Neutral sphingomyelinase-2 as a mediator of Doxorubicin-induced cardiotoxicity

摘要 阿霉素(Dox)是治疗多种癌症的主要药物，但其应用受到心血管毒性的限制。 虽然已经提出了导致这种心脏毒性的多种机制，但针对这些机制的策略 这些途径对该药物的抗癌作用产生了边际影响或干扰。这样的担忧已经 限制了Dexrazoxane的临床使用，Dexrazoxane是目前FDA批准的唯一心脏保护剂。AS 癌症存活率提高，更多患者暴露于Dox，迫切需要新的策略 以减轻心脏毒性，但不包括其治疗效果。生物活性鞘脂(SLS)，特别是 神经酰胺(Cer)是公认的跨多种癌症的化疗应激反应的介质。 虽然这增加了靶向SL代谢以增强化疗反应的兴趣，但靶向SL 减少化疗毒性的新陈代谢在很大程度上是未知的。我们最近发现了产生Ce的酶 中性鞘磷脂酶-2(NSMase2)在乳腺癌中作为Dox调节的主要SL酶。在这里，我们的 初步研究表明nSMase2来源的Cer参与了Dox诱导的DNA损伤反应 并表明，体内nSMase2活性的丧失对Dox诱导的心肌梗死具有保护作用 心脏功能障碍和损伤。至关重要的是，nSMase2似乎对于体外和体内的抗-HBs来说是不必要的。 阿昔洛韦对乳腺癌的致癌作用基于这些数据，中心假设是nSMase2- 神经酰胺途径是阿昔洛韦心脏毒性的必需途径，但对于阿昔洛韦的抗癌作用却是必不可少的。 活动。我们提出了三个具体目标：第一个目标是建立Dox诱导的nSMase2- 心肌细胞和组织中的CER途径结合体内外方法建立nSMase2 诱导CMS是Dox诱导心脏Cer生成的主要途径。第二个目标将定义 NSMase2-Cer途径在体内外介导Dox心脏毒性中的作用 在CMS中建立nSMase2作为Dox诱导的CM细胞死亡和心脏损伤的中介的功能途径 纤维化症。第三个目标是确定nSMase2抑制剂作为心脏保护药物的治疗潜力。 使用同基因异种乳腺移植模型的不干扰Dox抗癌活性的药物 癌症公司将证明nSMase2抑制剂作为心脏保护剂的有效性，这种药物不会干扰 DOX减少肿瘤生长和转移。总体而言，这些研究将为我们提供对 阿昔洛韦心脏毒性的发病机制和建立nSMase2作为治疗药物的新靶点 心脏保护。这将为nSMase2抑制剂作为新型药物的开发提供合理的基础 心脏保护剂。

ABSTRACT Doxorubicin (Dox) is a mainstay in the treatment of many cancers yet its utility is limited by cardiovascular toxicity. While multiple mechanisms underlying this cardiotoxicity have been proposed, strategies targeting these pathways have had marginal effects or interfere with anti-cancer effects of the drug. Such concerns have restricted the clinical use of dexrazoxane which is currently the only FDA-approved cardio-protective agent. As cancer survival rates improve and more patients are exposed to Dox, there is a critical need for new strategies to mitigate the cardiotoxicity without comprising its therapeutic efficacy. Bioactive sphingolipids (SLs), especially ceramide (Cer), are well-established mediators of the chemotherapy stress response across diverse cancers. While this increased interest in targeting SL metabolism to enhance chemotherapy responses, targeting SL metabolism to reduce chemotoxicities is largely unexplored. We recently identified the Cer-generating enzyme neutral sphingomyelinase-2 (nSMase2) as a primary Dox-regulated SL enzyme in breast cancer. Here, our preliminary studies begin to implicate nSMase2-derived Cer in the Dox-induced DNA damage response of cardiomyocytes (CMs) and show that in vivo loss of nSMase2 activity protects from the onset of Dox-induced cardiac dysfunction and damage. Crucially, nSMase2 appears to be dispensable for the in vitro and in vivo anti- cancer effects of Dox on breast cancer. Based on these data, the central hypothesis is that the nSMase2- ceramide pathway is essential for Dox-induced cardiotoxicity but dispensable for Dox-induced anti-cancer activity. We propose three specific aims: The first aim will establish Dox-induced activation of the nSMase2- Cer pathway in cardiac cells and tissues combining in vitro and in vivo approaches to establish nSMase2 induction in CMs as a major pathway of Dox-induced Cer generation in the heart. The second aim will define the role of the nSMase2-Cer pathway in mediating Dox-induced cardiotoxicity using in vitro and in vivo loss of function approaches to establish nSMase2 in CMs as a mediator of Dox-induced CM cell death and cardiac fibrosis. The third aim will establish the therapeutic potential of nSMase2 inhibitors as cardioprotective agents that do not interfere with the anti-cancer activity of Dox using syngeneic xenograft models of breast cancer to demonstrate the efficacy of nSMase2 inhibitors as cardioprotective agents that do not interfere with Dox reduction of tumor growth and metastasis. Overall, these studies will provide novel insight into the pathogenesis of Dox-induced cardiotoxicity and establish nSMase2 as a novel druggable target for cardioprotection. This will provide a rational basis for the development of nSMase2 inhibitors as novel cardioprotective agents.