Mohammed Samia, Alvarado Victoria, Jiang Ya-Ping, Velazquez Fabiola N, Alexander Monica E, Alvarez Folnetti A, Lambadis Danielle, Chiappone Sam B, Ostermeyer-Fay Anne G, Zhang Leiqing, Shamseddine Achraf A, Canals Daniel, Snider Ashley J, Lin Richard Z, Hannun Yusuf A, Clarke Christopher J
bioRxiv. 2025 Mar 20:2025.03.20.644150. doi: 10.1101/2025.03.20.644150.
Although Doxorubicin (Dox) is an effective chemotherapeutic, its clinical utility is limited by a cumulative dose-dependent cardiotoxicity. While mechanisms underlying this cardiotoxicity have been investigated, strategies targeting these pathways have had marginal effects or had potential to interfere with Dox's anti-cancer activity. Sphingolipids (SL) are central to the chemotherapy response in multiple cancers, yet comparatively little is known about their role in non-transformed tissue, and actionable SL targets have not been identified. Here, we identified the SL enzyme neutral sphingomyelinase-2 (nSMase2) as a crucial downstream effector of Dox that is critical for chronic Dox-induced cardiotoxicity. studies showed that Dox treatment induces nSMase2 mRNA, protein, activity, and Cer accumulation in cardiomyocytes (CM) but not in cardiac fibroblasts. Mechanistically, nSMase2 induction was downstream of Top2B and p53, two previously identified molecular regulators of Dox-induced cardiotoxicity. studies in a chronic Dox model of cardiotoxicity found that loss of nSMase2 activity-null fro/fro mice were significantly protected from Dox-induced cardiac damage, exhibiting maintained ejection fraction, fractional shortening, and reduced left ventricle mass compared to wild-type littermates. Biologically, nSMase2 was dispensable for Dox-induced cell death but was important for Dox-induced CM senescence both and . Microarray analysis identified the dual specificity phosphatase DUSP4 as a downstream target of nSMase2 in Dox-treated CMs and in the chronic Dox-treated heart. Taken together, these results establish nSMase2 as a key component of the DNA damage response pathway in CMs and define a critical role for nSMase2 as a SL mediator of Dox-induced cardiotoxicity through effects on CM senescence. In addition to cementing a role for SLs in Dox effects in normal tissue, this study further advances nSMase2 as a target of interest for cardioprotection.
尽管阿霉素（Dox）是一种有效的化疗药物，但其临床应用受到累积剂量依赖性心脏毒性的限制。虽然已经对这种心脏毒性的潜在机制进行了研究，但针对这些途径的策略效果甚微，或者有可能干扰阿霉素的抗癌活性。鞘脂（SL）在多种癌症的化疗反应中起着核心作用，但人们对它们在非转化组织中的作用了解相对较少，并且尚未确定可操作的鞘脂靶点。在此，我们确定鞘脂酶中性鞘磷脂酶2（nSMase2）是阿霉素的关键下游效应物，对慢性阿霉素诱导的心脏毒性至关重要。研究表明，阿霉素处理可诱导心肌细胞（CM）中nSMase2的mRNA、蛋白质、活性和神经酰胺（Cer）积累，但在心脏成纤维细胞中则不会。从机制上讲，nSMase2的诱导位于拓扑异构酶2B（Top2B）和p53的下游，这两者是先前确定的阿霉素诱导心脏毒性的分子调节因子。在慢性阿霉素诱导心脏毒性模型中的研究发现，nSMase2活性缺失的fro/fro小鼠可显著免受阿霉素诱导的心脏损伤，与野生型同窝小鼠相比，其射血分数、缩短分数得以维持，左心室质量减轻。从生物学角度来看，nSMase2对于阿霉素诱导的细胞死亡并非必需，但对于阿霉素诱导的心肌细胞衰老在体内和体外都很重要。微阵列分析确定双特异性磷酸酶DUSP4是阿霉素处理的心肌细胞以及慢性阿霉素处理的心脏中nSMase2的下游靶点。综上所述，这些结果确定nSMase2是心肌细胞中DNA损伤反应途径的关键组成部分，并通过对心肌细胞衰老的影响确定nSMase2作为阿霉素诱导心脏毒性的鞘脂介质的关键作用。除了巩固鞘脂在阿霉素对正常组织影响中的作用外，本研究进一步将nSMase2推进为心脏保护的一个有意义的靶点。
