Erastin触发全新的死亡方式Ferroptosis(铁死亡)增加肺癌放射敏感性的研究

Ferroptosis is a brand new cell death in morphological, biochemical, and genetic features, which is distinct from apoptosis, autophagy and necrosis.Inhibition of GPX4 activity, Depletion of GSH and boom of iron-dependent ROS play a key role in triggering Ferroptosis.Many compounds and drugs such as Erastin and sorafinib induced the ferroptosis of tumor cell.Some researchs had found radiation could induced morphological change with the GPX4 inhibition, GSH depletion and the explosion of iron-dependent ROS in lung cancer cells. These changes had been proved in our previous work. More importantly,We found the inhibition of Ferroptosis could protect the lung cancer cell from irradiation, which proved that Ferroptosis could be triggered by irradiated. What is more, radiosensitivity of cancer cell could be enhanced by GSH depletion, GPX4 inhibition and an overload of iron. Erastin, a compund could induced Ferroptosis, which have synergistic antitumor effect with irradiation in lung cancer cells. So we proposed that Ferroptosis activation could improve the radiosensitivity of lung cancer cells.This research is aim to value the role of Ferroptosis on the effect of irradiatied lung cancer cells, analyze the radiosensitivity of Ferroptosis through triggering multiple levels of Ferroptosis paths in lung cancer cells, and explore the machanism of Ferroptosis increasing the radiosensitivity of lung cancer cells by blocking the signal transduction of Ferroptosis.

Ferroptosis（铁死亡）是具有独特形态、基因表达、分子通路的全新发现的细胞死亡方式，完全不同于凋亡、自噬和坏死。GPX4活性抑制、GSH下降、铁依赖ROS爆发是触发细胞铁死亡的关键。多种化合物和药物可触发肿瘤细胞（肺癌）铁死亡。文献报道放疗改变肿瘤细胞形态、抑制GPX4活性、减少GSH含量、爆发铁依赖ROS。前期实验发现放疗后肺癌细胞也出现上述改变，而特异抑制铁死亡可对放疗的肺癌细胞起保护作用，证实放疗可触发肺癌细胞铁死亡。进一步，文献发现抑制GPX4活性、减少GSH含量，增加铁负荷增加肿瘤细胞的放射敏感性，我们前期也发现Erastin与放疗发挥协同抗肺癌作用，由此我们提出触发铁死亡可增加肺癌放射敏感性。本项目拟了解铁死亡对肺癌放疗疗效的预测价值；多水平触发铁死亡，正反两方面解析铁死亡的肺癌放疗增敏作用；特异性阻断通路，探索铁死亡增加肺癌放疗敏感性的机制。

Ferroptosis（铁死亡）是一种全新的细胞死亡方式，完全不同于凋亡、自噬和坏死，其具有独特形态、基因表达、分子通路。GPX4活性抑制、GSH下降、铁依赖ROS爆发是触发铁死亡的关键。本项目首次提出触发铁死亡可增加肺癌放射敏感性。.(1)我们从形态学证实放疗可以触发铁死亡，A549细胞接受10Gy，24h后电镜观察可见线粒体皱缩和双层膜增厚。进一步发现铁死亡特异性抑制剂Fer-1和DFO能够抑制放疗导致的细胞死亡，而且放疗或者放疗联合erastin能触发A549细胞发生铁死亡，其机制是减少细胞内GSH含量以及抑制GPX4活性。通过克隆形成试验发现erastin可增加HCT116细胞的放射敏感性。因此Ferroptosis是增加肿瘤放疗敏感性的新方法。.(2)多种化疗药物可触发铁死亡，前期实验中我们筛选了五种化疗药物，包括顺铂、5氟尿嘧啶、多柔比星、紫杉醇和硫氮磺胺吡啶，其中顺铂处理的A549和HCT116细胞能发生铁死亡特征性的超微形态学的改变，而且其杀伤作用可以被Fer-1所抑制。进一步研究发现顺铂可使HCT116细胞内ROS水平呈浓度依赖性增高，而Fer-1和ß-ME可明显抑制上述改变。此外，顺铂还可明显降低HCT16细胞内GSH含量，并导致GPXs活性下降。说明顺铂可以触发肿瘤细胞发生铁死亡。.(3)维生素C被发现具有抗肿瘤作用，但机制未明。我们发现维生素C被氧化为DHA后通过GLUT1转运进入胞内。通过MTT实验证实DHA可以抑制A549细胞增殖活性，并且铁死亡特异性抑制剂ß-ME能够抑制这种杀伤作用证实DHA能够触发铁死亡。