L-carnitine prevents doxorubicin-induced apoptosis of cardiac myocytes:: role of inhibition of ceramide generation
L-carnitine prevents doxorubicin-induced apoptosis of cardiac myocytes:: role of inhibition of ceramide generation
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DOI：
10.1096/fasebj.13.12.1501
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发表时间：
1999-09-01
期刊：
影响因子：
4.8
通讯作者：
Mercadier, JJ
中科院分区：
文献类型：
--
作者：
Andrieu-Abadie, N;Jaffrézou, JP;Mercadier, JJ
除了化疗药物阿霉素对自由基产生的影响外，其导致心脏损伤的确切信号机制在很大程度上仍不清楚，这对于理解蒽环类药物的心脏毒性至关重要。我们描述了用阿霉素（0.5 μ M）处理离体成年大鼠心肌细胞1小时后，在培养7天后观察到的与凋亡经典形态学特征相关的DNA片段。阿霉素毒性发生之前，细胞内神经酰胺水平增加，同时鞘磷脂减少，蒽环类药物诱导的神经酰胺积累是由鞘磷脂酶的激活引起的，在酸性条件下检测。一种与V-max增加有关的效应。用左旋肉碱（200 μ g/ml）预处理心肌细胞（一种已知对心脏代谢损伤具有保护作用的化合物）可以剂量依赖性地抑制阿霉素诱导的鞘磷脂水解和神经酰胺的产生以及随后的细胞死亡。然而，左旋肉碱对外源性细胞渗透神经酰胺诱导的心肌细胞凋亡没有保护作用，左旋肉碱预处理不影响鞘磷脂酶基础活性，但可消除阿霉素诱导的V-max升高。此外，对细胞提取物或纯化的酸性鞘磷脂酶进行的体外研究表明，左旋肉碱具有剂量依赖性的鞘磷脂酶抑制作用（通过降低V-max）。综上所述，这些发现表明，通过抑制（可能是新的）药物激活的酸性鞘磷脂酶和神经酰胺的产生，左旋肉碱可以防止阿霉素诱导的心肌细胞凋亡。
Besides the well-documented effect of the chemotherapeutic drug doxorubicin on free radical generation, the exact signaling mechanisms by which it causes cardiac damage remain largely unknown and are of fundamental importance in understanding anthracycline cardiotoxicity In this study, we describe that a 1 h treatment of isolated adult rat cardiac myocytes with doxorubicin (0.5 mu M) induced DNA fragmentation associated with the classical morphological features of apoptosis observed after 7 days of culture, The doxorubicin toxicity was preceded by an increase in intracellular ceramide levels with a concurrent decrease in sphingomyelin, Anthracycline-induced ceramide accumulation resulted from the activation of a sphingomyelinase assayed under acidic conditions, an effect related to an increase in V-max. Pretreatment of cardiac myocytes with L-carnitine (200 mu g/ml), a compound known for its protective effect on cardiac metabolic injuries, was found to dose-dependently inhibit the doxorubicin-induced sphingomyelin hydrolysis and ceramide generation as well as subsequent cell death. However, L-carnitine did not protect cardiac myocytes from apoptosis induced by exogenous cell-permeant ceramide, L-carnitine pretreatment did not affect the sphingomyelinase basal activity but abolished the doxorubicin-induced increase in V-max. Moreover, in vitro studies conducted on cell extracts or with purified acid sphingomyelinase demonstrated that L-carnitine exerted a dose-dependent, sphingomyelinase inhibitory effect (through V-max reduction). Taken together, these findings show that by inhibiting a (perhaps novel) drug-activated acid sphingomyelinase and ceramide generation, L-carnitine can prevent doxorubicin-induced apoptosis of cardiac myocytes.