未折叠蛋白反应在顺铂致耳蜗细胞毒性损伤过程中的作用及干预研究

Cisplatin is a widely used chemotherapeutic drug, however, its various side-effects such as sensorineural hearing loss strongly limit its application. In addition, the mechanisms of cisplatin-induced ototoxicity are still poorly understood. Unfolded protein responses (UPR) is one of the important mechanisms in maintaining cellular proteostasis via several pathways like autophagy. But, sever or persistent UPR leads to apoptosis. It has been proved that UPR is associated with several types of sensorineural hearing loss such as hereditary hearing loss and age-related hearing loss. Our previous study has demonstrated that cisplatin caused obvious up-regulation of UPR-related proteins, apoptosis and autophagy, while the mechanisms remain unclear. We hypothesize that the disruption of proteostasis in cochlea cells induced by cisplatin overloads the remediation capacity of the UPR may be an important reason of apoptosis. Spliced X-box binding protein 1 (XBP1s) may play an important role in the UPR-autophagy signal. To up-regulated autophagy via XBP1s may enhance the remediation capacity of the UPR and may be a new strategy to prevent and cure cisplatin-induced ototoxicity. No relative report has been found so far.

顺铂是临床上常用的抗肿瘤药物，但以感音神经性聋为代表的多种不良反应严重地限制了其应用。顺铂耳中毒性聋的发生机制目前仍无定论，临床上亦无有效的防治手段。未折叠蛋白反应（UPR）是真核细胞中广泛存在的蛋白稳态维持机制。一方面，UPR可以通过诱导自噬等方式使细胞恢复稳态，另一方面，UPR又可触发凋亡。目前已证实，UPR与多种感音神经性聋的发生密切相关。我们的前期研究也表明，顺铂可在大鼠耳蜗组织中激活UPR，凋亡与自噬水平也均有显著升高，但具体机制不明。我们在此基础上提出如下假说：1、顺铂对耳蜗细胞中蛋白质稳态的破坏超过了UPR的恢复能力是造成耳蜗细胞凋亡的原因之一；2、以UPR-自噬信号中剪切型X盒结合蛋白1（XBP1s）为靶点来上调自噬以增强UPR的稳态恢复能力，可能实现对顺铂耳毒性效应的改善。本项目拟采用电生理、分子生物学等方法对上述内容进行深入研究。该研究内容国内外未见报道。

顺铂的耳毒性严重影响接受顺铂化疗的肿瘤患者的生存质量，其发生机制至今尚未被完全阐明，临床上亦缺少可靠的防治方法。通过本项目的研究，我们发现：①未折叠蛋白反应及其介导的凋亡可能是顺铂致听毛细胞毒性损伤的原因。②未折叠蛋白反应中的PERK-CHOP分支可能是顺铂作用下介导听毛细胞凋亡的主要信号分支。③牛磺熊脱去氧胆酸（TUDCA）可以通过抑制听毛细胞中未成熟蛋白质的积聚，抑制未折叠蛋白反应及其相关凋亡的发生。④顺铂可使原代培养的乳鼠耳蜗血管纹边缘细胞发生伴有TXNIP表达增加、炎症因子IL1-β合成和分泌增加的细胞死亡。下调TXNIP在抑制NLRP3表达、减轻炎症反应的同时，可提高顺铂作用下边缘细胞的存活率。该项目的上述发现进一步阐明了顺铂致听觉上皮细胞毒性损伤的分子机制，为临床上顺铂耳中毒性聋防治新策略的制定提供了实验基础。