小鼠模型也验证了长时程TTFields治疗后Kv1.3表达显著上升。线粒体有Kv1.3表达，参与调控线粒体膜电位，在调控细胞凋亡中发挥了重要的作用。本项目的研究发现了逆转胶质瘤TTFields治疗抵抗的潜在干预靶点。