Table 2_Mechanisms of sorafenib-induced cardiotoxicity: ER stress induces upregulation of ATF3, leading to downregulation of NDUFS1 expression and mitochondrial dysfunction.xlsx

BackgroundSorafenib, a widely used tyrosine kinase inhibitor (TKI), has been associated with cardiotoxic effects; however, the precise molecular basis of this toxicity remains incompletely characterized. This study examined sorafenib’s impact on cardiac cells, focusing on endoplasmic reticulum (ER) stress signaling, specifically the PERK-eIF2α-ATF4 pathway and its downstream network.
MethodsTo elucidate these mechanisms, we employed a comprehensive approach integrating in vivo rat models, H9C2 cell-based assays, transcriptomic and proteomic profiling, along with biochemical validation techniques.
ResultsOur study reveals that sorafenib compromises cardiac function by inducing ER stress in cardiomyocytes, which activates the PERK-eIF2α-ATF4 pathway, leading to mitochondrial damage and apoptosis. These outcomes were supported by Western blot analysis and microscopic imaging, and were significantly mitigated following treatment with the ER stress inhibitor GSK2606414. Transcriptome data highlighted activating transcription factor 3 (ATF3) as the most prominently induced gene post-treatment. Further enrichment analysis identified several related pathways, while RT-PCR and immunoblotting confirmed ATF3 upregulation in H9C2 cells. Proteomic screening revealed NDUFS1 as a potential downstream effector. Silencing ATF3 via siRNA partially restored mitochondrial function, suggesting a negative regulatory effect of ATF3 on NDUFS1 that contributes to sorafenib-induced mitochondrial impairment.
ConclusionCollectively, these results uncover a critical signaling cascade—PERK/eIF2α/ATF4/ATF3/NDUFS1—involved in sorafenib-mediated cardiotoxicity and point to ATF3 modulation as a promising target for preventing or reducing cardiac injury caused by this drug.

背景：索拉非尼（Sorafenib）是一种临床广泛应用的酪氨酸激酶抑制剂（TKI），已被证实可引发心脏毒性作用，但其确切的分子机制尚未完全阐明。本研究探讨了索拉非尼对心肌细胞的影响，重点聚焦于内质网（ER）应激信号通路，特别是PERK-eIF2α-ATF4通路及其下游调控网络。
方法：为阐明该作用机制，本研究采用了整合性研究策略，涵盖体内大鼠模型、基于H9C2细胞的体外实验、转录组与蛋白质组学分析，以及生化验证技术。
结果：本研究结果显示，索拉非尼可通过诱导心肌细胞内质网应激，激活PERK-eIF2α-ATF4通路，进而引发线粒体损伤与细胞凋亡，最终损害心脏功能。上述结论得到了蛋白质免疫印迹（Western blot）分析与显微成像实验的验证，且经内质网应激抑制剂GSK2606414处理后，上述毒性效应得到显著缓解。转录组数据显示，激活转录因子3（ATF3）是给药后诱导表达最显著的基因。进一步富集分析揭示了多条相关信号通路，逆转录聚合酶链式反应（RT-PCR）与免疫印迹实验证实了H9C2细胞中ATF3的上调表达。蛋白质组筛选发现NDUFS1是潜在的下游效应分子。通过小干扰RNA（siRNA）沉默ATF3可部分恢复线粒体功能，提示ATF3对NDUFS1存在负调控作用，这一机制参与了索拉非尼诱导的线粒体功能损伤。
结论：综上，本研究揭示了一条参与索拉非尼介导心脏毒性的关键信号级联通路——PERK/eIF2α/ATF4/ATF3/NDUFS1，并指出调控ATF3有望成为预防或减轻该药物所致心脏损伤的潜在靶点。