双氢青蒿素通过上调铁结合蛋白自噬性降解诱导膀胱癌细胞铁死亡(ferroptosis)机制的研究

Ferroptosis is a kind of iron-dependent programmed cell death reported in recent years. Because it is essentially distinct from apoptosis, so not affected by the machinery of apoptosis resistance. Therefore, the elicitation of ferroptosis is a practicable way to kill malignant cells such as bladder carcinoma, effectively. The results of our previous study showed that artemisinin and dihydroartemisinin (DHA) upregulate intracellular iron pool level by increasing autophagic ferritin degradation, leading to accumulation of lipid ROS, and ultimately induced ferroptosis. The mechanism of DHA increases the autophagy mediated ferritin degradation may be regulated by the activation of transcription factor ATF4 and its downstream targeting autophagy related gene (ATG) and nuclear receptor coactivator 4 (NCOA4). In this study, firstly, we aim to clarify the pathway of DHA induced ATF4 activation; secondly, confirm the ATF4 targeting ATG that are essential in the regulation of ferritin autophagic degradation; elucidate the function of NCOA4 in autophagic ferritin degradation; finally, observe DHA therapeutic effect towards bladder carcinoma and validate the above mechanism in orthotropic murine bladder tumor model experiments. The results of this study can not only reveal the precise mechanism of DHA-induced ferroptosis in bladder carcinoma cells, but also provide a meaningful theoretical basis for the therapy of bladder carcinoma in clinic.

铁死亡(ferroptosis)是近几年报道的铁离子依赖性的细胞死亡方式，因本质上区别于凋亡，故不受凋亡抵抗性机制影响。因此，诱导铁死亡是高效杀灭膀胱癌等恶性肿瘤细胞的可行思路。课题组经前期研究发现，青蒿素及双氢青蒿素(DHA)等洐生物通过上调自噬介导的铁结合蛋白降解提高细胞内铁池水平，促使脂质活性氧蓄积，最终诱发铁死亡。DHA对铁结合蛋白自噬正向调节作用可能是通过激活转录因子ATF4及其转录调控的自噬相关基因(ATG)和核受体共激活因子4(NCOA4)引起的。本项目拟首先明确DHA活化ATF4的具体机制；进一步确定受ATF4转录调控且对铁结合蛋白自噬起关键调控作用的ATG；阐明NCOA4对铁结合蛋白自噬的调节作用；最后通过原位膀胱癌动物模型实验观察DHA治疗效果及验证上述机制。本研究结果不仅能揭示DHA诱导膀胱癌细胞发生铁死亡的具体机制，还将为其应用于膀胱癌临床治疗提供重要理论依据。

铁死亡(ferroptosis)是近几年报道的铁离子依赖性的细胞死亡方式，因本质上区别于凋亡，故不受凋亡抵抗性机制影响，其临床应用价值一直备受期待。因此，诱导铁死亡是高效杀灭膀胱癌等恶性肿瘤细胞的可行思路。课题组经前期研究发现，青蒿素及双氢青蒿素(DHA)等洐生物通过上调自噬介导的铁结合蛋白降解提高细胞内铁池水平，促使脂质活性氧蓄积，最终诱发铁死亡。DHA对铁结合蛋白自噬正向调节作用是通过激活转录因子ATF4及其转录调控的自噬相关基因(ATG)和核受体共激活因子4 (NCOA4)引起的。本项目明确了DHA活化ATF4的机制及主要细胞信号通路；确定了受ATF4转录调控且对铁结合蛋白自噬起关键调控作用的ATGs；阐明了NCOA4对铁结合蛋白自噬的调节作用；最后通过原位膀胱癌动物模型实验观察DHA治疗效果及验证了上述机制。本研究结果不仅能揭示DHA诱导膀胱癌细胞发生铁死亡的具体机制，还将为其应用于膀胱癌临床治疗提供重要理论依据。