GPX4去乙酰化诱导铁死亡增加肿瘤细胞辐射损伤的机制研究

It is an important means to enhance the ionizing radiation (IR) damage by increasing the level of intracellular ROS to destroy the redox equilibrium state. Glutathione peroxidase 4 (GPX4) can catalyze the decomposition of various peroxides, and protect tissue cells from peroxidation damage. The preliminary study found that the expression of GPX4 was up-regulated in IR-resistant cells, Suggesting that GPX4 expression was negatively correlated with IR sensitivity, but the mechanism is not yet clear. Ferroptosis is a new type of cell death caused by high intracellular ROS levels. We found that induction of ferroptosis can down-regulated GPX4 expression and thus increased IR sensitivity, the GPX4 expression and its acetylation level were down-regulated by inhibition of histone acetyltransferase activity. We hypothesize that GPX4 deacetylation can induce ferroptosis by down-regulating GPX4 protein levels, and then increase IR sensitivity. In this study, we design to alter the acetylation level of GPX4 in vitro and in vivo experiments, in order to detecting GPX4 protein expression and activity, ferroptosis and IR sensitivity, clarifying the role of ferroptosis in promoting IR sensitivity, determining the effect of acetylation on GPX4 expression and activity, elucidating the molecular mechanisms of inhibition of GPX4 acetylation induced ferroptosis and further enhance IR sensitivity. This project will provide new targets and strategies for improving the IR damage effect.

增加细胞内ROS水平，破坏氧化还原平衡状态是增加电离辐射（IR）损伤的重要手段。谷胱甘肽过氧化物酶4（GPX4）可催化多种过氧化物的分解，保护组织细胞免受过氧化损伤。本项目组发现，IR抵抗的细胞中GPX4表达上调，提示GPX4可能负调控IR敏感性，但机制尚不明确。铁死亡是ROS增加导致的新的细胞死亡方式，我们发现，诱导铁死亡可下调GPX4蛋白表达并增加IR敏感性；抑制组蛋白乙酰基转移酶的活性，可下调GPX4蛋白及乙酰化水平。因此推测GPX4去乙酰化可通过下调GPX4蛋白水平诱导铁死亡进而增加IR敏感性。本研究拟利用体内、外实验，通过调控GPX4乙酰化水平，检测细胞内GPX4蛋白含量与活性、铁死亡水平以及IR敏感性，明确铁死亡对IR敏感性的促进作用，明晰乙酰化修饰对GPX4表达和活性的影响，阐明GPX4去乙酰化诱导铁死亡进而增强细胞IR敏感性的分子机制，为提高IR损伤效应提供新的靶点和思路。

2020年的统计数据表明，在全球范围内，中国新发癌症及癌症死亡人数均位居全球第一。而针对大部分肿瘤患者，其标准治疗方案是采取手术治疗后辅助进行放化疗。放化疗是肿瘤重要治疗手段，然而部分患者或肿瘤细胞对放化疗的敏感性差，导致治疗效果不佳。因此，寻找增加放化疗损伤效应的重要靶点成为亟待解决的问题。铁死亡是一种新发现的细胞死亡方式，其本质是由于细胞内脂质氧化物代谢障碍，在铁离子的催化下产生大量脂质ROS，破坏细胞内氧化还原平衡，触发细胞死亡。已有的研究提示诱导铁死亡可能增强放化疗损伤作用，但是具体机制尚不明确。. 本研究应用不同肿瘤细胞模型，初步揭示了可以通过促进铁向细胞中转运，诱导ROS增加，抑制GPX4表达水平，诱导细胞发生铁死亡进而增加 IR敏感性，为提高IR损伤效应提供新的靶点和思路。进一步通过体内外实验，阐明了Erastin可以通过诱导铁死亡，下调AR-FL与AR-Vs的表达，从而抑制CRPC细胞的存活，增强多西紫杉醇抑瘤作用的机制，以上结果预示Erastin可以与多西紫杉醇联用，用于CRPC的治疗。本研究为铁死亡的调控提供新的分子生物学理论基础，为临床利用铁死亡增加肿瘤放化疗敏感性提供了理论基础及实验依据。