Yamamoto Yasuhiro, Hoshino Yuki, Ito Takashi, Nariai Tetsuro, Mohri Tomomi, Obana Masanori, Hayata Nozomi, Uozumi Yoriko, Maeda Makiko, Fujio Yasushi, Azuma Junichi
Department of Clinical Pharmacology and Pharmacogenomics, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka565-0871, Japan.
Cardiovasc Res. 2008 Jul 1;79(1):89-96. doi: 10.1093/cvr/cvn076. Epub 2008 Mar 17.
Doxorubicin (DOX) is one of the most effective anti-neoplastic agents; however, its clinical use is limited by drug-induced cardiomyopathy. The molecular mechanisms responsible for this toxicity remain to be fully addressed. In the present study, we investigated the involvement of atrogin-1, one of the muscle-specific ubiquitin ligases, in DOX-induced cardiotoxicity.
This method involved intraperitoneal administration of DOX-induced atrogin-1 in the hearts and skeletal muscles of C57BL/6 mice. Consistently, atrogin-1 mRNA was upregulated with DOX treatment in cultured rat neonatal cardiomyocytes. Adenoviral transfer of atrogin-1 induced a reduction in cell size that was ameliorated by the ubiquitin proteasome inhibitor, MG-132. The transduction of constitutively active Akt (caAkt), a serine/threonine protein kinase, inhibited the DOX-mediated induction of atrogin-1. The phosphorylation status of Akt and its downstream target, FOXO, was not affected by DOX. DOX treatment did not activate the atrogin-1 promoter that contains FOXO-binding sites, suggesting that DOX induced atrogin-1 without modulating the Akt/FOXO pathway; importantly, DOX activated p38-mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK). Furthermore, pharmacological inhibition of p38-MAPK, but not JNK, abrogated DOX-mediated induction of atrogin-1. Finally, adenoviral transfer of caAkt inhibited the DOX-induced p38-MAPK activation.
DOX induces atrogin-1 through a p38-MAPK-dependent pathway in cardiac myocytes. Constitutive activation of Akt negatively regulates DOX-mediated atrogin-1 induction by inhibiting p38-MAPK activity as a novel mechanism.
阿霉素（DOX）是最有效的抗肿瘤药物之一；然而，其临床应用受到药物性心肌病的限制。导致这种毒性的分子机制仍有待充分阐明。在本研究中，我们研究了肌肉特异性泛素连接酶之一的atrogin-1在DOX诱导的心脏毒性中的作用。
本方法涉及对C57BL/6小鼠心脏和骨骼肌进行腹腔注射DOX诱导atrogin-1。同样，在培养的大鼠新生心肌细胞中，DOX处理可使atrogin-1 mRNA上调。atrogin-1的腺病毒转导导致细胞大小减小，泛素蛋白酶体抑制剂MG-132可改善这种情况。组成型活性Akt（caAkt）（一种丝氨酸/苏氨酸蛋白激酶）的转导抑制了DOX介导的atrogin-1诱导。Akt及其下游靶点FOXO的磷酸化状态不受DOX影响。DOX处理未激活含有FOXO结合位点的atrogin-1启动子，表明DOX诱导atrogin-1而不调节Akt/FOXO途径；重要的是，DOX激活了p38丝裂原活化蛋白激酶（MAPK）和c-Jun氨基末端激酶（JNK）。此外，p38-MAPK的药理学抑制而非JNK的抑制消除了DOX介导的atrogin-1诱导。最后，caAkt的腺病毒转导抑制了DOX诱导的p38-MAPK激活。
DOX通过心肌细胞中p38-MAPK依赖的途径诱导atrogin-1。Akt的组成型激活通过抑制p38-MAPK活性作为一种新机制负向调节DOX介导的atrogin-1诱导。
