Mitochondrial Dysfunction Underlies the Integrated Stress Response Activation in Ponatinib-Induced Cardiotoxicity

项目摘要 与癌症相关的死亡率已经显著下降，部分原因是分子生物学的出现。 靶向治疗。不幸的是，包括酪氨酸激酶抑制剂（TKI）在内的这些药物的成功已经被证明是有效的。 与癌症治疗相关的心脏毒性的患病率随之上升。帕纳替尼目前 FDA批准的第三代TKI，用于治疗慢性粒细胞白血病（CML）患者， 看门突变断点簇区域-Abelson（BCR-ABL）T315 I。尽管它的有效性， 相当多接受泊那替尼的患者患有各种心脏并发症。几项研究 已将ponatinib诱导的心脏毒性与导致细胞死亡的促存活信号通路受损联系起来。 然而，导致这些事件的分子信号通路仍然模糊不清， 心肌细胞对泊那替尼的反应可能为新型缓解疗法提供新的见解。心脏 必须适应由于细胞内或细胞外因素而发生的应激条件。整合应激 应激反应（ISR）是应激反应的一种，通过调节蛋白质的表达来恢复蛋白质稳态 合成，尽管延长的ISR活化导致细胞死亡。ISR是否已激活并播放 在泊那替尼诱导的心脏毒性中的保护或有害作用在很大程度上是未知的， 这将是我目前建议的重点。我的初步数据显示， 泊那替尼导致人诱导多能干细胞衍生的心肌细胞线粒体功能障碍 （hiPSC-CM）。有趣的是，线粒体损伤似乎触发ISR的激活，并由一种介导。 激酶称为一般控制非阻遏2（GCN 2）。我还发现，抑制ISR使用一种新的小， 一种名为ISR抑制剂（ISRIB）的分子成功地在体外和体内减弱了泊那替尼的心脏毒性作用。 vivo.因此，我的建议的中心假设是，ISR途径，这是在感知激活 线粒体损伤在介导泊那替尼诱导的心脏毒性中起关键作用。目标1将调查 GCN 2的激活是否将线粒体损伤与线粒体损伤后的ISR激活相结合 活性氧（ROS）和三磷酸腺苷（ATP）水平。目标2将评估泊那替尼是否 通过GCN 2/eIF 2 α/ATF 4轴诱导细胞凋亡和心功能障碍。最后，目标3将探讨是否 即使在泊那替尼诱导的心脏毒性发作后，ISR的药理学抑制仍然存在 心脏保护而不损害泊那替尼对肿瘤细胞的功效。总的来说， 这些研究的结论，我们将大大扩展我们的知识，通过这些知识， 感觉到线粒体功能障碍触发ISR;这种激活是否有助于心脏病理学; 如果这两种途径之间的串扰可以作为缓解泊那替尼的治疗途径， 临床上引起心脏毒性。

PROJECT SUMMARY There has been a significant decline in cancer related mortality, partly due to the emergence of molecular targeted therapies. Unfortunately, the success of these drugs including tyrosine kinase inhibitors (TKIs) has been tempered by a concomitant rise in the prevalence of cancer therapies-related cardiotoxicity. Ponatinib, a currently FDA-approved third-generation TKI, is used to treat chronic myeloid leukemia (CML) patients carrying the gatekeeper mutation breakpoint cluster region-Abelson (BCR-ABL) T315I. Despite its effectiveness, a considerable number of patients receiving ponatinib suffers from various cardiac complications. Several studies have linked ponatinib-induced cardiotoxicity to impaired pro-survival signaling pathways leading to cell death. However, the molecular signaling pathways leading to these events remain obscure and a better understanding of how cardiomyocytes respond to ponatinib may provide new insights into novel mitigation therapies. The heart must adapt to stress conditions that occur as a result of intracellular or extracellular factors. The integrated stress response (ISR) is one of the circuits responding to stress and serving to restore proteostasis by regulating protein synthesis, although prolonged ISR activation leads to cell death. Whether the ISR is activated and plays a protective or detrimental role in ponatinib-induced cardiotoxicity are largely unknown and may represent an amenable therapeutic target which will be the focus of my current proposal. My preliminary data suggests that ponatinib causes mitochondrial dysfunction in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Interestingly, mitochondrial damage appears to trigger activation of the ISR and is mediated by a kinase called general control non-repressed 2 (GCN2). I also found that inhibition of the ISR using a novel small molecule called ISR inhibitor (ISRIB) successfully blunted the cardiotoxic effects of ponatinib both in vitro and in vivo. Hence, the central hypothesis of my proposal is that the ISR pathway which is activated upon sensing mitochondrial damage plays a pivotal role in mediating ponatinib-induced cardiotoxicity. Aim 1 will investigate whether activation of GCN2 couples mitochondrial damage to ISR activation upon impaired mitochondrial reactive oxygen species (ROS) and adenosine triphosphate (ATP) level. Aim 2 will assess whether ponatinib induces apoptosis and cardiac dysfunction through the GCN2/eIF2α/ATF4 axis. Lastly, aim 3 will explore whether pharmacological suppression of the ISR even after the onset of ponatinib-induced cardiotoxicity remains cardioprotective without compromising the efficacy of ponatinib against tumor cells. Taken together, at the conclusion of these studies, we will have significantly expanded our knowledge by which how ponatinib-induced mitochondrial dysfunction is sensed to trigger the ISR; whether this activation contributes to cardiac pathology; and if crosstalk between these two pathways can be targeted as a therapeutic avenue to mitigate ponatinib- induced cardiotoxicity clinically.